package com.nq.utils;

import org.apache.pdfbox.pdmodel.PDDocument;
import org.apache.pdfbox.rendering.PDFRenderer;
import org.apache.pdfbox.rendering.ImageType;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.imageio.ImageIO;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileInputStream;
import java.util.ArrayList;
import java.util.List;

/**
 * PDF转图片工具类
 */
public class PdfToImageUtil {
    private static final Logger log = LoggerFactory.getLogger(PdfToImageUtil.class);

    /**
     * 将PDF文件转换为图片
     * @param pdfFile PDF文件
     * @param outputDir 输出目录
     * @param imagePrefix 图片文件名前缀
     * @return 图片文件路径列表
     */
    public static List<String> convertPdfToImages(File pdfFile, String outputDir, String imagePrefix) {
        List<String> imagePaths = new ArrayList<>();
        PDDocument document = null;

        try {
            if (!pdfFile.exists()) {
                log.error("PDF文件不存在: {}", pdfFile.getAbsolutePath());
                return imagePaths;
            }

            // 确保输出目录存在
            File outputDirectory = new File(outputDir);
            if (!outputDirectory.exists()) {
                outputDirectory.mkdirs();
            }

            // 加载PDF文档
            document = PDDocument.load(new FileInputStream(pdfFile));
            PDFRenderer pdfRenderer = new PDFRenderer(document);

            int pageCount = document.getNumberOfPages();
            log.info("PDF总页数: {}", pageCount);

            long timestamp = System.currentTimeMillis();

            // 遍历每一页
            for (int page = 0; page < pageCount; page++) {
                // 使用RGB模式渲染，DPI设置为300确保文字清晰
                BufferedImage image = pdfRenderer.renderImageWithDPI(page, 300, ImageType.RGB);

                // 优化图片
                BufferedImage optimizedImage = optimizeImage(image);

                // 生成图片文件名
                String imageFileName;
                if (page == 0) {
                    imageFileName = imagePrefix + "_" + timestamp + ".png";
                } else {
                    imageFileName = imagePrefix + "_" + timestamp + "_" + (page + 1) + ".png";
                }

                File imageFile = new File(outputDirectory, imageFileName);

                // 保存图片
                ImageIO.write(optimizedImage, "png", imageFile);

                imagePaths.add(imageFile.getAbsolutePath());
                log.info("PDF第{}页已转换为图片: {}", page + 1, imageFile.getAbsolutePath());
            }

        } catch (Exception e) {
            log.error("PDF转图片失败: {}", pdfFile.getAbsolutePath(), e);
        } finally {
            if (document != null) {
                try {
                    document.close();
                } catch (Exception e) {
                    log.error("关闭PDF文档失败", e);
                }
            }
        }

        return imagePaths;
    }

    /**
     * 优化图片，确保文字清晰
     */
    private static BufferedImage optimizeImage(BufferedImage originalImage) {
        int width = originalImage.getWidth();
        int height = originalImage.getHeight();

        BufferedImage optimizedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        Graphics2D g2d = optimizedImage.createGraphics();

        // 设置高质量渲染
        g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
        g2d.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
        g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        g2d.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
        g2d.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS, RenderingHints.VALUE_FRACTIONALMETRICS_ON);

        g2d.drawImage(originalImage, 0, 0, null);
        g2d.dispose();

        return optimizedImage;
    }

    /**
     * 测试方法：将指定PDF转换为图片
     */
    public static void main(String[] args) {
        // 示例：转换agreement_19998.pdf
        String pdfPath = "D:/work/A-stock/agreement_pdf/agreement_19998.pdf";
        String outputDir = "D:/work/A-stock/agreement_pdf/";
        String imagePrefix = "agreement_19998";

        File pdfFile = new File(pdfPath);
        List<String> imagePaths = convertPdfToImages(pdfFile, outputDir, imagePrefix);

        System.out.println("转换完成，共生成 " + imagePaths.size() + " 张图片：");
        for (String path : imagePaths) {
            System.out.println("  - " + path);
        }
    }
}