Create utils.py

utils.py

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+import os
+import re
+import img2pdf
+
+# --- 全局配置 ---
+BASE_DIR = "download_cache"
+PDF_FINAL_DIR = os.path.join(BASE_DIR, "final_pdfs")
+
+# 确保基础目录存在
+os.makedirs(PDF_FINAL_DIR, exist_ok=True)
+
+# --- 工具函数 ---
+
+def natural_sort_key(s):
+    """自然排序：让 1.jpg, 2.jpg, 10.jpg 正确排序"""
+    return [int(text) if text.isdigit() else text.lower()
+            for text in re.split(r'(\d+)', s)]
+
+def sanitize_filename(name):
+    """清理文件名：去除非法字符"""
+    return re.sub(r'[\\/*?:"<>|]', '_', name)
+
+def manual_merge_pdf(album_dir, output_pdf_path):
+    """核心功能：将目录下的图片合并为 PDF"""
+    image_paths = []
+    for root, _, files in os.walk(album_dir):
+        for file in files:
+            if file.lower().endswith(('.jpg', '.jpeg', '.png', '.webp')):
+                image_paths.append(os.path.join(root, file))
+    
+    if not image_paths:
+        raise Exception("目录中未找到任何图片")
+
+    # 按文件名自然排序
+    image_paths.sort(key=natural_sort_key)
+
+    # 转换为 PDF
+    with open(output_pdf_path, "wb") as f:
+        f.write(img2pdf.convert(image_paths))