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

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.verticalScroll
import androidx.compose.material.icons.Icons
import androidx.compose.material.icons.automirrored.filled.ArrowBack
import androidx.compose.material.icons.filled.Add
import androidx.compose.material.icons.filled.Check
import androidx.compose.material.icons.filled.CheckCircle
import androidx.compose.material.icons.filled.LocationOn
import androidx.compose.material.icons.filled.Payment
import androidx.compose.material.icons.outlined.Info
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.ExperimentalMaterial3Api
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.Scaffold
import androidx.compose.material3.Surface
import androidx.compose.material3.Text
import androidx.compose.material3.TopAppBar
import androidx.compose.material3.TopAppBarDefaults
import androidx.compose.runtime.Composable
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.platform.testTag
import androidx.compose.ui.text.font.FontWeight
import androidx.compose.ui.unit.dp
import androidx.compose.ui.unit.sp
import com.aistudio.bonjuteri.jwlry.data.CartRepository
import com.aistudio.bonjuteri.jwlry.model.Address
import com.aistudio.bonjuteri.jwlry.model.CartItem
import com.aistudio.bonjuteri.jwlry.model.Order
import com.aistudio.bonjuteri.jwlry.model.Product
import com.aistudio.bonjuteri.jwlry.ui.theme.GoldPrimary
import com.aistudio.bonjuteri.jwlry.ui.theme.GoldSubtle
import com.aistudio.bonjuteri.jwlry.ui.theme.InfoBlue
import com.aistudio.bonjuteri.jwlry.ui.theme.MutedGrey
import com.aistudio.bonjuteri.jwlry.ui.theme.OffWhite
import com.aistudio.bonjuteri.jwlry.ui.theme.PrimaryBlack
import com.aistudio.bonjuteri.jwlry.ui.theme.PureWhite
import com.aistudio.bonjuteri.jwlry.ui.theme.SuccessGreen
import com.aistudio.bonjuteri.jwlry.ui.theme.SurfaceBorder
import kotlinx.coroutines.launch

@OptIn(ExperimentalMaterial3Api::class)
@Composable
fun CheckoutScreen(
    cartItems: List<CartItem>,
    addresses: List<Address>,
    onBackClick: () -> Unit,
    onSaveNewAddress: suspend (Address) -> Result<Address>,
    onCreateOrder: suspend (Address, String) -> Result<Order>,
    onOrderSuccess: (Order) -> Unit,
    modifier: Modifier = Modifier
) {
    val subtotal = cartItems.sumOf { it.totalPrice }
    val isFreeShipping = subtotal >= CartRepository.FREE_SHIPPING_THRESHOLD
    val shippingCost = if (isFreeShipping) 0.0 else CartRepository.STANDARD_SHIPPING_COST
    val totalAmount = subtotal + shippingCost

    var selectedAddressId by remember(addresses) {
        mutableStateOf(addresses.firstOrNull()?.id ?: "")
    }

    var isAddingNewAddress by remember { mutableStateOf(addresses.isEmpty()) }
    var newAddressTitle by remember { mutableStateOf("Evim") }
    var newFullName by remember { mutableStateOf("") }
    var newPhone by remember { mutableStateOf("") }
    var newCity by remember { mutableStateOf("İstanbul") }
    var newDistrict by remember { mutableStateOf("") }
    var newNeighborhood by remember { mutableStateOf("") }
    var newFullAddress by remember { mutableStateOf("") }
    var newPostalCode by remember { mutableStateOf("") }

    var selectedPaymentMethod by remember { mutableStateOf("Havale / EFT & Kapıda Ödeme") }
    var isSubmitting by remember { mutableStateOf(false) }
    var errorMessage by remember { mutableStateOf<String?>(null) }
    val scope = rememberCoroutineScope()

