import SwiftUI

struct FilmAnimation5: View {
    // 设备尺寸
    private let deviceWidth = UIScreen.main.bounds.width
    private let deviceHeight = UIScreen.main.bounds.height
    
    // 动画状态控制
    @State private var animationProgress: CGFloat = 0.0  // 0-1总进度
    @State private var isAnimating: Bool = false
    @State private var animationComplete: Bool = false
    
    // 胶卷数据
    private let reelImages: [[String]] = [
        (0..<150).map { "film1-\($0+1)" },  // 上方倾斜胶卷
        (0..<180).map { "film2-\($0+1)" },  // 中间胶卷
        (0..<150).map { "film3-\($0+1)" }   // 下方倾斜胶卷
    ]
    
    // 胶卷参数
    private let frameWidth: CGFloat = 90
    private let frameHeight: CGFloat = 130
    private let totalDistance: CGFloat = 1800  // 总移动距离
    
    // 动画阶段时间参数（核心调整）
    private let accelerationDuration: Double = 5.0   // 0-5s加速
    private let constantSpeedDuration: Double = 1.0  // 5-6s匀速移动
    private let scaleDuration: Double = 2.0          // 6-8s共同放大
    private var totalDuration: Double { accelerationDuration + constantSpeedDuration + scaleDuration }
    
    // 各阶段进度阈值
    private var accelerationEnd: CGFloat { accelerationDuration / totalDuration }
    private var constantSpeedEnd: CGFloat { (accelerationDuration + constantSpeedDuration) / totalDuration }
    
    // 对称倾斜参数
    private let symmetricTiltAngle: Double = 10  // 上下胶卷对称倾斜角度
    private let verticalOffset: CGFloat = 120    // 上下胶卷垂直距离（对称）
    private let finalScale: CGFloat = 4.0        // 最终放大倍数
    
    var body: some View {
        ZStack {
            // 深色背景
            Color(red: 0.08, green: 0.08, blue: 0.08)
                .edgesIgnoringSafeArea(.all)
            
            // 上方倾斜胶卷（向右移动）
            FilmReelView5(images: reelImages[0])
                .rotationEffect(Angle(degrees: -symmetricTiltAngle))
                .offset(x: topReelPosition, y: -verticalOffset)
                .scaleEffect(currentScale)
                .opacity(upperLowerOpacity)
                .zIndex(2)
            
            // 下方倾斜胶卷（向右移动）
            FilmReelView5(images: reelImages[2])
                .rotationEffect(Angle(degrees: symmetricTiltAngle))
                .offset(x: bottomReelPosition, y: verticalOffset)
                .scaleEffect(currentScale)
                .opacity(upperLowerOpacity)
                .zIndex(2)
            
            // 中间胶卷（向左移动，最终保留）
            FilmReelView5(images: reelImages[1])
                .offset(x: middleReelPosition, y: 0)
                .scaleEffect(currentScale)
                .opacity(1.0)  // 始终不透明
                .zIndex(1)
                .edgesIgnoringSafeArea(.all)
        }
        .onAppear {
            startAnimation()
        }
    }
    
    // MARK: - 动画逻辑
    
    private func startAnimation() {
        guard !isAnimating && !animationComplete else { return }
        isAnimating = true
        
        // 分阶段动画曲线：先加速后匀速
        withAnimation(Animation.timingCurve(0.3, 0.0, 0.7, 1.0, duration: totalDuration)) {
            animationProgress = 1.0
        }
        
        // 动画结束标记
        DispatchQueue.main.asyncAfter(deadline: .now() + totalDuration) {
            isAnimating = false
            animationComplete = true
        }
    }
    
    // MARK: - 动画计算
    
    // 共同放大比例（6s后开始放大）
    private var currentScale: CGFloat {
        guard animationProgress >= constantSpeedEnd else {
            return 1.0  // 前6s保持原尺寸
        }
        
        // 放大阶段相对进度（0-1）
        let scalePhaseProgress = (animationProgress - constantSpeedEnd) / (1.0 - constantSpeedEnd)
        return 1.0 + (finalScale - 1.0) * scalePhaseProgress
    }
    
    // 上下胶卷透明度（放大阶段逐渐隐藏）
    private var upperLowerOpacity: Double {
        guard animationProgress >= constantSpeedEnd else {
            return 0.8  // 前6s保持可见
        }
        
        // 放大阶段同步淡出
        let fadeProgress = (animationProgress - constantSpeedEnd) / (1.0 - constantSpeedEnd)
        return 0.8 * (1.0 - fadeProgress)
    }
    
    // MARK: - 移动速度控制（确保匀速阶段速度一致）
    
    private var motionProgress: CGFloat {
        if animationProgress < accelerationEnd {
            // 0-5s加速阶段：二次方曲线加速
            let t = animationProgress / accelerationEnd
            return t * t
        } else {
            // 5s后匀速阶段：保持最大速度
            return 1.0 + (animationProgress - accelerationEnd) * 
                (accelerationEnd / (1.0 - accelerationEnd))
        }
    }
    
    // 上方胶卷位置（向右移动）
    private var topReelPosition: CGFloat {
        totalDistance * 0.8 * motionProgress
    }
    
    // 中间胶卷位置（向左移动）
    private var middleReelPosition: CGFloat {
        -totalDistance * 0.8 * motionProgress  // 与上下胶卷速度大小相同，方向相反
    }
    
    // 下方胶卷位置（向右移动）
    private var bottomReelPosition: CGFloat {
        totalDistance * 0.8 * motionProgress  // 与上方胶卷速度完全一致，保持对称
    }
}

// MARK: - 胶卷组件

struct FilmReelView5: View {
    let images: [String]
    
    var body: some View {
        HStack(spacing: 10) {
            ForEach(images.indices, id: \.self) { index in
                FilmFrameView5(imageName: images[index])
            }
        }
    }
}

struct FilmFrameView5: View {
    let imageName: String
    
    var body: some View {
        ZStack {
            // 胶卷边框
            RoundedRectangle(cornerRadius: 4)
                .stroke(Color.gray, lineWidth: 2)
                .background(Color(red: 0.15, green: 0.15, blue: 0.15))
            
            // 帧内容
            Rectangle()
                .fill(gradientColor)
                .cornerRadius(2)
                .padding(2)
            
            // 帧标识
            Text(imageName)
                .foregroundColor(.white)
                .font(.caption2)
        }
        .frame(width: 90, height: 130)
        // 胶卷孔洞
        .overlay(
            HStack {
                VStack(spacing: 6) {
                    ForEach(0..<6) { _ in
                        Circle()
                            .frame(width: 6, height: 6)
                            .foregroundColor(.gray)
                    }
                }
                Spacer()
                VStack(spacing: 6) {
                    ForEach(0..<6) { _ in
                        Circle()
                            .frame(width: 6, height: 6)
                            .foregroundColor(.gray)
                    }
                }
            }
        )
    }
    
    private var gradientColor: LinearGradient {
        if imageName.hasPrefix("film1") {
            return LinearGradient(gradient: Gradient(colors: [.blue, .indigo]), startPoint: .topLeading, endPoint: .bottomTrailing)
        } else if imageName.hasPrefix("film2") {
            return LinearGradient(gradient: Gradient(colors: [.yellow, .orange]), startPoint: .topLeading, endPoint: .bottomTrailing)
        } else {
            return LinearGradient(gradient: Gradient(colors: [.teal, .cyan]), startPoint: .topLeading, endPoint: .bottomTrailing)
        }
    }
}

// 预览
struct FilmAnimation_Previews5: PreviewProvider {
    static var previews: some View {
        FilmAnimation5()
    }
}