Sportstime/SportsTime/Export/Views/SharePreviewView.swift

//
//  SharePreviewView.swift
//  SportsTime
//
//  Unified preview and customization UI for all shareable content.
//

import SwiftUI

struct SharePreviewView<Content: ShareableContent>: View {
    let content: Content

    @Environment(\.dismiss) private var dismiss
    @Environment(\.colorScheme) private var colorScheme

    @State private var selectedTheme: ShareTheme
    @State private var generatedImage: UIImage?
    @State private var isGenerating = false
    @State private var error: String?
    @State private var showCopiedToast = false
    @State private var loadTask: Task<Void, Never>?

    init(content: Content) {
        self.content = content
        _selectedTheme = State(initialValue: ShareThemePreferences.theme(for: content.cardType))
    }

    var body: some View {
        NavigationStack {
            ScrollView {
                VStack(spacing: Theme.Spacing.lg) {
                    // Preview
                    previewSection

                    // Theme selector
                    themeSelector

                    // Action buttons
                    actionButtons
                }
                .padding(Theme.Spacing.md)
            }
            .themedBackground()
            .navigationTitle("Share")
            .navigationBarTitleDisplayMode(.inline)
            .toolbar {
                ToolbarItem(placement: .cancellationAction) {
                    Button("Cancel") { dismiss() }
                }
            }
            .alert("Error", isPresented: .constant(error != nil)) {
                Button("OK") { error = nil }
            } message: {
                Text(error ?? "")
            }
            .overlay {
                if showCopiedToast {
                    copiedToast
                }
            }
            .task {
                await generatePreview()
            }
            .onChange(of: selectedTheme) { _, _ in
                loadTask?.cancel()
                loadTask = Task {
                    guard !Task.isCancelled else { return }
                    await generatePreview()
                }
            }
        }
    }

    // MARK: - Preview Section

    private var previewSection: some View {
        VStack(spacing: Theme.Spacing.sm) {
            Text("Preview")
                .font(.subheadline)
                .foregroundStyle(Theme.textMuted(colorScheme))

            if let image = generatedImage {
                Image(uiImage: image)
                    .resizable()
                    .aspectRatio(9/16, contentMode: .fit)
                    .frame(maxHeight: 400)
                    .clipShape(RoundedRectangle(cornerRadius: Theme.CornerRadius.medium))
                    .shadow(color: .black.opacity(0.2), radius: 10, x: 0, y: 5)
                    .accessibilityLabel("Share card preview")
            } else if isGenerating {
                RoundedRectangle(cornerRadius: Theme.CornerRadius.medium)
                    .fill(Theme.cardBackground(colorScheme))
                    .aspectRatio(9/16, contentMode: .fit)
                    .frame(maxHeight: 400)
                    .overlay {
                        ProgressView()
                    }
            }
        }
    }

    // MARK: - Theme Selector

    private var themeSelector: some View {
        VStack(alignment: .leading, spacing: Theme.Spacing.sm) {
            Text("Theme")
                .font(.subheadline)
                .foregroundStyle(Theme.textMuted(colorScheme))

            ScrollView(.horizontal, showsIndicators: false) {
                HStack(spacing: Theme.Spacing.sm) {
                    ForEach(ShareTheme.all) { theme in
                        themeButton(theme)
                    }
                }
            }
        }
    }

    private func themeButton(_ theme: ShareTheme) -> some View {
        Button {
            withAnimation {
                selectedTheme = theme
                ShareThemePreferences.setTheme(theme, for: content.cardType)
            }
        } label: {
            VStack(spacing: 4) {
                ZStack {
                    RoundedRectangle(cornerRadius: 8)
                        .fill(
                            LinearGradient(
                                colors: theme.gradientColors,
                                startPoint: .top,
                                endPoint: .bottom
                            )
                        )
                        .frame(width: 50, height: 50)

                    Circle()
                        .fill(theme.accentColor)
                        .frame(width: 16, height: 16)
                }
                .overlay {
                    if selectedTheme.id == theme.id {
                        RoundedRectangle(cornerRadius: 8)
                            .stroke(Theme.warmOrange, lineWidth: 3)
                    }
                }

                Text(theme.name)
                    .font(.caption2)
                    .foregroundStyle(Theme.textSecondary(colorScheme))
            }
        }
        .buttonStyle(.plain)
        .accessibilityLabel("Select \(theme.name) theme")
        .accessibilityHint(selectedTheme.id == theme.id ? "Currently selected" : "Double-tap to select this theme")
        .accessibilityAddTraits(selectedTheme.id == theme.id ? .isSelected : [])
    }

    // MARK: - Action Buttons

    private var actionButtons: some View {
        VStack(spacing: Theme.Spacing.sm) {
            // Primary: Share to Instagram
            Button {
                shareToInstagram()
            } label: {
                HStack {
                    Image(systemName: "camera.fill")
                        .accessibilityHidden(true)
                    Text("Share to Instagram")
                }
                .frame(maxWidth: .infinity)
                .padding(Theme.Spacing.md)
                .background(Theme.warmOrange)
                .foregroundStyle(.white)
                .clipShape(RoundedRectangle(cornerRadius: Theme.CornerRadius.medium))
            }
            .disabled(generatedImage == nil)

            // Copy Image
            Button {
                copyImage()
            } label: {
                HStack {
                    Image(systemName: "doc.on.doc")
                        .accessibilityHidden(true)
                    Text("Copy to Clipboard")
                }
                .frame(maxWidth: .infinity)
                .padding(Theme.Spacing.md)
                .background(Theme.cardBackgroundElevated(colorScheme))
                .foregroundStyle(Theme.textPrimary(colorScheme))
                .clipShape(RoundedRectangle(cornerRadius: Theme.CornerRadius.medium))
            }
            .disabled(generatedImage == nil)
        }
    }

    // MARK: - Copied Toast

    private var copiedToast: some View {
        VStack {
            Spacer()

            HStack {
                Image(systemName: "checkmark.circle.fill")
                    .accessibilityHidden(true)
                Text("Copied to clipboard")
            }
            .padding()
            .background(.ultraThinMaterial)
            .clipShape(Capsule())
            .padding(.bottom, 100)
        }
        .transition(.move(edge: .bottom).combined(with: .opacity))
    }

    // MARK: - Actions

    private func generatePreview() async {
        isGenerating = true

        do {
            generatedImage = try await content.render(theme: selectedTheme)
        } catch {
            self.error = error.localizedDescription
        }

        isGenerating = false
    }

    private func shareToInstagram() {
        guard let image = generatedImage else { return }

        if !ShareService.shared.shareToInstagram(image: image) {
            // Fallback to system share
            showSystemShare()
        }
    }

    private func copyImage() {
        guard let image = generatedImage else { return }

        ShareService.shared.copyToClipboard(image: image)

        withAnimation {
            showCopiedToast = true
        }

        DispatchQueue.main.asyncAfter(deadline: .now() + 2) {
            withAnimation {
                showCopiedToast = false
            }
        }
    }

    private func showSystemShare() {
        guard let image = generatedImage,
              let windowScene = UIApplication.shared.connectedScenes.first as? UIWindowScene,
              let rootVC = windowScene.windows.first?.rootViewController else { return }

        ShareService.shared.presentShareSheet(image: image, from: rootVC)
    }
}