package chats.presentation.chat_detail

import androidx.lifecycle.ViewModel
import androidx.lifecycle.viewModelScope
import chats.data.remote.signalr.ChatEvent
import chats.data.remote.signalr.ChatHubClient
import chats.domain.model.Message
import chats.domain.repository.ChatRepository
import chats.data.repository.toDomain
import core.network.ServerConfig
import core.security.TokenManager
import dagger.hilt.android.lifecycle.HiltViewModel
import kotlinx.coroutines.Job
import kotlinx.coroutines.delay
import kotlinx.coroutines.flow.*
import kotlinx.coroutines.launch
import java.io.File
import javax.inject.Inject

import chats.data.remote.api.KlipyGifDto

data class ChatDetailState(
    val messages: List<Message> = emptyList(),
    val chatName: String? = null,
    val chatAvatar: String? = null,
    val isLoading: Boolean = false,
    val isTyping: Boolean = false,
    val typingUser: String? = null,
    val error: String? = null,
    val canCall: Boolean = true,
    val maxFileSize: Long = 100 * 1024 * 1024,
    val trendingGifs: List<KlipyGifDto> = emptyList(),
    val searchedGifs: List<KlipyGifDto> = emptyList(),
    val recentGifs: List<KlipyGifDto> = emptyList(),
    val gifCategories: List<chats.data.remote.api.GifCategoryDto> = emptyList(),
    val isGifsLoading: Boolean = false,
    val initialScrollIndex: Int? = null
)

@HiltViewModel
class ChatDetailViewModel @Inject constructor(
    private val repository: ChatRepository,
    private val signalrClient: ChatHubClient,
    private val serverConfig: ServerConfig,
    private val tokenManager: TokenManager
) : ViewModel() {

    private val _state = MutableStateFlow(ChatDetailState())
    val state: StateFlow<ChatDetailState> = _state.asStateFlow()

    private var currentChatId: String? = null
    private var typingTimerJob: Job? = null
    private var lastTypingSentTime: Long = 0

    init {
        val config = serverConfig.getServerConfig()
        _state.update { it.copy(
            canCall = config.features.calls,
            maxFileSize = config.limits.maxFileSize
        ) }
    }

    fun getCurrentUserId(): String {
        return tokenManager.getUserId() ?: ""
    }

    fun setChatId(chatId: String) {
        currentChatId = chatId
        
        // Ensure SignalR is connected
        val token = tokenManager.getToken()
        if (token != null) {
            val baseUrl = serverConfig.getBaseUrl().removeSuffix("/api")
            signalrClient.connect(baseUrl, token)
        }
        
        loadChatInfo(chatId)
        observeMessages(chatId)
        observeSignalREvents()
        
        // Initial sync from network
        refreshMessages(chatId)
    }

    private fun observeMessages(chatId: String) {
        repository.getMessagesFlow(chatId)
            .onEach { messages ->
                _state.update { it.copy(messages = messages) }
                // Calculate scroll index if not set
                if (_state.value.initialScrollIndex == null && messages.isNotEmpty()) {
                    val firstUnreadIndex = messages.indexOfFirst { !it.isRead && it.senderId != getCurrentUserId() }
                    val targetIndex = if (firstUnreadIndex != -1) firstUnreadIndex else messages.size - 1
                    _state.update { it.copy(initialScrollIndex = targetIndex) }
                    
                    // Automark as read
                    markAsRead()
                }
            }
            .launchIn(viewModelScope)
    }

    fun refreshMessages(chatId: String) {
        viewModelScope.launch {
            repository.getMessages(chatId)
        }
    }

    private fun loadChatInfo(chatId: String) {
        viewModelScope.launch {
            try {
                val chats = repository.getChats()
                val chat = chats.find { it.id == chatId }
                chat?.let { c ->
                    _state.update { it.copy(chatName = c.name, chatAvatar = c.avatar) }
                }
            } catch (e: Exception) {
                // Ignore info load error
            }
        }
    }

    private fun updateMessageReaction(messageId: String, userId: String, emoji: String) {
        _state.update { s ->
            val updatedMessages = s.messages.map { msg ->
                if (msg.id == messageId) {
                    val currentReactions = msg.reactions.toMutableMap()
                    currentReactions[emoji] = (currentReactions[emoji] ?: 0) + 1
                    msg.copy(reactions = currentReactions)
                } else msg
            }
            s.copy(messages = updatedMessages)
        }
    }

    private fun observeSignalREvents() {
        signalrClient.events
            .filter { event -> 
                when(event) {
                    is ChatEvent.NewMessage -> event.message.chatId == currentChatId
                    is ChatEvent.ReactionUpdated -> event.chatId == currentChatId
                    is ChatEvent.UserTyping -> event.chatId == currentChatId
                    else -> false
                }
            }
            .onEach { event ->
                when (event) {
                    is ChatEvent.NewMessage -> {
                        val baseUrl = serverConfig.getBaseUrl().removeSuffix("/api/")
                        val domainMsg = event.message.toDomain(baseUrl)
                        viewModelScope.launch {
                            repository.saveMessage(domainMsg)
                        }
                    }
                    is ChatEvent.ReactionUpdated -> {
                        updateMessageReaction(event.messageId, event.userId, event.emoji)
                    }
                    is ChatEvent.UserTyping -> {
                        _state.update { it.copy(isTyping = true) }
                        // Reset typing status after some delay would be better, 
                        // but usually server sends stopped_typing event.
                    }
                    else -> Unit
                }
            }
            .launchIn(viewModelScope)
    }

