import re
from PIL import Image
import os

# ==================== 手動配置區 ====================
TARGET_PATH = r'D:\【your_folder】' 
IMAGES_PER_GROUP = 9           
ROWS = 3                       
COLS = 3       
BOTTOM_PADDING = 20  
# ===================================================

def natural_sort_key(s):
    """自然排序：確保 1.jpg, 2.jpg, 10.jpg 按數字順序排列"""
    return [int(text) if text.isdigit() else text.lower()
            for text in re.split('([0-9]+)', s)]

def create_collage(folder_path):

    if not os.path.exists(folder_path):
        print("路徑不存在，請檢查 TARGET_PATH。")
        return

    valid_extensions = ('.jpg', '.jpeg', '.png', '.bmp', '.webp', '.tiff')
    raw_files = [
        f for f in os.listdir(folder_path) 
        if f.lower().endswith(valid_extensions)
    ]
    
    raw_files = [f for f in raw_files if "collage_final" not in f]

    image_files = sorted(
        [os.path.join(folder_path, f) for f in raw_files],
        key=lambda x: natural_sort_key(os.path.basename(x))
    )
    
    if not image_files:
        print("未找到圖片，請檢查路徑。")
        return

    with Image.open(image_files[0]) as first_img:
        img_width, img_height = first_img.size
        input_extension = os.path.splitext(image_files[0])[1]
        img_mode = first_img.mode
        img_dpi = first_img.info.get('dpi') 

        print(f"單圖尺寸: {img_width} x {img_height}")

    canvas_width = COLS * img_width
    canvas_height = (ROWS * img_height) + BOTTOM_PADDING
    
    groups = [
        image_files[i:i + IMAGES_PER_GROUP]
        for i in range(0, len(image_files), IMAGES_PER_GROUP)
    ]
    
    for group_num, group_images in enumerate(groups):

        canvas = Image.new(img_mode, (canvas_width, canvas_height), color='white')
        
        for idx, img_path in enumerate(group_images):
            try:
                with Image.open(img_path) as img:

                    if img.size != (img_width, img_height):
                        img = img.resize((img_width, img_height), Image.Resampling.LANCZOS)
                    
                    if img.mode != img_mode:
                        img = img.convert(img_mode)
                        
                    row_idx = idx // COLS
                    col_idx = idx % COLS
                    x = col_idx * img_width
                    y = row_idx * img_height
                    
                    canvas.paste(img, (x, y))
                
            except Exception as e:
                print(f"處理出錯: {img_path}, 原因: {e}")
        
        suffix = f"_{group_num + 1}" if len(groups) > 1 else ""
        save_filename = f"collage_final{suffix}{input_extension}"
        save_path = os.path.join(folder_path, save_filename)
        
        save_params = {}

        if input_extension.lower() in ['.jpg', '.jpeg']:
            save_params['quality'] = 100
            save_params['subsampling'] = 0
        
        if img_dpi:
            save_params['dpi'] = img_dpi
            
        canvas.save(save_path, **save_params)
        print(f"成功生成: {save_filename}")

if __name__ == "__main__":
    create_collage(TARGET_PATH)