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

import androidx.compose.foundation.background
import androidx.compose.foundation.border
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.lazy.LazyColumn
import androidx.compose.foundation.lazy.items
import androidx.compose.foundation.shape.RoundedCornerShape
import androidx.compose.material.icons.Icons
import androidx.compose.material.icons.filled.Add
import androidx.compose.material.icons.filled.DeleteOutline
import androidx.compose.material.icons.filled.Remove
import androidx.compose.material.icons.filled.ShoppingCart
import androidx.compose.material.icons.outlined.Diamond
import androidx.compose.material.icons.outlined.LocalShipping
import androidx.compose.material3.Button
import androidx.compose.material3.ButtonDefaults
import androidx.compose.material3.Card
import androidx.compose.material3.CardDefaults
import androidx.compose.material3.DividerDefaults
import androidx.compose.material3.HorizontalDivider
import androidx.compose.material3.Icon
import androidx.compose.material3.IconButton
import androidx.compose.material3.LinearProgressIndicator
import androidx.compose.material3.MaterialTheme
import androidx.compose.material3.Surface
import androidx.compose.material3.Text
import androidx.compose.runtime.Composable
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.draw.clip
import androidx.compose.ui.layout.ContentScale
import androidx.compose.ui.platform.LocalContext
import androidx.compose.ui.platform.testTag
import androidx.compose.ui.text.font.FontWeight
import androidx.compose.ui.text.style.TextOverflow
import androidx.compose.ui.unit.dp
import androidx.compose.ui.unit.sp
import coil.compose.AsyncImage
import coil.request.ImageRequest
import com.aistudio.bonjuteri.jwlry.data.CartRepository
import com.aistudio.bonjuteri.jwlry.model.CartItem
import com.aistudio.bonjuteri.jwlry.model.Product
import com.aistudio.bonjuteri.jwlry.ui.components.EmptyStateView
import com.aistudio.bonjuteri.jwlry.ui.theme.ErrorRed
import com.aistudio.bonjuteri.jwlry.ui.theme.GoldPrimary
import com.aistudio.bonjuteri.jwlry.ui.theme.GoldSubtle
import com.aistudio.bonjuteri.jwlry.ui.theme.LightSurface
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

@Composable
fun CartScreen(
    cartItems: List<CartItem>,
    onUpdateQuantity: (String, Long) -> Unit,
    onRemoveItem: (String) -> Unit,
    onCheckoutClick: () -> Unit,
    onStartShoppingClick: () -> 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
    val remainingForFreeShipping = (CartRepository.FREE_SHIPPING_THRESHOLD - subtotal).coerceAtLeast(0.0)

    if (cartItems.isEmpty()) {
        EmptyStateView(
            icon = Icons.Filled.ShoppingCart,
            title = "Sepetiniz Boş",
            description = "Henüz sepetinize bir ürün eklemediniz. BONJUTERİ'nin benzersiz koleksiyonlarını keşfedin!",
            actionButtonText = "Alışverişe Başla",
            onActionClick = onStartShoppingClick,
            modifier = modifier.fillMaxSize()
        )
        return
    }

    Column(
        modifier = modifier
            .fillMaxSize()
            .background(OffWhite)
    ) {
        // Free shipping banner
        Surface(
            color = if (isFreeShipping) GoldSubtle else PureWhite,
            modifier = Modifier.fillMaxWidth(),
            shadowElevation = 1.dp
        ) {
            Column(modifier = Modifier.padding(14.dp)) {
                Row(verticalAlignment = Alignment.CenterVertically) {
                    Icon(
                        imageVector = Icons.Outlined.LocalShipping,
                        contentDescription = null,
                        tint = if (isFreeShipping) SuccessGreen else GoldPrimary,
                        modifier = Modifier.size(20.dp)
                    )
                    Spacer(modifier = Modifier.width(8.dp))
                    Text(
                        text = if (isFreeShipping)
                            "Tebrikler! Kargo ÜCRETSİZ!"
                        else
                            "Kargonun ÜCRETSİZ olması için ${Product.formatCurrency(remainingForFreeShipping)} daha ekleyin!",
                        style = MaterialTheme.typography.bodySmall.copy(
                            fontWeight = FontWeight.Bold,
                            color = if (isFreeShipping) SuccessGreen else PrimaryBlack
                        )
                    )
                }
                Spacer(modifier = Modifier.height(6.dp))
                LinearProgressIndicator(
                    progress = { (subtotal / CartRepository.FREE_SHIPPING_THRESHOLD).toFloat().coerceIn(0f, 1f) },
                    modifier = Modifier
                        .fillMaxWidth()
                        .height(6.dp)
                        .clip(RoundedCornerShape(3.dp)),
                    color = GoldPrimary,
                    trackColor = SurfaceBorder
                )
            }
        }

