import SwiftUI

/// 主上传视图
/// 提供媒体选择、预览和上传功能
@MainActor
struct MediaUploadView: View {
    // MARK: - 属性
    
    /// 上传管理器，负责处理上传逻辑
    @StateObject private var uploadManager = MediaUploadManager()
    /// 控制媒体选择器的显示/隐藏
    @State private var showMediaPicker = false
    /// 当前选中的媒体项
    @State private var selectedMedia: MediaType? = nil
    /// 当前选中的媒体索引集合
    @State private var selectedIndices: Set<Int> = []
    
    // MARK: - 视图主体
    
    var body: some View {
        VStack(spacing: 0) {
            // 顶部导航栏
            topNavigationBar
            
            // 上传提示信息
            uploadHintView
            
            // 主上传区域
            MainUploadArea(
                uploadManager: uploadManager,
                showMediaPicker: $showMediaPicker,
                selectedMedia: $selectedMedia,
                selectedIndices: $selectedIndices
            )
            .padding()
            .id("mainUploadArea\(uploadManager.selectedMedia.count)")
            
            Spacer()
            
            // 继续按钮
            continueButton
                .padding(.bottom, 24)
        }
        .background(Color.themeTextWhiteSecondary)
        .navigationBarTitleDisplayMode(.inline)
        .navigationBarBackButtonHidden(true)
        .sheet(isPresented: $showMediaPicker) {
            // 媒体选择器
            mediaPickerView
        }
        .onChange(of: uploadManager.selectedMedia) { [oldMedia = uploadManager.selectedMedia] newMedia in
            handleMediaChange(newMedia, oldMedia: oldMedia)
        }
    }
    
    // MARK: - 子视图
    
    /// 顶部导航栏
    private var topNavigationBar: some View {
        HStack {
            // 返回按钮
            Button(action: { Router.shared.pop() }) {
                Image(systemName: "chevron.left")
                    .font(.system(size: 17, weight: .semibold))
                    .foregroundColor(.themeTextMessageMain)
            }
            .padding(.leading, 16)
            
            Spacer()
            
            // 标题
            Text("Complete Your Profile")
                .font(Typography.font(for: .title2, family: .quicksandBold))
                .foregroundColor(.themeTextMessageMain)
            
            Spacer()
            
            // 右侧占位视图（保持布局平衡）
            Color.clear
                .frame(width: 24, height: 24)
                .padding(.trailing, 16)
        }
        .background(Color.themeTextWhiteSecondary)
        .padding(.horizontal)
        .zIndex(1) // 确保导航栏显示在最上层
    }
    
    /// 上传提示视图
    private var uploadHintView: some View {
        HStack {
            Text("The upload process will take approximately 2 minutes. Thank you for your patience.")
                .font(.caption)
                .foregroundColor(.black)
                .frame(maxWidth: .infinity, alignment: .leading)
                .padding(12)
                .background(
                    LinearGradient(
                        gradient: Gradient(colors: [
                            Color(red: 1.0, green: 0.97, blue: 0.87),
                            .white,
                            Color(red: 1.0, green: 0.97, blue: 0.84)
                        ]),
                        startPoint: .topLeading,
                        endPoint: .bottomTrailing
                    )
                    .cornerRadius(8)
                )
                .padding(.horizontal)
        }
        .padding(.vertical, 8)
    }
    
    /// 继续按钮
    private var continueButton: some View {
        Button(action: {
            // 处理继续操作
            // Router.shared.navigate(to: .avatarBox)
        }) {
            Text("Continue")
                .font(.headline)
                .foregroundColor(uploadManager.selectedMedia.isEmpty ? Color.themeTextMessage : Color.themeTextMessageMain)
                .frame(maxWidth: .infinity)
                .frame(height: 56)
                .background(uploadManager.selectedMedia.isEmpty ? Color.white : Color.themePrimary)
                .cornerRadius(28)
                .padding(.horizontal, 24)
        }
        .buttonStyle(PlainButtonStyle())
        .disabled(uploadManager.selectedMedia.isEmpty)
    }
    
