extensions.py

"""
Extension Manager for Spec Kit

Handles installation, removal, and management of Spec Kit extensions.
Extensions are modular packages that add commands and functionality to spec-kit
without bloating the core framework.
"""

import json
import hashlib
import os
import tempfile
import zipfile
import shutil
import copy
from dataclasses import dataclass
from pathlib import Path
from typing import Optional, Dict, List, Any, Callable, Set
from datetime import datetime, timezone
import re

import pathspec

import yaml
from packaging import version as pkg_version
from packaging.specifiers import SpecifierSet, InvalidSpecifier


class ExtensionError(Exception):
    """Base exception for extension-related errors."""
    pass


class ValidationError(ExtensionError):
    """Raised when extension manifest validation fails."""
    pass


class CompatibilityError(ExtensionError):
    """Raised when extension is incompatible with current environment."""
    pass


def normalize_priority(value: Any, default: int = 10) -> int:
    """Normalize a stored priority value for sorting and display.

    Corrupted registry data may contain missing, non-numeric, or non-positive
    values. In those cases, fall back to the default priority.

    Args:
        value: Priority value to normalize (may be int, str, None, etc.)
        default: Default priority to use for invalid values (default: 10)

    Returns:
        Normalized priority as positive integer (>= 1)
    """
    try:
        priority = int(value)
    except (TypeError, ValueError):
        return default
    return priority if priority >= 1 else default


@dataclass
class CatalogEntry:
    """Represents a single catalog entry in the catalog stack."""
    url: str
    name: str
    priority: int
    install_allowed: bool
    description: str = ""


class ExtensionManifest:
    """Represents and validates an extension manifest (extension.yml)."""

    SCHEMA_VERSION = "1.0"
    REQUIRED_FIELDS = ["schema_version", "extension", "requires", "provides"]

    def __init__(self, manifest_path: Path):
        """Load and validate extension manifest.

        Args:
            manifest_path: Path to extension.yml file

        Raises:
            ValidationError: If manifest is invalid
        """
        self.path = manifest_path
        self.data = self._load_yaml(manifest_path)
        self._validate()

    def _load_yaml(self, path: Path) -> dict:
        """Load YAML file safely."""
        try:
            with open(path, 'r') as f:
                return yaml.safe_load(f) or {}
        except yaml.YAMLError as e:
            raise ValidationError(f"Invalid YAML in {path}: {e}")
        except FileNotFoundError:
            raise ValidationError(f"Manifest not found: {path}")

    def _validate(self):
        """Validate manifest structure and required fields."""
        # Check required top-level fields
        for field in self.REQUIRED_FIELDS:
            if field not in self.data:
                raise ValidationError(f"Missing required field: {field}")

        # Validate schema version
        if self.data["schema_version"] != self.SCHEMA_VERSION:
            raise ValidationError(
                f"Unsupported schema version: {self.data['schema_version']} "
                f"(expected {self.SCHEMA_VERSION})"
            )

        # Validate extension metadata
        ext = self.data["extension"]
        for field in ["id", "name", "version", "description"]:
            if field not in ext:
                raise ValidationError(f"Missing extension.{field}")

        # Validate extension ID format
        if not re.match(r'^[a-z0-9-]+$', ext["id"]):
            raise ValidationError(
                f"Invalid extension ID '{ext['id']}': "
                "must be lowercase alphanumeric with hyphens only"
            )

        # Validate semantic version
        try:
            pkg_version.Version(ext["version"])
        except pkg_version.InvalidVersion:
            raise ValidationError(f"Invalid version: {ext['version']}")

        # Validate requires section
        requires = self.data["requires"]
        if "speckit_version" not in requires:
            raise ValidationError("Missing requires.speckit_version")

        # Validate provides section
        provides = self.data["provides"]
        has_commands = "commands" in provides and provides["commands"]
        has_scripts = "scripts" in provides and provides["scripts"]
        if not has_commands and not has_scripts:
            raise ValidationError(
                "Extension must provide at least one command or script"
            )

        # Validate commands
        for cmd in provides.get("commands", []):
            if "name" not in cmd or "file" not in cmd:
                raise ValidationError("Command missing 'name' or 'file'")

            # Validate command name format
            if not re.match(r'^speckit\.[a-z0-9-]+\.[a-z0-9-]+$', cmd["name"]):
                raise ValidationError(
                    f"Invalid command name '{cmd['name']}': "
                    "must follow pattern 'speckit.{extension}.{command}'"
                )

        # Validate scripts
        for script in provides.get("scripts", []):
            if "name" not in script or "file" not in script:
                raise ValidationError("Script missing 'name' or 'file'")

            # Validate script name format
            if not re.match(r'^[a-z0-9-]+$', script["name"]):
                raise ValidationError(
                    f"Invalid script name '{script['name']}': "
                    "must be lowercase alphanumeric with hyphens only"
                )

            # Validate file path safety: must be relative, no anchored/drive
            # paths, and no parent traversal components
            file_path = script["file"]
            p = Path(file_path)
            if p.is_absolute() or p.anchor:
                raise ValidationError(
                    f"Invalid script file path '{file_path}': "
                    "must be a relative path within the extension directory"
                )
            if ".." in p.parts:
                raise ValidationError(
                    f"Invalid script file path '{file_path}': "
                    "must be a relative path within the extension directory"
                )

    @property
    def id(self) -> str:
        """Get extension ID."""
        return self.data["extension"]["id"]

    @property
    def name(self) -> str:
        """Get extension name."""
        return self.data["extension"]["name"]

    @property
    def version(self) -> str:
        """Get extension version."""
        return self.data["extension"]["version"]

    @property
    def description(self) -> str:
        """Get extension description."""
        return self.data["extension"]["description"]

    @property
    def requires_speckit_version(self) -> str:
        """Get required spec-kit version range."""
        return self.data["requires"]["speckit_version"]

    @property
    def commands(self) -> List[Dict[str, Any]]:
        """Get list of provided commands."""
        return self.data["provides"].get("commands", [])

    @property
    def scripts(self) -> List[Dict[str, Any]]:
        """Get list of provided scripts."""
        return self.data["provides"].get("scripts", [])

    @property
    def hooks(self) -> Dict[str, Any]:
        """Get hook definitions."""
        return self.data.get("hooks", {})

    def get_hash(self) -> str:
        """Calculate SHA256 hash of manifest file."""
        with open(self.path, 'rb') as f:
            return f"sha256:{hashlib.sha256(f.read()).hexdigest()}"


class ExtensionRegistry:
    """Manages the registry of installed extensions."""

    REGISTRY_FILE = ".registry"
    SCHEMA_VERSION = "1.0"

    def __init__(self, extensions_dir: Path):
        """Initialize registry.

        Args:
            extensions_dir: Path to .specify/extensions/ directory
        """
        self.extensions_dir = extensions_dir
        self.registry_path = extensions_dir / self.REGISTRY_FILE
        self.data = self._load()

    def _load(self) -> dict:
        """Load registry from disk."""
        if not self.registry_path.exists():
            return {
                "schema_version": self.SCHEMA_VERSION,
                "extensions": {}
            }

        try:
            with open(self.registry_path, 'r') as f:
                data = json.load(f)
            # Validate loaded data is a dict (handles corrupted registry files)
            if not isinstance(data, dict):
                return {
                    "schema_version": self.SCHEMA_VERSION,
                    "extensions": {}
                }
            # Normalize extensions field (handles corrupted extensions value)
            if not isinstance(data.get("extensions"), dict):
                data["extensions"] = {}
            return data
        except (json.JSONDecodeError, FileNotFoundError):
            # Corrupted or missing registry, start fresh
            return {
                "schema_version": self.SCHEMA_VERSION,
                "extensions": {}
            }

    def _save(self):
        """Save registry to disk."""
        self.extensions_dir.mkdir(parents=True, exist_ok=True)
        with open(self.registry_path, 'w') as f:
            json.dump(self.data, f, indent=2)

    def add(self, extension_id: str, metadata: dict):
        """Add extension to registry.

        Args:
            extension_id: Extension ID
            metadata: Extension metadata (version, source, etc.)
        """
        self.data["extensions"][extension_id] = {
            **copy.deepcopy(metadata),
            "installed_at": datetime.now(timezone.utc).isoformat()
        }
        self._save()

    def update(self, extension_id: str, metadata: dict):
        """Update extension metadata in registry, merging with existing entry.

        Merges the provided metadata with the existing entry, preserving any
        fields not specified in the new metadata. The installed_at timestamp
        is always preserved from the original entry.

        Use this method instead of add() when updating existing extension
        metadata (e.g., enabling/disabling) to preserve the original
        installation timestamp and other existing fields.

