package com.tt.honeyDue.viewmodel

import androidx.lifecycle.ViewModel
import androidx.lifecycle.viewModelScope
import com.tt.honeyDue.data.DataManager
import com.tt.honeyDue.models.AuthResponse
import com.tt.honeyDue.models.LoginRequest
import com.tt.honeyDue.models.RegisterRequest
import com.tt.honeyDue.models.ResidenceCreateRequest
import com.tt.honeyDue.models.TaskCreateRequest
import com.tt.honeyDue.models.TaskTemplate
import com.tt.honeyDue.models.VerifyEmailRequest
import com.tt.honeyDue.network.ApiResult
import com.tt.honeyDue.network.APILayer
import com.tt.honeyDue.repository.LookupsRepository
import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.StateFlow
import kotlinx.coroutines.launch

/**
 * User's intent during onboarding
 */
enum class OnboardingIntent {
    UNKNOWN,
    START_FRESH,    // Creating a new residence
    JOIN_EXISTING   // Joining with a share code
}

/**
 * Steps in the onboarding flow
 */
enum class OnboardingStep {
    WELCOME,
    VALUE_PROPS,
    NAME_RESIDENCE,
    CREATE_ACCOUNT,
    VERIFY_EMAIL,
    JOIN_RESIDENCE,
    RESIDENCE_LOCATION,
    FIRST_TASK,
    SUBSCRIPTION_UPSELL
}

/**
 * ViewModel for managing the onboarding flow state
 */
class OnboardingViewModel : ViewModel() {

    private val _currentStep = MutableStateFlow(OnboardingStep.WELCOME)
    val currentStep: StateFlow<OnboardingStep> = _currentStep

    private val _userIntent = MutableStateFlow(OnboardingIntent.UNKNOWN)
    val userIntent: StateFlow<OnboardingIntent> = _userIntent

    private val _residenceName = MutableStateFlow("")
    val residenceName: StateFlow<String> = _residenceName

    private val _shareCode = MutableStateFlow("")
    val shareCode: StateFlow<String> = _shareCode

    // Registration state
    private val _registerState = MutableStateFlow<ApiResult<AuthResponse>>(ApiResult.Idle)
    val registerState: StateFlow<ApiResult<AuthResponse>> = _registerState

    // Login state (for returning users)
    private val _loginState = MutableStateFlow<ApiResult<AuthResponse>>(ApiResult.Idle)
    val loginState: StateFlow<ApiResult<AuthResponse>> = _loginState

    // Email verification state
    private val _verifyEmailState = MutableStateFlow<ApiResult<Unit>>(ApiResult.Idle)
    val verifyEmailState: StateFlow<ApiResult<Unit>> = _verifyEmailState

    // Residence creation state
    private val _createResidenceState = MutableStateFlow<ApiResult<Unit>>(ApiResult.Idle)
    val createResidenceState: StateFlow<ApiResult<Unit>> = _createResidenceState

    // Join residence state
    private val _joinResidenceState = MutableStateFlow<ApiResult<Unit>>(ApiResult.Idle)
    val joinResidenceState: StateFlow<ApiResult<Unit>> = _joinResidenceState

    // Task creation state
    private val _createTasksState = MutableStateFlow<ApiResult<Unit>>(ApiResult.Idle)
    val createTasksState: StateFlow<ApiResult<Unit>> = _createTasksState

    // Regional templates state
    private val _regionalTemplates = MutableStateFlow<ApiResult<List<TaskTemplate>>>(ApiResult.Idle)
    val regionalTemplates: StateFlow<ApiResult<List<TaskTemplate>>> = _regionalTemplates

    // ZIP code entered during location step (persisted on residence)
    private val _postalCode = MutableStateFlow("")
    val postalCode: StateFlow<String> = _postalCode

