package com.aistudio.bonjuteri.jwlry.ui.screens

import android.app.Activity
import android.content.Context
import android.util.Log
import androidx.compose.foundation.Image
import androidx.compose.foundation.background
import androidx.compose.foundation.border
import androidx.compose.ui.draw.clip
import androidx.compose.ui.res.painterResource
import androidx.compose.foundation.clickable
import androidx.compose.foundation.layout.Arrangement
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.Row
import androidx.compose.foundation.layout.Spacer
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.height
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.size
import androidx.compose.foundation.layout.width
import androidx.compose.foundation.rememberScrollState
import androidx.compose.foundation.shape.CircleShape
import androidx.compose.foundation.shape.RoundedCornerShape
import androidx.compose.foundation.text.KeyboardOptions
import androidx.compose.foundation.verticalScroll
import androidx.compose.material.icons.Icons
import androidx.compose.material.icons.filled.Email
import androidx.compose.material.icons.filled.Lock
import androidx.compose.material.icons.filled.Person
import androidx.compose.material.icons.filled.Visibility
import androidx.compose.material.icons.filled.VisibilityOff
import androidx.compose.material.icons.outlined.Diamond
import androidx.compose.material3.AlertDialog
import androidx.compose.material3.Button
import androidx.compose.material3.ButtonDefaults
import androidx.compose.material3.Card
import androidx.compose.material3.CardDefaults
import androidx.compose.material3.CircularProgressIndicator
import androidx.compose.material3.HorizontalDivider
import androidx.compose.material3.Icon
import androidx.compose.material3.IconButton
import androidx.compose.material3.MaterialTheme
import androidx.compose.material3.OutlinedButton
import androidx.compose.material3.OutlinedTextField
import androidx.compose.material3.SnackbarHostState
import androidx.compose.material3.Tab
import androidx.compose.material3.TabRow
import androidx.compose.material3.TabRowDefaults
import androidx.compose.material3.TabRowDefaults.tabIndicatorOffset
import androidx.compose.material3.Text
import androidx.compose.runtime.Composable
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableIntStateOf
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.rememberCoroutineScope
import androidx.compose.runtime.setValue
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.platform.LocalContext
import androidx.compose.ui.platform.testTag
import androidx.compose.ui.text.font.FontWeight
import androidx.compose.ui.text.input.KeyboardType
import androidx.compose.ui.text.input.PasswordVisualTransformation
import androidx.compose.ui.text.input.VisualTransformation
import androidx.compose.ui.text.style.TextAlign
import androidx.compose.ui.unit.dp
import androidx.compose.ui.unit.sp
import androidx.credentials.ClearCredentialStateRequest
import androidx.credentials.CredentialManager
import androidx.credentials.CustomCredential
import androidx.credentials.GetCredentialRequest
import androidx.credentials.exceptions.GetCredentialCancellationException
import com.aistudio.bonjuteri.jwlry.R
import com.aistudio.bonjuteri.jwlry.model.UserProfile
import com.aistudio.bonjuteri.jwlry.ui.theme.GoldDark
import com.aistudio.bonjuteri.jwlry.ui.theme.GoldPrimary
import com.aistudio.bonjuteri.jwlry.ui.theme.GoldSubtle
import com.aistudio.bonjuteri.jwlry.ui.theme.MutedGrey
import com.aistudio.bonjuteri.jwlry.ui.theme.PrimaryBlack
import com.aistudio.bonjuteri.jwlry.ui.theme.PureWhite
import com.aistudio.bonjuteri.jwlry.ui.theme.SurfaceBorder
import com.google.android.libraries.identity.googleid.GetSignInWithGoogleOption
import com.google.android.libraries.identity.googleid.GoogleIdTokenCredential
import com.google.firebase.auth.AuthCredential
import com.google.firebase.auth.GoogleAuthProvider
import kotlinx.coroutines.launch

@Composable
fun AuthScreen(
    onSignInWithEmail: suspend (String, String) -> Result<UserProfile>,
    onSignUpWithEmail: suspend (String, String, String, String) -> Result<UserProfile>,
    onSignInWithCredential: suspend (AuthCredential) -> Result<UserProfile>,
    onSendPasswordReset: suspend (String) -> Result<Unit>,
    onAuthSuccess: (UserProfile) -> Unit,
    snackbarHostState: SnackbarHostState,
    modifier: Modifier = Modifier
) {
    val context = LocalContext.current
    val scope = rememberCoroutineScope()
    var selectedTab by remember { mutableIntStateOf(0) } // 0: Giriş Yap, 1: Kayıt Ol