    Scaffold(
        topBar = {
            TopAppBar(
                title = { Text("Siparişi Tamamla", fontWeight = FontWeight.Bold) },
                navigationIcon = {
                    IconButton(onClick = onBackClick) {
                        Icon(Icons.AutoMirrored.Filled.ArrowBack, contentDescription = "Geri")
                    }
                },
                colors = TopAppBarDefaults.topAppBarColors(containerColor = PureWhite)
            )
        },
        bottomBar = {
            Surface(
                color = PureWhite,
                shadowElevation = 8.dp,
                modifier = Modifier.fillMaxWidth()
            ) {
                Column(modifier = Modifier.padding(16.dp)) {
                    if (errorMessage != null) {
                        Text(
                            text = errorMessage!!,
                            color = MaterialTheme.colorScheme.error,
                            fontSize = 12.sp,
                            modifier = Modifier.padding(bottom = 8.dp)
                        )
                    }

                    Row(
                        modifier = Modifier.fillMaxWidth(),
                        horizontalArrangement = Arrangement.SpaceBetween,
                        verticalAlignment = Alignment.CenterVertically
                    ) {
                        Column {
                            Text("Ödenecek Tutar", color = MutedGrey, fontSize = 11.sp)
                            Text(
                                text = Product.formatCurrency(totalAmount),
                                fontWeight = FontWeight.Black,
                                fontSize = 18.sp,
                                color = PrimaryBlack
                            )
                        }

                        Button(
                            onClick = {
                                scope.launch {
                                    isSubmitting = true
                                    errorMessage = null

                                    var chosenAddress = addresses.firstOrNull { it.id == selectedAddressId }

                                    // If adding new address inline
                                    if (chosenAddress == null || isAddingNewAddress) {
                                        val newAddr = Address(
                                            title = newAddressTitle,
                                            fullName = newFullName,
                                            phone = newPhone,
                                            city = newCity,
                                            district = newDistrict,
                                            neighborhood = newNeighborhood,
                                            fullAddress = newFullAddress,
                                            postalCode = newPostalCode
                                        )
                                        val saveResult = onSaveNewAddress(newAddr)
                                        if (saveResult.isFailure) {
                                            errorMessage = saveResult.exceptionOrNull()?.message ?: "Adres kaydedilemedi."
                                            isSubmitting = false
                                            return@launch
                                        }
                                        chosenAddress = saveResult.getOrNull()
                                    }

                                    if (chosenAddress == null) {
                                        errorMessage = "Lütfen bir teslimat adresi seçiniz veya ekleyiniz."
                                        isSubmitting = false
                                        return@launch
                                    }

                                    val orderResult = onCreateOrder(chosenAddress, selectedPaymentMethod)
                                    isSubmitting = false
                                    if (orderResult.isSuccess) {
                                        onOrderSuccess(orderResult.getOrThrow())
                                    } else {
                                        errorMessage = orderResult.exceptionOrNull()?.message ?: "Sipariş oluşturulamadı."
                                    }
                                }
                            },
                            enabled = !isSubmitting,
                            modifier = Modifier
                                .height(48.dp)
                                .testTag("confirm_order_button"),
                            shape = RoundedCornerShape(10.dp),
                            colors = ButtonDefaults.buttonColors(
                                containerColor = PrimaryBlack,
                                contentColor = PureWhite
                            )
                        ) {
                            if (isSubmitting) {
                                CircularProgressIndicator(color = PureWhite, modifier = Modifier.size(20.dp))
                            } else {
                                Text("Siparişi Onayla", fontWeight = FontWeight.Bold, fontSize = 14.sp)
                            }
                        }
                    }
                }
            }
        }
    ) { padding ->
        Column(
            modifier = modifier
                .fillMaxSize()
                .padding(padding)
                .background(OffWhite)
                .verticalScroll(rememberScrollState())
                .padding(16.dp),
            verticalArrangement = Arrangement.spacedBy(16.dp)
        ) {
            // Address Section
            Card(
                modifier = Modifier.fillMaxWidth(),
                colors = CardDefaults.cardColors(containerColor = PureWhite),
                shape = RoundedCornerShape(12.dp)
            ) {
                Column(modifier = Modifier.padding(14.dp)) {
                    Row(
                        modifier = Modifier.fillMaxWidth(),
                        horizontalArrangement = Arrangement.SpaceBetween,
                        verticalAlignment = Alignment.CenterVertically
                    ) {
                        Row(verticalAlignment = Alignment.CenterVertically) {
                            Icon(Icons.Filled.LocationOn, contentDescription = null, tint = GoldPrimary, modifier = Modifier.size(20.dp))
                            Spacer(modifier = Modifier.width(8.dp))
                            Text("Teslimat Adresi", fontWeight = FontWeight.Bold, fontSize = 15.sp)
                        }