    // Whether onboarding is complete
    private val _isComplete = MutableStateFlow(false)
    val isComplete: StateFlow<Boolean> = _isComplete

    fun setUserIntent(intent: OnboardingIntent) {
        _userIntent.value = intent
    }

    fun setResidenceName(name: String) {
        _residenceName.value = name
    }

    fun setShareCode(code: String) {
        _shareCode.value = code
    }

    /**
     * Move to the next step in the flow
     * Flow: Welcome → Features → Name Residence → Create Account → Verify → Tasks → Upsell
     */
    fun nextStep() {
        _currentStep.value = when (_currentStep.value) {
            OnboardingStep.WELCOME -> {
                if (_userIntent.value == OnboardingIntent.JOIN_EXISTING) {
                    OnboardingStep.CREATE_ACCOUNT
                } else {
                    OnboardingStep.VALUE_PROPS
                }
            }
            OnboardingStep.VALUE_PROPS -> OnboardingStep.NAME_RESIDENCE
            OnboardingStep.NAME_RESIDENCE -> OnboardingStep.CREATE_ACCOUNT
            OnboardingStep.CREATE_ACCOUNT -> OnboardingStep.VERIFY_EMAIL
            OnboardingStep.VERIFY_EMAIL -> {
                if (_userIntent.value == OnboardingIntent.JOIN_EXISTING) {
                    OnboardingStep.JOIN_RESIDENCE
                } else {
                    OnboardingStep.RESIDENCE_LOCATION
                }
            }
            OnboardingStep.JOIN_RESIDENCE -> OnboardingStep.SUBSCRIPTION_UPSELL
            OnboardingStep.RESIDENCE_LOCATION -> OnboardingStep.FIRST_TASK
            OnboardingStep.FIRST_TASK -> OnboardingStep.SUBSCRIPTION_UPSELL
            OnboardingStep.SUBSCRIPTION_UPSELL -> {
                completeOnboarding()
                OnboardingStep.SUBSCRIPTION_UPSELL
            }
        }
    }

    /**
     * Go to a specific step
     */
    fun goToStep(step: OnboardingStep) {
        _currentStep.value = step
    }

    /**
     * Go back to the previous step
     */
    fun previousStep() {
        _currentStep.value = when (_currentStep.value) {
            OnboardingStep.VALUE_PROPS -> OnboardingStep.WELCOME
            OnboardingStep.NAME_RESIDENCE -> OnboardingStep.VALUE_PROPS
            OnboardingStep.CREATE_ACCOUNT -> {
                if (_userIntent.value == OnboardingIntent.JOIN_EXISTING) {
                    OnboardingStep.WELCOME
                } else {
                    OnboardingStep.NAME_RESIDENCE
                }
            }
            OnboardingStep.VERIFY_EMAIL -> OnboardingStep.CREATE_ACCOUNT
            else -> _currentStep.value
        }
    }

    /**
     * Skip the current step (for skippable screens)
     */
    fun skipStep() {
        when (_currentStep.value) {
            OnboardingStep.VALUE_PROPS,
            OnboardingStep.JOIN_RESIDENCE,
            OnboardingStep.RESIDENCE_LOCATION,
            OnboardingStep.FIRST_TASK -> nextStep()
            OnboardingStep.SUBSCRIPTION_UPSELL -> completeOnboarding()
            else -> {}
        }
    }

    /**
     * Register a new user
     */
    fun register(username: String, email: String, password: String) {
        viewModelScope.launch {
            _registerState.value = ApiResult.Loading
            val result = APILayer.register(
                RegisterRequest(
                    username = username,
                    email = email,
                    password = password
                )
            )
            _registerState.value = when (result) {
                is ApiResult.Success -> {
                    DataManager.setAuthToken(result.data.token)
                    DataManager.setCurrentUser(result.data.user)
                    LookupsRepository.initialize()
                    ApiResult.Success(result.data)
                }
                is ApiResult.Error -> result
                else -> ApiResult.Error("Unknown error")
            }
        }
    }

    /**
     * Login an existing user
     */
    fun login(username: String, password: String) {
        viewModelScope.launch {
            _loginState.value = ApiResult.Loading
            val result = APILayer.login(LoginRequest(username, password))
            _loginState.value = when (result) {
                is ApiResult.Success -> {
                    LookupsRepository.initialize()
                    ApiResult.Success(result.data)
                }
                is ApiResult.Error -> result
                else -> ApiResult.Error("Unknown error")
            }
        }
    }

