# compose_poster.py - 合成图层
import os
from PIL import Image
import logging

# 设置日志
logging.basicConfig(level=logging.INFO, format='%(asctime)s - %(levelname)s - %(message)s')
logger = logging.getLogger(__name__)

# 设置默认图片目录
DEFAULT_IMAGE_DIR = os.path.join(os.path.dirname(os.path.dirname(os.path.abspath(__file__))), 'images')

def compose_layers(layers, output_path, canvas_size=(1080, 1920)):
    """
    合成多个图层为一个图像
    
    Args:
        layers: 图层文件名列表，从底到顶排序
        output_path: 输出文件路径
        canvas_size: 画布大小，默认为(1080, 1920)
        
    Returns:
        str: 输出文件的路径
    """
    logger.info(f"开始合成{len(layers)}个图层...")
    
    # 创建空白画布
    canvas = Image.new('RGBA', canvas_size, (0, 0, 0, 0))
    
    # 逐个添加图层
    for i, layer_name in enumerate(layers):
        try:
            # 构建完整的图层路径
            layer_path = os.path.join(DEFAULT_IMAGE_DIR, layer_name)
            
            if os.path.exists(layer_path):
                # 打开图层图像
                layer = Image.open(layer_path).convert('RGBA')
                
                # 调整图层大小以适应画布
                # 如果图层尺寸与画布不同，将其居中
                if layer.size != canvas_size:
                    new_layer = Image.new('RGBA', canvas_size, (0, 0, 0, 0))
                    paste_x = (canvas_size[0] - layer.width) // 2
                    paste_y = (canvas_size[1] - layer.height) // 2
                    new_layer.paste(layer, (paste_x, paste_y), layer)
                    layer = new_layer
                
                # 合成图层
                canvas = Image.alpha_composite(canvas, layer)
                logger.info(f"已添加第{i+1}个图层: {layer_path}")
            else:
                logger.error(f"图层文件不存在: {layer_path}")
        except Exception as e:
            logger.error(f"处理图层{layer_path}时出错: {str(e)}")
    
    # 设置默认输出目录
    default_output_dir = os.path.join(os.path.dirname(os.path.dirname(os.path.abspath(__file__))), 'outputs')
    
    # 确保输出目录存在
    if not os.path.exists(default_output_dir):
        os.makedirs(default_output_dir)
    
    # 构建输出文件的完整路径
    output_path = os.path.join(default_output_dir, os.path.basename(output_path))
    
    # 保存合成图像
    canvas.save(output_path)
    logger.info(f"图层合成完成，已保存到: {output_path}")
    
    return output_path

if __name__ == "__main__":
    # 简单测试
    from sys import argv
    
    if len(argv) >= 3:
        # 从命令行接收参数
        layers = argv[1:-1]  # 现在只需要提供文件名，不需要完整路径
        output = argv[-1]
        compose_layers(layers, output)
    else:
        print("用法: python compose_poster.py layer1.png layer2.png ... output.png")
        print(f"图片将从默认目录加载: {DEFAULT_IMAGE_DIR}")