    fun markAsRead() {
        val chatId = currentChatId ?: return
        val messages = _state.value.messages
        if (messages.isEmpty()) return
        
        val lastMessage = messages.last()
        viewModelScope.launch {
            try {
                repository.markMessagesAsRead(chatId, lastMessage.id, lastMessage.sequenceId)
            } catch (e: Exception) {
                // Ignore
            }
        }
    }
    fun sendMessage(text: String) {
        val chatId = currentChatId ?: return
        if (text.isBlank()) return

        val tempId = "temp_${System.currentTimeMillis()}"
        val userId = getCurrentUserId()
        
        val tempMessage = Message(
            id = tempId,
            chatId = chatId,
            senderId = userId,
            content = text,
            createdAt = java.util.Date().toString(),
            mediaType = chats.domain.model.MediaType.TEXT,
            media = emptyList(),
            senderName = "Вы",
            senderAvatar = null,
            reactions = emptyMap(),
            isRead = false,
            sequenceId = 0
        )

        viewModelScope.launch {
            repository.saveMessage(tempMessage)
        }

        viewModelScope.launch {
            try {
                val sentMessage = repository.sendMessage(chatId, text)
                repository.deleteLocalMessage(tempId)
                repository.saveMessage(sentMessage)
            } catch (e: Exception) {
                repository.deleteLocalMessage(tempId)
                _state.update { it.copy(error = e.localizedMessage) }
            }
        }
    }

    fun addReaction(messageId: String, emoji: String) {
        viewModelScope.launch {
            try {
                repository.addReaction(messageId, emoji)
            } catch (e: Exception) {
                // Ignore
            }
        }
    }

    fun uploadMedia(file: File) {
        if (file.length() > _state.value.maxFileSize) {
            _state.update { it.copy(error = "File too large") }
            return
        }
        viewModelScope.launch {
             try {
                 val url = repository.uploadMedia(file)
                 // After upload, we might want to send a message with this media
                 // For now, let's just log it or handle as per app requirements
             } catch (e: Exception) {
                 _state.update { it.copy(error = e.localizedMessage) }
             }
        }
    }

    fun loadTrendingGifs() {
        if (_state.value.trendingGifs.isNotEmpty()) return 
        
        viewModelScope.launch {
            _state.update { it.copy(isGifsLoading = true) }
            try {
                val gifs = repository.getTrendingGifs(0)
                _state.update { it.copy(trendingGifs = gifs, isGifsLoading = false) }
            } catch (e: Exception) {
                _state.update { it.copy(isGifsLoading = false, error = "GIF load error: ${e.message}") }
            }
        }
    }

    fun loadGifCategories() {
        if (_state.value.gifCategories.isNotEmpty()) return
        viewModelScope.launch {
            try {
                val categories = repository.getGifCategories()
                _state.update { it.copy(gifCategories = categories) }
            } catch (e: Exception) {
                // Ignore failure
            }
        }
    }

    private var searchJob: Job? = null
    fun searchGifs(query: String) {
        searchJob?.cancel()
        if (query.isBlank()) {
            _state.update { it.copy(searchedGifs = emptyList()) }
            return
        }
        searchJob = viewModelScope.launch {
            delay(500)
            _state.update { it.copy(isGifsLoading = true) }
            try {
                val gifs = repository.searchGifs(query, 0)
                _state.update { it.copy(searchedGifs = gifs, isGifsLoading = false) }
            } catch (e: Exception) {
                _state.update { it.copy(isGifsLoading = false) }
            }
        }
    }

    fun sendGif(url: String) {
        val chatId = currentChatId ?: return
        val tempId = "temp_gif_${System.currentTimeMillis()}"
        val userId = getCurrentUserId()

        val tempMessage = Message(
            id = tempId,
            chatId = chatId,
            senderId = userId,
            content = url,
            createdAt = java.util.Date().toString(),
            mediaType = chats.domain.model.MediaType.IMAGE, // We map GIF to IMAGE for rendering
            media = listOf(chats.domain.model.Media(url = url, type = "image", id = "temp_media")),
            senderName = "Вы",
            senderAvatar = null,
            reactions = emptyMap(),
            isRead = false,
            sequenceId = 0
        )

        viewModelScope.launch {
            repository.saveMessage(tempMessage)
        }

        viewModelScope.launch {
            try {
                val attachment = chats.data.remote.api.AttachmentRequest(
                    type = "image",
                    url = url,
                    fileName = "gif.gif",
                    fileSize = 0
                )
                val sentMessage = repository.sendMessage(chatId, null, "image", listOf(attachment))
                
                repository.deleteLocalMessage(tempId)
                repository.saveMessage(sentMessage)

                // Add to recent
                val allGifs = _state.value.trendingGifs + _state.value.searchedGifs + _state.value.recentGifs
                val selectedGif = allGifs.find { gif ->
                    val gifUrl = gif.files?.get("hd")?.get("gif")?.url 
                        ?: gif.files?.get("sd")?.get("gif")?.url 
                        ?: gif.file?.get("hd")?.get("gif")?.url 
                        ?: gif.file?.get("sd")?.get("gif")?.url 
                        ?: gif.media_formats?.get("gif")?.url 
                        ?: gif.images?.original?.url
                    gifUrl == url
                }
                
                selectedGif?.let { gif ->
                    val newList = (listOf(gif) + _state.value.recentGifs).distinctBy { it.id }.take(20)
                    _state.update { it.copy(recentGifs = newList) }
                }
            } catch (e: Exception) {
                repository.deleteLocalMessage(tempId)
                _state.update { it.copy(error = e.localizedMessage) }
            }
        }
    }
}