package com.example.ui.screens

import androidx.compose.animation.AnimatedVisibility
import androidx.compose.foundation.background
import androidx.compose.foundation.border
import androidx.compose.foundation.layout.*
import androidx.compose.foundation.rememberScrollState
import androidx.compose.foundation.shape.RoundedCornerShape
import androidx.compose.foundation.verticalScroll
import androidx.compose.material.icons.Icons
import androidx.compose.material.icons.filled.*
import androidx.compose.material3.*
import androidx.compose.runtime.*
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.draw.clip
import androidx.compose.ui.graphics.Color
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.style.TextAlign
import androidx.compose.ui.unit.dp
import androidx.compose.ui.unit.sp
import com.example.data.model.AppLanguage
import com.example.ui.components.CustomLabeledTextField
import com.example.ui.theme.*

@Composable
fun AuthScreen(
    lang: AppLanguage,
    onAuthSuccess: (name: String, phone: String, isNidVerified: Boolean) -> Unit,
    modifier: Modifier = Modifier
) {
    var isRegisterTab by remember { mutableStateOf(false) }
    var phoneInput by remember { mutableStateOf("1712345678") }
    var nameInput by remember { mutableStateOf("Mohammad Shakib") }
    var otpOrPassword by remember { mutableStateOf("123456") }
    var nidInput by remember { mutableStateOf("19952691234567890") }
    var verifyNidChecked by remember { mutableStateOf(true) }
    var errorMessage by remember { mutableStateOf<String?>(null) }
    var isLoading by remember { mutableStateOf(false) }

    Scaffold(
        containerColor = MaterialTheme.colorScheme.background,
        modifier = modifier.fillMaxSize()
    ) { innerPadding ->
        Column(
            modifier = Modifier
                .fillMaxSize()
                .padding(innerPadding)
                .statusBarsPadding()
                .navigationBarsPadding()
                .verticalScroll(rememberScrollState())
                .padding(24.dp),
            horizontalAlignment = Alignment.CenterHorizontally
        ) {
            Spacer(modifier = Modifier.height(16.dp))

            // Logo & Title
            Box(
                modifier = Modifier
                    .size(64.dp)
                    .clip(RoundedCornerShape(18.dp))
                    .background(BrandNavyPrimary),
                contentAlignment = Alignment.Center
            ) {
                Icon(
                    imageVector = Icons.Default.Shield,
                    contentDescription = null,
                    tint = Color.White,
                    modifier = Modifier.size(36.dp)
                )
            }

            Spacer(modifier = Modifier.height(16.dp))

            Text(
                text = if (lang == AppLanguage.BN) "সতর্ক বিডি অ্যাকাউন্ট" else "Satark BD Account",
                style = MaterialTheme.typography.headlineSmall.copy(
                    fontWeight = FontWeight.Bold,
                    color = MaterialTheme.colorScheme.onBackground
                )
            )

            Text(
                text = if (lang == AppLanguage.BN) 
                    "সুরক্ষিতভাবে লগইন করে অভিযোগ জমা ও কোম্পানি যাচাই করুন"
                else 
                    "Log in securely to verify entities and submit fraud reports",
                style = MaterialTheme.typography.bodySmall.copy(
                    color = LightTextSecondary,
                    textAlign = TextAlign.Center
                ),
                modifier = Modifier.padding(top = 4.dp)
            )

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

            // Segmented Tab for Login / Register
            Surface(
                color = LightSurfaceVariant,
                shape = RoundedCornerShape(12.dp),
                modifier = Modifier.fillMaxWidth()
            ) {
                Row(
                    modifier = Modifier.padding(4.dp)
                ) {
                    Surface(
                        onClick = { isRegisterTab = false; errorMessage = null },
                        color = if (!isRegisterTab) BrandNavyPrimary else Color.Transparent,
                        shape = RoundedCornerShape(8.dp),
                        modifier = Modifier
                            .weight(1f)
                            .height(44.dp)
                            .testTag("tab_login")
                    ) {
                        Box(contentAlignment = Alignment.Center) {
                            Text(
                                text = if (lang == AppLanguage.BN) "লগইন (Login)" else "Login",
                                style = MaterialTheme.typography.labelLarge.copy(
                                    fontWeight = FontWeight.Bold,
                                    color = if (!isRegisterTab) Color.White else LightTextSecondary
                                )
                            )
                        }
                    }

