import SwiftUI

struct BusinessSelectionScreen: View {
    @EnvironmentObject var appState: AppState
    @State private var businesses: [Employment] = []
    @State private var isLoading = true
    @State private var error: String?

    var body: some View {
        NavigationStack {
            Group {
                if isLoading {
                    ProgressView("Loading businesses...")
                        .frame(maxWidth: .infinity, maxHeight: .infinity)
                } else if let error = error {
                    VStack(spacing: 16) {
                        Image(systemName: "exclamationmark.triangle")
                            .font(.largeTitle)
                            .foregroundColor(.orange)
                        Text(error)
                            .foregroundColor(.secondary)
                            .multilineTextAlignment(.center)
                        Button("Retry") { loadBusinesses() }
                            .buttonStyle(.borderedProminent)
                            .tint(.payfritGreen)
                    }
                    .padding()
                } else if businesses.isEmpty {
                    VStack(spacing: 16) {
                        Image(systemName: "building.2")
                            .font(.largeTitle)
                            .foregroundColor(.secondary)
                        Text("No businesses found")
                            .foregroundColor(.secondary)
                    }
                } else {
                    ScrollView {
                        LazyVStack(spacing: 12) {
                            ForEach(businesses) { biz in
                                NavigationLink(value: biz) {
                                    VStack(spacing: 0) {
                                        BusinessHeaderImage(businessId: biz.businessId)

                                        HStack {
                                            VStack(alignment: .leading, spacing: 2) {
                                                Text(biz.businessName)
                                                    .font(.subheadline.weight(.semibold))
                                                    .foregroundColor(.primary)
                                                if !biz.businessCity.isEmpty {
                                                    Text(biz.businessCity)
                                                        .font(.caption)
                                                        .foregroundColor(.secondary)
                                                }
                                            }
                                            Spacer()
                                            Image(systemName: "chevron.right")
                                                .font(.caption)
                                                .foregroundColor(.secondary)
                                        }
                                        .padding(.horizontal, 12)
                                        .padding(.vertical, 8)
                                    }
                                    .background(Color(.systemBackground))
                                    .clipShape(RoundedRectangle(cornerRadius: 12, style: .continuous))
                                    .overlay(
                                        RoundedRectangle(cornerRadius: 12, style: .continuous)
                                            .stroke(Color(.systemGray4), lineWidth: 0.5)
                                    )
                                    .shadow(color: .black.opacity(0.06), radius: 4, x: 0, y: 2)
                                }
                                .buttonStyle(.plain)
                            }
                        }
                        .padding(.horizontal, 16)
                        .padding(.top, 8)
                        .padding(.bottom, 20)
                    }
                }
            }
            .navigationTitle("Select Business")
            .navigationDestination(for: Employment.self) { biz in
                BeaconDashboard(business: biz)
            }
            .toolbar {
                ToolbarItem(placement: .navigationBarTrailing) {
                    Button {
                        logout()
                    } label: {
                        Image(systemName: "rectangle.portrait.and.arrow.right")
                    }
                }
            }
        }
        .task { loadBusinesses() }
    }

    private func loadBusinesses() {
        isLoading = true
        error = nil
        Task {
            do {
                businesses = try await APIService.shared.getMyBusinesses()
                isLoading = false
            } catch let apiError as APIError where apiError == .unauthorized {
                await appState.handleUnauthorized()
            } catch {
                self.error = error.localizedDescription
                isLoading = false
            }
        }
    }

    private func logout() {
        Task {
            await AuthStorage.shared.clearAuth()
            await APIService.shared.logout()
            appState.clearAuth()
        }
    }
}

// Make Employment Hashable for NavigationLink
extension Employment: Hashable {
    static func == (lhs: Employment, rhs: Employment) -> Bool {
        lhs.employeeId == rhs.employeeId && lhs.businessId == rhs.businessId
    }
    func hash(into hasher: inout Hasher) {
        hasher.combine(employeeId)
        hasher.combine(businessId)
    }
}

// MARK: - Business Header Image

struct BusinessHeaderImage: View {
    let businessId: Int

    @State private var loadedImage: UIImage?
    @State private var isLoading = true

    private var imageURLs: [URL] {
        [
            "https://dev.payfrit.com/uploads/headers/\(businessId).png",
            "https://dev.payfrit.com/uploads/headers/\(businessId).jpg",
        ].compactMap { URL(string: $0) }
    }

    var body: some View {
        ZStack {
            Color(.systemGray6)

            if let image = loadedImage {
                Image(uiImage: image)
                    .resizable()
                    .aspectRatio(contentMode: .fit)
                    .frame(maxWidth: .infinity)
            } else if isLoading {
                ProgressView()
                    .tint(.payfritGreen)
                    .frame(maxWidth: .infinity)
                    .frame(height: 100)
            } else {
                Image(systemName: "building.2")
                    .font(.system(size: 30))
                    .foregroundColor(.secondary)
                    .frame(maxWidth: .infinity)
                    .frame(height: 100)
            }
        }
        .task {
            await loadImage()
        }
    }

    private func loadImage() async {
        for url in imageURLs {
            do {
                let (data, response) = try await URLSession.shared.data(from: url)
                if let httpResponse = response as? HTTPURLResponse,
                   httpResponse.statusCode == 200,
                   let image = UIImage(data: data) {
                    await MainActor.run {
                        loadedImage = image
                        isLoading = false
                    }
                    return
                }
            } catch {
                continue
            }
        }
        await MainActor.run {
            isLoading = false
        }
    }
}