package com.jovan.assistant.ui

import androidx.compose.foundation.layout.Arrangement
import androidx.compose.foundation.layout.Column
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.imePadding
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.size
import androidx.compose.foundation.rememberScrollState
import androidx.compose.foundation.text.KeyboardOptions
import androidx.compose.foundation.verticalScroll
import androidx.compose.material.icons.Icons
import androidx.compose.material.icons.filled.GraphicEq
import androidx.compose.material3.Button
import androidx.compose.material3.CircularProgressIndicator
import androidx.compose.material3.Icon
import androidx.compose.material3.MaterialTheme
import androidx.compose.material3.OutlinedTextField
import androidx.compose.material3.Text
import androidx.compose.material3.TextButton
import androidx.compose.runtime.Composable
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableIntStateOf
import androidx.compose.runtime.mutableLongStateOf
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.text.input.KeyboardType
import androidx.compose.ui.text.input.PasswordVisualTransformation
import androidx.compose.ui.unit.dp
import com.jovan.assistant.data.FirebaseRepo
import kotlinx.coroutines.launch

private const val MAX_FAILS = 3
private const val COOLDOWN_MS = 30_000L

@Composable
fun AuthScreen() {
    val scope = rememberCoroutineScope()
    var registering by remember { mutableStateOf(false) }
    var email by remember { mutableStateOf("") }
    var password by remember { mutableStateOf("") }
    var confirm by remember { mutableStateOf("") }
    var error by remember { mutableStateOf<String?>(null) }
    var loading by remember { mutableStateOf(false) }
    var fails by remember { mutableIntStateOf(0) }
    var lockedUntil by remember { mutableLongStateOf(0L) }

    Column(
        Modifier.fillMaxSize().imePadding().verticalScroll(rememberScrollState()).padding(28.dp),
        verticalArrangement = Arrangement.Center,
        horizontalAlignment = Alignment.CenterHorizontally
    ) {
        Icon(Icons.Filled.GraphicEq, null, Modifier.size(56.dp), tint = MaterialTheme.colorScheme.primary)
        Spacer(Modifier.height(12.dp))
        Text("AI Voice Assistant", style = MaterialTheme.typography.headlineMedium)
        Text(
            if (registering) "Create your account" else "Sign in to continue",
            color = MaterialTheme.colorScheme.onSurfaceVariant
        )
        Spacer(Modifier.height(28.dp))

        OutlinedTextField(
            email, { email = it }, label = { Text("Email") }, singleLine = true,
            keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Email),
            modifier = Modifier.fillMaxWidth()
        )
        Spacer(Modifier.height(12.dp))
        OutlinedTextField(
            password, { password = it }, label = { Text("Password") }, singleLine = true,
            visualTransformation = PasswordVisualTransformation(),
            keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Password),
            modifier = Modifier.fillMaxWidth()
        )
        if (registering) {
            Spacer(Modifier.height(12.dp))
            OutlinedTextField(
                confirm, { confirm = it }, label = { Text("Confirm password") }, singleLine = true,
                visualTransformation = PasswordVisualTransformation(),
                keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Password),
                modifier = Modifier.fillMaxWidth()
            )
        }

        error?.let {
            Spacer(Modifier.height(12.dp))
            Text(it, color = MaterialTheme.colorScheme.error, style = MaterialTheme.typography.bodyMedium)
        }
        Spacer(Modifier.height(20.dp))

        Button(
            onClick = {
                val now = System.currentTimeMillis()
                if (now < lockedUntil) {
                    error = "Too many attempts. Try again in ${(lockedUntil - now) / 1000 + 1}s."
                    return@Button
                }
                if (email.isBlank() || password.length < 6) {
                    error = "Enter a valid email and a password of at least 6 characters."
                    return@Button
                }
                if (registering && password != confirm) {
                    error = "Passwords don't match."
                    return@Button
                }
                loading = true; error = null
                scope.launch {
                    try {
                        if (registering) FirebaseRepo.register(email, password) else FirebaseRepo.login(email, password)
                        fails = 0
                    } catch (e: Exception) {
                        fails++
                        if (fails >= MAX_FAILS) {
                            lockedUntil = System.currentTimeMillis() + COOLDOWN_MS
                            fails = 0
                        }
                        error = e.localizedMessage ?: "Authentication failed."
                    } finally {
                        loading = false
                    }
                }
            },
            enabled = !loading,
            modifier = Modifier.fillMaxWidth().height(52.dp)
        ) {
            if (loading) CircularProgressIndicator(Modifier.size(22.dp), strokeWidth = 2.dp)
            else Text(if (registering) "Create account" else "Sign in")
        }

        TextButton(onClick = { registering = !registering; error = null }) {
            Text(if (registering) "Already have an account? Sign in" else "New here? Create an account")
        }
    }
}