feat: Add subtitle download and VTT to SRT conversion, refactor Linkkf queue to class-level, improve video URL extraction, and introduce downloader factory.

lib/util.py

@@ -75,3 +75,63 @@ class Util(object):
         except Exception as exception:
             logger.debug('Exception:%s', exception)
             logger.debug(traceback.format_exc())
+
+    @staticmethod
+    def download_subtitle(vtt_url, output_path, headers=None):
+        try:
+            import requests
+            # 자막 파일 경로 생성 (비디오 파일명.srt)
+            video_basename = os.path.splitext(output_path)[0]
+            srt_path = video_basename + ".srt"
+            
+            logger.info(f"Downloading subtitle from: {vtt_url}")
+            response = requests.get(vtt_url, headers=headers, timeout=30)
+            
+            if response.status_code == 200:
+                vtt_content = response.text
+                srt_content = Util.vtt_to_srt(vtt_content)
+                with open(srt_path, "w", encoding="utf-8") as f:
+                    f.write(srt_content)
+                logger.info(f"Subtitle saved to: {srt_path}")
+                return True
+        except Exception as e:
+            logger.error(f"Failed to download subtitle: {e}")
+            logger.error(traceback.format_exc())
+        return False
+
+    @staticmethod
+    def vtt_to_srt(vtt_content):
+        if not vtt_content.startswith("WEBVTT"):
+            return vtt_content
+            
+        lines = vtt_content.split("\n")
+        srt_lines = []
+        cue_index = 1
+        i = 0
+        while i < len(lines):
+            line = lines[i].strip()
+            # WEBVTT, NOTE, STYLE 등 메타데이터 스킵
+            if line.startswith("WEBVTT") or line.startswith("NOTE") or line.startswith("STYLE"):
+                i += 1
+                continue
+            # 빈 줄 스킵
+            if not line:
+                i += 1
+                continue
+            # 타임코드 라인 (00:00:00.000 --> 00:00:00.000)
+            if "-->" in line:
+                # VTT 타임코드를 SRT 형식으로 변환 (. -> ,)
+                srt_timecode = line.replace(".", ",")
+                srt_lines.append(str(cue_index))
+                srt_lines.append(srt_timecode)
+                cue_index += 1
+                i += 1
+                # 자막 텍스트 읽기
+                while i < len(lines) and lines[i].strip():
+                    srt_lines.append(lines[i].rstrip())
+                    i += 1
+                srt_lines.append("")
+            else:
+                # 캡션 텍스트가 바로 나오는 경우 등을 대비
+                i += 1
+        return "\n".join(srt_lines)