        Args:
            extension_id: Extension ID
            metadata: Extension metadata fields to update (merged with existing)

        Raises:
            KeyError: If extension is not installed
        """
        extensions = self.data.get("extensions")
        if not isinstance(extensions, dict) or extension_id not in extensions:
            raise KeyError(f"Extension '{extension_id}' is not installed")
        # Merge new metadata with existing, preserving original installed_at
        existing = extensions[extension_id]
        # Handle corrupted registry entries (e.g., string/list instead of dict)
        if not isinstance(existing, dict):
            existing = {}
        # Merge: existing fields preserved, new fields override (deep copy to prevent caller mutation)
        merged = {**existing, **copy.deepcopy(metadata)}
        # Always preserve original installed_at based on key existence, not truthiness,
        # to handle cases where the field exists but may be falsy (legacy/corruption)
        if "installed_at" in existing:
            merged["installed_at"] = existing["installed_at"]
        else:
            # If not present in existing, explicitly remove from merged if caller provided it
            merged.pop("installed_at", None)
        extensions[extension_id] = merged
        self._save()

    def restore(self, extension_id: str, metadata: dict):
        """Restore extension metadata to registry without modifying timestamps.

        Use this method for rollback scenarios where you have a complete backup
        of the registry entry (including installed_at) and want to restore it
        exactly as it was.

        Args:
            extension_id: Extension ID
            metadata: Complete extension metadata including installed_at

        Raises:
            ValueError: If metadata is None or not a dict
        """
        if metadata is None or not isinstance(metadata, dict):
            raise ValueError(f"Cannot restore '{extension_id}': metadata must be a dict")
        # Ensure extensions dict exists (handle corrupted registry)
        if not isinstance(self.data.get("extensions"), dict):
            self.data["extensions"] = {}
        self.data["extensions"][extension_id] = copy.deepcopy(metadata)
        self._save()

    def remove(self, extension_id: str):
        """Remove extension from registry.

        Args:
            extension_id: Extension ID
        """
        extensions = self.data.get("extensions")
        if not isinstance(extensions, dict):
            return
        if extension_id in extensions:
            del extensions[extension_id]
            self._save()

    def get(self, extension_id: str) -> Optional[dict]:
        """Get extension metadata from registry.

        Returns a deep copy to prevent callers from accidentally mutating
        nested internal registry state without going through the write path.

        Args:
            extension_id: Extension ID

        Returns:
            Deep copy of extension metadata, or None if not found or corrupted
        """
        extensions = self.data.get("extensions")
        if not isinstance(extensions, dict):
            return None
        entry = extensions.get(extension_id)
        # Return None for missing or corrupted (non-dict) entries
        if entry is None or not isinstance(entry, dict):
            return None
        return copy.deepcopy(entry)

    def list(self) -> Dict[str, dict]:
        """Get all installed extensions with valid metadata.

        Returns a deep copy of extensions with dict metadata only.
        Corrupted entries (non-dict values) are filtered out.

        Returns:
            Dictionary of extension_id -> metadata (deep copies), empty dict if corrupted
        """
        extensions = self.data.get("extensions", {}) or {}
        if not isinstance(extensions, dict):
            return {}
        # Filter to only valid dict entries to match type contract
        return {
            ext_id: copy.deepcopy(meta)
            for ext_id, meta in extensions.items()
            if isinstance(meta, dict)
        }

    def keys(self) -> set:
        """Get all extension IDs including corrupted entries.

        Lightweight method that returns IDs without deep-copying metadata.
        Use this when you only need to check which extensions are tracked.

        Returns:
            Set of extension IDs (includes corrupted entries)
        """
        extensions = self.data.get("extensions", {}) or {}
        if not isinstance(extensions, dict):
            return set()
        return set(extensions.keys())

    def is_installed(self, extension_id: str) -> bool:
        """Check if extension is installed.

        Args:
            extension_id: Extension ID

        Returns:
            True if extension is installed, False if not or registry corrupted
        """
        extensions = self.data.get("extensions")
        if not isinstance(extensions, dict):
            return False
        return extension_id in extensions

    def list_by_priority(self, include_disabled: bool = False) -> List[tuple]:
        """Get all installed extensions sorted by priority.

        Lower priority number = higher precedence (checked first).
        Extensions with equal priority are sorted alphabetically by ID
        for deterministic ordering.

        Args:
            include_disabled: If True, include disabled extensions. Default False.

        Returns:
            List of (extension_id, metadata_copy) tuples sorted by priority.
            Metadata is deep-copied to prevent accidental mutation.
        """
        extensions = self.data.get("extensions", {}) or {}
        if not isinstance(extensions, dict):
            extensions = {}
        sortable_extensions = []
        for ext_id, meta in extensions.items():
            if not isinstance(meta, dict):
                continue
            # Skip disabled extensions unless explicitly requested
            if not include_disabled and not meta.get("enabled", True):
                continue
            metadata_copy = copy.deepcopy(meta)
            metadata_copy["priority"] = normalize_priority(metadata_copy.get("priority", 10))
            sortable_extensions.append((ext_id, metadata_copy))
        return sorted(
            sortable_extensions,
            key=lambda item: (item[1]["priority"], item[0]),
        )


class ExtensionManager:
    """Manages extension lifecycle: installation, removal, updates."""

    def __init__(self, project_root: Path):
        """Initialize extension manager.

        Args:
            project_root: Path to project root directory
        """
        self.project_root = project_root
        self.extensions_dir = project_root / ".specify" / "extensions"
        self.registry = ExtensionRegistry(self.extensions_dir)

    @staticmethod
    def _load_extensionignore(source_dir: Path) -> Optional[Callable[[str, List[str]], Set[str]]]:
        """Load .extensionignore and return an ignore function for shutil.copytree.

        The .extensionignore file uses .gitignore-compatible patterns (one per line).
        Lines starting with '#' are comments. Blank lines are ignored.
        The .extensionignore file itself is always excluded.

        Pattern semantics mirror .gitignore:
        - '*' matches anything except '/'
        - '**' matches zero or more directories
        - '?' matches any single character except '/'
        - Trailing '/' restricts a pattern to directories only
        - Patterns with '/' (other than trailing) are anchored to the root
        - '!' negates a previously excluded pattern

        Args:
            source_dir: Path to the extension source directory

        Returns:
            An ignore function compatible with shutil.copytree, or None
            if no .extensionignore file exists.
        """
        ignore_file = source_dir / ".extensionignore"
        if not ignore_file.exists():
            return None

        lines: List[str] = ignore_file.read_text().splitlines()

        # Normalise backslashes in patterns so Windows-authored files work
        normalised: List[str] = []
        for line in lines:
            stripped = line.strip()
            if stripped and not stripped.startswith("#"):
                normalised.append(stripped.replace("\\", "/"))
            else:
                # Preserve blanks/comments so pathspec line numbers stay stable
                normalised.append(line)

        # Always ignore the .extensionignore file itself
        normalised.append(".extensionignore")

        spec = pathspec.GitIgnoreSpec.from_lines(normalised)

        def _ignore(directory: str, entries: List[str]) -> Set[str]:
            ignored: Set[str] = set()
            rel_dir = Path(directory).relative_to(source_dir)
            for entry in entries:
                rel_path = str(rel_dir / entry) if str(rel_dir) != "." else entry
                # Normalise to forward slashes for consistent matching
                rel_path_fwd = rel_path.replace("\\", "/")

                entry_full = Path(directory) / entry
                if entry_full.is_dir():
                    # Append '/' so directory-only patterns (e.g. tests/) match
                    if spec.match_file(rel_path_fwd + "/"):
                        ignored.add(entry)
                else:
                    if spec.match_file(rel_path_fwd):
                        ignored.add(entry)
            return ignored

        return _ignore

    def check_compatibility(
        self,
        manifest: ExtensionManifest,
        speckit_version: str
    ) -> bool:
        """Check if extension is compatible with current spec-kit version.

        Args:
            manifest: Extension manifest
            speckit_version: Current spec-kit version

        Returns:
            True if compatible

        Raises:
            CompatibilityError: If extension is incompatible
        """
        required = manifest.requires_speckit_version
        current = pkg_version.Version(speckit_version)

        # Parse version specifier (e.g., ">=0.1.0,<2.0.0")
        try:
            specifier = SpecifierSet(required)
            if current not in specifier:
                raise CompatibilityError(
                    f"Extension requires spec-kit {required}, "
                    f"but {speckit_version} is installed.\n"
                    f"Upgrade spec-kit with: uv tool install specify-cli --force"
                )
        except InvalidSpecifier:
            raise CompatibilityError(f"Invalid version specifier: {required}")

        return True

    def install_from_directory(
        self,
        source_dir: Path,
        speckit_version: str,
        register_commands: bool = True,
        priority: int = 10,
    ) -> ExtensionManifest:
        """Install extension from a local directory.

