import 'dart:ui' as ui;
import 'package:flutter/material.dart';
import 'package:google_fonts/google_fonts.dart';
import 'package:aesthetica_wallpaper/models/recipe.dart';

// -------------------------------------
// --- 3. 画布绘制器 (WallpaperPainter) ---
// -------------------------------------
class WallpaperPainter extends CustomPainter {
  final ui.Image image;
  final Recipe recipe;
  final Color timeOverlay;
  final double batterySaturation; // 1.0 = 正常, 0.0 = 黑白

  WallpaperPainter({
    required this.image,
    required this.recipe,
    required this.timeOverlay,
    required this.batterySaturation,
  });

  // 辅助函数，用于根据 亮度、对比度、饱和度 生成 5x5 颜色矩阵
  ColorFilter _buildColorMatrix() {
    // 亮度 (-1 to 1, default 0)
    final double brightness = recipe.brightness;
    // 对比度 (0 to 4, default 1)
    final double contrast = recipe.contrast;
    // 饱和度 (0 to 4, default 1)
    final double saturation = recipe.saturation * batterySaturation; // 应用电量效果

    // 矩阵从单位矩阵开始
    List<double> matrix = [
      1,
      0,
      0,
      0,
      0,
      0,
      1,
      0,
      0,
      0,
      0,
      0,
      1,
      0,
      0,
      0,
      0,
      0,
      1,
      0,
    ];

    // 1. 应用饱和度
    if (saturation != 1.0) {
      final sat = saturation;
      const lumR = 0.3086;
      const lumG = 0.6094;
      const lumB = 0.0820;
      matrix = [
        lumR * (1 - sat) + sat,
        lumG * (1 - sat),
        lumB * (1 - sat),
        0,
        0,
        lumR * (1 - sat),
        lumG * (1 - sat) + sat,
        lumB * (1 - sat),
        0,
        0,
        lumR * (1 - sat),
        lumG * (1 - sat),
        lumB * (1 - sat) + sat,
        0,
        0,
        0,
        0,
        0,
        1,
        0,
      ];
    }

    // 2. 应用对比度
    if (contrast != 1.0) {
      final translate = (1.0 - contrast) * 128;
      // 注意：这里需要矩阵乘法，为了简单起见，我们假设在饱和度*之后*应用
      matrix[0] *= contrast;
      matrix[5] *= contrast;
      matrix[10] *= contrast;
      matrix[4] += translate;
      matrix[9] += translate;
      matrix[14] += translate;
    }

    // 3. 应用亮度
    if (brightness != 0.0) {
      final b = brightness * 255;
      matrix[4] += b;
      matrix[9] += b;
      matrix[14] += b;
    }

    return ColorFilter.matrix(matrix);
  }

  // 获取字体样式
  TextStyle _getFont() {
    final style = TextStyle(fontSize: 32, color: Color(recipe.textColor));

    try {
      if (recipe.fontFamily == 'Roboto') {
        return GoogleFonts.roboto(
          fontSize: 32,
          color: Color(recipe.textColor),
          fontWeight: FontWeight.bold,
        );
      }
      // 默认
      return GoogleFonts.lato(fontSize: 32, color: Color(recipe.textColor));
    } catch (e) {
      // 字体加载失败时的回退
      return style;
    }
  }

  @override
  void paint(Canvas canvas, Size size) {
    // 裁剪画布，防止绘制到边界之外
    canvas.clipRect(Offset.zero & size);

    // --- 1. 准备画笔 ---
    final Paint paint = Paint()
      ..filterQuality = FilterQuality.low; // 默认使用低质量（更快）

    // 定义源矩形 (整张图片)
    final Rect srcRect = Rect.fromLTWH(
      0,
      0,
      image.width.toDouble(),
      image.height.toDouble(),
    );
    // 定义目标矩形 (填满画布)
    final Rect dstRect = Rect.fromLTWH(0, 0, size.width, size.height);

    // --- 2. 应用滤镜 ---
    // 应用颜色矩阵 (B/C/S + Battery)
    paint.colorFilter = _buildColorMatrix();

    // 应用模糊
    if (recipe.blur > 0.0) {
      paint.imageFilter = ui.ImageFilter.blur(
        sigmaX: recipe.blur,
        sigmaY: recipe.blur,
      );
    }

    // --- 3. 绘制图片 ---
    // `drawImageRect` 会使用 `paint` 中定义的滤镜来绘制
    canvas.drawImageRect(image, srcRect, dstRect, paint);

    // --- 4. 绘制动态蒙版 ---
    if (timeOverlay.a > 0) {
      canvas.drawRect(dstRect, Paint()..color = timeOverlay);
    }

    // --- 5. 绘制文字 (使用 TextPainter) ---
    if (recipe.overlayText.isNotEmpty) {
      final textPainter = TextPainter(
        text: TextSpan(text: recipe.overlayText, style: _getFont()),
        textDirection: ui.TextDirection.ltr,
        textAlign: TextAlign.center,
      );

      // 布局文字，限制最大宽度
      textPainter.layout(maxWidth: size.width - 40); // 左右各留 20 padding

      // 计算居中位置
      final offset = Offset(
        (size.width - textPainter.width) / 2,
        (size.height - textPainter.height) / 2,
      );

      // 绘制文字
      textPainter.paint(canvas, offset);
    }
  }

  // 优化 shouldRepaint
  // 仅当绘制所需的数据发生变化时才重绘
  @override
  bool shouldRepaint(covariant WallpaperPainter oldDelegate) {
    // 简单的比较 (因为 Recipe 是可变的，这可能不总是触发)
    // return oldDelegate.image != image ||
    //     oldDelegate.recipe != recipe ||
    //     oldDelegate.timeOverlay != timeOverlay ||
    //     oldDelegate.batterySaturation != batterySaturation;

    // 优化：比较所有字段
    final oldRecipe = oldDelegate.recipe;
    final newRecipe = recipe;

    return oldDelegate.image != image ||
        oldRecipe.baseImagePath != newRecipe.baseImagePath ||
        oldRecipe.brightness != newRecipe.brightness ||
        oldRecipe.contrast != newRecipe.contrast ||
        oldRecipe.saturation != newRecipe.saturation ||
        oldRecipe.blur != newRecipe.blur ||
        oldRecipe.pixelate != newRecipe.pixelate ||
        oldRecipe.overlayText != newRecipe.overlayText ||
        oldRecipe.fontFamily != newRecipe.fontFamily ||
        oldRecipe.textColor != newRecipe.textColor ||
        oldDelegate.timeOverlay != timeOverlay ||
        oldDelegate.batterySaturation != batterySaturation;
  }
}