// toLandscape 转置变换的像素级验证：纵向四象限色块 → 转置后对角象限互换。
// 转置语义：P(x, y) -> out(y, x)，即左上/右下不动，右上↔左下互换。
import 'dart:convert';

import 'package:desktop_plugin/image/card_image.dart';
import 'package:image/image.dart';
import 'package:flutter_test/flutter_test.dart';

void main() {
  test('toLandscape 把纵向卡面转置为横向（对角象限互换）', () {
    // 构造 642×1014 纵向源图：四象限填不同颜色（fromDataUrl 尺寸相同不触发缩放）
    final src = Image(width: 642, height: 1014);
    fillRect(src, x1: 0, y1: 0, x2: 641, y2: 506, color: ColorRgb8(255, 0, 0)); // 上：红
    fillRect(src, x1: 0, y1: 507, x2: 320, y2: 1013, color: ColorRgb8(0, 255, 0)); // 左下：绿
    fillRect(src, x1: 321, y1: 507, x2: 641, y2: 1013, color: ColorRgb8(0, 0, 255)); // 右下：蓝
    final dataUrl = 'data:image/png;base64,${base64Encode(encodePng(src))}';

    final card = CardImage.fromDataUrl(dataUrl);
    expect(card.isLandscape, isFalse, reason: '源图应为纵向');

    final out = card.toLandscape();
    expect(out.isLandscape, isTrue, reason: '转置后应为横向 1014×642');
    expect(out.width, 1014);
    expect(out.height, 642);

    // 像素断言：转置后 out(x', y') = src(y', x')（以中心附近取样避免象限边界）
    final bgr = out.toBgr24();
    // 转置后左上（原上半红区）≈ 红
    (int, int, int) px(int x, int y) {
      final o = (y * out.width + x) * 3;
      return (bgr[o + 2], bgr[o + 1], bgr[o]); // BGR 转回 RGB
    }
    expect(px(300, 100), (255, 0, 0), reason: '左上应保持红（源上半）');
    // 转置把源的"右上"(x大,y小)映到"左下"：源上半仍红，源左下绿映到右半
    expect(px(800, 300), (0, 255, 0), reason: '右半上应为绿（源左下转置）');
    expect(px(800, 500), (0, 0, 255), reason: '右半下应为蓝（源右下转置）');
  });
}