// SPDX-License-Identifier: GPL-3.0-or-later
// MyIce Kotlin Multiplatform — schedule/convocation viewer
// Copyright (C) 2026  parano.ch
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

package ch.parano.myicek.viewmodel

import ch.parano.myicek.auth.AuthSettings
import ch.parano.myicek.auth.OAuthClient
import ch.parano.myicek.network.ApiConfig
import ch.parano.myicek.network.ApiService
import ch.parano.myicek.network.AuthTokenHolder
import androidx.lifecycle.ViewModel
import androidx.lifecycle.viewModelScope
import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.StateFlow
import kotlinx.coroutines.flow.asStateFlow
import kotlinx.coroutines.launch

sealed class AuthState {
    data object Loading : AuthState()
    data class Authenticated(val email: String) : AuthState()
    data object Unauthenticated : AuthState()
}

class AuthViewModel(
    private val apiService: ApiService,
    private val authSettings: AuthSettings,
    private val oauthClient: OAuthClient,
) : ViewModel() {

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

    fun init() {
        viewModelScope.launch {
            val token = authSettings.getStoredToken()
            if (token != null) {
                AuthTokenHolder.token = token
                try {
                    val userInfo = apiService.getUserInfo()
                    _state.value = AuthState.Authenticated(userInfo.email)
                } catch (e: Exception) {
                    authSettings.clear()
                    _state.value = AuthState.Unauthenticated
                }
            } else {
                _state.value = AuthState.Unauthenticated
            }
        }
    }

    fun login() {
        viewModelScope.launch {
            _state.value = AuthState.Loading
            try {
                val loginUrl = "${ApiConfig.baseUrl}/login?redirect_uri=" +
                    oauthClient.redirectUri()
                val token = oauthClient.authenticate(loginUrl)
                if (token != null) {
                    authSettings.setToken(token)
                    val userInfo = apiService.getUserInfo()
                    _state.value = AuthState.Authenticated(userInfo.email)
                } else {
                    _state.value = AuthState.Unauthenticated
                }
            } catch (e: Exception) {
                _state.value = AuthState.Unauthenticated
            }
        }
    }

    fun logout() {
        authSettings.clear()
        _state.value = AuthState.Unauthenticated
    }
}