    /// 媒体选择器视图
    private var mediaPickerView: some View {
        MediaPicker(
            selectedMedia: $uploadManager.selectedMedia,
            imageSelectionLimit: 20,
            videoSelectionLimit: 5,
            onDismiss: handleMediaPickerDismiss,
            onUploadProgress: { index, progress in
                print("文件 \(index) 上传进度: \(progress * 100)%")
            }
        )
    }
    
    // MARK: - 私有方法
    
    /// 处理媒体选择器关闭事件
    private func handleMediaPickerDismiss() {
        showMediaPicker = false
        print("媒体选择器关闭 - 开始处理")
        
        // 如果有选中的媒体，开始上传
        if !uploadManager.selectedMedia.isEmpty {
            uploadManager.startUpload()
        }
    }
    
    /// 处理媒体变化
    /// - Parameters:
    ///   - newMedia: 新的媒体数组
    ///   - oldMedia: 旧的媒体数组
    private func handleMediaChange(_ newMedia: [MediaType], oldMedia: [MediaType]) {
        print("开始处理媒体变化，新数量: \(newMedia.count), 原数量: \(oldMedia.count)")
        
        // 如果没有变化，直接返回
        guard newMedia != oldMedia else {
            print("媒体未发生变化，跳过处理")
            return
        }
        
        // 在后台线程处理媒体变化
        DispatchQueue.global(qos: .userInitiated).async {
            let startTime = Date()
            
            // 找出新增的媒体（在newMedia中但不在oldMedia中的项）
            let newItems = newMedia.filter { newItem in
                !oldMedia.contains { $0.id == newItem.id }
            }
            
            print("检测到\(newItems.count)个新增媒体项")
            
            // 如果有新增媒体
            if !newItems.isEmpty {
                print("准备添加\(newItems.count)个新项...")
                
                // 回到主线程更新UI状态
                DispatchQueue.main.async {
                    // 如果当前没有选中的媒体，则选中第一个新增的媒体
                    if self.selectedIndices.isEmpty && !newItems.isEmpty {
                        self.selectedIndices = [self.uploadManager.selectedMedia.count] // 选择第一个新增项的索引
                        self.selectedMedia = newItems.first
                    }
                    
                    // 开始上传新添加的媒体
                    self.uploadManager.startUpload()
                    print("媒体添加完成，总数量: \(self.uploadManager.selectedMedia.count)")
                }
            } else if newMedia.isEmpty {
                // 清空选择
                DispatchQueue.main.async {
                    self.selectedIndices = []
                    self.selectedMedia = nil
                    print("媒体已清空，重置选择状态")
                }
            }
            
            print("媒体变化处理完成，总耗时: \(String(format: "%.3f", Date().timeIntervalSince(startTime)))s")
        }
    }
    
    /// 检查是否有正在上传的文件
    /// - Returns: 是否正在上传
    private func isUploading() -> Bool {
        return uploadManager.uploadStatus.values.contains { status in
            if case .uploading = status { return true }
            return false
        }
    }
}

// MARK: - 主上传区域

/// 主上传区域视图
/// 显示上传提示、媒体预览和添加更多按钮
struct MainUploadArea: View {
    // MARK: - 属性
    
    /// 上传管理器
    @ObservedObject var uploadManager: MediaUploadManager
    /// 控制媒体选择器的显示/隐藏
    @Binding var showMediaPicker: Bool
    /// 当前选中的媒体
    @Binding var selectedMedia: MediaType?
    /// 当前选中的媒体索引
    @Binding var selectedIndices: Set<Int>
    
    // MARK: - 视图主体
    
    var body: some View {
        VStack(spacing: 16) {
            // 标题
            Text("Click to upload 20 images and 5 videos to generate your next blind box.")
                .font(Typography.font(for: .title2, family: .quicksandBold))
                .fontWeight(.bold)
                .foregroundColor(.black)
                .multilineTextAlignment(.center)
                .padding(.horizontal)
            
