feat: find and use import alias

Author: mnahkies

integration-tests/typescript-nextjs/src/generated/api.github.com.yaml/app/route.ts

@@ -12,7 +12,7 @@ import {
 
 export type CompilerOptions = Pick<
   TsCompilerOptions,
-  "exactOptionalPropertyTypes"
+  "exactOptionalPropertyTypes" | "paths"
 >
 
 export async function loadTsConfigCompilerOptions(

packages/openapi-code-generator/src/core/loaders/tsconfig.loader.ts

@@ -35,6 +35,7 @@ export const tsconfigSchema = z.object({
       noPropertyAccessFromIndexSignature: z.boolean(),
       allowUnusedLabels: z.boolean(),
       allowUnreachableCode: z.boolean(),
+      paths: z.record(z.array(z.string())),
     })
     .partial(),
 })

packages/openapi-code-generator/src/core/schemas/tsconfig.schema.ts

@@ -6,6 +6,10 @@ export function isDefined<T>(it: T | undefined): it is T {
   return it !== undefined
 }
 
+export function isTruthy<T>(it: T | undefined | null | "" | 0): it is T {
+  return Boolean(it)
+}
+
 export function hasSingleElement<T>(it: T[]): it is [T] {
   return it.length === 1
 }

packages/openapi-code-generator/src/core/utils.ts

@@ -5,7 +5,10 @@ export class ImportBuilder {
   private readonly imports: Record<string, Set<string>> = {}
   private readonly importAll: Record<string, string> = {}
 
-  constructor(private readonly unit?: {filename: string}) {}
+  constructor(
+    private readonly unit?: {filename: string},
+    private readonly importAlias?: string,
+  ) {}
 
   from(from: string) {
     return {
@@ -76,7 +79,7 @@ export class ImportBuilder {
 
   private add(name: string, from: string, isAll: boolean): void {
     // biome-ignore lint/style/noParameterAssign: <explanation>
-    from = ImportBuilder.normalizeFrom(from, this.unit?.filename)
+    from = this.normalizeFrom(from, this.unit?.filename)
     // biome-ignore lint/suspicious/noAssignInExpressions: <explanation>
     const imports = (this.imports[from] =
       this.imports[from] ?? new Set<string>())
@@ -88,14 +91,18 @@ export class ImportBuilder {
     }
   }
 
-  public static normalizeFrom(from: string, filename?: string) {
+  public normalizeFrom(from: string, filename?: string) {
     if (from.endsWith(".ts")) {
       // biome-ignore lint/style/noParameterAssign: <explanation>
       from = from.substring(0, from.length - ".ts".length)
     }
 
     // TODO: does this work on windows?
     if (filename && from.startsWith("./")) {
+      if (this.importAlias) {
+        return this.importAlias + from.split(path.sep).slice(1).join(path.sep)
+      }
+
       const unitDirname = path.dirname(filename)
       const fromDirname = path.dirname(from)
 

packages/openapi-code-generator/src/typescript/common/import-builder.ts

@@ -11,11 +11,13 @@ import {
   VariableDeclarationKind,
 } from "ts-morph"
 import type {Input} from "../../core/input"
+import type {CompilerOptions} from "../../core/loaders/tsconfig.loader"
 import type {
   IRModelObject,
   IROperation,
   IRParameter,
 } from "../../core/openapi-types-normalized"
+import {isTruthy} from "../../core/utils"
 import {
   type HttpMethod,
   isDefined,
@@ -321,6 +323,7 @@ ${routes.join("\n\n")}
 export class NextJSAppRouterBuilder implements ICompilable {
   constructor(
     public readonly filename: string,
+    private readonly imports: ImportBuilder,
     private readonly companionFilename: string,
     private readonly sourceFile: SourceFile,
   ) {}
@@ -394,7 +397,7 @@ export class NextJSAppRouterBuilder implements ICompilable {
   toCompilationUnit(): CompilationUnit {
     // Reconcile imports - attempt to find an existing one and replace it with correct one
     const imports = this.sourceFile.getImportDeclarations()
-    const from = ImportBuilder.normalizeFrom(
+    const from = this.imports.normalizeFrom(
       "./" + this.companionFilename,
       "./" + this.filename,
     )
@@ -418,26 +421,43 @@ export class NextJSAppRouterBuilder implements ICompilable {
 
     return new CompilationUnit(
       this.filename,
-      new ImportBuilder(),
+      this.imports,
       this.toString(),
       false,
     )
   }
 }
 
+function findImportAlias(dest: string, compilerOptions: CompilerOptions) {
+  const relative = `./${path.relative(process.cwd(), dest)}/*`
+
+  const alias = Object.entries(compilerOptions.paths || {}).find(([, paths]) =>
+    paths.includes(relative),
+  )
+
+  return alias ? alias[0].replace("*", "") : undefined
+}
+
 export async function generateTypescriptNextJS(
   config: OpenapiTypescriptGeneratorConfig,
 ): Promise<void> {
   const {input, emitter, allowAny} = config
 
+  const importAlias = findImportAlias(
+    config.emitter.config.destinationDirectory,
+    config.compilerOptions,
+  )
+
   // biome-ignore lint/complexity/useLiteralKeys: <explanation>
   const subDirectory = process.env["OPENAPI_INTEGRATION_TESTS"]
     ? path.basename(config.input.loader.entryPointKey)
     : ""
 
-  const appDirectory = ["./app", subDirectory].filter(isDefined).join(path.sep)
-  const generatedDirectory = ["./generated", subDirectory]
-    .filter(isDefined)
+  const appDirectory = [".", "app", subDirectory]
+    .filter(isTruthy)
+    .join(path.sep)
+  const generatedDirectory = [".", "generated", subDirectory]
+    .filter(isTruthy)
     .join(path.sep)
 
   const rootTypeBuilder = await TypeBuilder.fromInput(
@@ -464,7 +484,7 @@ export async function generateTypescriptNextJS(
           routeToNextJSFilepath(group.name),
         )
 
-        const imports = new ImportBuilder({filename})
+        const imports = new ImportBuilder({filename}, importAlias)
 
         const routerBuilder = new ServerRouterBuilder(
           filename,
@@ -500,6 +520,7 @@ export async function generateTypescriptNextJS(
 
         const nextJSAppRouterBuilder = new NextJSAppRouterBuilder(
           nextJsAppRouterPath,
+          imports,
           filename,
           sourceFile,
         )
@@ -520,7 +541,10 @@ export async function generateTypescriptNextJS(
   const clientOutputPath = [generatedDirectory, "clients", "client.ts"].join(
     path.sep,
   )
-  const clientImportBuilder = new ImportBuilder({filename: clientOutputPath})
+  const clientImportBuilder = new ImportBuilder(
+    {filename: clientOutputPath},
+    importAlias,
+  )
 
   const fetchClientBuilder = new TypescriptFetchClientBuilder(
     clientOutputPath,