import SwiftUI

/// The notification inbox: `notifications list [--all]`, paginated, with
/// a switch between the default unread-only listing and everything.
struct NotificationsView: View {

    @State private var model: NotificationsViewModel

    init(client: GitbayClient) {
        _model = State(initialValue: NotificationsViewModel(client: client))
    }

    var body: some View {
        List {
            Picker("Filter", selection: Bindable(model).showAll) {
                Text("Unread").tag(false)
                Text("All").tag(true)
            }
            .pickerStyle(.segmented)
            .listRowBackground(Color.clear)
            .listRowInsets(EdgeInsets())

            if let actionError = model.actionError {
                Section { GBNotice(actionError) }
            }

            ForEach(model.state.value ?? []) { notification in
                NotificationLink(notification: notification)
                    .swipeActions {
                        if notification.isUnread {
                            Button("Mark read") {
                                Task { await model.markRead(notification.id) }
                            }
                            .tint(.gbAccent)
                        }
                    }
            }
            PageFooter(list: model.list)
        }
        .overlay { LoadStateOverlay(state: model.state) }
        .navigationTitle("Notifications")
        .navigationBarTitleDisplayMode(.inline)
        .toolbar {
            ToolbarItem(placement: .topBarTrailing) {
                Button("Mark all read") {
                    Task { await model.markAllRead() }
                }
                .disabled(model.working)
            }
        }
        .task { await model.load() }
        .refreshable { await model.load() }
    }
}

/// Routes to `destination` when the path resolves to a screen; a
/// notification the app cannot route renders plainly and is not
/// tappable.
private struct NotificationLink: View {
    let notification: InboxNotification

    @ViewBuilder
    var body: some View {
        switch notification.destination {
        case .issue(let repo, let number):
            NavigationLink(value: IssueRoute.issue(repo: repo, number: number)) {
                NotificationRow(notification: notification)
            }
        case .mr(let repo, let number):
            NavigationLink(value: MRRoute.mr(repo: repo, number: number)) {
                NotificationRow(notification: notification)
            }
        case .build(let repo, let number):
            NavigationLink(value: BuildRoute.detail(repo: repo, number: number)) {
                NotificationRow(notification: notification)
            }
        case nil:
            NotificationRow(notification: notification)
        }
    }
}

private struct NotificationRow: View {
    let notification: InboxNotification

    var body: some View {
        VStack(alignment: .leading, spacing: 4) {
            HStack(alignment: .firstTextBaseline) {
                Text(notification.actor)
                    .font(.gbSans(.subheadline).weight(notification.isUnread ? .semibold : .regular))
                Spacer()
                Text(notification.createdAt, format: .relative(presentation: .named))
                    .font(.gbSans(.caption))
                    .foregroundStyle(.secondary)
            }
            Text(notification.summary)
                .font(.gbSans(.subheadline).weight(notification.isUnread ? .semibold : .regular))
                .foregroundStyle(notification.isUnread ? .primary : .secondary)
                .lineLimit(2)
        }
        .padding(.vertical, 2)
    }
}