import { Ionicons } from "@expo/vector-icons";
import { router } from "expo-router";
import {
  Alert,
  Image,
  Pressable,
  ScrollView,
  TextInput,
  View,
} from "react-native";
import { useSafeAreaInsets } from "react-native-safe-area-context";
import { useTranslation } from "react-i18next";
import { Button } from "@/components/ui/Button";
import { Card, InfoRow } from "@/components/ui/Card";
import { EmptyState } from "@/components/ui/EmptyState";
import { QtyStepper } from "@/components/ui/QtyStepper";
import { Screen, TAB_BAR_INSET } from "@/components/ui/Screen";
import { StickyBar } from "@/components/ui/StickyBar";
import { Text } from "@/components/ui/Text";
import { DELIVERY_FEE, DEMO_VOUCHER, voucherDiscount } from "@/lib/commerce";
import { routes } from "@/lib/routes";
import { useCartStore } from "@/lib/stores/cartStore";
import { colors, fonts, gutter, radii } from "@/lib/theme";
import { formatETB } from "@/lib/utils";

export default function CartScreen() {
  const { t } = useTranslation();
  const insets = useSafeAreaInsets();
  const items = useCartStore((s) => s.items);
  const setQuantity = useCartStore((s) => s.setQuantity);
  const removeItem = useCartStore((s) => s.removeItem);
  const subtotal = useCartStore((s) => s.subtotal());
  const voucher = useCartStore((s) => s.voucherCode);
  const setVoucher = useCartStore((s) => s.setVoucher);
  const delivery = items.length ? DELIVERY_FEE : 0;
  const discount = voucherDiscount(subtotal, voucher);
  const total = subtotal + delivery - discount;

  return (
    <Screen>
      <ScrollView
        contentContainerStyle={{
          paddingTop: insets.top + 16,
          paddingBottom: TAB_BAR_INSET + 100,
          paddingHorizontal: gutter,
        }}
      >
        <Text variant="h1">{t("common.cart")}</Text>
        <Text variant="bodySm" color={colors.subtle} style={{ marginTop: 4 }}>
          {items.length} item{items.length === 1 ? "" : "s"} in your bag
        </Text>

        {items.length === 0 ? (
          <EmptyState
            icon="bag-handle-outline"
            title={t("common.emptyCart")}
            body="Browse the shop and add medicines or wellness products."
            actionTitle="Explore products"
            onAction={() => router.push(routes.shop)}
          />
        ) : (
          <View style={{ marginTop: 16, gap: 12 }}>
            {items.map((item) => (
              <Card key={item.productId} elevated>
                <View style={{ flexDirection: "row", gap: 12 }}>
                  <Image
                    source={{ uri: item.image }}
                    style={{
                      width: 72,
                      height: 72,
                      borderRadius: radii.sm,
                      backgroundColor: colors.surfaceAlt,
                    }}
                    resizeMode="contain"
                  />
                  <View style={{ flex: 1 }}>
                    <View style={{ flexDirection: "row", justifyContent: "space-between" }}>
                      <Text variant="h3" style={{ flex: 1 }} numberOfLines={2}>
                        {item.name}
                      </Text>
                      <Pressable onPress={() => removeItem(item.productId)} hitSlop={8}>
                        <Ionicons name="trash-outline" size={18} color={colors.subtle} />
                      </Pressable>
                    </View>
                    <Text variant="caption" color={colors.subtle} style={{ marginTop: 2 }}>
                      {item.unit}
                      {item.requiresPrescription ? " · RX" : ""}
                    </Text>
                    <View
                      style={{
                        marginTop: 10,
                        flexDirection: "row",
                        justifyContent: "space-between",
                        alignItems: "center",
                      }}
                    >
                      <Text variant="price">{formatETB(item.price)}</Text>
                      <QtyStepper
                        size="sm"
                        value={item.quantity}
                        onChange={(n) => setQuantity(item.productId, n)}
                        min={0}
                      />
                    </View>
                  </View>
                </View>
              </Card>
            ))}

            <Pressable onPress={() => router.push(routes.shop)}>
              <Text variant="label" color={colors.brandText}>
                + Add product
              </Text>
            </Pressable>

            <Card elevated={false} style={{ marginTop: 8 }}>
              <Text variant="h3" style={{ marginBottom: 8 }}>
                Voucher
              </Text>
              <View
                style={{
                  flexDirection: "row",
                  alignItems: "center",
                  borderWidth: 1,
                  borderColor: colors.line,
                  borderRadius: radii.pill,
                  paddingLeft: 14,
                  paddingRight: 6,
                  height: 48,
                }}
              >
                <TextInput
                  value={voucher ?? ""}
                  onChangeText={(v) => setVoucher(v || null)}
                  placeholder="Try GISHEN10"
                  placeholderTextColor={colors.subtle}
                  style={{
                    flex: 1,
                    fontFamily: fonts.regular,
                    fontSize: 14,
                    color: colors.ink,
                  }}
                />
                <Button
                  title="Apply"
                  size="sm"
                  fullWidth={false}
                  onPress={() => {
                    if ((voucher ?? "").toUpperCase() === DEMO_VOUCHER) {
                      setVoucher(DEMO_VOUCHER);
                      Alert.alert("Applied", "10% off your basket.");
                    } else {
                      Alert.alert("Invalid code", `Use ${DEMO_VOUCHER} for a demo discount.`);
                    }
                  }}
                />
              </View>
            </Card>

            <Card elevated={false}>
              <InfoRow label="Payment" value={formatETB(subtotal)} />
              <InfoRow label="Delivery" value={formatETB(delivery)} />
              {discount > 0 ? (
                <InfoRow label="Discount" value={`- ${formatETB(discount)}`} valueColor={colors.brandText} />
              ) : null}
              <InfoRow label={t("common.total")} value={formatETB(total)} emphasis last />
            </Card>
          </View>
        )}
      </ScrollView>

      {items.length > 0 ? (
        <StickyBar>
          <Button
            title={t("common.payNow")}
            iconRight="arrow-forward"
            onPress={() => router.push(routes.checkout)}
          />
        </StickyBar>
      ) : null}
    </Screen>
  );
}