import SwiftUI

struct ChatsListScreen: 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.ChatsList.title),
                    rightButton: .init(
                        image: Image(systemName: "square.and.pencil"),
                        action: {
                            router.showScreen(.fullScreenCover) { _ in
                                ChatsCreateScreenMain()
                            }
                        }
                    )
                )

                // Chats list
                if !clientsStore.actualChats.isEmpty {
                    List {
                        ForEach(elements.indices, id: \.self) { index in
                            let element = elements[index]
                            if let chat = element as? Chat {
                                ChatsRow(chat: chat)
                            } else if let account = element as? String {
                                SharedSectionTitle(text: account)
                            }
                        }
                    }
                    .listStyle(.plain)
                    .background(Color.Material.Background.light)
                } else {
                    Spacer()
                }
            }
        }
    }

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

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

    var chat: Chat

    var body: some View {
        SharedListRow(iconType: .charCircle(chat.participant), text: chat.participant, controlType: .none)
            .onTapGesture {
                Task {
                    router.showModal {
                        LoadingScreen()
                    }
                    defer {
                        router.dismissModal()
                    }

                    do {
                        try? await clientsStore.addRosterForNewChatIfNeeded(chat)
                        let (messages, attachments, settings) = try await clientsStore.conversationStores(for: chat)
                        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) {}
                        }
                    }
                }
            }
    }
}