import SwiftUI

struct ShareExtensionView: View {

    @ObservedObject var viewModel: ShareViewModel

    var onCancel:   () -> Void
    var onComplete: () -> Void
    var onOpenURL:  (URL) -> Void

    // MARK: - Body

    var body: some View {
        NavigationStack {
            Group {
                if !viewModel.isConfigured {
                    notConfiguredView
                } else if viewModel.isSaved {
                    successView
                } else {
                    formView
                }
            }
            .navigationTitle("Save to BookStax")
            .navigationBarTitleDisplayMode(.inline)
            .toolbar {
                ToolbarItem(placement: .cancellationAction) {
                    Button("Cancel", action: onCancel)
                }
            }
        }
        .task {
            guard viewModel.isConfigured, !viewModel.isSaved else { return }
            await viewModel.loadShelves()
        }
        .alert(
            "Error",
            isPresented: Binding(
                get: { viewModel.errorMessage != nil },
                set: { if !$0 { viewModel.errorMessage = nil } }
            ),
            actions: {
                Button("OK") { viewModel.errorMessage = nil }
            },
            message: {
                Text(viewModel.errorMessage ?? "")
            }
        )
    }

    // MARK: - Not configured

    private var notConfiguredView: some View {
        VStack(spacing: 20) {
            Image(systemName: "exclamationmark.triangle.fill")
                .font(.system(size: 48))
                .foregroundStyle(.orange)
            Text("BookStax Not Configured")
                .font(.headline)
            Text("Please open BookStax and sign in to your BookStack server.")
                .multilineTextAlignment(.center)
                .foregroundStyle(.secondary)
                .padding(.horizontal)
            Button("Close", action: onCancel)
                .buttonStyle(.borderedProminent)
        }
        .padding()
    }

    // MARK: - Success

    private var successView: some View {
        VStack(spacing: 24) {
            Image(systemName: "checkmark.circle.fill")
                .font(.system(size: 64))
                .foregroundStyle(.green)

            VStack(spacing: 8) {
                Text("Page saved!")
                    .font(.headline)
                Text(viewModel.pageTitle)
                    .font(.subheadline)
                    .foregroundStyle(.secondary)
                    .multilineTextAlignment(.center)
            }

            VStack(spacing: 12) {
                if let url = URL(string: viewModel.serverURL), !viewModel.serverURL.isEmpty {
                    Button {
                        onOpenURL(url)
                        onComplete()
                    } label: {
                        Label("Open BookStax", systemImage: "safari")
                            .frame(maxWidth: .infinity)
                    }
                    .buttonStyle(.borderedProminent)
                }

                Button("Done", action: onComplete)
                    .buttonStyle(.bordered)
            }
            .padding(.horizontal)
        }
        .padding()
        .task {
            try? await Task.sleep(for: .milliseconds(1500))
            onComplete()
        }
    }

    // MARK: - Form

    private var formView: some View {
        Form {
            Section("Selected Text") {
                Text(viewModel.sharedText)
                    .lineLimit(4)
                    .font(.footnote)
                    .foregroundStyle(.secondary)
            }

            Section("Page Title") {
                TextField("Page title", text: $viewModel.pageTitle)
                    .autocorrectionDisabled()
            }

            Section("Location") {
                NavigationLink {
                    ShelfPickerView(viewModel: viewModel)
                } label: {
                    LabeledRow(label: "Shelf", value: viewModel.selectedShelf?.name)
                }

                NavigationLink {
                    BookPickerView(viewModel: viewModel)
                } label: {
                    LabeledRow(label: "Book", value: viewModel.selectedBook?.name)
                }
                .disabled(viewModel.selectedShelf == nil)

                NavigationLink {
                    ChapterPickerView(viewModel: viewModel)
                } label: {
                    LabeledRow(label: "Chapter", value: viewModel.selectedChapter?.name,
                               placeholder: "Optional")
                }
                .disabled(viewModel.selectedBook == nil)
            }

            Section {
                Button {
                    Task { await viewModel.savePage() }
                } label: {
                    HStack {
                        Spacer()
                        if viewModel.isLoading {
                            ProgressView()
                        } else {
                            Text("Save")
                                .fontWeight(.semibold)
                        }
                        Spacer()
                    }
                }
                .disabled(viewModel.isSaveDisabled)
            }
        }
    }
}

// MARK: - Helper

private struct LabeledRow: View {
    let label: String
    let value: String?
    var placeholder: String = "Select"

    var body: some View {
        HStack {
            Text(LocalizedStringKey(label))
            Spacer()
            Text(value.map { LocalizedStringKey($0) } ?? LocalizedStringKey(placeholder))
                .foregroundStyle(value == nil ? .secondary : .primary)
        }
    }
}