refactor: enhance error handling and add support for large file translations in subtitle processing

Author: garanda21

package-lock.json

@@ -1,10 +1,12 @@
 import { Router } from 'express';
 import { join } from 'path';
-import { translateDocument } from '../services/deepl.js';
+import { translateDocument, translateLargeDocument } from '../services/deepl.js';
 import { extractSubtitles } from '../services/ffmpeg.js';
 import { DATA_DIR, MOVIES_DIR } from '../utils/paths.js';
+import fs from 'fs';
 
 const router = Router();
+const MAX_FILE_SIZE = 130 * 1024; // 130KB as a safe threshold (below the 150KB limit)
 
 router.post('/translate_subtitle', async (req, res) => {
   try {
@@ -20,31 +22,89 @@ router.post('/translate_subtitle', async (req, res) => {
     if (!process.env.DEEPL_API_KEY) {
       return res.status(400).json({ message: 'DeepL API key not configured' });     
     }
+    
+    let subtitlePath;
     if (type === 'series') {
-      const subtitlePath = join(DATA_DIR, serie, season, srt_path);
-      const translatedPath = await translateDocument(
+      subtitlePath = join(DATA_DIR, serie, season, srt_path);
+    } else {
+      subtitlePath = join(MOVIES_DIR, serie, srt_path);
+    }
+      
+    // Check the file size
+    const stats = fs.statSync(subtitlePath);
+    let translatedPath;
+    
+    if (stats.size > MAX_FILE_SIZE) {
+      console.log(`Large SRT file detected (${Math.round(stats.size/1024)}KB). Using large file translation method.`);
+      translatedPath = await translateLargeDocument(
         subtitlePath,
         source_lang,
         target_lang
       );
-
-      res.json({ path: translatedPath });
-    }
-    else
-    {
-      const subtitlePath = join(MOVIES_DIR, serie, srt_path);
-      const translatedPath = await translateDocument(
+    } else {
+      translatedPath = await translateDocument(
         subtitlePath,
         source_lang,
         target_lang
       );
-
-      res.json({ path: translatedPath });
     }
+
+    res.json({ path: translatedPath });
   } catch (error) {
-    res.status(500).json({ 
-      message: error.message,        
+    console.error('Error in subtitle translation:', error);
+    
+    // Format status code based on the error
+    let statusCode = 500;
+    if (error.status) {
+      statusCode = error.status;
+    }
+    
+    // Specific handling for size errors
+    if (error.message && error.message.includes('exceeds the size limit')) {
+      return res.status(statusCode).json({
+        message: 'The SRT file is too large to translate in a single operation. Please try again so it can be processed in smaller parts.',
+        originalError: error.toString(),
+        isLargeFile: true
+      });
+    }
+    
+    // Authentication errors
+    if (error.response && error.response.status === 403) {
+      return res.status(403).json({
+        message: 'Authentication failed with DeepL API. Please check your API key.',
+        originalError: error.toString()
+      });
+    }
+    
+    // API limit errors 
+    if (error.message && (error.message.includes('quota') || error.message.includes('limit'))) {
+      return res.status(statusCode).json({
+        message: 'DeepL API quota exceeded. Please try again later or upgrade your DeepL subscription.',
+        originalError: error.toString()
+      });
+    }
+    
+    // Handle DeepL-specific errors with more details
+    if (error.deeplRequest) {
+      // This is a enhanced error from our DeepL service
+      return res.status(statusCode).json({
+        message: `DeepL translation failed: ${error.message}`,
+        originalError: error.toString(),
+        apiDetails: error.apiDetails || null,
+        deeplRequest: error.deeplRequest,
+        status: error.status || 500,
+        stack: error.stack
+      });
+    }
+    
+    // Format a user-friendly error message with technical details
+    const userMessage = 'Translation failed: ' + (error.message || 'Unknown error');
+    
+    res.status(statusCode).json({ 
+      message: userMessage,        
       originalError: error.toString(),
+      apiDetails: error.apiDetails || null,
+      status: error.status || 500,
       stack: error.stack
     });
   }
@@ -61,26 +121,37 @@ router.post('/extract_subtitles', async (req, res) => {
       return res.status(400).json({ error: 'Missing parameters' });
     }
 
+    let videoPath, outputPath;
     if (type === 'series') {
-      const videoPath = join(DATA_DIR, serie, season, video_file);
+      videoPath = join(DATA_DIR, serie, season, video_file);
       const videoFileName = video_file.substring(0, video_file.lastIndexOf('.'));
-      const outputPath = join(DATA_DIR, serie, season, `${videoFileName}.${source_lang.toLowerCase()}.srt`);
-
-      await extractSubtitles(videoPath, outputPath);
-      res.json({ path: outputPath });
-    }
-    else
-    {
-      const videoPath = join(MOVIES_DIR, serie, video_file);
+      outputPath = join(DATA_DIR, serie, season, `${videoFileName}.${source_lang.toLowerCase()}.srt`);
+    } else {
+      videoPath = join(MOVIES_DIR, serie, video_file);
       const videoFileName = video_file.substring(0, video_file.lastIndexOf('.'));
-      const outputPath = join(MOVIES_DIR, serie, `${videoFileName}.${source_lang.toLowerCase()}.srt`);
-
-      await extractSubtitles(videoPath, outputPath);
-      res.json({ path: outputPath });
+      outputPath = join(MOVIES_DIR, serie, `${videoFileName}.${source_lang.toLowerCase()}.srt`);
     }
+
+    await extractSubtitles(videoPath, outputPath);
+    res.json({ path: outputPath });
   } catch (error) {
-    res.status(500).json({ 
-      message: error.message,        
+    console.error('Error extracting subtitles:', error);
+    
+    // Format a user-friendly error message with technical details
+    let userMessage = 'Failed to extract subtitles: ' + (error.message || 'Unknown error');
+    let statusCode = 500;
+    
+    // Handle specific ffmpeg errors
+    if (error.message && error.message.includes('No such file')) {
+      userMessage = 'Video file not found or inaccessible';
+      statusCode = 404;
+    } else if (error.message && error.message.includes('No subtitle')) {
+      userMessage = 'No subtitles found in this video file';
+      statusCode = 422;
+    }
+    
+    res.status(statusCode).json({ 
+      message: userMessage,        
       originalError: error.toString(),
       stack: error.stack
     });