        Args:
            source_dir: Path to extension directory
            speckit_version: Current spec-kit version
            register_commands: If True, register commands with AI agents
            priority: Resolution priority (lower = higher precedence, default 10)

        Returns:
            Installed extension manifest

        Raises:
            ValidationError: If manifest is invalid or priority is invalid
            CompatibilityError: If extension is incompatible
        """
        # Validate priority
        if priority < 1:
            raise ValidationError("Priority must be a positive integer (1 or higher)")

        # Load and validate manifest
        manifest_path = source_dir / "extension.yml"
        manifest = ExtensionManifest(manifest_path)

        # Check compatibility
        self.check_compatibility(manifest, speckit_version)

        # Check if already installed
        if self.registry.is_installed(manifest.id):
            raise ExtensionError(
                f"Extension '{manifest.id}' is already installed. "
                f"Use 'specify extension remove {manifest.id}' first."
            )

        # Install extension
        dest_dir = self.extensions_dir / manifest.id
        if dest_dir.exists():
            shutil.rmtree(dest_dir)

        ignore_fn = self._load_extensionignore(source_dir)
        shutil.copytree(source_dir, dest_dir, ignore=ignore_fn)

        # Set execute permissions on extension scripts (POSIX only)
        if os.name == "posix":
            for script in manifest.scripts:
                script_path = dest_dir / script["file"]
                if script_path.exists() and script_path.suffix == ".sh":
                    script_path.chmod(script_path.stat().st_mode | 0o111)

        # Register commands with AI agents
        registered_commands = {}
        if register_commands:
            registrar = CommandRegistrar()
            # Register for all detected agents
            registered_commands = registrar.register_commands_for_all_agents(
                manifest, dest_dir, self.project_root
            )

        # Register hooks
        hook_executor = HookExecutor(self.project_root)
        hook_executor.register_hooks(manifest)

        # Update registry
        self.registry.add(manifest.id, {
            "version": manifest.version,
            "source": "local",
            "manifest_hash": manifest.get_hash(),
            "enabled": True,
            "priority": priority,
            "registered_commands": registered_commands
        })

        return manifest

    def install_from_zip(
        self,
        zip_path: Path,
        speckit_version: str,
        priority: int = 10,
    ) -> ExtensionManifest:
        """Install extension from ZIP file.

        Args:
            zip_path: Path to extension ZIP file
            speckit_version: Current spec-kit version
            priority: Resolution priority (lower = higher precedence, default 10)

        Returns:
            Installed extension manifest

        Raises:
            ValidationError: If manifest is invalid or priority is invalid
            CompatibilityError: If extension is incompatible
        """
        # Validate priority early
        if priority < 1:
            raise ValidationError("Priority must be a positive integer (1 or higher)")

        with tempfile.TemporaryDirectory() as tmpdir:
            temp_path = Path(tmpdir)

            # Extract ZIP safely (prevent Zip Slip attack)
            with zipfile.ZipFile(zip_path, 'r') as zf:
                # Validate all paths first before extracting anything
                temp_path_resolved = temp_path.resolve()
                for member in zf.namelist():
                    member_path = (temp_path / member).resolve()
                    # Use is_relative_to for safe path containment check
                    try:
                        member_path.relative_to(temp_path_resolved)
                    except ValueError:
                        raise ValidationError(
                            f"Unsafe path in ZIP archive: {member} (potential path traversal)"
                        )
                # Only extract after all paths are validated
                zf.extractall(temp_path)

            # Find extension directory (may be nested)
            extension_dir = temp_path
            manifest_path = extension_dir / "extension.yml"

            # Check if manifest is in a subdirectory
            if not manifest_path.exists():
                subdirs = [d for d in temp_path.iterdir() if d.is_dir()]
                if len(subdirs) == 1:
                    extension_dir = subdirs[0]
                    manifest_path = extension_dir / "extension.yml"

            if not manifest_path.exists():
                raise ValidationError("No extension.yml found in ZIP file")

            # Install from extracted directory
            return self.install_from_directory(extension_dir, speckit_version, priority=priority)

    def remove(self, extension_id: str, keep_config: bool = False) -> bool:
        """Remove an installed extension.

        Args:
            extension_id: Extension ID
            keep_config: If True, preserve config files (don't delete extension dir)

        Returns:
            True if extension was removed
        """
        if not self.registry.is_installed(extension_id):
            return False

        # Get registered commands before removal
        metadata = self.registry.get(extension_id)
        registered_commands = metadata.get("registered_commands", {}) if metadata else {}

        extension_dir = self.extensions_dir / extension_id

        # Unregister commands from all AI agents
        if registered_commands:
            registrar = CommandRegistrar()
            registrar.unregister_commands(registered_commands, self.project_root)

        if keep_config:
            # Preserve config files, only remove non-config files
            if extension_dir.exists():
                for child in extension_dir.iterdir():
                    # Keep top-level *-config.yml and *-config.local.yml files
                    if child.is_file() and (
                        child.name.endswith("-config.yml") or
                        child.name.endswith("-config.local.yml")
                    ):
                        continue
                    if child.is_dir():
                        shutil.rmtree(child)
                    else:
                        child.unlink()
        else:
            # Backup config files before deleting
            if extension_dir.exists():
                # Use subdirectory per extension to avoid name accumulation
                # (e.g., jira-jira-config.yml on repeated remove/install cycles)
                backup_dir = self.extensions_dir / ".backup" / extension_id
                backup_dir.mkdir(parents=True, exist_ok=True)

                # Backup both primary and local override config files
                config_files = list(extension_dir.glob("*-config.yml")) + list(
                    extension_dir.glob("*-config.local.yml")
                )
                for config_file in config_files:
                    backup_path = backup_dir / config_file.name
                    shutil.copy2(config_file, backup_path)

            # Remove extension directory
            if extension_dir.exists():
                shutil.rmtree(extension_dir)

        # Unregister hooks
        hook_executor = HookExecutor(self.project_root)
        hook_executor.unregister_hooks(extension_id)

        # Update registry
        self.registry.remove(extension_id)

        return True

    def list_installed(self) -> List[Dict[str, Any]]:
        """List all installed extensions with metadata.

        Returns:
            List of extension metadata dictionaries
        """
        result = []

        for ext_id, metadata in self.registry.list().items():
            # Ensure metadata is a dictionary to avoid AttributeError when using .get()
            if not isinstance(metadata, dict):
                metadata = {}
            ext_dir = self.extensions_dir / ext_id
            manifest_path = ext_dir / "extension.yml"

            try:
                manifest = ExtensionManifest(manifest_path)
                result.append({
                    "id": ext_id,
                    "name": manifest.name,
                    "version": metadata.get("version", "unknown"),
                    "description": manifest.description,
                    "enabled": metadata.get("enabled", True),
                    "priority": normalize_priority(metadata.get("priority")),
                    "installed_at": metadata.get("installed_at"),
                    "command_count": len(manifest.commands),
                    "script_count": len(manifest.scripts),
                    "hook_count": len(manifest.hooks)
                })
            except ValidationError:
                # Corrupted extension
                result.append({
                    "id": ext_id,
                    "name": ext_id,
                    "version": metadata.get("version", "unknown"),
                    "description": "⚠️ Corrupted extension",
                    "enabled": False,
                    "priority": normalize_priority(metadata.get("priority")),
                    "installed_at": metadata.get("installed_at"),
                    "command_count": 0,
                    "script_count": 0,
                    "hook_count": 0
                })

        return result

    def get_extension(self, extension_id: str) -> Optional[ExtensionManifest]:
        """Get manifest for an installed extension.

        Args:
            extension_id: Extension ID

        Returns:
            Extension manifest or None if not installed
        """
        if not self.registry.is_installed(extension_id):
            return None

        ext_dir = self.extensions_dir / extension_id
        manifest_path = ext_dir / "extension.yml"

        try:
            return ExtensionManifest(manifest_path)
        except ValidationError:
            return None


class ExtensionResolver:
    """Resolves and discovers templates provided by installed extensions.

    Handles priority-based ordering of extensions, template resolution,
    and source attribution for extension-provided templates.

    This class owns the extension tier of the template resolution stack.
    PresetResolver delegates to it for extension lookups rather than
    walking extension directories directly.
    """

    def __init__(self, project_root: Path):
        self.project_root = project_root
        self.extensions_dir = project_root / ".specify" / "extensions"

    def get_all_by_priority(self) -> List[tuple]:
        """Build unified list of registered and unregistered extensions sorted by priority.