    // Login Form State
    var loginEmail by remember { mutableStateOf("") }
    var loginPassword by remember { mutableStateOf("") }
    var isLoginPasswordVisible by remember { mutableStateOf(false) }

    // Register Form State
    var registerFirstName by remember { mutableStateOf("") }
    var registerLastName by remember { mutableStateOf("") }
    var registerEmail by remember { mutableStateOf("") }
    var registerPassword by remember { mutableStateOf("") }
    var isRegisterPasswordVisible by remember { mutableStateOf(false) }

    var isLoading by remember { mutableStateOf(false) }
    var errorMessage by remember { mutableStateOf<String?>(null) }

    // Forgot password dialog
    var showForgotPasswordDialog by remember { mutableStateOf(false) }
    var resetEmail by remember { mutableStateOf("") }
    var resetMessage by remember { mutableStateOf<String?>(null) }
    var isResetLoading by remember { mutableStateOf(false) }

    Column(
        modifier = modifier
            .fillMaxSize()
            .background(PureWhite)
            .verticalScroll(rememberScrollState())
            .padding(24.dp),
        horizontalAlignment = Alignment.CenterHorizontally
    ) {
        Spacer(modifier = Modifier.height(24.dp))

        // Luxury Boutique Brand 3D Emblem
        Image(
            painter = painterResource(id = R.drawable.img_app_icon_3d),
            contentDescription = "BONJUTERİ",
            modifier = Modifier
                .size(76.dp)
                .clip(CircleShape)
        )

        Spacer(modifier = Modifier.height(12.dp))

        Text(
            text = "BONJUTERİ",
            style = MaterialTheme.typography.headlineMedium.copy(
                fontWeight = FontWeight.Black,
                letterSpacing = 2.5.sp,
                color = PrimaryBlack
            )
        )

        Text(
            text = "ÖZEL TASARIM & MÜCEVHER BUTİĞİ",
            style = MaterialTheme.typography.labelSmall.copy(
                fontSize = 9.sp,
                fontWeight = FontWeight.Bold,
                letterSpacing = 1.5.sp,
                color = GoldDark
            )
        )

        Spacer(modifier = Modifier.height(28.dp))

        // Tabs: Giriş Yap / Kayıt Ol
        TabRow(
            selectedTabIndex = selectedTab,
            containerColor = PureWhite,
            indicator = { tabPositions ->
                TabRowDefaults.SecondaryIndicator(
                    modifier = Modifier.tabIndicatorOffset(tabPositions[selectedTab]),
                    color = PrimaryBlack,
                    height = 2.5.dp
                )
            }
        ) {
            Tab(
                selected = selectedTab == 0,
                onClick = {
                    selectedTab = 0
                    errorMessage = null
                },
                text = {
                    Text(
                        text = "Giriş Yap",
                        fontWeight = if (selectedTab == 0) FontWeight.Bold else FontWeight.Medium,
                        color = if (selectedTab == 0) PrimaryBlack else MutedGrey,
                        fontSize = 15.sp
                    )
                },
                modifier = Modifier.testTag("auth_tab_login")
            )
            Tab(
                selected = selectedTab == 1,
                onClick = {
                    selectedTab = 1
                    errorMessage = null
                },
                text = {
                    Text(
                        text = "Kayıt Ol",
                        fontWeight = if (selectedTab == 1) FontWeight.Bold else FontWeight.Medium,
                        color = if (selectedTab == 1) PrimaryBlack else MutedGrey,
                        fontSize = 15.sp
                    )
                },
                modifier = Modifier.testTag("auth_tab_register")
            )
        }

        Spacer(modifier = Modifier.height(20.dp))

