Update app.py

app.py

@@ -146,7 +146,6 @@ def get_user_ip(request: Request) -> str:
 def download_track(request: Request, download_request: DownloadRequest):
     try:
         user_ip = get_user_ip(request)
-
         if rate_limiter.is_rate_limited(user_ip):
             current_count = rate_limiter.get_current_count(user_ip)
             raise HTTPException(
@@ -156,84 +155,121 @@ def download_track(request: Request, download_request: DownloadRequest):
                     "help": "https://t.me/chrunoss"
                 }
             )
+
         if download_request.arl is None or download_request.arl.strip() == "":
             ARL = ARL_TOKEN
         else:
             ARL = download_request.arl
+
         logger.info(f'arl: {ARL}')
         url = download_request.url
+
         if 'dzr.page' in url or 'deezer.page' in url or 'link.deezer' in url:
             url = convert_deezer_short_link_async(url)
-        quality = download_request.quality
+
+        requested_quality = download_request.quality
         dl = DeeLogin(arl=ARL)
         logger.info(f'track_url: {url}')
 
-        if quality not in ["MP3_320", "MP3_128", "FLAC"]:
+        # 1. 定义降级序列 (从高到低)
+        QUALITY_HIERARCHY = ["FLAC", "MP3_320", "MP3_128"]
+        if requested_quality not in QUALITY_HIERARCHY:
             raise HTTPException(status_code=400, detail="Invalid quality specified")
 
-        # 提取 track_id （假设 url 格式为 https://api.deezer.com/track/{track_id}）
-        track_id = url.split("/")[-1]
+        # 确定需要尝试的音质列表（从用户指定的音质开始，截取列表后半段）
+        start_index = QUALITY_HIERARCHY.index(requested_quality)
+        qualities_to_try = QUALITY_HIERARCHY[start_index:]
 
-        # Fetch track info
+        track_id = url.split("/")[-1]
         track_info = get_track_info(track_id)
         track_link = track_info.get("link")
+
         if not track_link:
             raise HTTPException(status_code=404, detail="Track link not found")
 
-        # Sanitize filename
         track_title = track_info.get("title", "track")
         artist_name = track_info.get("artist", {}).get("name", "unknown")
-        file_extension = "flac" if quality == "FLAC" else "mp3"
-        expected_filename = f"{artist_name} - {track_title}.{file_extension}".replace("/", "_")  # Sanitize filename
 
-        # Clear the downloads directory
+        # Clear the downloads directory (保持原样，在下载前清空一次即可)
         for root, dirs, files in os.walk("downloads"):
             for file in files:
                 os.remove(os.path.join(root, file))
             for dir in dirs:
                 shutil.rmtree(os.path.join(root, dir))
 
-        # Download the track using deezspot
-        try:
-            # 下载文件的代码
-            dl.download_trackdee(
-                link_track=track_link,
-                output_dir="downloads",
-                quality_download=quality,
-                recursive_quality=False,
-                recursive_download=False
-            )
-        except Exception as e:
-            logger.error(f"Error downloading file: {e}")
-            raise HTTPException(status_code=500, detail="File download failed")
-
-        # Recursively search for the file in the downloads directory
+        # 2. 循环尝试下载降级队列中的音质
         filepath = None
-        for root, dirs, files in os.walk("downloads"):
-            for file in files:
-                if file.endswith(f'.{file_extension}'):
-                    filepath = os.path.join(root, file)
+        actual_quality_downloaded = None
+        actual_extension = None
+
+        for current_quality in qualities_to_try:
+            try:
+                logger.info(f"Attempting download with quality: {current_quality}")
+                
+                # 执行下载
+                dl.download_trackdee(
+                    link_track=track_link,
+                    output_dir="downloads",
+                    quality_download=current_quality,
+                    recursive_quality=False,
+                    recursive_download=False
+                )
+
+                # 下载完成后，立即在目录下查找文件是否真的生成了
+                temp_extension = "flac" if current_quality == "FLAC" else "mp3"
+                found_path = None
+                
+                for root, dirs, files in os.walk("downloads"):
+                    for file in files:
+                        if file.endswith(f'.{temp_extension}'):
+                            found_path = os.path.join(root, file)
+                            break
+                    if found_path:
+                        break
+                
+                # 如果文件找到了，说明这一档的音质下载成功，跳出循环
+                if found_path:
+                    filepath = found_path
+                    actual_quality_downloaded = current_quality
+                    actual_extension = temp_extension
+                    logger.info(f"Successfully downloaded in {current_quality}")
                     break
-            if filepath:
-                break
+                else:
+                    logger.warning(f"Download command executed but .{temp_extension} file not found for {current_quality}. Trying next lower quality...")
+
+            except Exception as e:
+                logger.warning(f"Error downloading {current_quality}: {e}. Falling back to next lower quality...")
+                # 出现异常，继续循环体，尝试下一种音质
 
+        # 如果循环结束 filepath 还是 None，说明所有音质都失败了
         if not filepath:
-            raise HTTPException(status_code=500, detail=f"{file_extension} file not found after download")
-        if filepath:
-            file_size = os.path.getsize(filepath)
-            logger.info(f"Downloaded file size: {file_size} bytes")
+            logger.error(f"All download attempts failed for track: {track_link}")
+            raise HTTPException(status_code=500, detail="File download failed for all available qualities")
+
+        file_size = os.path.getsize(filepath)
+        logger.info(f"Downloaded file size: {file_size} bytes")
 
         # Return the download URL
         relative_path = quote(str(os.path.relpath(filepath, "downloads")))
-        # Remove spaces from the relative path
-        # Auto-detect base URL from request
         base_url = str(request.base_url).rstrip('/')
         download_url = f"{base_url}/downloads/{relative_path}"
         logger.info(f"Download successful: {download_url}")
+        
         gc.collect()
-        return {"download_url": download_url, "requests_remaining": rate_limiter.max_requests - rate_limiter.get_current_count(user_ip)}
+        
+        # 3. 建议在返回值中加上实际下载的音质，方便客户端/前端知道是否发生了降级
+        return {
+            "download_url": download_url, 
+            "requested_quality": requested_quality,
+            "actual_quality": actual_quality_downloaded, # 告知客户端实际下到的音质
+            "requests_remaining": rate_limiter.max_requests - rate_limiter.get_current_count(user_ip)
+        }
+
+    except HTTPException:
+        # FastAPI 自带的 HTTPException 直接抛出，不经过下面的通用异常处理
+        raise
     except Exception as e:
-        logger.error(f"Error downloading track: {e}")
+        logger.error(f"Error processing track download: {e}")
         raise HTTPException(status_code=500, detail=str(e))