        Registered extensions use their stored priority; unregistered directories
        get implicit priority=10. Results are sorted by (priority, ext_id) for
        deterministic ordering.

        Returns:
            List of (priority, ext_id, metadata_or_none) tuples sorted by priority.
        """
        if not self.extensions_dir.exists():
            return []

        registry = ExtensionRegistry(self.extensions_dir)
        registered_extension_ids = registry.keys()
        all_registered = registry.list_by_priority(include_disabled=True)

        all_extensions: list[tuple[int, str, dict | None]] = []

        for ext_id, metadata in all_registered:
            if not metadata.get("enabled", True):
                continue
            priority = normalize_priority(metadata.get("priority") if metadata else None)
            all_extensions.append((priority, ext_id, metadata))

        for ext_dir in self.extensions_dir.iterdir():
            if not ext_dir.is_dir() or ext_dir.name.startswith("."):
                continue
            if ext_dir.name not in registered_extension_ids:
                all_extensions.append((10, ext_dir.name, None))

        all_extensions.sort(key=lambda x: (x[0], x[1]))
        return all_extensions

    def resolve(
        self,
        template_name: str,
        template_type: str = "template",
    ) -> Optional[Path]:
        """Resolve a template name to its file path within extensions.

        Args:
            template_name: Template name (e.g., "spec-template")
            template_type: Template type ("template", "command", or "script")

        Returns:
            Path to the resolved template file, or None if not found
        """
        subdirs, ext = self._type_config(template_type)

        for _priority, ext_id, _metadata in self.get_all_by_priority():
            ext_dir = self.extensions_dir / ext_id
            if not ext_dir.is_dir():
                continue
            for subdir in subdirs:
                if subdir:
                    candidate = ext_dir / subdir / f"{template_name}{ext}"
                else:
                    candidate = ext_dir / f"{template_name}{ext}"
                if candidate.exists():
                    return candidate

        return None

    def resolve_with_source(
        self,
        template_name: str,
        template_type: str = "template",
    ) -> Optional[Dict[str, str]]:
        """Resolve a template name and return source attribution.

        Args:
            template_name: Template name (e.g., "spec-template")
            template_type: Template type ("template", "command", or "script")

        Returns:
            Dictionary with 'path' and 'source' keys, or None if not found
        """
        subdirs, ext = self._type_config(template_type)

        for _priority, ext_id, ext_meta in self.get_all_by_priority():
            ext_dir = self.extensions_dir / ext_id
            if not ext_dir.is_dir():
                continue
            for subdir in subdirs:
                if subdir:
                    candidate = ext_dir / subdir / f"{template_name}{ext}"
                else:
                    candidate = ext_dir / f"{template_name}{ext}"
                if candidate.exists():
                    if ext_meta:
                        version = ext_meta.get("version", "?")
                        source = f"extension:{ext_id} v{version}"
                    else:
                        source = f"extension:{ext_id} (unregistered)"
                    return {"path": str(candidate), "source": source}

        return None

    def list_templates(
        self,
        template_type: str = "template",
    ) -> List[Dict[str, str]]:
        """List all templates of a given type provided by extensions.

        Returns templates sorted by extension priority, then alphabetically.

        Args:
            template_type: Template type ("template", "command", or "script")

        Returns:
            List of dicts with 'name', 'path', and 'source' keys.
        """
        subdirs, ext = self._type_config(template_type)
        results: List[Dict[str, str]] = []
        seen: set[str] = set()

        for _priority, ext_id, ext_meta in self.get_all_by_priority():
            ext_dir = self.extensions_dir / ext_id
            if not ext_dir.is_dir():
                continue

            if ext_meta:
                version = ext_meta.get("version", "?")
                source_label = f"extension:{ext_id} v{version}"
            else:
                source_label = f"extension:{ext_id} (unregistered)"

            for subdir in subdirs:
                scan_dir = ext_dir / subdir if subdir else ext_dir
                if not scan_dir.is_dir():
                    continue
                for f in sorted(scan_dir.iterdir()):
                    if f.is_file() and f.suffix == ext:
                        name = f.stem
                        if name not in seen:
                            seen.add(name)
                            results.append({
                                "name": name,
                                "path": str(f),
                                "source": source_label,
                            })

        return results

    @staticmethod
    def _type_config(template_type: str) -> tuple:
        """Return (subdirs, file_extension) for a template type."""
        if template_type == "template":
            return ["templates", ""], ".md"
        elif template_type == "command":
            return ["commands"], ".md"
        elif template_type == "script":
            return ["scripts"], ".sh"
        return [""], ".md"


def version_satisfies(current: str, required: str) -> bool:
    """Check if current version satisfies required version specifier.

    Args:
        current: Current version (e.g., "0.1.5")
        required: Required version specifier (e.g., ">=0.1.0,<2.0.0")

    Returns:
        True if version satisfies requirement
    """
    try:
        current_ver = pkg_version.Version(current)
        specifier = SpecifierSet(required)
        return current_ver in specifier
    except (pkg_version.InvalidVersion, InvalidSpecifier):
        return False


class CommandRegistrar:
    """Handles registration of extension commands with AI agents.

    This is a backward-compatible wrapper around the shared CommandRegistrar
    in agents.py. Extension-specific methods accept ExtensionManifest objects
    and delegate to the generic API.
    """

    # Re-export AGENT_CONFIGS at class level for direct attribute access
    from .agents import CommandRegistrar as _AgentRegistrar
    AGENT_CONFIGS = _AgentRegistrar.AGENT_CONFIGS

    def __init__(self):
        from .agents import CommandRegistrar as _Registrar
        self._registrar = _Registrar()

    # Delegate static/utility methods
    @staticmethod
    def parse_frontmatter(content: str) -> tuple[dict, str]:
        from .agents import CommandRegistrar as _Registrar
        return _Registrar.parse_frontmatter(content)

    @staticmethod
    def render_frontmatter(fm: dict) -> str:
        from .agents import CommandRegistrar as _Registrar
        return _Registrar.render_frontmatter(fm)

    @staticmethod
    def _write_copilot_prompt(project_root, cmd_name: str) -> None:
        from .agents import CommandRegistrar as _Registrar
        _Registrar.write_copilot_prompt(project_root, cmd_name)

    def _render_markdown_command(self, frontmatter, body, ext_id):
        # Preserve extension-specific comment format for backward compatibility
        context_note = f"\n<!-- Extension: {ext_id} -->\n<!-- Config: .specify/extensions/{ext_id}/ -->\n"
        return self._registrar.render_frontmatter(frontmatter) + "\n" + context_note + body

    def _render_toml_command(self, frontmatter, body, ext_id):
        # Preserve extension-specific context comments for backward compatibility
        base = self._registrar.render_toml_command(frontmatter, body, ext_id)
        context_lines = f"# Extension: {ext_id}\n# Config: .specify/extensions/{ext_id}/\n"
        return base.rstrip("\n") + "\n" + context_lines

    @staticmethod
    def _filter_commands_for_installed_extensions(
        commands: List[Dict[str, Any]],
        project_root: Path,
    ) -> List[Dict[str, Any]]:
        """Filter out commands targeting extensions that are not installed.

        Command names follow the pattern: speckit.<ext-id>.<cmd-name>
        Core commands (e.g. speckit.specify) have only two parts — always kept.
        Extension-specific commands are only kept if the target extension
        directory exists under .specify/extensions/.

        If the extensions directory does not exist, it is treated as empty
        and all extension-scoped commands are filtered out (matching the
        preset filtering behavior at presets.py:518-529).

