import SwiftUI
import PhotosUI

// MARK: - Photo Picker

/// 照片选择器，封装了系统相册选择功能
struct PhotoPicker: UIViewControllerRepresentable {
    @Binding var selectedImages: [UIImage]
    
    /// 最多可选图片数量
    let selectionLimit: Int
    
    /// 图片过滤器，默认为图片类型
    let filter: PHPickerFilter
    
    init(selectedImages: Binding<[UIImage]>, selectionLimit: Int = 1, filter: PHPickerFilter = .images) {
        self._selectedImages = selectedImages
        self.selectionLimit = selectionLimit
        self.filter = filter
        self.onImageUploaded = onImageUploaded
        self.onUploadProgress = onUploadProgress
    }
    
    // MARK: - UIViewControllerRepresentable
    
    // MARK: - UIViewControllerRepresentable 协议方法
    
    /// 创建并返回PHPickerViewController实例
    /// - Parameter context: 上下文
    /// - Returns: 配置好的PHPickerViewController
    func makeUIViewController(context: Context) -> PHPickerViewController {
        // 配置照片选择器
        var configuration = PHPickerConfiguration(photoLibrary: PHPhotoLibrary.shared())
        configuration.filter = filter
        configuration.selectionLimit = selectionLimit
        configuration.preferredAssetRepresentationMode = .current
        
        let picker = PHPickerViewController(configuration: configuration)
        picker.delegate = context.coordinator
        return picker
    }
    
    /// 更新视图控制器
    /// - Parameters:
    ///   - uiViewController: 要更新的视图控制器
    ///   - context: 上下文
    func updateUIViewController(_ uiViewController: PHPickerViewController, context: Context) {}
    
    /// 创建协调器
    /// - Returns: 协调器实例
    func makeCoordinator() -> Coordinator {
        Coordinator(self)
    }
    
    // MARK: - Coordinator
    
    // MARK: - 协调器类
    
    /// 协调器，处理PHPickerViewController的代理方法
    class Coordinator: NSObject, PHPickerViewControllerDelegate {
        /// 父视图引用
        let parent: PhotoPicker
        private let uploadService = ImageUploadService.shared
        
        /// 初始化方法
        /// - Parameter parent: 父视图
        init(_ parent: PhotoPicker) {
            self.parent = parent
        }
        
        /// 用户完成图片选择时调用
        /// - Parameters:
        ///   - picker: 图片选择器
        ///   - results: 选中的图片结果
        func picker(_ picker: PHPickerViewController, didFinishPicking results: [PHPickerResult]) {
            parent.selectedImages.removeAll()
            
            let group = DispatchGroup()
            var loadedImages: [Int: UIImage] = [:] 
            var uploadResults: [Int: ImageUploadService.UploadResults] = [:]
            var lastError: Error?
            
            // 遍历所有选中的图片
            for (index, result) in results.enumerated() {
                group.enter()
                
                // 检查是否支持加载图片
                if result.itemProvider.canLoadObject(ofClass: UIImage.self) {
                    // 异步加载图片
                    result.itemProvider.loadObject(ofClass: UIImage.self) { (image, error) in
                        if let image = image as? UIImage {
                            loadedImages[index] = image
                        }
                        group.leave()
                    }
                } else {
                    group.leave()
                }
            }
            
            group.notify(queue: .main) {
                // Sort the images by their original index to maintain selection order
                let sortedImages = loadedImages.sorted { $0.key < $1.key }.map { $0.value }
                self.parent.selectedImages.append(contentsOf: sortedImages)
                
                // Dismiss the picker
                picker.dismiss(animated: true)
            }
        }
    }
}

// MARK: - Avatar Uploader Component
struct AvatarUploader: View {
    // MARK: - 属性
    
    /// 当前选中的头像图片
    @Binding var selectedImage: UIImage?
    
    /// 头像尺寸
    let size: CGFloat
    var onUploadComplete: ((Result<ImageUploadService.UploadResults, Error>) -> Void)?
    
    // MARK: - 状态
    
    /// 是否显示图片选择器
    @State private var isImagePickerPresented = false
    
    // MARK: - 视图
    
    var body: some View {
        Button(action: {
            isImagePickerPresented = true
        }) {
            ZStack {
                // Avatar Image or Placeholder
                if let selectedImage = selectedImage {
                    // 已选择的头像图片
                    Image(uiImage: selectedImage)
                        .resizable()
                        .scaledToFill()
                        .frame(width: size, height: size)
                        .clipShape(RoundedRectangle(cornerRadius: size * 0.1))
                } else {
                    // Default avatar container
                    Color.gray.opacity(0.1)
                        .frame(width: size, height: size)
                        .overlay(
                            SVGImage(svgName: "Avatar")
                                .frame(width: size * 0.8, height: size * 0.8)
                        )
                        .clipShape(RoundedRectangle(cornerRadius: size * 0.1))
                        .overlay(
                            RoundedRectangle(cornerRadius: size * 0.1)
                                .stroke(Color.gray.opacity(0.3), lineWidth: 1)
                        )
                }
            }
            .frame(width: size, height: size)
            .contentShape(Rectangle()) // Make the entire area tappable
        }
        .buttonStyle(PlainButtonStyle()) // Remove button highlight effect
        .sheet(isPresented: $isImagePickerPresented) {
            PhotoPicker(
                // 绑定选中的图片
                selectedImages: Binding(
                    get: { [selectedImage].compactMap { $0 } },
                    set: { images in
                        selectedImage = images.first
                    }
                ),
                selectionLimit: 1
            )
        }
    }
}