package cn.iocoder.yudao.module.mes.framework.qrcode;

import cn.hutool.core.util.StrUtil;
import cn.hutool.extra.qrcode.QrCodeUtil;
import cn.hutool.extra.qrcode.QrConfig;
import cn.iocoder.yudao.framework.common.util.http.HttpUtils;
import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel;
import jakarta.servlet.http.HttpServletResponse;
import lombok.extern.slf4j.Slf4j;

import javax.imageio.ImageIO;
import java.awt.Color;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics2D;
import java.awt.GraphicsEnvironment;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;

/**
 * 二维码标签图片工具类
 * <p>
 * 生成"二维码 + 右侧可读文本"的合成图片：二维码只编码纯码值，文本叠加关键信息，
 * 即使数据库丢失也能从打印图片还原关键信息。
 */
@Slf4j
public final class QrCodeImageUtils {

    private QrCodeImageUtils() {
    }

    /** 批量导出二维码数量上限（防止一次性生成过多导致内存/响应过大） */
    public static final int MAX_QR_EXPORT = 2000;

    /** 二维码边长 */
    private static final int QR_SIZE = 260;
    /** 图片四周留白 */
    private static final int PADDING = 16;
    /** 二维码与文本间距 */
    private static final int GAP = 24;
    /** 文本区域宽度 */
    private static final int TEXT_WIDTH = 380;
    /** 字体大小 */
    private static final int FONT_SIZE = 15;
    /** 行高 */
    private static final int LINE_HEIGHT = 24;
    /** 字段间距 */
    private static final int FIELD_GAP = 6;

    /** 中文字体候选（按优先级），避免 Linux headless 下文字变方框 */
    private static final String[] FONT_CANDIDATES = {
            "Noto Sans CJK SC", "WenQuanYi Zen Hei", "Microsoft YaHei", "SimSun", "Arial"
    };

    private static final String FONT_NAME = resolveFontName();

    /**
     * 生成二维码标签图片
     *
     * @param code      二维码内容（纯码值）
     * @param keyValues 叠加的可读文本（顺序即绘制顺序）
     * @return 合成图片
     */
    public static BufferedImage createQrLabel(String code, LinkedHashMap<String, String> keyValues) {
        QrConfig config = new QrConfig();
        config.setErrorCorrection(ErrorCorrectionLevel.H); // 打印标签易磨损，用高容错
        config.setMargin(1); // 保证静区，扫码率
        config.setWidth(QR_SIZE);
        config.setHeight(QR_SIZE);
        BufferedImage qrImage = QrCodeUtil.generate(code, config);

        Font labelFont = new Font(FONT_NAME, Font.BOLD, FONT_SIZE);
        Font valueFont = new Font(FONT_NAME, Font.PLAIN, FONT_SIZE);

        // 第一遍：测量文本块总高度，用于确定图片高度
        int textHeight = measureTextHeight(keyValues, labelFont, valueFont);

        int height = PADDING * 2 + Math.max(QR_SIZE, textHeight);
        int width = PADDING * 2 + QR_SIZE + GAP + TEXT_WIDTH;

        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        Graphics2D g = image.createGraphics();
        try {
            g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
            g.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
            g.setColor(Color.WHITE);
            g.fillRect(0, 0, width, height);
            // 二维码（垂直居中）
            int qrY = (height - QR_SIZE) / 2;
            g.drawImage(qrImage, PADDING, qrY, null);
            // 可读文本
            int textX = PADDING + QR_SIZE + GAP;
            int textY = (height - textHeight) / 2;
            drawKeyValues(g, keyValues, labelFont, valueFont, textX, textY);
        } finally {
            g.dispose();
        }
        return image;
    }

    /**
     * 将多张二维码标签图片写入 ZIP 响应（流式，逐张生成，内存只占一张）
     *
     * @param response 响应
     * @param zipName  ZIP 文件名（不含后缀）
     * @param labels   标签列表
     */
    public static void writeZip(HttpServletResponse response, String zipName, List<QrLabelInfo> labels) throws IOException {
        response.setContentType("application/zip");
        response.setHeader("Content-Disposition",
                "attachment;filename=" + HttpUtils.encodeUtf8(zipName + ".zip"));
        ZipOutputStream zip = new ZipOutputStream(response.getOutputStream());
        try {
            for (QrLabelInfo label : labels) {
                BufferedImage image = createQrLabel(label.getCode(), label.getKeyValues());
                zip.putNextEntry(new ZipEntry(label.getFileName() + ".png"));
                ImageIO.write(image, "png", zip);
                zip.closeEntry();
            }
            zip.finish();
            zip.flush();
        } finally {
            // 不 close ZipOutputStream，避免关闭底层 ServletOutputStream（与 FileTypeUtils 同理）
        }
    }