        // Error message banner
        if (errorMessage != null) {
            Card(
                colors = CardDefaults.cardColors(containerColor = MaterialTheme.colorScheme.errorContainer),
                shape = RoundedCornerShape(8.dp),
                modifier = Modifier
                    .fillMaxWidth()
                    .padding(bottom = 14.dp)
            ) {
                Text(
                    text = errorMessage!!,
                    color = MaterialTheme.colorScheme.onErrorContainer,
                    fontSize = 13.sp,
                    modifier = Modifier.padding(12.dp)
                )
            }
        }

        if (selectedTab == 0) {
            // LOGIN FORM
            Column(
                modifier = Modifier.fillMaxWidth(),
                verticalArrangement = Arrangement.spacedBy(14.dp)
            ) {
                OutlinedTextField(
                    value = loginEmail,
                    onValueChange = { loginEmail = it },
                    label = { Text("E-posta Adresi") },
                    leadingIcon = { Icon(Icons.Filled.Email, contentDescription = null, tint = MutedGrey) },
                    modifier = Modifier
                        .fillMaxWidth()
                        .testTag("login_email_input"),
                    singleLine = true,
                    keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Email)
                )

                OutlinedTextField(
                    value = loginPassword,
                    onValueChange = { loginPassword = it },
                    label = { Text("Şifre") },
                    leadingIcon = { Icon(Icons.Filled.Lock, contentDescription = null, tint = MutedGrey) },
                    trailingIcon = {
                        IconButton(onClick = { isLoginPasswordVisible = !isLoginPasswordVisible }) {
                            Icon(
                                imageVector = if (isLoginPasswordVisible) Icons.Filled.VisibilityOff else Icons.Filled.Visibility,
                                contentDescription = "Şifreyi Göster",
                                tint = MutedGrey
                            )
                        }
                    },
                    visualTransformation = if (isLoginPasswordVisible) VisualTransformation.None else PasswordVisualTransformation(),
                    modifier = Modifier
                        .fillMaxWidth()
                        .testTag("login_password_input"),
                    singleLine = true,
                    keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Password)
                )

                // Forgot Password link
                Row(
                    modifier = Modifier.fillMaxWidth(),
                    horizontalArrangement = Arrangement.End
                ) {
                    Text(
                        text = "Şifremi Unuttum",
                        color = GoldDark,
                        fontWeight = FontWeight.SemiBold,
                        fontSize = 12.sp,
                        modifier = Modifier
                            .clickable {
                                resetEmail = loginEmail
                                resetMessage = null
                                showForgotPasswordDialog = true
                            }
                            .testTag("forgot_password_link")
                    )
                }

                Spacer(modifier = Modifier.height(6.dp))

                Button(
                    onClick = {
                        scope.launch {
                            isLoading = true
                            errorMessage = null
                            val result = onSignInWithEmail(loginEmail, loginPassword)
                            isLoading = false
                            if (result.isSuccess) {
                                onAuthSuccess(result.getOrThrow())
                            } else {
                                errorMessage = result.exceptionOrNull()?.message ?: "Giriş başarısız oldu."
                            }
                        }
                    },
                    enabled = !isLoading,
                    modifier = Modifier
                        .fillMaxWidth()
                        .height(50.dp)
                        .testTag("login_submit_button"),
                    shape = RoundedCornerShape(10.dp),
                    colors = ButtonDefaults.buttonColors(
                        containerColor = PrimaryBlack,
                        contentColor = PureWhite
                    )
                ) {
                    if (isLoading) {
                        CircularProgressIndicator(color = PureWhite, modifier = Modifier.size(22.dp))
                    } else {
                        Text("Giriş Yap", fontWeight = FontWeight.Bold, fontSize = 15.sp)
                    }
                }
            }
        } else {
            // REGISTER FORM
            Column(
                modifier = Modifier.fillMaxWidth(),
                verticalArrangement = Arrangement.spacedBy(14.dp)
            ) {
                Row(horizontalArrangement = Arrangement.spacedBy(10.dp)) {
                    OutlinedTextField(
                        value = registerFirstName,
                        onValueChange = { registerFirstName = it },
                        label = { Text("Ad") },
                        leadingIcon = { Icon(Icons.Filled.Person, contentDescription = null, tint = MutedGrey) },
                        modifier = Modifier
                            .weight(1f)
                            .testTag("register_first_name_input"),
                        singleLine = true
                    )
                    OutlinedTextField(
                        value = registerLastName,
                        onValueChange = { registerLastName = it },
                        label = { Text("Soyad") },
                        modifier = Modifier
                            .weight(1f)
                            .testTag("register_last_name_input"),
                        singleLine = true
                    )
                }

