import { nextTick } from 'vue';

/**
 * 前端实时渲染防作弊当前时间戳水印
 * @param {Object} options
 * @param {string} options.tempFilePath - 原始图片临时路径
 * @param {string} options.canvasId - canvas的ID名（默认为 watermarkCanvas）
 * @param {Object} options.canvasWidthRef - 绑定的 canvasWidth 响应式变量(ref)
 * @param {Object} options.canvasHeightRef - 绑定的 canvasHeight 响应式变量(ref)
 * @param {Object} options.instance - 当前Vue组件的实例 (通过 getCurrentInstance() 获取)
 * @returns {Promise<string>} 渲染添加完水印后的新图片临时路径
 */
export function addTimestampWatermark({ tempFilePath, canvasId = 'watermarkCanvas', canvasWidthRef, canvasHeightRef, instance }) {
	return new Promise((resolve, reject) => {
		uni.getImageInfo({
			src: tempFilePath,
			success: (imageInfo) => {
				const imgWidth = imageInfo.width;
				const imgHeight = imageInfo.height;
				
				// 动态配置 Canvas 宽高与图片 1:1 比例，确保高清晰度不失真
				if (canvasWidthRef && canvasWidthRef.value !== undefined) {
					canvasWidthRef.value = imgWidth;
				}
				if (canvasHeightRef && canvasHeightRef.value !== undefined) {
					canvasHeightRef.value = imgHeight;
				}
				
				// 延迟至 nextTick 等待 UniApp 应用并渲染新的 Canvas 尺寸
				nextTick(() => {
					const ctx = uni.createCanvasContext(canvasId, instance);
					if (!ctx) {
						reject('创建水印画布上下文失败');
						return;
					}
					
					// 1. 绘制原始图片
					ctx.drawImage(tempFilePath, 0, 0, imgWidth, imgHeight);
					
					// 2. 构造防作弊当前真实时间戳字符串
					const now = new Date();
					const year = now.getFullYear();
					const month = String(now.getMonth() + 1).padStart(2, '0');
					const day = String(now.getDate()).padStart(2, '0');
					const hours = String(now.getHours()).padStart(2, '0');
					const minutes = String(now.getMinutes()).padStart(2, '0');
					const seconds = String(now.getSeconds()).padStart(2, '0');
					const timeStr = `${year}-${month}-${day} ${hours}:${minutes}:${seconds}`;
					
					// 3. 动态计算合适的水印字体大小（以标准 375px 屏幕下的 14px 为基准，按图片实际宽度等比缩放，保证大图下不模糊且比例完美）
					const fontSize = Math.max(14, Math.floor(imgWidth * (14 / 375)));
					ctx.setFontSize(fontSize);
					ctx.setFillStyle('#C9CBD4'); // 水印文字颜色 #C9CBD4
					
					// 设置半透明黑色文字阴影，确保在亮色背景下时间戳也具有极强的辨识度
					ctx.setShadow(2, 2, 4, 'rgba(0, 0, 0, 0.6)');
					
					// 4. 计算右下角坐标
					const padding = fontSize;
					const textWidth = timeStr.length * (fontSize * 0.55); // 估算英文字符占用宽度
					const x = imgWidth - textWidth - padding;
					const y = imgHeight - padding;
					
					// 5. 渲染防作弊时间戳
					ctx.fillText(timeStr, x, y);
					
					// 6. 执行画布绘制并导出文件路径
					ctx.draw(false, () => {
						setTimeout(() => {
							uni.canvasToTempFilePath({
								canvasId: canvasId,
								destWidth: imgWidth,
								destHeight: imgHeight,
								fileType: 'jpg',
								quality: 0.9,
								success: (exportRes) => {
									resolve(exportRes.tempFilePath);
								},
								fail: (err) => {
									console.error('导出带水印图片失败:', err);
									reject(err);
								}
							}, instance);
						}, 150);
					});
				});
			},
			fail: (err) => {
				console.error('获取图片信息失败:', err);
				reject(err);
			}
		});
	});
}