                    Surface(
                        onClick = { isRegisterTab = true; errorMessage = null },
                        color = if (isRegisterTab) BrandNavyPrimary else Color.Transparent,
                        shape = RoundedCornerShape(8.dp),
                        modifier = Modifier
                            .weight(1f)
                            .height(44.dp)
                            .testTag("tab_register")
                    ) {
                        Box(contentAlignment = Alignment.Center) {
                            Text(
                                text = if (lang == AppLanguage.BN) "নিবন্ধন (Register)" else "Register",
                                style = MaterialTheme.typography.labelLarge.copy(
                                    fontWeight = FontWeight.Bold,
                                    color = if (isRegisterTab) Color.White else LightTextSecondary
                                )
                            )
                        }
                    }
                }
            }

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

            // Fields
            if (isRegisterTab) {
                CustomLabeledTextField(
                    label = if (lang == AppLanguage.BN) "আপনার পূর্ণ নাম (Full Name)" else "Full Name",
                    value = nameInput,
                    onValueChange = { nameInput = it },
                    placeholder = if (lang == AppLanguage.BN) "যেমন: মোহাম্মদ সাকিব" else "e.g., Mohammad Shakib",
                    isRequired = true,
                    leadingIcon = Icons.Default.Person,
                    testTag = "input_auth_name"
                )
                Spacer(modifier = Modifier.height(16.dp))
            }

            // Phone Number Input with BD flag / prefix
            Column(modifier = Modifier.fillMaxWidth()) {
                Text(
                    text = if (lang == AppLanguage.BN) "বাংলাদেশি মোবাইল নম্বর" else "Bangladeshi Mobile Number",
                    style = MaterialTheme.typography.labelLarge.copy(
                        fontWeight = FontWeight.SemiBold,
                        color = MaterialTheme.colorScheme.onSurface
                    ),
                    modifier = Modifier.padding(bottom = 6.dp)
                )
                Row(
                    modifier = Modifier.fillMaxWidth(),
                    verticalAlignment = Alignment.CenterVertically
                ) {
                    Surface(
                        color = LightSurfaceVariant,
                        shape = RoundedCornerShape(10.dp),
                        border = androidx.compose.foundation.BorderStroke(1.dp, LightOutline),
                        modifier = Modifier.height(56.dp)
                    ) {
                        Row(
                            verticalAlignment = Alignment.CenterVertically,
                            modifier = Modifier.padding(horizontal = 12.dp)
                        ) {
                            Text(text = "🇧🇩 +880", style = MaterialTheme.typography.bodyMedium.copy(fontWeight = FontWeight.Bold))
                        }
                    }
                    Spacer(modifier = Modifier.width(8.dp))
                    OutlinedTextField(
                        value = phoneInput,
                        onValueChange = { phoneInput = it },
                        placeholder = { Text("17XXXXXXXX") },
                        singleLine = true,
                        keyboardOptions = androidx.compose.foundation.text.KeyboardOptions(keyboardType = KeyboardType.Phone),
                        shape = RoundedCornerShape(10.dp),
                        colors = OutlinedTextFieldDefaults.colors(
                            focusedBorderColor = BrandBlueAccent,
                            unfocusedBorderColor = LightOutline,
                            focusedContainerColor = MaterialTheme.colorScheme.surface,
                            unfocusedContainerColor = MaterialTheme.colorScheme.surface
                        ),
                        modifier = Modifier
                            .weight(1f)
                            .testTag("input_auth_phone")
                    )
                }
            }

            Spacer(modifier = Modifier.height(16.dp))

            CustomLabeledTextField(
                label = if (isRegisterTab) {
                    if (lang == AppLanguage.BN) "পাসওয়ার্ড অথবা ওটিপি পিন" else "Password or OTP PIN"
                } else {
                    if (lang == AppLanguage.BN) "পাসওয়ার্ড" else "Password"
                },
                value = otpOrPassword,
                onValueChange = { otpOrPassword = it },
                placeholder = "••••••••",
                isRequired = true,
                leadingIcon = Icons.Default.Lock,
                keyboardType = KeyboardType.Password,
                testTag = "input_auth_password"
            )

            if (isRegisterTab) {
                Spacer(modifier = Modifier.height(16.dp))

                CustomLabeledTextField(
                    label = if (lang == AppLanguage.BN) "জাতীয় পরিচয়পত্র নম্বর (ঐচ্ছিক NID)" else "National ID No (Optional NID)",
                    value = nidInput,
                    onValueChange = { nidInput = it },
                    placeholder = "10 or 17 digit NID",
                    isRequired = false,
                    leadingIcon = Icons.Default.Badge,
                    keyboardType = KeyboardType.Number,
                    testTag = "input_auth_nid"
                )