            // 上传提示视图
            UploadPromptView(showMediaPicker: $showMediaPicker)
            
            // 媒体预览区域
            mediaPreviewSection
            
            // 当没有选择媒体时显示添加更多按钮
            if !uploadManager.selectedMedia.isEmpty {
                addMoreButton
            }
        }
        .background(Color.white)
        .cornerRadius(16)
        .shadow(radius: 2)
    }
    
    // MARK: - 子视图
    
    /// 媒体预览区域
    private var mediaPreviewSection: some View {
        Group {
            if !uploadManager.selectedMedia.isEmpty {
                VStack(spacing: 8) {
                    // 已选择文件数量
                    Text("已选择 \(uploadManager.selectedMedia.count) 个文件")
                        .font(.subheadline)
                        .foregroundColor(.gray)
                    
                    // 横向滚动的缩略图列表
                    ScrollView(.horizontal, showsIndicators: false) {
                        LazyHStack(spacing: 10) {
                            ForEach(Array(uploadManager.selectedMedia.enumerated()), id: \.element.id) { index, media in
                                mediaItemView(for: media, at: index)
                            }
                        }
                        .padding(.horizontal)
                    }
                    .frame(height: 140)
                }
                .padding(.vertical, 8)
            }
        }
    }
    
    /// 单个媒体项视图
    /// - Parameters:
    ///   - media: 媒体项
    ///   - index: 索引
    /// - Returns: 媒体项视图
    private func mediaItemView(for media: MediaType, at index: Int) -> some View {
        VStack(spacing: 4) {
            // 媒体预览
            MediaPreview(media: media, uploadManager: uploadManager)
                .frame(width: 80, height: 80)
                .cornerRadius(8)
                .shadow(radius: 1)
                .onTapGesture {
                    // 更新选中的媒体
                    selectedIndices = [index]
                    selectedMedia = media
                }
            
            // 上传状态指示器
            uploadStatusView(for: index)
        }
        .padding(4)
    }
    
    /// 上传状态视图
    /// - Parameter index: 媒体索引
    /// - Returns: 状态视图
    @ViewBuilder
    private func uploadStatusView(for index: Int) -> some View {
        if let status = uploadManager.uploadStatus["\(index)"] {
            switch status {
            case .uploading(let progress):
                // 上传中，显示进度条
                VStack(alignment: .center, spacing: 2) {
                    Text("\(Int(progress * 100))%")
                        .font(.caption2)
                        .foregroundColor(.gray)
                    ProgressView(value: progress, total: 1.0)
                        .progressViewStyle(LinearProgressViewStyle())
                        .frame(height: 3)
                        .tint(Color.themePrimary)
                }
                .frame(width: 60)
                
            case .completed:
                // 上传完成，显示完成图标
                Image(systemName: "checkmark.circle.fill")
                    .font(.caption)
                    .foregroundColor(.green)
                    
            case .failed:
                // 上传失败，显示错误图标
                Image(systemName: "exclamationmark.triangle.fill")
                    .font(.caption)
                    .foregroundColor(.red)
                    
            default:
                EmptyView()
            }
        }
    }
    
    /// 添加更多按钮
    private var addMoreButton: some View {
        Button(action: { showMediaPicker = true }) {
            VStack(spacing: 8) {
                Image(systemName: "plus.circle.fill")
                    .font(.system(size: 30))
                    .foregroundColor(.themePrimary)
                
                Text("Add More")
                    .font(.subheadline)
                    .foregroundColor(.gray)
            }
            .frame(width: 80, height: 80)
            .background(Color.gray.opacity(0.1))
            .cornerRadius(8)
            .overlay(
                RoundedRectangle(cornerRadius: 8)
                    .strokeBorder(style: StrokeStyle(
                        lineWidth: 2,
                        dash: [8, 4]
                    ))
                    .foregroundColor(.gray.opacity(0.5))
            )
            .padding(4)
        }
    }
}