        Note: This method is not applied during extension self-registration
        (all commands in an extension's own manifest are always registered).
        It is designed for cross-boundary filtering, e.g. when presets provide
        commands for extensions that may not be installed.
        """
        extensions_dir = project_root / ".specify" / "extensions"
        filtered = []
        for cmd in commands:
            parts = cmd["name"].split(".")
            if len(parts) >= 3 and parts[0] == "speckit":
                ext_id = parts[1]
                if not (extensions_dir / ext_id).is_dir():
                    continue
            filtered.append(cmd)
        return filtered

    def register_commands_for_agent(
        self,
        agent_name: str,
        manifest: ExtensionManifest,
        extension_dir: Path,
        project_root: Path
    ) -> List[str]:
        """Register extension commands for a specific agent."""
        if agent_name not in self.AGENT_CONFIGS:
            raise ExtensionError(f"Unsupported agent: {agent_name}")
        context_note = f"\n<!-- Extension: {manifest.id} -->\n<!-- Config: .specify/extensions/{manifest.id}/ -->\n"
        return self._registrar.register_commands(
            agent_name, manifest.commands, manifest.id, extension_dir, project_root,
            context_note=context_note
        )

    def register_commands_for_all_agents(
        self,
        manifest: ExtensionManifest,
        extension_dir: Path,
        project_root: Path
    ) -> Dict[str, List[str]]:
        """Register extension commands for all detected agents."""
        context_note = f"\n<!-- Extension: {manifest.id} -->\n<!-- Config: .specify/extensions/{manifest.id}/ -->\n"
        return self._registrar.register_commands_for_all_agents(
            manifest.commands, manifest.id, extension_dir, project_root,
            context_note=context_note
        )

    def unregister_commands(
        self,
        registered_commands: Dict[str, List[str]],
        project_root: Path
    ) -> None:
        """Remove previously registered command files from agent directories."""
        self._registrar.unregister_commands(registered_commands, project_root)

    def register_commands_for_claude(
        self,
        manifest: ExtensionManifest,
        extension_dir: Path,
        project_root: Path
    ) -> List[str]:
        """Register extension commands for Claude Code agent."""
        return self.register_commands_for_agent("claude", manifest, extension_dir, project_root)


class ExtensionCatalog:
    """Manages extension catalog fetching, caching, and searching."""

    DEFAULT_CATALOG_URL = "https://raw.githubusercontent.com/github/spec-kit/main/extensions/catalog.json"
    COMMUNITY_CATALOG_URL = "https://raw.githubusercontent.com/github/spec-kit/main/extensions/catalog.community.json"
    CACHE_DURATION = 3600  # 1 hour in seconds

    def __init__(self, project_root: Path):
        """Initialize extension catalog manager.

        Args:
            project_root: Root directory of the spec-kit project
        """
        self.project_root = project_root
        self.extensions_dir = project_root / ".specify" / "extensions"
        self.cache_dir = self.extensions_dir / ".cache"
        self.cache_file = self.cache_dir / "catalog.json"
        self.cache_metadata_file = self.cache_dir / "catalog-metadata.json"

    def _validate_catalog_url(self, url: str) -> None:
        """Validate that a catalog URL uses HTTPS (localhost HTTP allowed).

        Args:
            url: URL to validate

        Raises:
            ValidationError: If URL is invalid or uses non-HTTPS scheme
        """
        from urllib.parse import urlparse

        parsed = urlparse(url)
        is_localhost = parsed.hostname in ("localhost", "127.0.0.1", "::1")
        if parsed.scheme != "https" and not (parsed.scheme == "http" and is_localhost):
            raise ValidationError(
                f"Catalog URL must use HTTPS (got {parsed.scheme}://). "
                "HTTP is only allowed for localhost."
            )
        if not parsed.netloc:
            raise ValidationError("Catalog URL must be a valid URL with a host.")

    def _load_catalog_config(self, config_path: Path) -> Optional[List[CatalogEntry]]:
        """Load catalog stack configuration from a YAML file.

        Args:
            config_path: Path to extension-catalogs.yml

        Returns:
            Ordered list of CatalogEntry objects, or None if file doesn't exist.

        Raises:
            ValidationError: If any catalog entry has an invalid URL,
                the file cannot be parsed, a priority value is invalid,
                or the file exists but contains no valid catalog entries
                (fail-closed for security).
        """
        if not config_path.exists():
            return None
        try:
            data = yaml.safe_load(config_path.read_text(encoding="utf-8")) or {}
        except (yaml.YAMLError, OSError, UnicodeError) as e:
            raise ValidationError(
                f"Failed to read catalog config {config_path}: {e}"
            )
        catalogs_data = data.get("catalogs", [])
        if not catalogs_data:
            # File exists but has no catalogs key or empty list - fail closed
            raise ValidationError(
                f"Catalog config {config_path} exists but contains no 'catalogs' entries. "
                f"Remove the file to use built-in defaults, or add valid catalog entries."
            )
        if not isinstance(catalogs_data, list):
            raise ValidationError(
                f"Invalid catalog config: 'catalogs' must be a list, got {type(catalogs_data).__name__}"
            )
        entries: List[CatalogEntry] = []
        skipped_entries: List[int] = []
        for idx, item in enumerate(catalogs_data):
            if not isinstance(item, dict):
                raise ValidationError(
                    f"Invalid catalog entry at index {idx}: expected a mapping, got {type(item).__name__}"
                )
            url = str(item.get("url", "")).strip()
            if not url:
                skipped_entries.append(idx)
                continue
            self._validate_catalog_url(url)
            try:
                priority = int(item.get("priority", idx + 1))
            except (TypeError, ValueError):
                raise ValidationError(
                    f"Invalid priority for catalog '{item.get('name', idx + 1)}': "
                    f"expected integer, got {item.get('priority')!r}"
                )
            raw_install = item.get("install_allowed", False)
            if isinstance(raw_install, str):
                install_allowed = raw_install.strip().lower() in ("true", "yes", "1")
            else:
                install_allowed = bool(raw_install)
            entries.append(CatalogEntry(
                url=url,
                name=str(item.get("name", f"catalog-{idx + 1}")),
                priority=priority,
                install_allowed=install_allowed,
                description=str(item.get("description", "")),
            ))
        entries.sort(key=lambda e: e.priority)
        if not entries:
            # All entries were invalid (missing URLs) - fail closed for security
            raise ValidationError(
                f"Catalog config {config_path} contains {len(catalogs_data)} entries but none have valid URLs "
                f"(entries at indices {skipped_entries} were skipped). "
                f"Each catalog entry must have a 'url' field."
            )
        return entries

    def get_active_catalogs(self) -> List[CatalogEntry]:
        """Get the ordered list of active catalogs.

        Resolution order:
        1. SPECKIT_CATALOG_URL env var — single catalog replacing all defaults
        2. Project-level .specify/extension-catalogs.yml
        3. User-level ~/.specify/extension-catalogs.yml
        4. Built-in default stack (default + community)

        Returns:
            List of CatalogEntry objects sorted by priority (ascending)

        Raises:
            ValidationError: If a catalog URL is invalid
        """
        import sys

        # 1. SPECKIT_CATALOG_URL env var replaces all defaults for backward compat
        if env_value := os.environ.get("SPECKIT_CATALOG_URL"):
            catalog_url = env_value.strip()
            self._validate_catalog_url(catalog_url)
            if catalog_url != self.DEFAULT_CATALOG_URL:
                if not getattr(self, "_non_default_catalog_warning_shown", False):
                    print(
                        "Warning: Using non-default extension catalog. "
                        "Only use catalogs from sources you trust.",
                        file=sys.stderr,
                    )
                    self._non_default_catalog_warning_shown = True
            return [CatalogEntry(url=catalog_url, name="custom", priority=1, install_allowed=True, description="Custom catalog via SPECKIT_CATALOG_URL")]

        # 2. Project-level config overrides all defaults
        project_config_path = self.project_root / ".specify" / "extension-catalogs.yml"
        catalogs = self._load_catalog_config(project_config_path)
        if catalogs is not None:
            return catalogs

        # 3. User-level config
        user_config_path = Path.home() / ".specify" / "extension-catalogs.yml"
        catalogs = self._load_catalog_config(user_config_path)
        if catalogs is not None:
            return catalogs

        # 4. Built-in default stack
        return [
            CatalogEntry(url=self.DEFAULT_CATALOG_URL, name="default", priority=1, install_allowed=True, description="Built-in catalog of installable extensions"),
            CatalogEntry(url=self.COMMUNITY_CATALOG_URL, name="community", priority=2, install_allowed=False, description="Community-contributed extensions (discovery only)"),
        ]

    def get_catalog_url(self) -> str:
        """Get the primary catalog URL.

        Returns the URL of the highest-priority catalog. Kept for backward
        compatibility. Use get_active_catalogs() for full multi-catalog support.

        Returns:
            URL of the primary catalog

        Raises:
            ValidationError: If a catalog URL is invalid
        """
        active = self.get_active_catalogs()
        return active[0].url if active else self.DEFAULT_CATALOG_URL

    def _fetch_single_catalog(self, entry: CatalogEntry, force_refresh: bool = False) -> Dict[str, Any]:
        """Fetch a single catalog with per-URL caching.

        For the DEFAULT_CATALOG_URL, uses legacy cache files (self.cache_file /
        self.cache_metadata_file) for backward compatibility. For all other URLs,
        uses URL-hash-based cache files in self.cache_dir.

