Implement a form validation logic

Author: ns-vasilev

Sources/ValidatorUI/Classes/SUI/Extensions/View+ValidationModifier.swift

@@ -7,6 +7,14 @@ import SwiftUI
 import ValidatorCore
 
 public extension View {
+    /// Creates a view validation modifier.
+    ///
+    /// - Parameters:
+    ///   - item: The binding item to validate.
+    ///   - rules: The array of validation rules to apply to the item’s value.
+    ///   - content: A custom parameter attribute that constructs an error view from closures.
+    ///
+    /// - Returns: A modified view.
     func validate<T, ErrorView: View>(
         item: Binding<T>,
         rules: [any IValidationRule<T>],
@@ -20,4 +28,23 @@ public extension View {
             )
         )
     }
+
+    /// Creates a view validation modifier.
+    ///
+    /// - Parameters:
+    ///   - validationContainer: The container to validate.
+    ///   - content: A custom parameter attribute that constructs an error view from closures.
+    ///
+    /// - Returns: A modified view.
+    func validate<ErrorView: View>(
+        validationContainer: any IFormValidationContainer,
+        @ViewBuilder content: @escaping ([any IValidationError]) -> ErrorView
+    ) -> some View {
+        modifier(
+            FormValidationViewModifier(
+                validationContainer: validationContainer,
+                content: content
+            )
+        )
+    }
 }

Sources/ValidatorUI/Classes/SUI/Managers/FormField/FormField/FormField.swift

@@ -0,0 +1,67 @@
+//
+// Validator
+// Copyright © 2023 Space Code. All rights reserved.
+//
+
+import Combine
+import Foundation
+import ValidatorCore
+
+public typealias ValidationPublisher = AnyPublisher<ValidationResult, Never>
+
+// MARK: - FormField
+
+@propertyWrapper
+public final class FormField<Value>: IFormField {
+    // MARK: Properties
+
+    @Published
+    /// The value to validate.
+    private var value: Value
+
+    /// The validation.
+    private let validator: IValidator
+
+    /// The validation rules.
+    private let rules: [any IValidationRule<Value>]
+
+    public var wrappedValue: Value {
+        get { value }
+        set { value = newValue }
+    }
+
+    // MARK: Initialization
+
+    public init(
+        wrappedValue: Value,
+        validator: IValidator = Validator(),
+        rules: [any IValidationRule<Value>]
+    ) {
+        value = wrappedValue
+        self.validator = validator
+        self.rules = rules
+    }
+
+    // MARK: IFormField
+
+    public func validate(manager: some IFormFieldManager) -> any IFormValidationContainer {
+        let subject = CurrentValueSubject<Value, Never>(value)
+
+        let publisher = $value
+            .receive(on: RunLoop.main)
+            .handleEvents(receiveOutput: { subject.send($0) })
+            .map { self.validator.validate(input: $0, rules: self.rules) }
+            .eraseToAnyPublisher()
+
+        let container = FormValidationContainter(
+            value: subject,
+            publisher: publisher,
+            validator: validator,
+            rules: rules
+        )
+
+        manager.append(validator: container)
+
+        return container
+    }
+}

Sources/ValidatorUI/Classes/SUI/Managers/FormField/FormField/IFormField.swift

@@ -0,0 +1,20 @@
+//
+// Validator
+// Copyright © 2023 Space Code. All rights reserved.
+//
+
+import Combine
+import Foundation
+import ValidatorCore
+
+/// A type that represents a field on a form.
+public protocol IFormField {
+    /// Performs field validation.
+    ///
+    /// - Note: Create a form validation container that keeps track of the validation.
+    ///
+    /// - Parameter manager: The form field manager.
+    ///
+    /// - Returns: A validation container.
+    func validate(manager: some IFormFieldManager) -> any IFormValidationContainer
+}

Sources/ValidatorUI/Classes/SUI/Managers/FormField/FormFieldManager/FormFieldManager.swift

@@ -0,0 +1,34 @@
+//
+// Validator
+// Copyright © 2023 Space Code. All rights reserved.
+//
+
+import Combine
+import Foundation
+import ValidatorCore
+
+public final class FormFieldManager: IFormFieldManager {
+    // MARK: Properties
+
+    @Published public var isValid = true
+
+    private var validators: [any IFormValidationContainer] = []
+
+    // MARK: Initialization
+
+    public init() {}
+
+    // MARK: IFormFieldManager
+
+    public func append(validator: some IFormValidationContainer) {
+        validators.append(validator)
+        validate()
+    }
+
+    public func validate() {
+        // swiftlint:disable:next contains_over_filter_is_empty
+        isValid = validators
+            .filter { $0.validate() != .valid }
+            .isEmpty
+    }
+}