// MARK: - 上传提示视图

/// 上传提示视图
/// 显示上传区域的占位图和提示
struct UploadPromptView: View {
    /// 控制媒体选择器的显示/隐藏
    @Binding var showMediaPicker: Bool
    
    var body: some View {
        Button(action: { showMediaPicker = true }) {
            // 上传图标
            SVGImage(svgName: "IP")
                .frame(width: 225, height: 225)
                .contentShape(Rectangle())
                .overlay(
                    RoundedRectangle(cornerRadius: 20)
                    .stroke(style: StrokeStyle(
                        lineWidth: 5,
                        lineCap: .round,
                        dash: [12, 8]
                    ))
                    .foregroundColor(Color.themePrimary)
            )
        }
    }
}

// MARK: - 媒体预览视图

/// 媒体预览视图
/// 显示图片或视频的预览图
struct MediaPreview: View {
    // MARK: - 属性
    
    /// 图片处理队列
    private let imageProcessingQueue = DispatchQueue(
        label: "com.yourapp.imageprocessing",
        qos: .userInitiated,
        attributes: .concurrent
    )
    
    /// 媒体类型
    let media: MediaType
    /// 上传管理器
    @ObservedObject var uploadManager: MediaUploadManager
    
    // MARK: - 状态
    
    /// 加载的图片
    @State private var image: UIImage?
    
    /// 加载状态
    enum LoadState {
        /// 加载成功
        case success(UIImage)
        /// 加载失败
        case failure(Error)
    }
    
    /// 当前加载状态
    @State private var loadState: LoadState?
    
    // MARK: - 图片缓存
    
    /// 图片缓存
    private struct ImageCache {
        static let shared = NSCache<NSString, UIImage>()
    }
    
    // MARK: - 计算属性
    
    /// 上传进度
    private var uploadProgress: Double {
        guard let index = uploadManager.selectedMedia.firstIndex(where: { $0.id == media.id }) else {
            return 0
        }
        
        if case .uploading(let progress) = uploadManager.uploadStatus["\(index)"] {
            return progress
        } else if case .completed = uploadManager.uploadStatus["\(index)"] {
            return 1.0
        }
        return 0
    }
    
    /// 是否正在上传
    private var isUploading: Bool {
        guard let index = uploadManager.selectedMedia.firstIndex(where: { $0.id == media.id }) else {
            return false
        }
        
        if case .uploading = uploadManager.uploadStatus["\(index)"] {
            return true
        }
        return false
    }
    
    // MARK: - 视图主体
    
    var body: some View {
        ZStack {
            // 显示图片或错误状态
            if let image = image {
                loadedImageView(image)
                
                // 视频播放按钮
                if case .video = media {
                    playButton
                }
                
                // 上传进度指示器（仅在上传时显示）
                if isUploading || uploadProgress > 0 {
                    loadingOverlay
                }
            } else if case .failure(let error) = loadState {
                // 加载失败状态
                errorView(error: error)
            } else {
                // 初始加载时显示占位图
                placeholderView
                    .onAppear {
                        loadImage()
                    }
            }
        }
        .aspectRatio(1, contentMode: .fill)
        .clipped()
        .cornerRadius(8)
        .overlay(
            RoundedRectangle(cornerRadius: 8)
                .stroke(Color.themePrimary.opacity(0.3), lineWidth: 1)
        )
    }
    
    // MARK: - 子视图
    
    /// 加载中的占位图
    private var placeholderView: some View {
        Color.gray.opacity(0.1)
            .overlay(
                ProgressView()
                    .progressViewStyle(CircularProgressViewStyle())
            )
    }
    
    /// 加载完成的图片视图
    private func loadedImageView(_ image: UIImage) -> some View {
        Image(uiImage: image)
            .resizable()
            .scaledToFill()
            .transition(.opacity.animation(.easeInOut(duration: 0.2)))
    }
    
