import Foundation
import Combine

@MainActor
public final class SessionStore: ObservableObject {
    @Published public private(set) var account: Account
    @Published public private(set) var authState: AuthState = .waitTdlibParameters
    @Published public private(set) var networkState: NetworkState = .ready
    @Published public private(set) var typingState: TypingState = .idle
    @Published public private(set) var errorMessage: String?

    public let bridge: SessionBridge

    public init(account: Account, bridge: SessionBridge) {
        self.account = account
        self.bridge = bridge
    }

    public func refreshAuthState() async {
        do {
            authState = try await bridge.authState()
            errorMessage = nil
        } catch {
            errorMessage = error.localizedDescription
        }
    }

    public func refreshNetworkState() async {
        do {
            networkState = try await bridge.networkState()
            errorMessage = nil
        } catch {
            errorMessage = error.localizedDescription
        }
    }

    public func apply(events: [SessionEvent]) {
        for event in events {
            switch event {
            case let .authChanged(state):
                authState = state
            case let .networkChanged(state):
                networkState = state
            case let .typingChanged(state):
                typingState = state
            default:
                break
            }
        }
    }
}

@MainActor
public final class AuthViewModel: ObservableObject {
    @Published public var phone = ""
    @Published public var code = ""
    @Published public var password = ""
    @Published public private(set) var isLoading = false
    @Published public private(set) var errorMessage: String?

    private let store: SessionStore

    public init(store: SessionStore) {
        self.store = store
    }

    public func submitCurrentStep() async {
        isLoading = true
        defer { isLoading = false }

        do {
            switch store.authState {
            case .waitPhoneNumber:
                try await store.bridge.sendPhoneNumber(phone)
            case .waitCode:
                try await store.bridge.sendCode(code)
            case .waitPassword:
                try await store.bridge.sendPassword(password)
            default:
                break
            }
            let events = try await store.bridge.pollEvents()
            store.apply(events: events)
            errorMessage = nil
        } catch {
            errorMessage = error.localizedDescription
        }
    }
}

@MainActor
public final class ChatListViewModel: ObservableObject {
    @Published public private(set) var folders: [Folder] = []
    @Published public private(set) var chats: [ChatSummary] = []
    @Published public var selectedFolderId: Int32?
    @Published public var searchText = ""
    @Published public private(set) var isLoading = false
    @Published public private(set) var errorMessage: String?

    private let bridge: SessionBridge

    public init(bridge: SessionBridge) {
        self.bridge = bridge
    }

    public var filteredChats: [ChatSummary] {
        guard !searchText.isEmpty else {
            return chats
        }
        return chats.filter { chat in
            chat.title.localizedCaseInsensitiveContains(searchText)
                || (chat.username?.localizedCaseInsensitiveContains(searchText) ?? false)
        }
    }

    public func load() async {
        isLoading = true
        defer { isLoading = false }

        do {
            folders = try await bridge.loadFolders()
            chats = try await bridge.loadChats(folderId: selectedFolderId)
            errorMessage = nil
        } catch {
            errorMessage = error.localizedDescription
        }
    }
}

@MainActor
public final class ChatViewModel: ObservableObject {
    @Published public private(set) var chat: ChatSummary
    @Published public private(set) var messages: [Message] = []
    @Published public var composeText: String
    @Published public var replyTo: Message?
    @Published public var searchText = ""
    @Published public private(set) var searchResults: [Message] = []
    @Published public private(set) var pinnedMessages: [Message] = []
    @Published public private(set) var copiedPayload: String?
    @Published public private(set) var isLoading = false
    @Published public private(set) var errorMessage: String?

    private let bridge: SessionBridge

    public init(chat: ChatSummary, bridge: SessionBridge) {
        self.chat = chat
        self.bridge = bridge
        self.composeText = chat.draft?.text ?? ""
    }

    public func load() async {
        isLoading = true
        defer { isLoading = false }

        do {
            messages = try await bridge.loadHistory(chatId: chat.id)
            pinnedMessages = try await bridge.pinnedMessages(chatId: chat.id)
            errorMessage = nil
        } catch {
            errorMessage = error.localizedDescription
        }
    }

    public func send() async {
        let text = composeText.trimmingCharacters(in: .whitespacesAndNewlines)
        guard !text.isEmpty else {
            return
        }

