feat(civitai): implement URL rewriting for Civitai previews and enhance download handling, fixes #499

py/utils/civitai_utils.py

@@ -0,0 +1,48 @@
+"""Utilities for working with Civitai assets."""
+
+from __future__ import annotations
+
+from urllib.parse import urlparse, urlunparse
+
+
+def rewrite_preview_url(source_url: str | None, media_type: str | None = None) -> tuple[str | None, bool]:
+    """Rewrite Civitai preview URLs to use optimized renditions.
+
+    Args:
+        source_url: Original preview URL from the Civitai API.
+        media_type: Optional media type hint (e.g. ``"image"`` or ``"video"``).
+
+    Returns:
+        A tuple of the potentially rewritten URL and a flag indicating whether the
+        replacement occurred. When the URL is not rewritten, the original value is
+        returned with ``False``.
+    """
+    if not source_url:
+        return source_url, False
+
+    try:
+        parsed = urlparse(source_url)
+    except ValueError:
+        return source_url, False
+
+    if parsed.netloc.lower() != "image.civitai.com":
+        return source_url, False
+
+    replacement = "/width=450,optimized=true"
+    if (media_type or "").lower() == "video":
+        replacement = "/transcode=true,width=450,optimized=true"
+
+    if "/original=true" not in parsed.path:
+        return source_url, False
+
+    updated_path = parsed.path.replace("/original=true", replacement, 1)
+    if updated_path == parsed.path:
+        return source_url, False
+
+    rewritten = urlunparse(parsed._replace(path=updated_path))
+    print(rewritten)
+    return rewritten, True
+
+
+__all__ = ["rewrite_preview_url"]
+