    /**
     * Verify email with 6-digit code
     */
    fun verifyEmail(code: String) {
        viewModelScope.launch {
            _verifyEmailState.value = ApiResult.Loading
            val token = DataManager.authToken.value ?: run {
                _verifyEmailState.value = ApiResult.Error("Not authenticated")
                return@launch
            }
            val result = APILayer.verifyEmail(token, VerifyEmailRequest(code = code))
            _verifyEmailState.value = when (result) {
                is ApiResult.Success -> ApiResult.Success(Unit)
                is ApiResult.Error -> result
                else -> ApiResult.Error("Unknown error")
            }
        }
    }

    /**
     * Create the residence with the name from onboarding
     */
    fun createResidence() {
        viewModelScope.launch {
            if (_residenceName.value.isBlank()) {
                _createResidenceState.value = ApiResult.Success(Unit)
                return@launch
            }

            _createResidenceState.value = ApiResult.Loading

            val result = APILayer.createResidence(
                ResidenceCreateRequest(
                    name = _residenceName.value,
                    propertyTypeId = null,
                    streetAddress = null,
                    apartmentUnit = null,
                    city = null,
                    stateProvince = null,
                    postalCode = _postalCode.value.takeIf { it.isNotBlank() },
                    country = null,
                    bedrooms = null,
                    bathrooms = null,
                    squareFootage = null,
                    lotSize = null,
                    yearBuilt = null,
                    description = null,
                    purchaseDate = null,
                    purchasePrice = null,
                    isPrimary = true
                )
            )

            _createResidenceState.value = when (result) {
                is ApiResult.Success -> ApiResult.Success(Unit)
                is ApiResult.Error -> result
                else -> ApiResult.Error("Failed to create residence")
            }
        }
    }

    /**
     * Join an existing residence with a share code
     */
    fun joinResidence(code: String) {
        viewModelScope.launch {
            _joinResidenceState.value = ApiResult.Loading
            val result = APILayer.joinWithCode(code)
            _joinResidenceState.value = when (result) {
                is ApiResult.Success -> ApiResult.Success(Unit)
                is ApiResult.Error -> result
                else -> ApiResult.Error("Failed to join residence")
            }
        }
    }

    /**
     * Create selected tasks during onboarding
     */
    fun createTasks(taskRequests: List<TaskCreateRequest>) {
        viewModelScope.launch {
            if (taskRequests.isEmpty()) {
                _createTasksState.value = ApiResult.Success(Unit)
                return@launch
            }

            _createTasksState.value = ApiResult.Loading

            var successCount = 0
            for (request in taskRequests) {
                val result = APILayer.createTask(request)
                if (result is ApiResult.Success) {
                    successCount++
                }
            }

            _createTasksState.value = if (successCount > 0) {
                ApiResult.Success(Unit)
            } else {
                ApiResult.Error("Failed to create tasks")
            }
        }
    }

    /**
     * Load regional templates by ZIP code (backend resolves ZIP → state → climate zone).
     * Also stores the ZIP code for later use when creating the residence.
     */
    fun loadRegionalTemplates(zip: String) {
        _postalCode.value = zip
        viewModelScope.launch {
            _regionalTemplates.value = ApiResult.Loading
            _regionalTemplates.value = APILayer.getRegionalTemplates(zip = zip)
        }
    }

    /**
     * Mark onboarding as complete
     */
    fun completeOnboarding() {
        _isComplete.value = true
    }

    /**
     * Reset all state (useful for testing)
     */
    fun reset() {
        _currentStep.value = OnboardingStep.WELCOME
        _userIntent.value = OnboardingIntent.UNKNOWN
        _residenceName.value = ""
        _shareCode.value = ""
        _registerState.value = ApiResult.Idle
        _loginState.value = ApiResult.Idle
        _verifyEmailState.value = ApiResult.Idle
        _createResidenceState.value = ApiResult.Idle
        _joinResidenceState.value = ApiResult.Idle
        _createTasksState.value = ApiResult.Idle
        _regionalTemplates.value = ApiResult.Idle
        _postalCode.value = ""
        _isComplete.value = false
    }

    fun resetRegisterState() {
        _registerState.value = ApiResult.Idle
    }

    fun resetLoginState() {
        _loginState.value = ApiResult.Idle
    }

    fun resetVerifyEmailState() {
        _verifyEmailState.value = ApiResult.Idle
    }
}