                OutlinedTextField(
                    value = registerEmail,
                    onValueChange = { registerEmail = it },
                    label = { Text("E-posta Adresi") },
                    leadingIcon = { Icon(Icons.Filled.Email, contentDescription = null, tint = MutedGrey) },
                    modifier = Modifier
                        .fillMaxWidth()
                        .testTag("register_email_input"),
                    singleLine = true,
                    keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Email)
                )

                OutlinedTextField(
                    value = registerPassword,
                    onValueChange = { registerPassword = it },
                    label = { Text("Şifre (En az 6 karakter)") },
                    leadingIcon = { Icon(Icons.Filled.Lock, contentDescription = null, tint = MutedGrey) },
                    trailingIcon = {
                        IconButton(onClick = { isRegisterPasswordVisible = !isRegisterPasswordVisible }) {
                            Icon(
                                imageVector = if (isRegisterPasswordVisible) Icons.Filled.VisibilityOff else Icons.Filled.Visibility,
                                contentDescription = "Şifreyi Göster",
                                tint = MutedGrey
                            )
                        }
                    },
                    visualTransformation = if (isRegisterPasswordVisible) VisualTransformation.None else PasswordVisualTransformation(),
                    modifier = Modifier
                        .fillMaxWidth()
                        .testTag("register_password_input"),
                    singleLine = true,
                    keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Password)
                )

                Spacer(modifier = Modifier.height(6.dp))

                Button(
                    onClick = {
                        scope.launch {
                            isLoading = true
                            errorMessage = null
                            val result = onSignUpWithEmail(
                                registerFirstName,
                                registerLastName,
                                registerEmail,
                                registerPassword
                            )
                            isLoading = false
                            if (result.isSuccess) {
                                onAuthSuccess(result.getOrThrow())
                            } else {
                                errorMessage = result.exceptionOrNull()?.message ?: "Kayıt işlemi başarısız."
                            }
                        }
                    },
                    enabled = !isLoading,
                    modifier = Modifier
                        .fillMaxWidth()
                        .height(50.dp)
                        .testTag("register_submit_button"),
                    shape = RoundedCornerShape(10.dp),
                    colors = ButtonDefaults.buttonColors(
                        containerColor = PrimaryBlack,
                        contentColor = PureWhite
                    )
                ) {
                    if (isLoading) {
                        CircularProgressIndicator(color = PureWhite, modifier = Modifier.size(22.dp))
                    } else {
                        Text("Hesap Oluştur", fontWeight = FontWeight.Bold, fontSize = 15.sp)
                    }
                }
            }
        }

        Spacer(modifier = Modifier.height(24.dp))

        // Divider
        Row(
            modifier = Modifier.fillMaxWidth(),
            verticalAlignment = Alignment.CenterVertically
        ) {
            HorizontalDivider(modifier = Modifier.weight(1f), color = SurfaceBorder)
            Text(
                text = "VEYA",
                modifier = Modifier.padding(horizontal = 12.dp),
                color = MutedGrey,
                fontSize = 11.sp,
                fontWeight = FontWeight.Bold
            )
            HorizontalDivider(modifier = Modifier.weight(1f), color = SurfaceBorder)
        }

        Spacer(modifier = Modifier.height(20.dp))

        // Google Sign In Button via Credential Manager
        OutlinedButton(
            onClick = {
                handleGoogleSignIn(
                    context = context,
                    scope = scope,
                    onLoading = { isLoading = it },
                    onError = { errorMessage = it },
                    onCredential = { cred ->
                        scope.launch {
                            isLoading = true
                            val result = onSignInWithCredential(cred)
                            isLoading = false
                            if (result.isSuccess) {
                                onAuthSuccess(result.getOrThrow())
                            } else {
                                errorMessage = result.exceptionOrNull()?.message ?: "Google ile giriş başarısız."
                            }
                        }
                    }
                )
            },
            modifier = Modifier
                .fillMaxWidth()
                .height(50.dp)
                .testTag("google_sign_in_button"),
            shape = RoundedCornerShape(10.dp),
            border = androidx.compose.foundation.BorderStroke(1.dp, SurfaceBorder)
        ) {
            Text(
                text = "Google ile Giriş Yap",
                color = PrimaryBlack,
                fontWeight = FontWeight.Bold,
                fontSize = 14.sp
            )
        }