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

                Row(
                    verticalAlignment = Alignment.CenterVertically,
                    modifier = Modifier.fillMaxWidth()
                ) {
                    Checkbox(
                        checked = verifyNidChecked,
                        onCheckedChange = { verifyNidChecked = it },
                        colors = CheckboxDefaults.colors(checkedColor = BrandNavyPrimary)
                    )
                    Spacer(modifier = Modifier.width(4.dp))
                    Text(
                        text = if (lang == AppLanguage.BN) 
                            "নাগরিক নিরাপত্তা যাচাই ও বিশ্বস্ত রিপোর্টার ব্যাজ অনুমোদন করুন"
                        else 
                            "Request Verified Citizen Reporter status",
                        style = MaterialTheme.typography.bodySmall.copy(color = LightTextSecondary)
                    )
                }
            }

            if (errorMessage != null) {
                Spacer(modifier = Modifier.height(8.dp))
                Surface(
                    color = StatusWarningRedBg,
                    shape = RoundedCornerShape(8.dp),
                    modifier = Modifier.fillMaxWidth()
                ) {
                    Text(
                        text = errorMessage ?: "",
                        color = StatusWarningRed,
                        style = MaterialTheme.typography.bodySmall.copy(fontWeight = FontWeight.Medium),
                        modifier = Modifier.padding(10.dp)
                    )
                }
            }

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

            // Primary Action Button
            Button(
                onClick = {
                    if (phoneInput.length < 9) {
                        errorMessage = if (lang == AppLanguage.BN) "সঠিক মোবাইল নম্বর দিন" else "Please enter a valid mobile number"
                    } else {
                        errorMessage = null
                        onAuthSuccess(
                            if (isRegisterTab) nameInput else "Mohammad Shakib",
                            "+880 $phoneInput",
                            verifyNidChecked
                        )
                    }
                },
                colors = ButtonDefaults.buttonColors(containerColor = BrandNavyPrimary),
                shape = RoundedCornerShape(12.dp),
                modifier = Modifier
                    .fillMaxWidth()
                    .height(52.dp)
                    .testTag("btn_auth_submit")
            ) {
                Text(
                    text = if (isRegisterTab) {
                        if (lang == AppLanguage.BN) "নিবন্ধন সম্পন্ন করুন" else "Complete Registration"
                    } else {
                        if (lang == AppLanguage.BN) "লগইন করুন" else "Log In"
                    },
                    style = MaterialTheme.typography.titleMedium.copy(fontWeight = FontWeight.Bold)
                )
            }

            Spacer(modifier = Modifier.height(14.dp))

            // Continue as Guest Option
            OutlinedButton(
                onClick = {
                    onAuthSuccess("Guest Citizen", "+880 1700-000000", false)
                },
                shape = RoundedCornerShape(12.dp),
                border = androidx.compose.foundation.BorderStroke(1.dp, LightOutline),
                modifier = Modifier
                    .fillMaxWidth()
                    .height(50.dp)
                    .testTag("btn_auth_guest")
            ) {
                Icon(
                    imageVector = Icons.Default.Visibility,
                    contentDescription = null,
                    tint = LightTextSecondary,
                    modifier = Modifier.size(18.dp)
                )
                Spacer(modifier = Modifier.width(8.dp))
                Text(
                    text = if (lang == AppLanguage.BN) "অতিথি হিসেবে ব্রাউজ করুন (Guest Mode)" else "Continue as Guest",
                    style = MaterialTheme.typography.bodyMedium.copy(
                        color = LightTextSecondary,
                        fontWeight = FontWeight.SemiBold
                    )
                )
            }

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

            // Trust info notice
            Surface(
                color = Color(0xFFF1F5F9),
                shape = RoundedCornerShape(10.dp),
                modifier = Modifier.fillMaxWidth()
            ) {
                Row(
                    verticalAlignment = Alignment.CenterVertically,
                    modifier = Modifier.padding(12.dp)
                ) {
                    Icon(
                        imageVector = Icons.Default.Lock,
                        contentDescription = null,
                        tint = BrandCyan,
                        modifier = Modifier.size(18.dp)
                    )
                    Spacer(modifier = Modifier.width(10.dp))
                    Text(
                        text = if (lang == AppLanguage.BN) 
                            "আপনার তথ্য ডিজিটাল নিরাপত্তা ও ব্যক্তিগত গোপনীয়তা আইন অনুযায়ী সুরক্ষিত।"
                        else 
                            "Your personal data is encrypted & protected under BD Data Privacy Standards.",
                        style = MaterialTheme.typography.bodySmall.copy(
                            color = LightTextMuted,
                            fontSize = 11.sp
                        )
                    )
                }
            }
        }
    }
}