import SwiftUI

// MARK: - Main View
@MainActor
struct MediaUploadView: View {
    @StateObject private var uploadManager = MediaUploadManager()
    @State private var showMediaPicker = false
    @State private var selectedMedia: MediaType? = nil
    @State private var selectedIndices: Set<Int> = []
    
    var body: some View {
        VStack() {
            // 固定的顶部导航栏
            HStack {
                Button(action: {
                    Router.shared.pop()
                }) {
                    Image(systemName: "chevron.left")
                        .font(.system(size: 17, weight: .semibold))
                        .foregroundColor(.themeTextMessageMain)
                }
                .padding(.leading, 16)
                
                Spacer() 
                
                Text("Complete Your Profile")
                    .font(Typography.font(for: .title2, family: .quicksandBold))
                    .foregroundColor(.themeTextMessageMain)
                
                Spacer() 
                
                // 添加一个透明的占位视图来平衡布局
                Color.clear
                    .frame(width: 24, height: 24)
                    .padding(.trailing, 16)
            }
            .background(Color.themeTextWhiteSecondary)
            .padding(.bottom, -24)
            .zIndex(1) // 确保导航栏在最上层
            // 主体内容
            HStack(spacing: 20) {
                Text("The upload process will take approximately 2 minutes. Thank you for your patience. ")
                    .font(Typography.font(for: .caption))
                    .foregroundColor(.black)
                    .frame(maxWidth: .infinity, alignment: .leading)
                    .padding(6)
                    .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
                        )
                    )
            }
            .padding()

            Spacer()
                .frame(height: 20)

            MainUploadArea(
                uploadManager: uploadManager,
                showMediaPicker: $showMediaPicker,
                selectedMedia: $selectedMedia,
                selectedIndices: $selectedIndices
            )
            .padding()
            .id("mainUploadArea\(uploadManager.selectedMedia.count)")

            Spacer()
            
            // Navigation button
            Button(action: {
                // 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())

            Spacer()
        }
        .background(Color.themeTextWhiteSecondary)
        .navigationBarTitleDisplayMode(.inline)
        .navigationBarBackButtonHidden(true)
        .sheet(isPresented: $showMediaPicker) {
            MediaPicker(
                selectedMedia: $uploadManager.selectedMedia,
                imageSelectionLimit: 10,
                videoSelectionLimit: 10,
                onDismiss: handleMediaPickerDismiss
            )
        }
        .onChange(of: uploadManager.selectedMedia) { newMedia in
            handleMediaChange(newMedia)
        }
    }
    
    // MARK: - Private Methods
    
    private func handleMediaPickerDismiss() {
        showMediaPicker = false
        if !uploadManager.selectedMedia.isEmpty && selectedMedia == nil {
            selectedMedia = uploadManager.selectedMedia.first
            selectedIndices = [0]
            // Start upload when media picker is dismissed with new media
            uploadManager.startUpload()
        }
    }
    
    private func handleMediaChange(_ newMedia: [MediaType]) {
        if newMedia.isEmpty {
            selectedMedia = nil
            selectedIndices = []
            return
        }
        
        // Only update if needed
        if selectedIndices.isEmpty || selectedIndices.first! >= newMedia.count {
            selectedMedia = newMedia.first
            selectedIndices = [0]
        } else if let selectedIndex = selectedIndices.first, selectedIndex < newMedia.count {
            selectedMedia = newMedia[selectedIndex]
        }
        
        // Auto-upload when new media is added
        if !newMedia.isEmpty && !uploadManager.isUploading {
            uploadManager.startUpload()
        }
    }
}

// MARK: - Main Upload Area

struct MainUploadArea: View {
    @ObservedObject var uploadManager: MediaUploadManager
    @Binding var showMediaPicker: Bool
    @Binding var selectedMedia: MediaType?
    @Binding var selectedIndices: Set<Int>
    
    var body: some View {
        VStack(spacing: 16) {
            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)
                .frame(maxWidth: .infinity, alignment: .leading)
                .padding()

            if let media = selectedMedia {
                MediaPreview(media: media)
                    .frame(width: 225, height: 225)
                    .onTapGesture { showMediaPicker = true }
            } else {
                UploadPromptView(showMediaPicker: $showMediaPicker)
            }
            if !uploadManager.selectedMedia.isEmpty {
                ThumbnailScrollView(
                    uploadManager: uploadManager,
                    selectedIndices: $selectedIndices,
                    selectedMedia: $selectedMedia
                )
                .id("thumbnailScroll\(uploadManager.selectedMedia.count)")
            }
        }
        .background(Color.white)
        .cornerRadius(16)
    }
}

// MARK: - Upload Prompt View

struct UploadPromptView: View {
    @Binding var showMediaPicker: Bool
    
    var body: some View {
        Button(action: {
            showMediaPicker = true
        }) {
            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: - Thumbnail Scroll View

@MainActor
struct ThumbnailScrollView: View {
    @ObservedObject var uploadManager: MediaUploadManager
    @Binding var selectedIndices: Set<Int>
    @Binding var selectedMedia: MediaType?
    
