fix(api,frontend): render files by name without fetching, previewable share links

backend/src/utils/files.py

@@ -29,6 +29,42 @@ _KIND_EXTENSIONS = {
     "voice": ".ogg",
 }
 
+_EXTENSION_MIMES = {
+    ".flac": "audio/flac",
+    ".gif": "image/gif",
+    ".heic": "image/heic",
+    ".jpeg": "image/jpeg",
+    ".jpg": "image/jpeg",
+    ".m4a": "audio/mp4",
+    ".mov": "video/quicktime",
+    ".mp3": "audio/mpeg",
+    ".mp4": "video/mp4",
+    ".ogg": "audio/ogg",
+    ".pdf": "application/pdf",
+    ".png": "image/png",
+    ".svg": "image/svg+xml",
+    ".txt": "text/plain",
+    ".wav": "audio/wav",
+    ".webm": "video/webm",
+    ".webp": "image/webp",
+}
+
+_KIND_MIMES = {
+    "animation": "video/mp4",
+    "gif": "video/mp4",
+    "photo": "image/jpeg",
+    "video": "video/mp4",
+    "video_note": "video/mp4",
+    "voice": "audio/ogg",
+}
+
+_GENERIC_MIMES = {
+    "application/octet-stream",
+    "application/binary",
+    "binary/octet-stream",
+    "",
+}
+
 _INLINE_MIME_PREFIXES = ("image/", "video/", "audio/", "text/")
 _INLINE_MIMES = {"application/pdf", "application/json"}
 
@@ -57,6 +93,45 @@ _PREVIEW_AGENTS = (
     "python-requests",
 )
 
+_TRANSLIT = {
+    "а": "a",
+    "б": "b",
+    "в": "v",
+    "г": "g",
+    "д": "d",
+    "е": "e",
+    "ё": "e",
+    "ж": "zh",
+    "з": "z",
+    "и": "i",
+    "й": "y",
+    "к": "k",
+    "л": "l",
+    "м": "m",
+    "н": "n",
+    "о": "o",
+    "п": "p",
+    "р": "r",
+    "с": "s",
+    "т": "t",
+    "у": "u",
+    "ф": "f",
+    "х": "h",
+    "ц": "c",
+    "ч": "ch",
+    "ш": "sh",
+    "щ": "sch",
+    "ъ": "",
+    "ы": "y",
+    "ь": "",
+    "э": "e",
+    "ю": "yu",
+    "я": "ya",
+}
+
+_URL_UNSAFE = re.compile(r"[^A-Za-z0-9._-]+")
+_URL_REPEATS = re.compile(r"_{2,}")
+
 _UNSAFE_CHARS = re.compile(r'[\\/:*?"<>|\x00-\x1f]+')
 _SPACES = re.compile(r"\s+")
 _NAME_LIMIT = 120
@@ -86,6 +161,16 @@ def sanitize_name(name: str) -> str:
     return cleaned or "file"
 
 
+def url_slug(file_name: str) -> str:
+    lowered = "".join(
+        _TRANSLIT.get(ch, _TRANSLIT.get(ch.lower(), ch)) for ch in file_name
+    )
+    slug = _URL_REPEATS.sub("_", _URL_UNSAFE.sub("_", lowered)).strip("_.")
+    if not slug:
+        return "file"
+    return slug[:_NAME_LIMIT]
+
+
 def media_file_name(
     kind: str | None, mime: str | None, message_id: int, original: str | None = None
 ) -> str:
@@ -99,6 +184,18 @@ def story_file_name(peer_id: int, story_id: int, media_kind: str | None) -> str:
     return f"story_{peer_id}_{story_id}{extension_for(media_kind or 'photo', None)}"
 
 
+def resolve_mime(
+    kind: str | None, mime: str | None, file_name: str | None = None
+) -> str:
+    if mime and mime.lower() not in _GENERIC_MIMES:
+        return mime
+    if file_name and "." in file_name:
+        by_extension = _EXTENSION_MIMES.get(f".{file_name.rsplit('.', 1)[1].lower()}")
+        if by_extension:
+            return by_extension
+    return _KIND_MIMES.get(kind or "", mime or "application/octet-stream")
+
+
 def is_inline_mime(mime: str | None) -> bool:
     if not mime:
         return False