        do {
            let sent = try await bridge.sendMessage(
                chatId: chat.id,
                text: text,
                replyToMessageId: replyTo?.id
            )
            messages.append(sent)
            composeText = ""
            replyTo = nil
            errorMessage = nil
        } catch {
            errorMessage = error.localizedDescription
        }
    }

    public func search() async {
        do {
            searchResults = try await bridge.searchMessages(chatId: chat.id, query: searchText)
            errorMessage = nil
        } catch {
            errorMessage = error.localizedDescription
        }
    }

    public func beginReply(to message: Message) {
        replyTo = message
    }

    public func cancelReply() {
        replyTo = nil
    }

    public func edit(message: Message, text: String) async {
        do {
            let edited = try await bridge.editMessage(chatId: chat.id, messageId: message.id, text: text)
            replaceMessage(edited)
            errorMessage = nil
        } catch {
            errorMessage = error.localizedDescription
        }
    }

    public func delete(message: Message) async {
        do {
            try await bridge.deleteMessages(chatId: chat.id, messageIds: [message.id])
            messages.removeAll { $0.id == message.id }
            errorMessage = nil
        } catch {
            errorMessage = error.localizedDescription
        }
    }

    public func forward(message: Message, to chatId: Int64) async {
        do {
            try await bridge.forwardMessages(toChatId: chatId, fromChatId: chat.id, messageIds: [message.id])
            errorMessage = nil
        } catch {
            errorMessage = error.localizedDescription
        }
    }

    public func react(message: Message, reaction: String) async {
        do {
            let reactions = try await bridge.react(chatId: chat.id, messageId: message.id, reaction: reaction)
            var updated = message
            updated.reactions = reactions
            replaceMessage(updated)
            errorMessage = nil
        } catch {
            errorMessage = error.localizedDescription
        }
    }

    public func copyPayload(for message: Message) async {
        do {
            copiedPayload = try await bridge.copyPayload(chatId: chat.id, messageId: message.id)
            errorMessage = nil
        } catch {
            errorMessage = error.localizedDescription
        }
    }

    public func saveDraft() async {
        do {
            try await bridge.setDraft(chatId: chat.id, text: composeText)
            errorMessage = nil
        } catch {
            errorMessage = error.localizedDescription
        }
    }

    private func replaceMessage(_ message: Message) {
        if let index = messages.firstIndex(where: { $0.id == message.id }) {
            messages[index] = message
        }
    }
}

@MainActor
public final class ProfileViewModel: ObservableObject {
    @Published public private(set) var profile: Profile?
    @Published public private(set) var isLoading = false
    @Published public private(set) var errorMessage: String?

    private let bridge: SessionBridge

    public init(bridge: SessionBridge) {
        self.bridge = bridge
    }

    public func load(chatId: Int64) async {
        isLoading = true
        defer { isLoading = false }

        do {
            profile = try await bridge.openProfile(chatId: chatId)
            errorMessage = nil
        } catch {
            errorMessage = error.localizedDescription
        }
    }

    public func leave(chatId: Int64) async {
        do {
            try await bridge.leaveChat(chatId: chatId)
            errorMessage = nil
        } catch {
            errorMessage = error.localizedDescription
        }
    }
}

@MainActor
public final class MediaViewModel: ObservableObject {
    @Published public private(set) var activePhotoPath: String?
    @Published public private(set) var activeVoicePath: String?
    @Published public private(set) var isVoicePlaying = false

    private let cache: MediaCache?
    private let voicePlayer: VoicePlayback?

    public init(cache: MediaCache? = nil, voicePlayer: VoicePlayback? = nil) {
        self.cache = cache
        self.voicePlayer = voicePlayer
    }

    public func showPhoto(path: String) {
        activePhotoPath = path
    }

    public func showVoice(path: String) {
        activeVoicePath = path
    }

    public func cachedPhotoPath(fileId: Int32) -> URL? {
        cache?.photoPath(fileId: fileId)
    }

    public func cachedVoicePath(fileId: Int32) -> URL? {
        cache?.voicePath(fileId: fileId)
    }

    public func playVoice(url: URL) async {
        do {
            try await voicePlayer?.load(url: url)
            await voicePlayer?.play()
            isVoicePlaying = true
        } catch {
            isVoicePlaying = false
        }
    }

    public func pauseVoice() async {
        await voicePlayer?.pause()
        isVoicePlaying = false
    }
}