import os
import gradio as gr
from pdf2image import convert_from_path
from typing import List

def pdf_to_images(
    pdf_file: str,
    output_format: str = "jpg",
    dpi: int = 200,
    output_dir: str = "output_images"
) -> List[str]:
    """
    将PDF转换为图片并保存到指定目录
    :param pdf_file: 上传的PDF文件路径
    :param output_format: 输出格式（jpg/png）
    :param dpi: 分辨率（默认200）
    :param output_dir: 输出目录名
    :return: 生成的图片路径列表
    """
    # 创建输出目录（如果不存在）
    os.makedirs(output_dir, exist_ok=True)
    
    # 转换PDF为图片
    images = convert_from_path(pdf_file, dpi=dpi)
    
    # 保存图片
    saved_paths = []
    for i, image in enumerate(images):
        output_path = os.path.join(output_dir, f"page_{i+1}.{output_format}")
        image.save(output_path, "JPEG" if output_format == "jpg" else "PNG")
        saved_paths.append(output_path)
    
    return saved_paths

def process_pdf(
    pdf_file: gr.File,
    output_format: str,
    dpi: int
) -> gr.Gallery:
    """
    Gradio处理函数
    """
    if not pdf_file:
        raise gr.Error("请先上传PDF文件！")
    
    # 调用转换函数
    image_paths = pdf_to_images(
        pdf_file.name,
        output_format=output_format,
        dpi=dpi
    )
    
    return image_paths

# Gradio界面
with gr.Blocks(title="PDF转图片工具") as demo:
    gr.Markdown("## 📄 PDF转图片工具")
    gr.Markdown("上传PDF文件，选择输出格式和分辨率，点击“转换”按钮。")
    
    with gr.Row():
        with gr.Column():
            pdf_input = gr.File(label="上传PDF文件", file_types=[".pdf"])
            output_format = gr.Radio(
                choices=["jpg", "png"],
                label="输出格式",
                value="jpg"
            )
            dpi_slider = gr.Slider(
                minimum=100,
                maximum=600,
                step=50,
                value=200,
                label="分辨率 (DPI)"
            )
            convert_btn = gr.Button("转换", variant="primary")
        
        with gr.Column():
            gallery = gr.Gallery(
                label="生成的图片",
                columns=2,
                height="auto"
            )
    
    # 绑定事件
    convert_btn.click(
        fn=process_pdf,
        inputs=[pdf_input, output_format, dpi_slider],
        outputs=gallery
    )
    

# 启动应用
if __name__ == "__main__":
    demo.launch()