import SwiftUI

struct WallpaperItem: View {
    let wallpaper: Wallpaper
    let action: () -> Void
    @ObservedObject var favoritesManager = FavoritesManager.shared
    @State private var retryID = UUID()
    @State private var attempt = 0
    @State private var isHovering = false

    // Transient thumbnail failures (flaky network) are common; retry a few
    // times with growing backoff before giving up quietly.
    private let maxAttempts = 4

    var body: some View {
        Button(action: action) {
            AsyncImage(url: URL(string: wallpaper.thumbs.small)) { phase in
                switch phase {
                case .empty:
                    Rectangle()
                        .fill(Color.gray.opacity(0.2))
                        .overlay(ProgressView())
                case .success(let image):
                    image
                        .resizable()
                        .aspectRatio(contentMode: .fill)
                case .failure:
                    Rectangle()
                        .fill(Color.gray.opacity(0.2))
                        .overlay(
                            attempt < maxAttempts
                                ? AnyView(ProgressView())
                                : AnyView(Image(systemName: "photo")
                                    .foregroundColor(.gray.opacity(0.6)))
                        )
                        .task {
                            guard attempt < maxAttempts else { return }
                            // 0.8s, 1.6s, 2.4s, 3.2s
                            let delay = UInt64(attempt + 1) * 800_000_000
                            try? await Task.sleep(nanoseconds: delay)
                            guard !Task.isCancelled else { return }
                            attempt += 1
                            retryID = UUID()
                        }
                @unknown default:
                    EmptyView()
                }
            }
            .id(retryID)
            .frame(height: 100)
            .clipped()
            .cornerRadius(8)
            .overlay(
                RoundedRectangle(cornerRadius: 8)
                    .stroke(isHovering ? Color.accentColor : Color.clear, lineWidth: 2)
            )
            .shadow(radius: isHovering ? 4 : 0)
            .overlay(
                // Favorite Button
                Group {
                    if isHovering || favoritesManager.isFavorite(wallpaper) {
                        Button {
                            favoritesManager.toggleFavorite(wallpaper)
                        } label: {
                            Image(systemName: favoritesManager.isFavorite(wallpaper) ? "heart.fill" : "heart")
                                .foregroundColor(favoritesManager.isFavorite(wallpaper) ? .red : .white)
                                .shadow(radius: 2)
                                .font(.system(size: 16, weight: .bold))
                                .padding(6)
                                .background(Color.black.opacity(0.3))
                                .clipShape(Circle())
                        }
                        .buttonStyle(.plain)
                        .padding(6)
                        .transition(.opacity)
                    }
                },
                alignment: .topTrailing
            )
            .scaleEffect(isHovering ? 1.02 : 1.0)
            .animation(.spring(response: 0.3), value: isHovering)
        }
        .buttonStyle(.plain)
        .onHover { isHovering = $0 }
        .help("\(wallpaper.resolution)\n\(wallpaper.purity)")
    }
}