        Spacer(modifier = Modifier.height(24.dp))
    }

    // Forgot Password Dialog
    if (showForgotPasswordDialog) {
        AlertDialog(
            onDismissRequest = { showForgotPasswordDialog = false },
            title = { Text("Şifremi Unuttum", fontWeight = FontWeight.Bold) },
            text = {
                Column(verticalArrangement = Arrangement.spacedBy(10.dp)) {
                    Text(
                        text = "Kayıtlı e-posta adresinizi giriniz. Şifre sıfırlama bağlantısı gönderilecektir.",
                        fontSize = 13.sp,
                        color = MutedGrey
                    )
                    OutlinedTextField(
                        value = resetEmail,
                        onValueChange = { resetEmail = it },
                        label = { Text("E-posta Adresi") },
                        modifier = Modifier.fillMaxWidth(),
                        singleLine = true,
                        keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Email)
                    )
                    if (resetMessage != null) {
                        Text(
                            text = resetMessage!!,
                            color = if (resetMessage!!.contains("gönderildi", ignoreCase = true)) GoldDark else MaterialTheme.colorScheme.error,
                            fontSize = 12.sp,
                            fontWeight = FontWeight.Medium
                        )
                    }
                }
            },
            confirmButton = {
                Button(
                    onClick = {
                        scope.launch {
                            isResetLoading = true
                            val res = onSendPasswordReset(resetEmail)
                            isResetLoading = false
                            if (res.isSuccess) {
                                resetMessage = "Sıfırlama bağlantısı e-posta adresinize gönderildi!"
                            } else {
                                resetMessage = res.exceptionOrNull()?.message ?: "Sıfırlama e-postası gönderilemedi."
                            }
                        }
                    },
                    colors = ButtonDefaults.buttonColors(containerColor = PrimaryBlack)
                ) {
                    if (isResetLoading) {
                        CircularProgressIndicator(color = PureWhite, modifier = Modifier.size(16.dp))
                    } else {
                        Text("Gönder")
                    }
                }
            },
            dismissButton = {
                OutlinedButton(onClick = { showForgotPasswordDialog = false }) {
                    Text("Kapat")
                }
            }
        )
    }
}

private fun handleGoogleSignIn(
    context: Context,
    scope: kotlinx.coroutines.CoroutineScope,
    onLoading: (Boolean) -> Unit,
    onError: (String) -> Unit,
    onCredential: (AuthCredential) -> Unit
) {
    val clientId = try {
        context.getString(R.string.default_web_client_id)
    } catch (_: Exception) {
        onError("Google Sign-In yapılandırması bulunamadı (default_web_client_id eksik).")
        return
    }

    val credentialManager = CredentialManager.create(context)
    val signInOption = GetSignInWithGoogleOption.Builder(serverClientId = clientId).build()
    val request = GetCredentialRequest.Builder().addCredentialOption(signInOption).build()

    onLoading(true)
    scope.launch {
        try {
            val result = credentialManager.getCredential(context as Activity, request)
            val credential = result.credential
            if (credential is CustomCredential && credential.type == GoogleIdTokenCredential.TYPE_GOOGLE_ID_TOKEN_CREDENTIAL) {
                val googleIdToken = GoogleIdTokenCredential.createFrom(credential.data).idToken
                val authCredential = GoogleAuthProvider.getCredential(googleIdToken, null)
                onCredential(authCredential)
            } else {
                onError("Google kimlik bilgisi doğrulanamadı.")
                onLoading(false)
            }
        } catch (e: GetCredentialCancellationException) {
            Log.w("AuthScreen", "Google Giriş iptal edildi: ${e.message}")
            onLoading(false)
        } catch (e: Exception) {
            Log.e("AuthScreen", "Google Giriş hatası", e)
            onError(e.localizedMessage ?: "Google ile giriş yapılamadı.")
            onLoading(false)
        }
    }
}