    // ==================== 私有方法 ====================

    private static String resolveFontName() {
        Set<String> families = Set.of(GraphicsEnvironment.getLocalGraphicsEnvironment().getAvailableFontFamilyNames());
        for (String candidate : FONT_CANDIDATES) {
            if (families.contains(candidate)) {
                return candidate;
            }
        }
        return Font.SANS_SERIF;
    }

    private static int measureTextHeight(LinkedHashMap<String, String> keyValues, Font labelFont, Font valueFont) {
        BufferedImage scratch = new BufferedImage(1, 1, BufferedImage.TYPE_INT_RGB);
        Graphics2D g = scratch.createGraphics();
        try {
            return measureKeyValuesHeight(g, keyValues, labelFont, valueFont);
        } finally {
            g.dispose();
        }
    }

    private static int measureKeyValuesHeight(Graphics2D g, LinkedHashMap<String, String> keyValues,
                                              Font labelFont, Font valueFont) {
        int total = 0;
        for (Map.Entry<String, String> entry : keyValues.entrySet()) {
            String label = StrUtil.emptyToDefault(entry.getKey(), "") + "：";
            String value = StrUtil.emptyToDefault(entry.getValue(), "");
            g.setFont(labelFont);
            int labelWidth = g.getFontMetrics().stringWidth(label);
            g.setFont(valueFont);
            List<String> lines = wrapText(g, value, TEXT_WIDTH - labelWidth);
            total += Math.max(1, lines.size()) * LINE_HEIGHT + FIELD_GAP;
        }
        return total;
    }

    private static void drawKeyValues(Graphics2D g, LinkedHashMap<String, String> keyValues,
                                      Font labelFont, Font valueFont, int x, int y) {
        FontMetrics labelMetrics = g.getFontMetrics(labelFont);
        int baselineOffset = labelMetrics.getAscent(); // drawString 的 y 是基线，先下移一个 ascent
        int baseline = y + baselineOffset;
        for (Map.Entry<String, String> entry : keyValues.entrySet()) {
            String label = StrUtil.emptyToDefault(entry.getKey(), "") + "：";
            String value = StrUtil.emptyToDefault(entry.getValue(), "");

            g.setFont(labelFont);
            int labelWidth = g.getFontMetrics().stringWidth(label);
            g.setColor(Color.BLACK);
            g.drawString(label, x, baseline);

            g.setFont(valueFont);
            int remainingWidth = TEXT_WIDTH - labelWidth;
            List<String> lines = wrapText(g, value, remainingWidth);
            if (!lines.isEmpty()) {
                g.drawString(lines.get(0), x + labelWidth, baseline);
                baseline += LINE_HEIGHT;
                for (int i = 1; i < lines.size(); i++) {
                    g.drawString(lines.get(i), x, baseline);
                    baseline += LINE_HEIGHT;
                }
            } else {
                baseline += LINE_HEIGHT;
            }
            baseline += FIELD_GAP;
        }
    }

    /**
     * 文本按最大宽度换行（逐字测量，兼容中文）
     */
    private static List<String> wrapText(Graphics2D g, String text, int maxWidth) {
        List<String> lines = new ArrayList<>();
        if (StrUtil.isEmpty(text)) {
            return lines;
        }
        if (maxWidth <= 0) {
            lines.add(text);
            return lines;
        }
        StringBuilder current = new StringBuilder();
        FontMetrics metrics = g.getFontMetrics();
        for (int i = 0; i < text.length(); i++) {
            char ch = text.charAt(i);
            String test = current.toString() + ch;
            if (metrics.stringWidth(test) > maxWidth && current.length() > 0) {
                lines.add(current.toString());
                current = new StringBuilder().append(ch);
            } else {
                current.append(ch);
            }
        }
        if (current.length() > 0) {
            lines.add(current.toString());
        }
        return lines;
    }

}