                        if (addresses.isNotEmpty()) {
                            Text(
                                text = if (isAddingNewAddress) "Kayıtlı Adresler" else "+ Yeni Adres",
                                color = GoldPrimary,
                                fontWeight = FontWeight.Bold,
                                fontSize = 12.sp,
                                modifier = Modifier.clickable { isAddingNewAddress = !isAddingNewAddress }
                            )
                        }
                    }

                    Spacer(modifier = Modifier.height(10.dp))

                    if (!isAddingNewAddress && addresses.isNotEmpty()) {
                        addresses.forEach { addr ->
                            val isSelected = addr.id == selectedAddressId
                            Row(
                                modifier = Modifier
                                    .fillMaxWidth()
                                    .padding(vertical = 4.dp)
                                    .border(
                                        width = if (isSelected) 1.5.dp else 1.dp,
                                        color = if (isSelected) GoldPrimary else SurfaceBorder,
                                        shape = RoundedCornerShape(8.dp)
                                    )
                                    .clickable { selectedAddressId = addr.id }
                                    .padding(10.dp),
                                verticalAlignment = Alignment.CenterVertically
                            ) {
                                Box(
                                    modifier = Modifier
                                        .size(20.dp)
                                        .border(2.dp, if (isSelected) GoldPrimary else MutedGrey, CircleShape),
                                    contentAlignment = Alignment.Center
                                ) {
                                    if (isSelected) {
                                        Box(modifier = Modifier.size(10.dp).background(GoldPrimary, CircleShape))
                                    }
                                }
                                Spacer(modifier = Modifier.width(10.dp))
                                Column {
                                    Text("${addr.title} - ${addr.fullName}", fontWeight = FontWeight.Bold, fontSize = 13.sp)
                                    Text(addr.fullDisplayAddress, color = MutedGrey, fontSize = 12.sp)
                                    Text(addr.phone, color = MutedGrey, fontSize = 11.sp)
                                }
                            }
                        }
                    } else {
                        // New Address Input Form
                        Column(verticalArrangement = Arrangement.spacedBy(8.dp)) {
                            OutlinedTextField(
                                value = newAddressTitle,
                                onValueChange = { newAddressTitle = it },
                                label = { Text("Adres Başlığı (Ev, İş vb.)") },
                                modifier = Modifier.fillMaxWidth(),
                                singleLine = true
                            )
                            OutlinedTextField(
                                value = newFullName,
                                onValueChange = { newFullName = it },
                                label = { Text("Ad Soyad") },
                                modifier = Modifier.fillMaxWidth().testTag("checkout_name_input"),
                                singleLine = true
                            )
                            OutlinedTextField(
                                value = newPhone,
                                onValueChange = { newPhone = it },
                                label = { Text("Telefon") },
                                modifier = Modifier.fillMaxWidth().testTag("checkout_phone_input"),
                                singleLine = true
                            )
                            Row(horizontalArrangement = Arrangement.spacedBy(8.dp)) {
                                OutlinedTextField(
                                    value = newCity,
                                    onValueChange = { newCity = it },
                                    label = { Text("İl") },
                                    modifier = Modifier.weight(1f),
                                    singleLine = true
                                )
                                OutlinedTextField(
                                    value = newDistrict,
                                    onValueChange = { newDistrict = it },
                                    label = { Text("İlçe") },
                                    modifier = Modifier.weight(1f).testTag("checkout_district_input"),
                                    singleLine = true
                                )
                            }
                            OutlinedTextField(
                                value = newNeighborhood,
                                onValueChange = { newNeighborhood = it },
                                label = { Text("Mahalle") },
                                modifier = Modifier.fillMaxWidth(),
                                singleLine = true
                            )
                            OutlinedTextField(
                                value = newFullAddress,
                                onValueChange = { newFullAddress = it },
                                label = { Text("Açık Adres (Cadde, Sokak, No, Daire)") },
                                modifier = Modifier.fillMaxWidth().testTag("checkout_address_input"),
                                maxLines = 3
                            )
                            OutlinedTextField(
                                value = newPostalCode,
                                onValueChange = { newPostalCode = it },
                                label = { Text("Posta Kodu") },
                                modifier = Modifier.fillMaxWidth(),
                                singleLine = true
                            )
                        }
                    }
                }
            }

