import SwiftUI

struct HistoryScreen: View {
    @EnvironmentObject var appState: AppState
    @State private var history: [ScanHistoryItem] = []
    @State private var isLoading = true
    @State private var selectedProduct: Product?

    var body: some View {
        NavigationStack {
            Group {
                if !appState.isAuthenticated {
                    // Not logged in
                    VStack(spacing: 20) {
                        Spacer()
                        Image(systemName: "clock.fill")
                            .font(.system(size: 60))
                            .foregroundColor(.gray)

                        Text("Track Your Scans")
                            .font(.title2.bold())

                        Text("Log in to keep a history of all the products you've scanned.")
                            .font(.subheadline)
                            .foregroundColor(.secondary)
                            .multilineTextAlignment(.center)
                            .padding(.horizontal, 40)

                        Button {
                            appState.showLoginSheet = true
                        } label: {
                            Text("Log In")
                                .font(.headline)
                                .foregroundColor(.black)
                                .frame(maxWidth: .infinity)
                                .padding()
                                .background(Color.green)
                                .cornerRadius(12)
                        }
                        .padding(.horizontal, 40)

                        Spacer()
                    }
                } else if isLoading {
                    ProgressView("Loading history...")
                } else if history.isEmpty {
                    VStack(spacing: 20) {
                        Spacer()
                        Image(systemName: "clock")
                            .font(.system(size: 60))
                            .foregroundColor(.gray)

                        Text("No Scan History")
                            .font(.title2.bold())

                        Text("Products you scan will appear here.")
                            .font(.subheadline)
                            .foregroundColor(.secondary)
                            .multilineTextAlignment(.center)
                            .padding(.horizontal, 40)

                        Spacer()
                    }
                } else {
                    List {
                        ForEach(history) { item in
                            HistoryRow(item: item)
                                .onTapGesture {
                                    selectedProduct = item.product
                                }
                        }
                    }
                    .listStyle(.plain)
                }
            }
            .navigationTitle("History")
            .navigationDestination(isPresented: Binding(
                get: { selectedProduct != nil },
                set: { if !$0 { selectedProduct = nil } }
            )) {
                if let product = selectedProduct {
                    ProductScreen(product: product)
                        .environmentObject(appState)
                }
            }
            .task {
                if appState.isAuthenticated {
                    await loadHistory()
                }
            }
            .refreshable {
                await loadHistory()
            }
        }
    }

    private func loadHistory() async {
        isLoading = true
        do {
            let result = try await APIService.shared.getHistory()
            await MainActor.run {
                history = result
                isLoading = false
            }
        } catch {
            await MainActor.run {
                isLoading = false
                appState.showError(error.localizedDescription)
            }
        }
    }
}

struct HistoryRow: View {
    let item: ScanHistoryItem

    var body: some View {
        HStack(spacing: 12) {
            // Product Image
            if let imageURL = item.product.imageURL {
                AsyncImage(url: imageURL) { phase in
                    switch phase {
                    case .success(let image):
                        image
                            .resizable()
                            .aspectRatio(contentMode: .fill)
                    case .failure:
                        imagePlaceholder
                    default:
                        ProgressView()
                    }
                }
                .frame(width: 50, height: 50)
                .background(Color(.systemGray6))
                .cornerRadius(8)
                .clipped()
            } else {
                imagePlaceholder
                    .frame(width: 50, height: 50)
            }

            VStack(alignment: .leading, spacing: 4) {
                Text(item.product.name)
                    .font(.subheadline.bold())
                    .lineLimit(1)

                Text(item.product.brand)
                    .font(.caption)
                    .foregroundColor(.secondary)
            }

            Spacer()

            VStack(alignment: .trailing, spacing: 4) {
                // Score
                HStack(spacing: 4) {
                    Circle()
                        .fill(scoreColor(item.product.score))
                        .frame(width: 8, height: 8)
                    Text("\(item.product.score)")
                        .font(.caption.bold())
                }

                // Time ago
                Text(item.formattedDate)
                    .font(.caption2)
                    .foregroundColor(.secondary)
            }
        }
        .padding(.vertical, 4)
    }

    private var imagePlaceholder: some View {
        ZStack {
            Color(.systemGray5)
            Image(systemName: "carrot.fill")
                .font(.caption)
                .foregroundColor(.gray)
        }
        .cornerRadius(8)
    }

    private func scoreColor(_ score: Int) -> Color {
        switch score {
        case 80...100: return .green
        case 50..<80: return .yellow
        case 30..<50: return .orange
        default: return .red
        }
    }
}