        Args:
            entry: CatalogEntry describing the catalog to fetch
            force_refresh: If True, bypass cache

        Returns:
            Catalog data dictionary

        Raises:
            ExtensionError: If catalog cannot be fetched or has invalid format
        """
        import urllib.request
        import urllib.error

        # Determine cache file paths (backward compat for default catalog)
        if entry.url == self.DEFAULT_CATALOG_URL:
            cache_file = self.cache_file
            cache_meta_file = self.cache_metadata_file
            is_valid = not force_refresh and self.is_cache_valid()
        else:
            url_hash = hashlib.sha256(entry.url.encode()).hexdigest()[:16]
            cache_file = self.cache_dir / f"catalog-{url_hash}.json"
            cache_meta_file = self.cache_dir / f"catalog-{url_hash}-metadata.json"
            is_valid = False
            if not force_refresh and cache_file.exists() and cache_meta_file.exists():
                try:
                    metadata = json.loads(cache_meta_file.read_text())
                    cached_at = datetime.fromisoformat(metadata.get("cached_at", ""))
                    if cached_at.tzinfo is None:
                        cached_at = cached_at.replace(tzinfo=timezone.utc)
                    age = (datetime.now(timezone.utc) - cached_at).total_seconds()
                    is_valid = age < self.CACHE_DURATION
                except (json.JSONDecodeError, ValueError, KeyError, TypeError):
                    # If metadata is invalid or missing expected fields, treat cache as invalid
                    pass

        # Use cache if valid
        if is_valid:
            try:
                return json.loads(cache_file.read_text())
            except json.JSONDecodeError:
                pass

        # Fetch from network
        try:
            with urllib.request.urlopen(entry.url, timeout=10) as response:
                catalog_data = json.loads(response.read())

            if "schema_version" not in catalog_data or "extensions" not in catalog_data:
                raise ExtensionError(f"Invalid catalog format from {entry.url}")

            # Save to cache
            self.cache_dir.mkdir(parents=True, exist_ok=True)
            cache_file.write_text(json.dumps(catalog_data, indent=2))
            cache_meta_file.write_text(json.dumps({
                "cached_at": datetime.now(timezone.utc).isoformat(),
                "catalog_url": entry.url,
            }, indent=2))

            return catalog_data

        except urllib.error.URLError as e:
            raise ExtensionError(f"Failed to fetch catalog from {entry.url}: {e}")
        except json.JSONDecodeError as e:
            raise ExtensionError(f"Invalid JSON in catalog from {entry.url}: {e}")

    def _get_merged_extensions(self, force_refresh: bool = False) -> List[Dict[str, Any]]:
        """Fetch and merge extensions from all active catalogs.

        Higher-priority (lower priority number) catalogs win on conflicts
        (same extension id in two catalogs). Each extension dict is annotated with:
          - _catalog_name: name of the source catalog
          - _install_allowed: whether installation is allowed from this catalog

        Catalogs that fail to fetch are skipped. Raises ExtensionError only if
        ALL catalogs fail.

        Args:
            force_refresh: If True, bypass all caches

        Returns:
            List of merged extension dicts

        Raises:
            ExtensionError: If all catalogs fail to fetch
        """
        import sys

        active_catalogs = self.get_active_catalogs()
        merged: Dict[str, Dict[str, Any]] = {}
        any_success = False

        for catalog_entry in active_catalogs:
            try:
                catalog_data = self._fetch_single_catalog(catalog_entry, force_refresh)
                any_success = True
            except ExtensionError as e:
                print(
                    f"Warning: Could not fetch catalog '{catalog_entry.name}': {e}",
                    file=sys.stderr,
                )
                continue

            for ext_id, ext_data in catalog_data.get("extensions", {}).items():
                if ext_id not in merged:  # Higher-priority catalog wins
                    merged[ext_id] = {
                        **ext_data,
                        "id": ext_id,
                        "_catalog_name": catalog_entry.name,
                        "_install_allowed": catalog_entry.install_allowed,
                    }

        if not any_success and active_catalogs:
            raise ExtensionError("Failed to fetch any extension catalog")

        return list(merged.values())

    def is_cache_valid(self) -> bool:
        """Check if cached catalog is still valid.

        Returns:
            True if cache exists and is within cache duration
        """
        if not self.cache_file.exists() or not self.cache_metadata_file.exists():
            return False

        try:
            metadata = json.loads(self.cache_metadata_file.read_text())
            cached_at = datetime.fromisoformat(metadata.get("cached_at", ""))
            if cached_at.tzinfo is None:
                cached_at = cached_at.replace(tzinfo=timezone.utc)
            age_seconds = (datetime.now(timezone.utc) - cached_at).total_seconds()
            return age_seconds < self.CACHE_DURATION
        except (json.JSONDecodeError, ValueError, KeyError, TypeError):
            return False

    def fetch_catalog(self, force_refresh: bool = False) -> Dict[str, Any]:
        """Fetch extension catalog from URL or cache.

        Args:
            force_refresh: If True, bypass cache and fetch from network

        Returns:
            Catalog data dictionary

        Raises:
            ExtensionError: If catalog cannot be fetched
        """
        # Check cache first unless force refresh
        if not force_refresh and self.is_cache_valid():
            try:
                return json.loads(self.cache_file.read_text())
            except json.JSONDecodeError:
                pass  # Fall through to network fetch

        # Fetch from network
        catalog_url = self.get_catalog_url()

        try:
            import urllib.request
            import urllib.error

            with urllib.request.urlopen(catalog_url, timeout=10) as response:
                catalog_data = json.loads(response.read())

            # Validate catalog structure
            if "schema_version" not in catalog_data or "extensions" not in catalog_data:
                raise ExtensionError("Invalid catalog format")

            # Save to cache
            self.cache_dir.mkdir(parents=True, exist_ok=True)
            self.cache_file.write_text(json.dumps(catalog_data, indent=2))

            # Save cache metadata
            metadata = {
                "cached_at": datetime.now(timezone.utc).isoformat(),
                "catalog_url": catalog_url,
            }
            self.cache_metadata_file.write_text(json.dumps(metadata, indent=2))

            return catalog_data

        except urllib.error.URLError as e:
            raise ExtensionError(f"Failed to fetch catalog from {catalog_url}: {e}")
        except json.JSONDecodeError as e:
            raise ExtensionError(f"Invalid JSON in catalog: {e}")

    def search(
        self,
        query: Optional[str] = None,
        tag: Optional[str] = None,
        author: Optional[str] = None,
        verified_only: bool = False,
    ) -> List[Dict[str, Any]]:
        """Search catalog for extensions across all active catalogs.

        Args:
            query: Search query (searches name, description, tags)
            tag: Filter by specific tag
            author: Filter by author name
            verified_only: If True, show only verified extensions

        Returns:
            List of matching extension metadata, each annotated with
            ``_catalog_name`` and ``_install_allowed`` from its source catalog.
        """
        all_extensions = self._get_merged_extensions()

        results = []

        for ext_data in all_extensions:
            ext_id = ext_data["id"]

            # Apply filters
            if verified_only and not ext_data.get("verified", False):
                continue

            if author and ext_data.get("author", "").lower() != author.lower():
                continue

            if tag and tag.lower() not in [t.lower() for t in ext_data.get("tags", [])]:
                continue

            if query:
                # Search in name, description, and tags
                query_lower = query.lower()
                searchable_text = " ".join(
                    [
                        ext_data.get("name", ""),
                        ext_data.get("description", ""),
                        ext_id,
                    ]
                    + ext_data.get("tags", [])
                ).lower()

                if query_lower not in searchable_text:
                    continue

            results.append(ext_data)

        return results

    def get_extension_info(self, extension_id: str) -> Optional[Dict[str, Any]]:
        """Get detailed information about a specific extension.

        Searches all active catalogs in priority order.

        Args:
            extension_id: ID of the extension

        Returns:
            Extension metadata (annotated with ``_catalog_name`` and
            ``_install_allowed``) or None if not found.
        """
        all_extensions = self._get_merged_extensions()
        for ext_data in all_extensions:
            if ext_data["id"] == extension_id:
                return ext_data
        return None

    def download_extension(self, extension_id: str, target_dir: Optional[Path] = None) -> Path:
        """Download extension ZIP from catalog.