            // Payment Notice
            Card(
                modifier = Modifier.fillMaxWidth(),
                colors = CardDefaults.cardColors(containerColor = PureWhite),
                shape = RoundedCornerShape(12.dp)
            ) {
                Column(modifier = Modifier.padding(14.dp)) {
                    Row(verticalAlignment = Alignment.CenterVertically) {
                        Icon(Icons.Filled.Payment, contentDescription = null, tint = GoldPrimary, modifier = Modifier.size(20.dp))
                        Spacer(modifier = Modifier.width(8.dp))
                        Text("Ödeme Yöntemi", fontWeight = FontWeight.Bold, fontSize = 15.sp)
                    }

                    Spacer(modifier = Modifier.height(10.dp))

                    Card(
                        colors = CardDefaults.cardColors(containerColor = GoldSubtle),
                        shape = RoundedCornerShape(8.dp),
                        modifier = Modifier.fillMaxWidth()
                    ) {
                        Row(modifier = Modifier.padding(12.dp), verticalAlignment = Alignment.Top) {
                            Icon(Icons.Outlined.Info, contentDescription = null, tint = GoldPrimary, modifier = Modifier.size(18.dp))
                            Spacer(modifier = Modifier.width(8.dp))
                            Text(
                                text = "Ödeme Yöntemi: Havale / EFT & Kapıda Ödeme\nSiparişiniz 'Ödeme Bekleniyor' olarak sisteme kaydedilecek, BONJUTERİ müşteri temsilcimiz sizinle irtibata geçecektir.",
                                fontSize = 12.sp,
                                color = PrimaryBlack,
                                lineHeight = 16.sp
                            )
                        }
                    }
                }
            }

            // Order Summary
            Card(
                modifier = Modifier.fillMaxWidth(),
                colors = CardDefaults.cardColors(containerColor = PureWhite),
                shape = RoundedCornerShape(12.dp)
            ) {
                Column(modifier = Modifier.padding(14.dp), verticalArrangement = Arrangement.spacedBy(8.dp)) {
                    Text("Sipariş Özeti", fontWeight = FontWeight.Bold, fontSize = 15.sp)
                    Text("${cartItems.sumOf { it.quantity }} Ürün", color = MutedGrey, fontSize = 12.sp)

                    HorizontalDivider(color = SurfaceBorder)

                    Row(modifier = Modifier.fillMaxWidth(), horizontalArrangement = Arrangement.SpaceBetween) {
                        Text("Ara Toplam", color = MutedGrey, fontSize = 13.sp)
                        Text(Product.formatCurrency(subtotal), fontWeight = FontWeight.SemiBold, fontSize = 13.sp)
                    }

                    Row(modifier = Modifier.fillMaxWidth(), horizontalArrangement = Arrangement.SpaceBetween) {
                        Text("Kargo", color = MutedGrey, fontSize = 13.sp)
                        Text(
                            text = if (isFreeShipping) "ÜCRETSİZ" else Product.formatCurrency(shippingCost),
                            fontWeight = FontWeight.SemiBold,
                            color = if (isFreeShipping) SuccessGreen else PrimaryBlack,
                            fontSize = 13.sp
                        )
                    }

                    HorizontalDivider(color = SurfaceBorder)

                    Row(modifier = Modifier.fillMaxWidth(), horizontalArrangement = Arrangement.SpaceBetween) {
                        Text("Toplam", fontWeight = FontWeight.Bold, fontSize = 15.sp)
                        Text(Product.formatCurrency(totalAmount), fontWeight = FontWeight.Black, fontSize = 16.sp)
                    }
                }
            }
        }
    }
}