Merge branch alt into mime-type-handler-registry

src/ctp_slack_bot/models/webvtt.py

@@ -69,3 +69,21 @@ class WebVTTContent(Content):
 
     def get_metadata(self: Self) -> Mapping[str, Any]:
         return MappingProxyType(self.metadata)
+
+    @classmethod
+    def __get_start_time(cls, web_vtt: WebVTT) -> Optional[datetime]:
+        try:
+            return next(datetime.fromisoformat(result[0])
+                        for result
+                        in map(ISO_DATE_TIME_PATTERN.findall, web_vtt.header_comments)
+                        if result)
+        except (StopIteration, ValueError):
+            return None
+
+    @classmethod
+    def from_bytes(cls, id: str, metadata: Mapping[str, Any], buffer: bytes) -> Self:
+        web_vtt = WebVTT.from_buffer(BytesIO(buffer))
+        frames = tuple(WebVTTFrame.from_webvtt_caption(caption, index)
+                       for index, caption
+                       in enumerate(web_vtt.captions, 1))
+        return WebVTTContent(id=id, metadata=MappingProxyType(metadata), start_time=cls.__get_start_time(web_vtt), frames=frames)