fix(sort-images): Detect formats from file signatures

sort_images.py

@@ -14,6 +14,30 @@ from PIL import Image
 # --- Utility Functions ---
 
 
+class ImageFormat(enum.Enum):
+    JPEG = "jpeg"
+    PNG = "png"
+    WEBP = "webp"
+
+    @property
+    def suffix(self) -> str:
+        return ".jpg" if self is self.JPEG else f".{self.value}"
+
+
+def sniff_image_format(image_path: Path) -> ImageFormat:
+    """Identify a supported image format from its file signature."""
+    with image_path.open("rb") as file:
+        header = file.read(12)
+
+    if header.startswith(b"\xff\xd8\xff"):
+        return ImageFormat.JPEG
+    if header.startswith(b"\x89PNG\r\n\x1a\n"):
+        return ImageFormat.PNG
+    if len(header) >= 12 and header[:4] == b"RIFF" and header[8:12] == b"WEBP":
+        return ImageFormat.WEBP
+    raise ValueError(f"Unsupported or unrecognized image format: {image_path}")
+
+
 def read_dims_jpeg(image_path: Path) -> tuple[int, int]:
     with image_path.open("rb") as file:
         if file.read(2) != b"\xff\xd8":
@@ -129,14 +153,14 @@ def read_dims_webp(image_path: Path) -> tuple[int, int]:
 
 
 def read_dims(image_path: Path) -> tuple[int, int]:
-    if image_path.suffix.lower() in [".jpg", ".jpeg"]:
+    image_format = sniff_image_format(image_path)
+    if image_format is ImageFormat.JPEG:
         return read_dims_jpeg(image_path)
-    elif image_path.suffix.lower() == ".png":
+    elif image_format is ImageFormat.PNG:
         return read_dims_png(image_path)
-    elif image_path.suffix.lower() == ".webp":
+    elif image_format is ImageFormat.WEBP:
         return read_dims_webp(image_path)
-    else:
+    raise AssertionError(f"Unhandled image format: {image_format}")
-        raise ValueError(f"Unsupported image format: {image_path.suffix}")
 
 
 def parse_args() -> argparse.Namespace:
@@ -188,11 +212,8 @@ def main():
             logging.warning(f"{image_path} is not a file. Skipping.")
             continue
 
-        if image_path.suffix.lower() not in [".jpg", ".jpeg", ".png", ".webp"]:
-            logging.warning(f"{image_path} is not a JPEG, PNG, or WebP file. Skipping.")
-            continue
-
         try:
+            image_format = sniff_image_format(image_path)
             width, height = read_dims(image_path)
             target_dir = None
 
@@ -208,7 +229,7 @@ def main():
             make_dir(target_dir)
 
             target_path = target_dir / image_path.name
-            target_path = target_path.with_suffix(".jpg")
+            target_path = target_path.with_suffix(image_format.suffix)
 
             image_path.rename(target_path)
             logging.info(f"Moved {image_path} to {target_path}")