import SwiftUI

struct ContactsScreen: View {
    @Environment(\.router) var router
    @EnvironmentObject var clientsStore: ClientsStore

    var body: some View {
        ZStack {
            // Background color
            Color.Material.Background.light
                .ignoresSafeArea()

            // Content
            VStack(spacing: 0) {
                // Header
                SharedNavigationBar(
                    centerText: .init(text: L10n.Contacts.title),
                    rightButton: .init(
                        image: Image(systemName: "plus"),
                        action: {
                            router.showScreen(.fullScreenCover) { _ in
                                AddContactOrChannelScreen()
                            }
                        }
                    )
                )

                // Contacts list
                if !clientsStore.actualRosters.isEmpty {
                    List {
                        ForEach(elements.indices, id: \.self) { index in
                            let element = elements[index]
                            if let roster = element as? Roster {
                                ContactsScreenRow(
                                    roster: roster
                                )
                            } else if let bareJid = element as? String {
                                SharedSectionTitle(text: bareJid)
                            }
                        }
                    }
                    .listStyle(.plain)
                    .background(Color.Material.Background.light)
                } else {
                    Spacer()
                }
            }
        }
    }

    private var elements: [Any] {
        if clientsStore.clients.filter({ $0.credentials.isActive }).count == 1 {
            return clientsStore.actualRosters
        } else {
            var result: [Any] = []
            for roster in clientsStore.actualRosters {
                if result.isEmpty {
                    result.append(roster.bareJid)
                } else if let last = result.last as? Roster, last.bareJid != roster.bareJid {
                    result.append(roster.bareJid)
                }
                result.append(roster)
            }
            return result
        }
    }
}

private struct ContactsScreenRow: View {
    @Environment(\.router) var router
    @EnvironmentObject var clientsStore: ClientsStore

    var roster: Roster

    var body: some View {
        SharedListRow(
            iconType: .charCircle(roster.name?.firstLetter ?? roster.contactBareJid.firstLetter),
            text: roster.contactBareJid,
            controlType: .none
        )
        .onTapGesture {
            startChat()
        }
        .swipeActions(edge: .trailing, allowsFullSwipe: false) {
            Button {
                router.showAlert(.confirmationDialog, title: L10n.Contacts.deleteContact, subtitle: L10n.Contacts.Delete.message) {
                    deleteConfirmation
                }
            } label: {
                Label("", systemImage: "trash")
            }
            .tint(Color.red)
        }
        .contextMenu {
            Button(L10n.Contacts.sendMessage, systemImage: "message") {
                startChat()
            }
            Divider()

            Button(L10n.Contacts.editContact) {
                print("Edit contact")
            }

            Button(L10n.Contacts.selectContact) {
                print("Select contact")
            }

            Divider()
            Button(L10n.Contacts.deleteContact, systemImage: "trash", role: .destructive) {
                router.showAlert(.confirmationDialog, title: L10n.Contacts.deleteContact, subtitle: L10n.Contacts.Delete.message) {
                    deleteConfirmation
                }
            }
        }
    }

    @ViewBuilder private var deleteConfirmation: some View {
        Button(role: .destructive) {
            Task {
                await deleteFromDevice()
            }
        } label: {
            Text(L10n.Contacts.Delete.deleteFromDevice)
        }

        Button(role: .destructive) {
            Task {
                await deleteCompletely()
            }
        } label: {
            Text(L10n.Contacts.Delete.deleteCompletely)
        }

        Button(role: .cancel) {} label: {
            Text(L10n.Global.cancel)
        }
    }

    private func deleteFromDevice() async {
        router.showModal {
            LoadingScreen()
        }

        defer {
            router.dismissModal()
        }

        var roster = roster
        try? await roster.setLocallyDeleted(true)
    }

    private func deleteCompletely() async {
        router.showModal {
            LoadingScreen()
        }

        defer {
            router.dismissModal()
        }

        do {
            try await clientsStore.deleteRoster(roster)
        } catch {
            router.showAlert(
                .alert,
                title: L10n.Global.Error.title,
                subtitle: L10n.Contacts.Delete.error
            ) {
                Button(L10n.Global.ok, role: .cancel) {}
            }
        }
    }

    private func startChat() {
        Task {
            router.showModal {
                LoadingScreen()
            }
            defer {
                router.dismissModal()
            }

            do {
                let (messages, attachments, settings) = try await clientsStore.conversationStores(for: roster)
                router.showScreen(.push) { _ in
                    ConversationScreen(messagesStore: messages, attachments: attachments, settings: settings)
                        .navigationBarHidden(true)
                }
            } catch {
                router.showAlert(
                    .alert,
                    title: L10n.Global.Error.title,
                    subtitle: L10n.Conversation.startError
                ) {
                    Button(L10n.Global.ok, role: .cancel) {}
                }
            }
        }
    }
}