        Args:
            extension_id: ID of the extension to download
            target_dir: Directory to save ZIP file (defaults to temp directory)

        Returns:
            Path to downloaded ZIP file

        Raises:
            ExtensionError: If extension not found or download fails
        """
        import urllib.request
        import urllib.error

        # Get extension info from catalog
        ext_info = self.get_extension_info(extension_id)
        if not ext_info:
            raise ExtensionError(f"Extension '{extension_id}' not found in catalog")

        download_url = ext_info.get("download_url")
        if not download_url:
            raise ExtensionError(f"Extension '{extension_id}' has no download URL")

        # Validate download URL requires HTTPS (prevent man-in-the-middle attacks)
        from urllib.parse import urlparse
        parsed = urlparse(download_url)
        is_localhost = parsed.hostname in ("localhost", "127.0.0.1", "::1")
        if parsed.scheme != "https" and not (parsed.scheme == "http" and is_localhost):
            raise ExtensionError(
                f"Extension download URL must use HTTPS: {download_url}"
            )

        # Determine target path
        if target_dir is None:
            target_dir = self.cache_dir / "downloads"
        target_dir.mkdir(parents=True, exist_ok=True)

        version = ext_info.get("version", "unknown")
        zip_filename = f"{extension_id}-{version}.zip"
        zip_path = target_dir / zip_filename

        # Download the ZIP file
        try:
            with urllib.request.urlopen(download_url, timeout=60) as response:
                zip_data = response.read()

            zip_path.write_bytes(zip_data)
            return zip_path

        except urllib.error.URLError as e:
            raise ExtensionError(f"Failed to download extension from {download_url}: {e}")
        except IOError as e:
            raise ExtensionError(f"Failed to save extension ZIP: {e}")

    def clear_cache(self):
        """Clear the catalog cache (both legacy and URL-hash-based files)."""
        if self.cache_file.exists():
            self.cache_file.unlink()
        if self.cache_metadata_file.exists():
            self.cache_metadata_file.unlink()
        # Also clear any per-URL hash-based cache files
        if self.cache_dir.exists():
            for extra_cache in self.cache_dir.glob("catalog-*.json"):
                if extra_cache != self.cache_file:
                    extra_cache.unlink(missing_ok=True)
            for extra_meta in self.cache_dir.glob("catalog-*-metadata.json"):
                extra_meta.unlink(missing_ok=True)


class ConfigManager:
    """Manages layered configuration for extensions.

    Configuration layers (in order of precedence from lowest to highest):
    1. Defaults (from extension.yml)
    2. Project config (.specify/extensions/{ext-id}/{ext-id}-config.yml)
    3. Local config (.specify/extensions/{ext-id}/local-config.yml) - gitignored
    4. Environment variables (SPECKIT_{EXT_ID}_{KEY})
    """

    def __init__(self, project_root: Path, extension_id: str):
        """Initialize config manager for an extension.

        Args:
            project_root: Root directory of the spec-kit project
            extension_id: ID of the extension
        """
        self.project_root = project_root
        self.extension_id = extension_id
        self.extension_dir = project_root / ".specify" / "extensions" / extension_id

    def _load_yaml_config(self, file_path: Path) -> Dict[str, Any]:
        """Load configuration from YAML file.

        Args:
            file_path: Path to YAML file

        Returns:
            Configuration dictionary
        """
        if not file_path.exists():
            return {}

        try:
            return yaml.safe_load(file_path.read_text(encoding="utf-8")) or {}
        except (yaml.YAMLError, OSError, UnicodeError):
            return {}

    def _get_extension_defaults(self) -> Dict[str, Any]:
        """Get default configuration from extension manifest.

        Returns:
            Default configuration dictionary
        """
        manifest_path = self.extension_dir / "extension.yml"
        if not manifest_path.exists():
            return {}

        manifest_data = self._load_yaml_config(manifest_path)
        return manifest_data.get("config", {}).get("defaults", {})

    def _get_project_config(self) -> Dict[str, Any]:
        """Get project-level configuration.

        Returns:
            Project configuration dictionary
        """
        config_file = self.extension_dir / f"{self.extension_id}-config.yml"
        return self._load_yaml_config(config_file)

    def _get_local_config(self) -> Dict[str, Any]:
        """Get local configuration (gitignored, machine-specific).

        Returns:
            Local configuration dictionary
        """
        config_file = self.extension_dir / "local-config.yml"
        return self._load_yaml_config(config_file)

    def _get_env_config(self) -> Dict[str, Any]:
        """Get configuration from environment variables.

        Environment variables follow the pattern:
        SPECKIT_{EXT_ID}_{SECTION}_{KEY}

        For example:
        - SPECKIT_JIRA_CONNECTION_URL
        - SPECKIT_JIRA_PROJECT_KEY

        Returns:
            Configuration dictionary from environment variables
        """
        import os

        env_config = {}
        ext_id_upper = self.extension_id.replace("-", "_").upper()
        prefix = f"SPECKIT_{ext_id_upper}_"

        for key, value in os.environ.items():
            if not key.startswith(prefix):
                continue

            # Remove prefix and split into parts
            config_path = key[len(prefix):].lower().split("_")

            # Build nested dict
            current = env_config
            for part in config_path[:-1]:
                if part not in current:
                    current[part] = {}
                current = current[part]

            # Set the final value
            current[config_path[-1]] = value

        return env_config

    def _merge_configs(self, base: Dict[str, Any], override: Dict[str, Any]) -> Dict[str, Any]:
        """Recursively merge two configuration dictionaries.

        Args:
            base: Base configuration
            override: Configuration to merge on top

        Returns:
            Merged configuration
        """
        result = base.copy()

        for key, value in override.items():
            if key in result and isinstance(result[key], dict) and isinstance(value, dict):
                # Recursive merge for nested dicts
                result[key] = self._merge_configs(result[key], value)
            else:
                # Override value
                result[key] = value

        return result

    def get_config(self) -> Dict[str, Any]:
        """Get final merged configuration for the extension.

        Merges configuration layers in order:
        defaults -> project -> local -> env

        Returns:
            Final merged configuration dictionary
        """
        # Start with defaults
        config = self._get_extension_defaults()

        # Merge project config
        config = self._merge_configs(config, self._get_project_config())

        # Merge local config
        config = self._merge_configs(config, self._get_local_config())

        # Merge environment config
        config = self._merge_configs(config, self._get_env_config())

        return config

    def get_value(self, key_path: str, default: Any = None) -> Any:
        """Get a specific configuration value by dot-notation path.

        Args:
            key_path: Dot-separated path to config value (e.g., "connection.url")
            default: Default value if key not found

        Returns:
            Configuration value or default

        Example:
            >>> config = ConfigManager(project_root, "jira")
            >>> url = config.get_value("connection.url")
            >>> timeout = config.get_value("connection.timeout", 30)
        """
        config = self.get_config()
        keys = key_path.split(".")

        current = config
        for key in keys:
            if not isinstance(current, dict) or key not in current:
                return default
            current = current[key]

        return current

    def has_value(self, key_path: str) -> bool:
        """Check if a configuration value exists.

        Args:
            key_path: Dot-separated path to config value

        Returns:
            True if value exists (even if None), False otherwise
        """
        config = self.get_config()
        keys = key_path.split(".")

        current = config
        for key in keys:
            if not isinstance(current, dict) or key not in current:
                return False
            current = current[key]

        return True


class HookExecutor:
    """Manages extension hook execution."""

    def __init__(self, project_root: Path):
        """Initialize hook executor.

        Args:
            project_root: Root directory of the spec-kit project
        """
        self.project_root = project_root
        self.extensions_dir = project_root / ".specify" / "extensions"
        self.config_file = project_root / ".specify" / "extensions.yml"

    def get_project_config(self) -> Dict[str, Any]:
        """Load project-level extension configuration.

        Returns:
            Extension configuration dictionary
        """
        if not self.config_file.exists():
            return {
                "installed": [],
                "settings": {"auto_execute_hooks": True},
                "hooks": {},
            }

        try:
            return yaml.safe_load(self.config_file.read_text(encoding="utf-8")) or {}
        except (yaml.YAMLError, OSError, UnicodeError):
            return {
                "installed": [],
                "settings": {"auto_execute_hooks": True},
                "hooks": {},
            }

    def save_project_config(self, config: Dict[str, Any]):
        """Save project-level extension configuration.

        Args:
            config: Configuration dictionary to save
        """
        self.config_file.parent.mkdir(parents=True, exist_ok=True)
        self.config_file.write_text(
            yaml.dump(config, default_flow_style=False, sort_keys=False, allow_unicode=True),
            encoding="utf-8",
        )

    def register_hooks(self, manifest: ExtensionManifest):
        """Register extension hooks in project config.