Sources/ValidatorUI/Classes/SUI/Managers/FormField/FormFieldManager/IFormFieldManager.swift

@@ -0,0 +1,19 @@
+//
+// Validator
+// Copyright © 2023 Space Code. All rights reserved.
+//
+
+import Combine
+import Foundation
+import ValidatorCore
+
+/// A type that manages the validation state of a form.
+public protocol IFormFieldManager: ObservableObject {
+    /// A Boolean value that indicates whether all fields on a form are valid or not.
+    var isValid: Bool { get }
+
+    /// Appends a new validator to the manager.
+    ///
+    /// - Parameter validator: The validation container that encompasses required validation logic.
+    func append(validator: some IFormValidationContainer)
+}

Sources/ValidatorUI/Classes/SUI/Managers/FormField/FormValidationContainer/FormValidationContainter.swift

@@ -0,0 +1,37 @@
+//
+// Validator
+// Copyright © 2023 Space Code. All rights reserved.
+//
+
+import Combine
+import Foundation
+import ValidatorCore
+
+public struct FormValidationContainter<T>: IFormValidationContainer {
+    // MARK: Properties
+
+    public var value: FormValidatorValueSubject<T>
+    public let publisher: ValidationPublisher
+    public let validator: IValidator
+    public let rules: [any IValidationRule<T>]
+
+    // MARK: Initialization
+
+    public init(
+        value: FormValidatorValueSubject<T>,
+        publisher: ValidationPublisher,
+        validator: IValidator,
+        rules: [any IValidationRule<T>]
+    ) {
+        self.value = value
+        self.publisher = publisher
+        self.validator = validator
+        self.rules = rules
+    }
+
+    // MARK: IFormValidationContainer
+
+    public func validate() -> ValidationResult {
+        validator.validate(input: value.value, rules: rules)
+    }
+}

Sources/ValidatorUI/Classes/SUI/Managers/FormField/FormValidationContainer/IFormValidationContainer.swift

@@ -0,0 +1,34 @@
+//
+// Validator
+// Copyright © 2023 Space Code. All rights reserved.
+//
+
+import Combine
+import Foundation
+import ValidatorCore
+
+public typealias FormValidatorValueSubject<Value> = CurrentValueSubject<Value, Never>
+
+// MARK: - IFormValidationContainer
+
+/// A container for form validation logic.
+public protocol IFormValidationContainer<Value> {
+    associatedtype Value
+
+    /// The value subject used for form validation.
+    var value: FormValidatorValueSubject<Value> { get }
+
+    /// The publisher responsible for emitting validation events.
+    var publisher: ValidationPublisher { get }
+
+    /// The validator associated with this validation container.
+    var validator: IValidator { get }
+
+    /// An array of validation rules to apply to the form field.
+    var rules: [any IValidationRule<Value>] { get }
+
+    /// Performs form field validation.
+    ///
+    /// - Returns: The result of the validation process.
+    func validate() -> ValidationResult
+}

Sources/ValidatorUI/Classes/SUI/ViewModifiers/FormValidationViewModifier.swift

@@ -0,0 +1,52 @@
+//
+// Validator
+// Copyright © 2023 Space Code. All rights reserved.
+//
+
+import SwiftUI
+import ValidatorCore
+
+public struct FormValidationViewModifier<ErrorView: View>: ViewModifier {
+    // MARK: Properties
+
+    /// The result of the validation.
+    @State private var validationResult: ValidationResult = .valid
+
+    /// A container for form validation logic.
+    private let validationContainer: any IFormValidationContainer
+
+    /// A custom parameter attribute that constructs views from closures.
+    @ViewBuilder private let content: ([any IValidationError]) -> ErrorView
+
+    // MARK: Initialization
+
+    public init(
+        validationContainer: any IFormValidationContainer,
+        @ViewBuilder content: @escaping ([any IValidationError]) -> ErrorView
+    ) {
+        self.validationContainer = validationContainer
+        self.content = content
+    }
+
+    // MARK: ViewModifier
+
+    public func body(content: Content) -> some View {
+        VStack(alignment: .leading) {
+            content
+            validationMessageView
+        }.onReceive(validationContainer.publisher) { result in
+            self.validationResult = result
+        }
+    }
+
+    // MARK: Private
+
+    private var validationMessageView: some View {
+        switch validationResult {
+        case .valid:
+            return EmptyView().eraseToAnyView()
+        case let .invalid(errors):
+            return content(errors).eraseToAnyView()
+        }
+    }
+}