        // Cart items list
        LazyColumn(
            modifier = Modifier
                .weight(1f)
                .padding(horizontal = 14.dp, vertical = 8.dp),
            verticalArrangement = Arrangement.spacedBy(10.dp)
        ) {
            items(cartItems, key = { it.id }) { item ->
                Card(
                    modifier = Modifier
                        .fillMaxWidth()
                        .testTag("cart_item_${item.productId}"),
                    colors = CardDefaults.cardColors(containerColor = PureWhite),
                    shape = RoundedCornerShape(12.dp),
                    elevation = CardDefaults.cardElevation(defaultElevation = 1.dp)
                ) {
                    Row(
                        modifier = Modifier
                            .fillMaxWidth()
                            .padding(12.dp),
                        verticalAlignment = Alignment.CenterVertically
                    ) {
                        // Image
                        Box(
                            modifier = Modifier
                                .size(74.dp)
                                .clip(RoundedCornerShape(8.dp))
                                .background(LightSurface),
                            contentAlignment = Alignment.Center
                        ) {
                            if (item.imageUrl.isNotBlank()) {
                                AsyncImage(
                                    model = ImageRequest.Builder(LocalContext.current)
                                        .data(item.imageUrl)
                                        .crossfade(true)
                                        .build(),
                                    contentDescription = item.title,
                                    modifier = Modifier.fillMaxSize(),
                                    contentScale = ContentScale.Crop
                                )
                            } else {
                                Icon(Icons.Outlined.Diamond, contentDescription = null, tint = GoldPrimary)
                            }
                        }

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

                        // Details
                        Column(modifier = Modifier.weight(1f)) {
                            Text(
                                text = item.title,
                                style = MaterialTheme.typography.titleSmall.copy(
                                    fontWeight = FontWeight.Bold,
                                    color = PrimaryBlack,
                                    fontSize = 14.sp
                                ),
                                maxLines = 2,
                                overflow = TextOverflow.Ellipsis
                            )

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

                            Text(
                                text = item.formattedTotalPrice,
                                style = MaterialTheme.typography.titleMedium.copy(
                                    fontWeight = FontWeight.Black,
                                    color = PrimaryBlack
                                )
                            )

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

                            // Quantity controls
                            Row(verticalAlignment = Alignment.CenterVertically) {
                                Row(
                                    verticalAlignment = Alignment.CenterVertically,
                                    modifier = Modifier
                                        .border(1.dp, SurfaceBorder, RoundedCornerShape(6.dp))
                                        .padding(horizontal = 2.dp, vertical = 1.dp)
                                ) {
                                    IconButton(
                                        onClick = { onUpdateQuantity(item.productId, item.quantity - 1) },
                                        modifier = Modifier.size(28.dp)
                                    ) {
                                        Icon(
                                            imageVector = Icons.Filled.Remove,
                                            contentDescription = "Azalt",
                                            modifier = Modifier.size(14.dp)
                                        )
                                    }
                                    Text(
                                        text = item.quantity.toString(),
                                        fontWeight = FontWeight.Bold,
                                        fontSize = 12.sp,
                                        modifier = Modifier.padding(horizontal = 8.dp)
                                    )
                                    IconButton(
                                        onClick = {
                                            if (item.quantity < item.maxStock) {
                                                onUpdateQuantity(item.productId, item.quantity + 1)
                                            }
                                        },
                                        enabled = item.quantity < item.maxStock,
                                        modifier = Modifier.size(28.dp)
                                    ) {
                                        Icon(
                                            imageVector = Icons.Filled.Add,
                                            contentDescription = "Artır",
                                            modifier = Modifier.size(14.dp)
                                        )
                                    }
                                }

                                Spacer(modifier = Modifier.weight(1f))

                                IconButton(
                                    onClick = { onRemoveItem(item.productId) },
                                    modifier = Modifier.size(32.dp)
                                ) {
                                    Icon(
                                        imageVector = Icons.Filled.DeleteOutline,
                                        contentDescription = "Sil",
                                        tint = ErrorRed,
                                        modifier = Modifier.size(18.dp)
                                    )
                                }
                            }
                        }
                    }
                }
            }
        }

        // Summary and Checkout Bottom Bar
        Surface(
            color = PureWhite,
            shadowElevation = 8.dp,
            modifier = Modifier.fillMaxWidth()
        ) {
            Column(
                modifier = Modifier
                    .fillMaxWidth()
                    .padding(16.dp)
            ) {
                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)
                }

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

                Row(
                    modifier = Modifier.fillMaxWidth(),
                    horizontalArrangement = Arrangement.SpaceBetween
                ) {
                    Text("Kargo Ücreti", 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(modifier = Modifier.padding(vertical = 8.dp), color = DividerDefaults.color)

                Row(
                    modifier = Modifier.fillMaxWidth(),
                    horizontalArrangement = Arrangement.SpaceBetween,
                    verticalAlignment = Alignment.CenterVertically
                ) {
                    Column {
                        Text("Genel Toplam", color = MutedGrey, fontSize = 11.sp)
                        Text(
                            text = Product.formatCurrency(totalAmount),
                            style = MaterialTheme.typography.titleLarge.copy(
                                fontWeight = FontWeight.Black,
                                fontSize = 18.sp,
                                color = PrimaryBlack
                            )
                        )
                    }

                    Button(
                        onClick = onCheckoutClick,
                        modifier = Modifier
                            .height(48.dp)
                            .testTag("checkout_button"),
                        shape = RoundedCornerShape(10.dp),
                        colors = ButtonDefaults.buttonColors(
                            containerColor = PrimaryBlack,
                            contentColor = PureWhite
                        )
                    ) {
                        Text(
                            text = "Siparişi Tamamla",
                            fontWeight = FontWeight.Bold,
                            fontSize = 14.sp
                        )
                    }
                }
            }
        }
    }
}