feat: adopt ts-morph and flip implementation/generated code

Author: mnahkies

packages/openapi-code-generator/package.json

@@ -52,6 +52,7 @@
     "json5": "^2.2.3",
     "lodash": "^4.17.21",
     "source-map-support": "^0.5.21",
+    "ts-morph": "^22.0.0",
     "tslib": "^2.6.3",
     "zod": "^3.23.8"
   },

packages/openapi-code-generator/src/typescript/common/compilation-units.ts

@@ -15,6 +15,7 @@ export class CompilationUnit {
     readonly filename: string,
     readonly imports: ImportBuilder | undefined,
     readonly code: string,
+    readonly isAutogenerated: boolean = true,
   ) {}
 
   hasCode() {
@@ -26,7 +27,7 @@ export class CompilationUnit {
     includeHeader = true,
   }: {allowUnusedImports: boolean; includeHeader?: boolean}): string {
     return [
-      includeHeader ? FILE_HEADER : "",
+      includeHeader && this.isAutogenerated ? FILE_HEADER : "",
       this.imports
         ? this.imports.toString(allowUnusedImports ? "" : this.code)
         : "",

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

@@ -76,7 +76,7 @@ export class ImportBuilder {
 
   private add(name: string, from: string, isAll: boolean): void {
     // biome-ignore lint/style/noParameterAssign: <explanation>
-    from = this.normalizeFrom(from)
+    from = ImportBuilder.normalizeFrom(from, this.unit?.filename)
     // biome-ignore lint/suspicious/noAssignInExpressions: <explanation>
     const imports = (this.imports[from] =
       this.imports[from] ?? new Set<string>())
@@ -88,14 +88,15 @@ export class ImportBuilder {
     }
   }
 
-  private normalizeFrom(from: string) {
+  public static normalizeFrom(from: string, filename?: string) {
     if (from.endsWith(".ts")) {
       // biome-ignore lint/style/noParameterAssign: <explanation>
       from = from.substring(0, from.length - ".ts".length)
     }
 
-    if (this.unit && from.startsWith("./")) {
-      const unitDirname = path.dirname(this.unit.filename)
+    // TODO: does this work on windows?
+    if (filename && from.startsWith("./")) {
+      const unitDirname = path.dirname(filename)
       const fromDirname = path.dirname(from)
 
       const relative = path.relative(unitDirname, fromDirname)