repo-tools: Fix duplicate imports in OpenAPI client generation (#31297)

* repo-tools: Fix duplicate imports in OpenAPI client generation

Added automatic deduplication step to remove duplicate import/export
statements from generated TypeScript clients while preserving code
structure and different import syntaxes.

Signed-off-by: Ricardo Ferreira <r_ferreira@outlook.pt>

* repo-tools: changeset added

Signed-off-by: Ricardo Ferreira <r_ferreira@outlook.pt>

* repo-tools: changeset updated

Signed-off-by: Ricardo Ferreira <r_ferreira@outlook.pt>

* repo-tools: deduplicate imports on server files

Signed-off-by: Ricardo Ferreira <r_ferreira@outlook.pt>

* Update .changeset/forty-rooms-work.md

Signed-off-by: Aramis Sennyey <159921952+aramissennyeydd@users.noreply.github.com>

---------

Signed-off-by: Ricardo Ferreira <r_ferreira@outlook.pt>
Signed-off-by: Aramis Sennyey <159921952+aramissennyeydd@users.noreply.github.com>
Co-authored-by: Aramis Sennyey <159921952+aramissennyeydd@users.noreply.github.com>

.changeset/forty-rooms-work.md

@@ -0,0 +1,5 @@
+---
+'@backstage/repo-tools': patch
+---
+
+Fixed an issue with the OpenAPI generated client and server where import/export statements were duplicated.

packages/repo-tools/src/commands/package/schema/openapi/generate/client.ts

@@ -28,6 +28,7 @@ import {
   getPathToCurrentOpenApiSpec,
   toGeneratorAdditionalProperties,
 } from '../../../../../lib/openapi/helpers';
+import { deduplicateImports } from '../../../../../lib/openapi/dedupe-imports';
 
 async function generate(
   outputDirectory: string,
@@ -101,6 +102,14 @@ async function generate(
     });
   }
 
+  // Deduplicate imports in generated files
+  const generatedFiles = await fs.readdir(resolvedOutputDirectory);
+  for (const file of generatedFiles) {
+    if (file.endsWith('.ts')) {
+      deduplicateImports(resolve(resolvedOutputDirectory, file));
+    }
+  }
+
   fs.removeSync(resolve(resolvedOutputDirectory, '.openapi-generator-ignore'));
 
   fs.rmSync(resolve(resolvedOutputDirectory, '.openapi-generator'), {

packages/repo-tools/src/commands/package/schema/openapi/generate/server.ts

@@ -14,24 +14,25 @@
  * limitations under the License.
  */
 
+import { resolvePackagePath } from '@backstage/backend-plugin-api';
 import chalk from 'chalk';
-import { resolve, dirname, join } from 'path';
+import fs from 'fs-extra';
 import YAML from 'js-yaml';
+import { dirname, join, resolve } from 'path';
+import { exec } from '../../../../../lib/exec';
 import {
   OLD_SCHEMA_PATH,
   OPENAPI_IGNORE_FILES,
   OUTPUT_PATH,
   TS_SCHEMA_PATH,
 } from '../../../../../lib/openapi/constants';
-import { paths as cliPaths } from '../../../../../lib/paths';
-import fs from 'fs-extra';
-import { exec } from '../../../../../lib/exec';
-import { resolvePackagePath } from '@backstage/backend-plugin-api';
+import { deduplicateImports } from '../../../../../lib/openapi/dedupe-imports';
 import {
   getPathToCurrentOpenApiSpec,
   getRelativePathToFile,
   toGeneratorAdditionalProperties,
 } from '../../../../../lib/openapi/helpers';
+import { paths as cliPaths } from '../../../../../lib/paths';
 
 async function generateSpecFile() {
   const openapiPath = await getPathToCurrentOpenApiSpec();
@@ -133,6 +134,14 @@ async function generate(
     },
   );
 
+  // Deduplicate imports in generated files
+  const generatedFiles = await fs.readdir(resolvedOutputDirectory);
+  for (const file of generatedFiles) {
+    if (file.endsWith('.ts')) {
+      deduplicateImports(resolve(resolvedOutputDirectory, file));
+    }
+  }
+
   await exec(
     `yarn backstage-cli package lint --fix ${resolvedOutputDirectory}`,
     [],

packages/repo-tools/src/lib/openapi/dedupe-imports.ts

@@ -0,0 +1,74 @@
+/*
+ * Copyright 2025 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import fs from 'fs';
+
+/**
+ * Removes duplicate import and export statements from TypeScript/JavaScript files.
+ * Preserves different import syntaxes, multi-line imports, and code structure.
+ *
+ * @param filePath - Absolute path to the file to deduplicate
+ */
+export function deduplicateImports(filePath: string): void {
+  const content = fs.readFileSync(filePath, 'utf8');
+  const lines = content.split('\n');
+  const seen = new Set<string>();
+  const result: string[] = [];
+  let i = 0;
+
+  while (i < lines.length) {
+    const line = lines[i];
+    const trimmed = line.trim();
+
+    // Handle import/export statements
+    if (trimmed.startsWith('import ') || trimmed.startsWith('export ')) {
+      let fullStatement = line;
+      let endIndex = i;
+
+      // Check if multi-line (has { but no })
+      if (trimmed.includes('{') && !trimmed.includes('}')) {
+        // Collect full multi-line statement
+        while (endIndex < lines.length && !lines[endIndex].includes('}')) {
+          endIndex++;
+        }
+        if (endIndex < lines.length) {
+          fullStatement = lines.slice(i, endIndex + 1).join('\n');
+        }
+      }
+
+      // Normalize for comparison (remove comments, extra spaces)
+      const normalized = fullStatement
+        .replace(/\/\/.*$/gm, '')
+        .replace(/\s+/g, ' ')
+        .trim();
+
+      if (!seen.has(normalized)) {
+        seen.add(normalized);
+        // Add all lines of the statement
+        for (let j = i; j <= endIndex; j++) {
+          result.push(lines[j]);
+        }
+      }
+
+      i = endIndex + 1;
+    } else {
+      result.push(line);
+      i++;
+    }
+  }
+
+  fs.writeFileSync(filePath, result.join('\n'));
+}

packages/repo-tools/src/lib/openapi/helpers.ts

@@ -14,14 +14,13 @@
  * limitations under the License.
  */
 
-import { pathExists } from 'fs-extra';
-import { paths } from '../paths';
-import { YAML_SCHEMA_PATH } from './constants';
-import { resolve } from 'path';
+import Parser from '@apidevtools/swagger-parser';
+import fs, { pathExists } from 'fs-extra';
 import YAML from 'js-yaml';
 import { cloneDeep } from 'lodash';
-import Parser from '@apidevtools/swagger-parser';
-import fs from 'fs-extra';
+import { resolve } from 'path';
+import { paths } from '../paths';
+import { YAML_SCHEMA_PATH } from './constants';
 
 export const getPathToFile = async (directory: string, filename: string) => {
   return resolve(directory, filename);