import SwiftUI

struct AddBooksView: View {
    @EnvironmentObject private var router: AppRouter
    @ObservedObject var viewModel: AddBooksViewModel

    var body: some View {
        VStack(spacing: 12) {
            Picker("Mode", selection: $viewModel.mode) {
                ForEach(AddBooksViewModel.Mode.allCases, id: \.self) { mode in
                    Text(mode.title).tag(mode)
                }
            }
            .pickerStyle(.segmented)

            Group {
                switch viewModel.mode {
                case .title:
                    titleSearch
                case .scan:
                    scanSearch
                case .filter:
                    filterSearch
                }
            }

            if let error = viewModel.errorMessage {
                NetworkErrorView(message: error) {
                    Task { await viewModel.searchByTitle() }
                }
            }

            List(viewModel.results, id: \.id) { book in
                Button {
                    router.path.append(.detail(book))
                } label: {
                    HStack(spacing: 12) {
                        AsyncImage(url: book.coverImageUrl) { phase in
                            if let image = phase.image {
                                image.resizable().scaledToFill()
                            } else {
                                RoundedRectangle(cornerRadius: 8).fill(.gray.opacity(0.2))
                            }
                        }
                        .frame(width: 48, height: 72)
                        .clipShape(RoundedRectangle(cornerRadius: 8))

                        VStack(alignment: .leading, spacing: 4) {
                            Text(book.title)
                                .font(.headline)
                                .lineLimit(2)
                            Text(book.authors.joined(separator: ", "))
                                .font(.subheadline)
                                .foregroundStyle(.secondary)
                                .lineLimit(1)
                            if let year = book.publishedYear {
                                Text("\(year)")
                                    .font(.caption)
                                    .foregroundStyle(.secondary)
                            }
                        }
                    }
                }
            }
            .listStyle(.plain)
            .overlay {
                if viewModel.results.isEmpty, !viewModel.isLoading {
                    Text(String(localized: "common.empty"))
                        .font(.subheadline)
                        .foregroundStyle(.secondary)
                }
            }
        }
        .padding(.horizontal, 16)
        .navigationTitle(String(localized: "add.title"))
        .navigationBarTitleDisplayMode(.inline)
        .overlay {
            if viewModel.isLoading {
                ProgressView()
                    .controlSize(.large)
            }
        }
    }

    private var titleSearch: some View {
        TextField(String(localized: "add.searchPlaceholder"), text: $viewModel.titleQuery)
            .textFieldStyle(.roundedBorder)
            .onChange(of: viewModel.titleQuery) { _, _ in
                viewModel.titleChanged()
            }
    }

    private var scanSearch: some View {
        BarcodeScannerView { isbn in
            Task { await viewModel.searchByISBN(isbn) }
        }
        .frame(height: 260)
        .clipShape(RoundedRectangle(cornerRadius: 16))
    }

    private var filterSearch: some View {
        VStack(spacing: 8) {
            TextField("Title", text: $viewModel.filterTitle)
                .textFieldStyle(.roundedBorder)
            TextField("YYYY", text: $viewModel.filterYear)
                .textFieldStyle(.roundedBorder)
                .keyboardType(.numberPad)
            Button("Apply") {
                Task { await viewModel.applyFilter() }
            }
            .buttonStyle(.borderedProminent)
            .frame(maxWidth: .infinity, alignment: .trailing)
        }
    }
}