    // Track the currently selected index directly for faster access
    @State private var selectedIndex: Int = 0
    
    var body: some View {
        ScrollView(.horizontal, showsIndicators: false) {
            HStack(spacing: 12) {
                ForEach(0..<uploadManager.selectedMedia.count, id: \.self) { index in
                    let media = uploadManager.selectedMedia[index]
                    ThumbnailView(
                        media: media,
                        isSelected: selectedIndex == index,
                        showCheckmark: true
                    ) {
                        // Directly update the selection without animation for immediate response
                        selectedIndex = index
                        selectedMedia = media
                        selectedIndices = [index]
                    }
                }
                
                AddMoreButton(showMediaPicker: .constant(true))
            }
            .padding(.horizontal)
        }
        .frame(height: 100)
        .onAppear {
            // Initialize selection when view appears
            if !uploadManager.selectedMedia.isEmpty {
                selectedMedia = uploadManager.selectedMedia[selectedIndex]
                selectedIndices = [selectedIndex]
            }
        }
    }
}

// MARK: - Thumbnail View

@MainActor
struct ThumbnailView: View {
    let media: MediaType
    let isSelected: Bool
    let showCheckmark: Bool
    let onTap: () -> Void
    
    var body: some View {
        Button(action: onTap) {
            ZStack(alignment: .topTrailing) {
                Group {
                    if let thumbnail = media.thumbnail {
                        Image(uiImage: thumbnail)
                            .resizable()
                            .aspectRatio(contentMode: .fill)
                            .frame(width: 80, height: 80)
                            .clipped()
                    } else {
                        Color.gray
                            .frame(width: 80, height: 80)
                    }
                }
                .cornerRadius(8)
                .overlay(
                    RoundedRectangle(cornerRadius: 8)
                        .stroke(isSelected ? Color.themePrimary : Color.clear, lineWidth: 2)
                )
                
                // Selection checkmark
                if isSelected && showCheckmark {
                    Image(systemName: "checkmark.circle.fill")
                        .font(.system(size: 20))
                        .foregroundColor(.white)
                        .background(Circle().fill(Color.themePrimary))
                        .offset(x: 6, y: -6) // Adjusted offset to ensure visibility
                        .zIndex(1) // Ensure checkmark is above video icon
                }
                
                // Video icon
                if media.isVideo {
                    Image(systemName: "video.fill")
                        .font(.caption)
                        .foregroundColor(.white)
                        .padding(4)
                        .background(Color.black.opacity(0.6))
                        .clipShape(Circle())
                        .padding(4)
                        .offset(x: -4, y: 4) // Slight adjustment for better positioning
                }
            }
            .frame(width: 80, height: 80)
            .contentShape(Rectangle())
            .padding(4) // Add padding to prevent clipping
        }
        .buttonStyle(PlainButtonStyle())
    }
}

// MARK: - Add More Button

struct AddMoreButton: View {
    @Binding var showMediaPicker: Bool
    
    var body: some View {
        Button(action: { showMediaPicker = true }) {
            Image(systemName: "plus")
                .font(.title2)
                .foregroundColor(.gray)
                .frame(width: 80, height: 80)
                .overlay(
                    RoundedRectangle(cornerRadius: 8)
                        .stroke(style: StrokeStyle(
                            lineWidth: 1,
                            dash: [5, 3]
                        ))
                        .foregroundColor(.gray)
                )
        }
    }
}

// MARK: - Media Preview

struct MediaPreview: View {
    let media: MediaType
    
    var body: some View {
        Group {
            switch media {
            case .image(let uiImage):
                Image(uiImage: uiImage)
                    .resizable()
                    .scaledToFit()
                    .cornerRadius(12)
                    .drawingGroup() // Improves performance for large images
            case .video(_, let thumbnail):
                if let thumbnail = thumbnail {
                    Image(uiImage: thumbnail)
                        .resizable()
                        .scaledToFit()
                        .overlay(
                            Image(systemName: "play.circle.fill")
                                .font(.system(size: 48))
                                .foregroundColor(.white)
                                .shadow(radius: 10)
                        )
                        .cornerRadius(12)
                        .drawingGroup() // Improves performance for thumbnails
                }
            }
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity)
        .background(Color.themeTextWhiteSecondary)
        .cornerRadius(16)
        .overlay(
            RoundedRectangle(cornerRadius: 16)
                .stroke(Color.themePrimary, lineWidth: 2)
        )
        .contentShape(Rectangle()) // Better tap target
    }
}

// MARK: - Preview

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