import SwiftUI
import ComposableArchitecture
import PhotosUI

// MARK: - COS 上传组件

/// COS 上传组件
/// 提供图片选择、预览和上传功能
public struct COSUploadView: View {
    
    // MARK: - Properties
    
    let store: StoreOf<COSFeature>
    @State private var selectedImage: UIImage?
    @State private var showingImagePicker = false
    
    // MARK: - Initialization
    
    public init(store: StoreOf<COSFeature>) {
        self.store = store
    }
    
    // MARK: - Body
    
    public var body: some View {
        WithViewStore(store, observe: { $0 }) { viewStore in
            VStack(spacing: 20) {
                // 图片选择区域
                ImageSelectionArea(
                    selectedImage: $selectedImage,
                    showingImagePicker: $showingImagePicker
                )
                
                // 上传进度区域
                if let uploadState = viewStore.uploadState, 
                   uploadState.isUploading || uploadState.result != nil || uploadState.error != nil {
                    UploadProgressArea(uploadState: uploadState)
                }
                
                // 上传按钮
                UploadButton(
                    selectedImage: selectedImage,
                    isUploading: viewStore.uploadState?.isUploading == true,
                    isServiceReady: isServiceReady(viewStore),
                    onUpload: {
                        uploadImage(viewStore)
                    }
                )
                
                Spacer()
            }
            .padding()
            .sheet(isPresented: $showingImagePicker) {
                ImagePicker(selectedImage: $selectedImage)
            }
        }
    }
    
    // MARK: - 私有方法
    
    /// 检查服务是否就绪
    private func isServiceReady(_ viewStore: ViewStore<COSFeature.State, COSFeature.Action>) -> Bool {
        let isInitialized = viewStore.configurationState?.serviceStatus.isInitialized == true
        let hasValidToken = viewStore.tokenState?.currentToken?.isValid == true
        return isInitialized && hasValidToken
    }
    
    /// 上传图片
    private func uploadImage(_ viewStore: ViewStore<COSFeature.State, COSFeature.Action>) {
        guard let image = selectedImage else { return }
        
        let fileName = "image_\(Date().timeIntervalSince1970).jpg"
        viewStore.send(.upload(.uploadUIImage(image, fileName)))
    }
}

// MARK: - 图片选择区域

/// 图片选择区域组件
private struct ImageSelectionArea: View {
    @Binding var selectedImage: UIImage?
    @Binding var showingImagePicker: Bool
    
    var body: some View {
        VStack(spacing: 16) {
            if let image = selectedImage {
                // 显示选中的图片
                VStack(spacing: 12) {
                    Image(uiImage: image)
                        .resizable()
                        .aspectRatio(contentMode: .fit)
                        .frame(maxHeight: 200)
                        .cornerRadius(8)
                    
                    HStack(spacing: 12) {
                        Button("重新选择") {
                            showingImagePicker = true
                        }
                        .buttonStyle(.bordered)
                        
                        Button("清除") {
                            selectedImage = nil
                        }
                        .buttonStyle(.bordered)
                        .foregroundColor(.red)
                    }
                }
            } else {
                // 显示选择按钮
                VStack(spacing: 12) {
                    Image(systemName: "photo.badge.plus")
                        .font(.system(size: 48))
                        .foregroundColor(.blue)
                    
                    Text("选择图片")
                        .font(.headline)
                    
                    Text("点击选择要上传的图片")
                        .font(.caption)
                        .foregroundColor(.secondary)
                    
                    Button("选择图片") {
                        showingImagePicker = true
                    }
                    .buttonStyle(.borderedProminent)
                }
                .frame(maxWidth: .infinity)
                .padding(40)
                .background(Color(.systemGray6))
                .cornerRadius(12)
            }
        }
    }
}

// MARK: - 上传进度区域

/// 上传进度区域组件
private struct UploadProgressArea: View {
    let uploadState: UploadState
    
    var body: some View {
        VStack(alignment: .leading, spacing: 12) {
            HStack {
                Image(systemName: progressIcon)
                    .foregroundColor(progressColor)
                
                Text("上传进度")
                    .font(.headline)
                
                Spacer()
                
                if uploadState.isUploading {
                    Button("取消") {
                        // TODO: 实现取消上传
                    }
                    .font(.caption)
                    .foregroundColor(.red)
                }
            }
            
            if let task = uploadState.currentTask {
                VStack(alignment: .leading, spacing: 4) {
                    Text("文件: \(task.fileName)")
                        .font(.caption)
                        .foregroundColor(.secondary)
                    
                    Text("大小: \(ByteCountFormatter.string(fromByteCount: Int64(task.imageData.count), countStyle: .file))")
                        .font(.caption)
                        .foregroundColor(.secondary)
                }
            }
            
            if uploadState.isUploading {
                VStack(spacing: 8) {
                    ProgressView(value: uploadState.progress)
                        .progressViewStyle(LinearProgressViewStyle(tint: .blue))
                    
                    HStack {
                        Text("\(Int(uploadState.progress * 100))%")
                            .font(.caption)
                            .foregroundColor(.secondary)
                        
                        Spacer()
                        
                        Text(estimatedTimeRemaining)
                            .font(.caption)
                            .foregroundColor(.secondary)
                    }
                }
            }
            
            if let result = uploadState.result {
                VStack(alignment: .leading, spacing: 8) {
                    HStack {
                        Image(systemName: "checkmark.circle.fill")
                            .foregroundColor(.green)
                        
