import SwiftUI

struct GameView: View {
    let service: StreamingService

    @State private var isScanning = false
    @State private var isLoading = false
    @State private var alert: AlertInfo?

    var body: some View {
        ZStack {
            Color("Background").ignoresSafeArea()

            VStack(spacing: 48) {
                Image("AppLogo")
                    .resizable()
                    .scaledToFit()
                    .frame(width: 160, height: 160)

                if isLoading {
                    ProgressView()
                        .tint(Color("Primary"))
                        .scaleEffect(1.4)
                } else {
                    Button(action: { isScanning = true }) {
                        Text("Nächste Karte")
                            .font(.system(size: 17, weight: .bold))
                            .foregroundColor(.white)
                            .frame(width: 220, height: 56)
                            .background(Color("Primary"))
                            .cornerRadius(8)
                    }
                }
            }
        }
        .navigationBarTitleDisplayMode(.inline)
        .sheet(isPresented: $isScanning) {
            QRScannerView { scannedUrl in
                isScanning = false
                handleScanned(url: scannedUrl)
            }
        }
        .alert(item: $alert) { info in
            Alert(
                title: Text(info.title),
                message: Text(info.message),
                dismissButton: info.scanNext
                    ? .default(Text("Nächste Karte")) { isScanning = true }
                    : .default(Text("OK"))
            )
        }
        .onAppear { isScanning = true }
    }

    private func handleScanned(url: String) {
        isLoading = true
        Task {
            do {
                let song = try await ApiClient.shared.resolve(url: url)
                await MainActor.run {
                    isLoading = false
                    guard let song else {
                        alert = AlertInfo(
                            title: "Nicht gefunden",
                            message: "Dieser QR-Code ist keiner bekannten Hitster-Karte zugeordnet.",
                            scanNext: false
                        )
                        return
                    }
                    guard let serviceUrl = song.url(for: service) else {
                        alert = AlertInfo(
                            title: "Nicht verfügbar",
                            message: "\(song.artist) – \(song.title)\n\nist auf \(service.displayName) nicht verfügbar.\n\nBitte ziehe die nächste Karte.",
                            scanNext: true
                        )
                        return
                    }
                    UIApplication.shared.open(serviceUrl)
                }
            } catch {
                await MainActor.run {
                    isLoading = false
                    alert = AlertInfo(title: "Fehler", message: error.localizedDescription, scanNext: false)
                }
            }
        }
    }
}

private struct AlertInfo: Identifiable {
    let id = UUID()
    let title: String
    let message: String
    let scanNext: Bool
}