import UIKit

extension UIImage {
    func decodeImage(num: Int) -> UIImage {
        guard let decodedImage = decodeImage2(num: num) else {
            print("解密失败，返回原图")
            return self
        }
        
        // 将解密后的图片进行上下翻转
        // 2. 上下翻转图片
        //let flippedImage = decodedImage.flipVertically()
               
               // 3. 左右镜像图片
        let mirroredImage = decodedImage.wrongFlipHorizontally().correctFlipHorizontally()
        return mirroredImage
    }
    // 当前错误的水平翻转（保持原样）
    private func wrongFlipHorizontally() -> UIImage {
        UIGraphicsBeginImageContextWithOptions(self.size, false, self.scale)
        defer { UIGraphicsEndImageContext() }
        
        guard let context = UIGraphicsGetCurrentContext(),
              let cgImage = self.cgImage else {
            print("镜像失败：无法获取 CGImage")
            return self
        }
        
        // 当前错误的翻转逻辑（实际会产生垂直翻转效果）
        context.translateBy(x: self.size.width, y: 0)
        context.scaleBy(x: -1.0, y: 1.0)
        
        context.draw(cgImage, in: CGRect(origin: .zero, size: self.size))
        
        return UIGraphicsGetImageFromCurrentImageContext() ?? self
    }
    
    // 新增：正确的水平翻转方法
    private func correctFlipHorizontally() -> UIImage {
        UIGraphicsBeginImageContextWithOptions(self.size, false, self.scale)
        defer { UIGraphicsEndImageContext() }
        
        guard let context = UIGraphicsGetCurrentContext(),
              let cgImage = self.cgImage else {
            print("镜像失败：无法获取 CGImage")
            return self
        }
        
        // 正确的水平翻转逻辑
        context.translateBy(x: self.size.width, y: self.size.height)
        context.scaleBy(x: -1.0, y: -1.0)  // 只翻转x轴
        
        context.draw(cgImage, in: CGRect(origin: .zero, size: self.size))
        
        return UIGraphicsGetImageFromCurrentImageContext() ?? self
    }
    // 解密图片逻辑（与之前一致）
    private func decodeImage2(num: Int) -> UIImage? {
        guard num > 0 else {
            print("解密跳过：num 参数为 0，直接返回原图")
            return self
        }
        
        let width = Int(self.size.width * self.scale)
        let height = Int(self.size.height * self.scale)
        let totalHeight = height // 总高度为整数
        let totalWidth = width
        
        UIGraphicsBeginImageContextWithOptions(CGSize(width: totalWidth, height: totalHeight), false, self.scale)
        defer { UIGraphicsEndImageContext() }
        
        guard let context = UIGraphicsGetCurrentContext(),
              let cgImage = self.cgImage else {
            print("解密失败：无法创建图形上下文或获取 CGImage")
            return nil
        }
        
        let segmentHeight = totalHeight / num // 每段高度
        let remainder = totalHeight % num     // 余数
        
        print("图片总高度: \(totalHeight)，每段高度: \(segmentHeight)，余数: \(remainder)")
        
        for i in 0..<num {
            var currentSegmentHeight = segmentHeight
            let ySrc = segmentHeight * i // 从顶部开始裁剪
            var yDst = segmentHeight * i // 从顶部开始绘制
            
            if i == 0 {
                currentSegmentHeight += remainder // 第一段包含余数
            }
            
            let srcRect = CGRect(
                x: 0,
                y: CGFloat(ySrc),
                width: CGFloat(totalWidth),
                height: CGFloat(currentSegmentHeight)
            )
            
            let dstRect = CGRect(
                x: 0,
                y: CGFloat(yDst),
                width: CGFloat(totalWidth),
                height: CGFloat(currentSegmentHeight)
            )
            
            print("段 \(i): 源矩形: \(srcRect)，目标矩形: \(dstRect)")
            
            if let croppedImage = cgImage.cropping(to: srcRect) {
                context.draw(croppedImage, in: dstRect)
            } else {
                print("段 \(i): 裁剪失败")
            }
        }
        
        return UIGraphicsGetImageFromCurrentImageContext()
    }
    
    // 上下翻转图片逻辑
    private func flipVertically() -> UIImage {
        UIGraphicsBeginImageContextWithOptions(self.size, false, self.scale)
        defer { UIGraphicsEndImageContext() }
        
        guard let context = UIGraphicsGetCurrentContext(),
              let cgImage = self.cgImage else {
            print("翻转失败：无法获取 CGImage")
            return self
        }
        
        // 翻转坐标系
        context.translateBy(x: 0, y: self.size.height)
        context.scaleBy(x: 1.0, y: -1.0)
        
        // 绘制翻转后的图片
        context.draw(cgImage, in: CGRect(origin: .zero, size: self.size))
        
        return UIGraphicsGetImageFromCurrentImageContext() ?? self
    }
}