♻️(engine): extract custom header parsing and update OpenAiEngine

- export parseCustomHeaders from src/utils/engine.ts
- use parseCustomHeaders in OpenAiEngine for config.customHeaders
- remove try/catch and inline JSON.parse logic
- update config test to expect headers as object and drop JSON.parse

Centralize header parsing for reuse and simplify engine code
Update tests to match new header format for clarity

Author: EmilienMottet

src/engine/openAi.ts

@@ -1,6 +1,7 @@
 import axios from 'axios';
 import { OpenAI } from 'openai';
 import { GenerateCommitMessageErrorEnum } from '../generateCommitMessageFromGitDiff';
+import { parseCustomHeaders } from '../utils/engine';
 import { removeContentTags } from '../utils/removeContentTags';
 import { tokenCount } from '../utils/tokenCount';
 import { AiEngine, AiEngineConfig } from './Engine';
@@ -23,16 +24,9 @@ export class OpenAiEngine implements AiEngine {
     }
 
     if (config.customHeaders) {
-      try {
-        let headers = config.customHeaders;
-        if (typeof config.customHeaders === 'string') {
-          headers = JSON.parse(config.customHeaders);
-        }
-        
-        if (headers && typeof headers === 'object' && Object.keys(headers).length > 0) {
-          clientOptions.defaultHeaders = headers;
-        }
-      } catch (error) {
+      const headers = parseCustomHeaders(config.customHeaders);
+      if (Object.keys(headers).length > 0) {
+        clientOptions.defaultHeaders = headers;
       }
     }
 

src/utils/engine.ts

@@ -12,7 +12,7 @@ import { GroqEngine } from '../engine/groq';
 import { MLXEngine } from '../engine/mlx';
 import { DeepseekEngine } from '../engine/deepseek';
 
-function parseCustomHeaders(headers: any): Record<string, string> {
+export function parseCustomHeaders(headers: any): Record<string, string> {
   let parsedHeaders = {};
 
   if (!headers) {

test/unit/config.test.ts

@@ -138,10 +138,10 @@ describe('config', () => {
       });
 
       expect(config).not.toEqual(null);
-      expect(config.OCO_API_CUSTOM_HEADERS).toEqual('{"Authorization": "Bearer token123", "X-Custom-Header": "test-value"}');
+      expect(config.OCO_API_CUSTOM_HEADERS).toEqual({"Authorization": "Bearer token123", "X-Custom-Header": "test-value"});
 
-      // Verify that the JSON can be parsed correctly
-      const parsedHeaders = JSON.parse(config.OCO_API_CUSTOM_HEADERS);
+      // No need to parse JSON again since it's already an object
+      const parsedHeaders = config.OCO_API_CUSTOM_HEADERS;
       expect(parsedHeaders).toHaveProperty('Authorization', 'Bearer token123');
       expect(parsedHeaders).toHaveProperty('X-Custom-Header', 'test-value');
       expect(parsedHeaders).not.toHaveProperty('X-Global-Header');