                        Text("上传成功")
                            .font(.headline)
                            .foregroundColor(.green)
                    }
                    
                    Text("URL: \(result)")
                        .font(.caption)
                        .foregroundColor(.secondary)
                        .lineLimit(3)
                    
                    Button("复制链接") {
                        UIPasteboard.general.string = result
                    }
                    .buttonStyle(.bordered)
                    .font(.caption)
                }
                .padding()
                .background(Color(.systemGreen).opacity(0.1))
                .cornerRadius(8)
            }
            
            if let error = uploadState.error {
                VStack(alignment: .leading, spacing: 8) {
                    HStack {
                        Image(systemName: "exclamationmark.triangle.fill")
                            .foregroundColor(.red)
                        
                        Text("上传失败")
                            .font(.headline)
                            .foregroundColor(.red)
                    }
                    
                    Text(error)
                        .font(.caption)
                        .foregroundColor(.red)
                }
                .padding()
                .background(Color(.systemRed).opacity(0.1))
                .cornerRadius(8)
            }
        }
        .padding()
        .background(Color(.systemGray6))
        .cornerRadius(12)
    }
    
    private var progressIcon: String {
        if uploadState.isUploading {
            return "arrow.up.circle.fill"
        } else if uploadState.result != nil {
            return "checkmark.circle.fill"
        } else if uploadState.error != nil {
            return "xmark.circle.fill"
        } else {
            return "arrow.up.circle"
        }
    }
    
    private var progressColor: Color {
        if uploadState.isUploading {
            return .blue
        } else if uploadState.result != nil {
            return .green
        } else if uploadState.error != nil {
            return .red
        } else {
            return .gray
        }
    }
    
    private var estimatedTimeRemaining: String {
        // 简单的剩余时间估算
        let remainingProgress = 1.0 - uploadState.progress
        if remainingProgress > 0 {
            let estimatedSeconds = Int(remainingProgress * 30) // 假设总时间30秒
            return "预计剩余 \(estimatedSeconds) 秒"
        } else {
            return "即将完成"
        }
    }
}

// MARK: - 上传按钮

/// 上传按钮组件
private struct UploadButton: View {
    let selectedImage: UIImage?
    let isUploading: Bool
    let isServiceReady: Bool
    let onUpload: () -> Void
    
    var body: some View {
        VStack(spacing: 12) {
            if !isServiceReady {
                VStack(spacing: 8) {
                    Image(systemName: "exclamationmark.triangle")
                        .foregroundColor(.orange)
                    
                    Text("服务未就绪")
                        .font(.headline)
                        .foregroundColor(.orange)
                    
                    Text("请确保 Token 有效且服务已初始化")
                        .font(.caption)
                        .foregroundColor(.secondary)
                        .multilineTextAlignment(.center)
                }
                .padding()
                .background(Color(.systemOrange).opacity(0.1))
                .cornerRadius(8)
            }
            
            Button(action: onUpload) {
                HStack {
                    if isUploading {
                        ProgressView()
                            .scaleEffect(0.8)
                            .tint(.white)
                    } else {
                        Image(systemName: "arrow.up.circle.fill")
                    }
                    
                    Text(buttonTitle)
                }
                .frame(maxWidth: .infinity)
                .padding()
            }
            .buttonStyle(.borderedProminent)
            .disabled(selectedImage == nil || isUploading || !isServiceReady)
        }
    }
    
    private var buttonTitle: String {
        if isUploading {
            return "上传中..."
        } else if selectedImage == nil {
            return "请先选择图片"
        } else if !isServiceReady {
            return "服务未就绪"
        } else {
            return "开始上传"
        }
    }
}

// MARK: - 图片选择器

/// 图片选择器组件
private struct ImagePicker: UIViewControllerRepresentable {
    @Binding var selectedImage: UIImage?
    @Environment(\.presentationMode) var presentationMode
    
    func makeUIViewController(context: Context) -> PHPickerViewController {
        var configuration = PHPickerConfiguration()
        configuration.filter = .images
        configuration.selectionLimit = 1
        
        let picker = PHPickerViewController(configuration: configuration)
        picker.delegate = context.coordinator
        return picker
    }
    
    func updateUIViewController(_ uiViewController: PHPickerViewController, context: Context) {}
    
    func makeCoordinator() -> Coordinator {
        Coordinator(self)
    }
    
    class Coordinator: NSObject, PHPickerViewControllerDelegate {
        let parent: ImagePicker
        
        init(_ parent: ImagePicker) {
            self.parent = parent
        }
        
        func picker(_ picker: PHPickerViewController, didFinishPicking results: [PHPickerResult]) {
            parent.presentationMode.wrappedValue.dismiss()
            
            guard let provider = results.first?.itemProvider else { return }
            
            if provider.canLoadObject(ofClass: UIImage.self) {
                provider.loadObject(ofClass: UIImage.self) { [weak self] image, _ in
                    // 在回调中立即进行类型转换，避免数据竞争
                    guard let uiImage = image as? UIImage else { return }
                    
                    // 在主线程中安全地设置图片
                    DispatchQueue.main.async {
                        guard let self = self else { return }
                        self.parent.selectedImage = uiImage
                    }
                }
            }
        }
    }
}

// MARK: - 扩展

extension COSServiceStatus {
    var isInitialized: Bool {
        switch self {
        case .initialized:
            return true
        default:
            return false
        }
    }
}

// MARK: - 预览

#Preview {
    COSUploadView(
        store: Store(
            initialState: COSFeature.State(),
            reducer: { COSFeature() }
        )
    )
}