    /// 播放按钮
    private var playButton: some View {
        Image(systemName: "play.circle.fill")
            .font(.system(size: 24))
            .foregroundColor(.white)
            .shadow(radius: 4)
    }
    
    /// 错误视图
    private func errorView(error: Error) -> some View {
        VStack(spacing: 8) {
            Image(systemName: "exclamationmark.triangle")
                .font(.system(size: 20))
                .foregroundColor(.orange)
            
            Text("加载失败")
                .font(.caption2)
                .foregroundColor(.secondary)
            
            Button(action: {
                loadState = nil
                loadImage()
            }) {
                Image(systemName: "arrow.clockwise")
                    .font(.caption)
                    .padding(4)
                    .background(Color.gray.opacity(0.2))
                    .clipShape(Circle())
            }
            .padding(.top, 4)
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity)
        .background(Color.gray.opacity(0.1))
        .cornerRadius(8)
    }
    
    /// 上传进度遮罩
    private var loadingOverlay: some View {
        ZStack {
            // 半透明黑色背景
            Color.black.opacity(0.3)
            
            // 进度条
            VStack {
                Spacer()
                
                // 圆形进度指示器
                ZStack {
                    Circle()
                        .stroke(
                            Color.white.opacity(0.3),
                            lineWidth: 4
                        )
                    
                    Circle()
                        .trim(from: 0.0, to: uploadProgress)
                        .stroke(
                            Color.white,
                            style: StrokeStyle(
                                lineWidth: 4,
                                lineCap: .round
                            )
                        )
                        .rotationEffect(.degrees(-90))
                    
                    Text("\(Int(uploadProgress * 100))%")
                        .font(.system(size: 12, weight: .bold))
                        .foregroundColor(.white)
                }
                .frame(width: 40, height: 40)
                .padding(.bottom, 8)
            }
        }
        .cornerRadius(8)
    }
    
    // MARK: - 私有方法
    
    /// 加载图片
    private func loadImage() {
        let cacheKey = "\(media.id)" as NSString
        
        // 检查缓存
        if let cachedImage = ImageCache.shared.object(forKey: cacheKey) {
            self.image = cachedImage
            self.loadState = .success(cachedImage)
            return
        }
        
        // 使用专用的图片处理队列
        imageProcessingQueue.async {
            do {
                let imageToCache: UIImage
                
                switch self.media {
                case .image(let uiImage):
                    imageToCache = uiImage
                    
                case .video(_, let thumbnail):
                    guard let thumbnail = thumbnail else {
                        throw NSError(
                            domain: "com.yourapp.media", 
                            code: -1, 
                            userInfo: [NSLocalizedDescriptionKey: "视频缩略图加载失败"]
                        )
                    }
                    imageToCache = thumbnail
                }
                
                // 缓存图片
                ImageCache.shared.setObject(imageToCache, forKey: cacheKey)
                
                // 更新UI
                DispatchQueue.main.async {
                    withAnimation(.easeInOut(duration: 0.2)) {
                        self.image = imageToCache
                        self.loadState = .success(imageToCache)
                    }
                }
                
            } catch {
                print("图片加载失败: \(error.localizedDescription)")
                DispatchQueue.main.async {
                    self.loadState = .failure(error)
                }
            }
        }
    }
}

// MARK: - 扩展

/// 扩展 MediaType 以支持 Identifiable 协议
extension MediaType: Identifiable {
    /// 唯一标识符
    public var id: String {
        switch self {
        case .image(let uiImage):
            return "image_\(uiImage.hashValue)"
        case .video(let url, _):
            return "video_\(url.absoluteString)"
        }
    }
}

// MARK: - 预览

struct MediaUploadView_Previews: PreviewProvider {
    static var previews: some View {
        NavigationView {
            MediaUploadView()
        }
    }
}