        Args:
            manifest: Extension manifest with hooks to register
        """
        if not hasattr(manifest, "hooks") or not manifest.hooks:
            return

        config = self.get_project_config()

        # Ensure hooks dict exists
        if "hooks" not in config:
            config["hooks"] = {}

        # Register each hook
        for hook_name, hook_config in manifest.hooks.items():
            if hook_name not in config["hooks"]:
                config["hooks"][hook_name] = []

            # Add hook entry
            hook_entry = {
                "extension": manifest.id,
                "command": hook_config.get("command"),
                "enabled": True,
                "optional": hook_config.get("optional", True),
                "prompt": hook_config.get(
                    "prompt", f"Execute {hook_config.get('command')}?"
                ),
                "description": hook_config.get("description", ""),
                "condition": hook_config.get("condition"),
            }

            # Check if already registered
            existing = [
                h
                for h in config["hooks"][hook_name]
                if h.get("extension") == manifest.id
            ]

            if not existing:
                config["hooks"][hook_name].append(hook_entry)
            else:
                # Update existing
                for i, h in enumerate(config["hooks"][hook_name]):
                    if h.get("extension") == manifest.id:
                        config["hooks"][hook_name][i] = hook_entry

        self.save_project_config(config)

    def unregister_hooks(self, extension_id: str):
        """Remove extension hooks from project config.

        Args:
            extension_id: ID of extension to unregister
        """
        config = self.get_project_config()

        if "hooks" not in config:
            return

        # Remove hooks for this extension
        for hook_name in config["hooks"]:
            config["hooks"][hook_name] = [
                h
                for h in config["hooks"][hook_name]
                if h.get("extension") != extension_id
            ]

        # Clean up empty hook arrays
        config["hooks"] = {
            name: hooks for name, hooks in config["hooks"].items() if hooks
        }

        self.save_project_config(config)

    def get_hooks_for_event(self, event_name: str) -> List[Dict[str, Any]]:
        """Get all registered hooks for a specific event.

        Args:
            event_name: Name of the event (e.g., 'after_tasks')

        Returns:
            List of hook configurations
        """
        config = self.get_project_config()
        hooks = config.get("hooks", {}).get(event_name, [])

        # Filter to enabled hooks only
        return [h for h in hooks if h.get("enabled", True)]

    def should_execute_hook(self, hook: Dict[str, Any]) -> bool:
        """Determine if a hook should be executed based on its condition.

        Args:
            hook: Hook configuration

        Returns:
            True if hook should execute, False otherwise
        """
        condition = hook.get("condition")

        if not condition:
            return True

        # Parse and evaluate condition
        try:
            return self._evaluate_condition(condition, hook.get("extension"))
        except Exception:
            # If condition evaluation fails, default to not executing
            return False

    def _evaluate_condition(self, condition: str, extension_id: Optional[str]) -> bool:
        """Evaluate a hook condition expression.

        Supported condition patterns:
        - "config.key.path is set" - checks if config value exists
        - "config.key.path == 'value'" - checks if config equals value
        - "config.key.path != 'value'" - checks if config not equals value
        - "env.VAR_NAME is set" - checks if environment variable exists
        - "env.VAR_NAME == 'value'" - checks if env var equals value

        Args:
            condition: Condition expression string
            extension_id: Extension ID for config lookup

        Returns:
            True if condition is met, False otherwise
        """
        import os

        condition = condition.strip()

        # Pattern: "config.key.path is set"
        if match := re.match(r'config\.([a-z0-9_.]+)\s+is\s+set', condition, re.IGNORECASE):
            key_path = match.group(1)
            if not extension_id:
                return False

            config_manager = ConfigManager(self.project_root, extension_id)
            return config_manager.has_value(key_path)

        # Pattern: "config.key.path == 'value'" or "config.key.path != 'value'"
        if match := re.match(r'config\.([a-z0-9_.]+)\s*(==|!=)\s*["\']([^"\']+)["\']', condition, re.IGNORECASE):
            key_path = match.group(1)
            operator = match.group(2)
            expected_value = match.group(3)

            if not extension_id:
                return False

            config_manager = ConfigManager(self.project_root, extension_id)
            actual_value = config_manager.get_value(key_path)

            # Normalize boolean values to lowercase for comparison
            # (YAML True/False vs condition strings 'true'/'false')
            if isinstance(actual_value, bool):
                normalized_value = "true" if actual_value else "false"
            else:
                normalized_value = str(actual_value)

            if operator == "==":
                return normalized_value == expected_value
            else:  # !=
                return normalized_value != expected_value

        # Pattern: "env.VAR_NAME is set"
        if match := re.match(r'env\.([A-Z0-9_]+)\s+is\s+set', condition, re.IGNORECASE):
            var_name = match.group(1).upper()
            return var_name in os.environ

        # Pattern: "env.VAR_NAME == 'value'" or "env.VAR_NAME != 'value'"
        if match := re.match(r'env\.([A-Z0-9_]+)\s*(==|!=)\s*["\']([^"\']+)["\']', condition, re.IGNORECASE):
            var_name = match.group(1).upper()
            operator = match.group(2)
            expected_value = match.group(3)

            actual_value = os.environ.get(var_name, "")

            if operator == "==":
                return actual_value == expected_value
            else:  # !=
                return actual_value != expected_value

        # Unknown condition format, default to False for safety
        return False

    def format_hook_message(
        self, event_name: str, hooks: List[Dict[str, Any]]
    ) -> str:
        """Format hook execution message for display in command output.

        Args:
            event_name: Name of the event
            hooks: List of hooks to execute

        Returns:
            Formatted message string
        """
        if not hooks:
            return ""

        lines = ["\n## Extension Hooks\n"]
        lines.append(f"Hooks available for event '{event_name}':\n")

        for hook in hooks:
            extension = hook.get("extension")
            command = hook.get("command")
            optional = hook.get("optional", True)
            prompt = hook.get("prompt", "")
            description = hook.get("description", "")

            if optional:
                lines.append(f"\n**Optional Hook**: {extension}")
                lines.append(f"Command: `/{command}`")
                if description:
                    lines.append(f"Description: {description}")
                lines.append(f"\nPrompt: {prompt}")
                lines.append(f"To execute: `/{command}`")
            else:
                lines.append(f"\n**Automatic Hook**: {extension}")
                lines.append(f"Executing: `/{command}`")
                lines.append(f"EXECUTE_COMMAND: {command}")

        return "\n".join(lines)

    def check_hooks_for_event(self, event_name: str) -> Dict[str, Any]:
        """Check for hooks registered for a specific event.

        This method is designed to be called by AI agents after core commands complete.

        Args:
            event_name: Name of the event (e.g., 'after_spec', 'after_tasks')

        Returns:
            Dictionary with hook information:
            - has_hooks: bool - Whether hooks exist for this event
            - hooks: List[Dict] - List of hooks (with condition evaluation applied)
            - message: str - Formatted message for display
        """
        hooks = self.get_hooks_for_event(event_name)

        if not hooks:
            return {
                "has_hooks": False,
                "hooks": [],
                "message": ""
            }

        # Filter hooks by condition
        executable_hooks = []
        for hook in hooks:
            if self.should_execute_hook(hook):
                executable_hooks.append(hook)

        if not executable_hooks:
            return {
                "has_hooks": False,
                "hooks": [],
                "message": f"# No executable hooks for event '{event_name}' (conditions not met)"
            }

        return {
            "has_hooks": True,
            "hooks": executable_hooks,
            "message": self.format_hook_message(event_name, executable_hooks)
        }

    def execute_hook(self, hook: Dict[str, Any]) -> Dict[str, Any]:
        """Execute a single hook command.

        Note: This returns information about how to execute the hook.
        The actual execution is delegated to the AI agent.

        Args:
            hook: Hook configuration

        Returns:
            Dictionary with execution information:
            - command: str - Command to execute
            - extension: str - Extension ID
            - optional: bool - Whether hook is optional
            - description: str - Hook description
        """
        return {
            "command": hook.get("command"),
            "extension": hook.get("extension"),
            "optional": hook.get("optional", True),
            "description": hook.get("description", ""),
            "prompt": hook.get("prompt", "")
        }

    def enable_hooks(self, extension_id: str):
        """Enable all hooks for an extension.

        Args:
            extension_id: Extension ID
        """
        config = self.get_project_config()

        if "hooks" not in config:
            return

        # Enable all hooks for this extension
        for hook_name in config["hooks"]:
            for hook in config["hooks"][hook_name]:
                if hook.get("extension") == extension_id:
                    hook["enabled"] = True

        self.save_project_config(config)

    def disable_hooks(self, extension_id: str):
        """Disable all hooks for an extension.

        Args:
            extension_id: Extension ID
        """
        config = self.get_project_config()

        if "hooks" not in config:
            return

        # Disable all hooks for this extension
        for hook_name in config["hooks"]:
            for hook in config["hooks"][hook_name]:
                if hook.get("extension") == extension_id:
                    hook["enabled"] = False

        self.save_project_config(config)