import { Ionicons } from "@expo/vector-icons";
import { router, useLocalSearchParams } from "expo-router";
import { useMemo, useState } from "react";
import {
  Image,
  Pressable,
  ScrollView,
  View,
} from "react-native";
import { useSafeAreaInsets } from "react-native-safe-area-context";
import { useTranslation } from "react-i18next";
import { Badge, Price, Rating, StockLabel } from "@/components/ui/Badge";
import { Button, IconButton } from "@/components/ui/Button";
import { Card, InfoRow, Section } from "@/components/ui/Card";
import { Chip } from "@/components/ui/Chip";
import { QtyStepper } from "@/components/ui/QtyStepper";
import { StickyBar } from "@/components/ui/StickyBar";
import { Text } from "@/components/ui/Text";
import { branches } from "@/lib/data/branches";
import { getDrugFacts, getReviewBreakdown } from "@/lib/data/clinical";
import { products } from "@/lib/data/products";
import { useCartStore } from "@/lib/stores/cartStore";
import { useFavoritesStore } from "@/lib/stores/favoritesStore";
import { colors, gutter, radii, space } from "@/lib/theme";
import { formatETB } from "@/lib/utils";
import { routes } from "@/lib/routes";

export default function ProductDetailScreen() {
  const { id } = useLocalSearchParams<{ id: string }>();
  const product = products.find((p) => p.id === id) ?? products[0];
  const facts = useMemo(() => getDrugFacts(product), [product]);
  const reviews = useMemo(() => getReviewBreakdown(product), [product]);
  const [qty, setQty] = useState(1);
  const [dose, setDose] = useState(facts.dosages[0] ?? "");
  const [tab, setTab] = useState<"details" | "pharmacy">("details");
  const [more, setMore] = useState(false);
  const insets = useSafeAreaInsets();
  const { t } = useTranslation();
  const addProduct = useCartStore((s) => s.addProduct);
  const toggle = useFavoritesStore((s) => s.toggle);
  const liked = useFavoritesStore((s) => s.has(product.id));

  const addToCart = () => {
    addProduct(product, qty);
  };

  return (
    <View style={{ flex: 1, backgroundColor: colors.page }}>
      <ScrollView
        showsVerticalScrollIndicator={false}
        contentContainerStyle={{ paddingBottom: 120 }}
      >
        <View
          style={{
            backgroundColor: colors.surfaceAlt,
            paddingTop: insets.top + 8,
            paddingBottom: 28,
          }}
        >
          <View
            style={{
              paddingHorizontal: gutter,
              flexDirection: "row",
              justifyContent: "space-between",
              marginBottom: 8,
            }}
          >
            <IconButton
              icon="arrow-back"
              accessibilityLabel="Go back"
              onPress={() => router.back()}
            />
            <IconButton
              icon={liked ? "heart" : "heart-outline"}
              onPress={() => toggle(product.id)}
              color={liked ? colors.danger : colors.ink}
              accessibilityLabel={liked ? "Remove favorite" : "Add favorite"}
            />
          </View>
          <Image
            source={{ uri: product.image }}
            style={{ width: "100%", height: 240 }}
            resizeMode="contain"
          />
        </View>

        <View
          style={{
            marginTop: -24,
            marginHorizontal: gutter,
            backgroundColor: colors.surface,
            borderRadius: radii.xl,
            borderWidth: 1,
            borderColor: colors.line,
            padding: space.xl,
            gap: 14,
          }}
        >
          {product.requiresPrescription ? (
            <Badge label="RX needed" tone="info" icon="document-text-outline" />
          ) : (
            <Badge label={facts.useCase} tone="neutral" />
          )}

          <View style={{ flexDirection: "row", justifyContent: "space-between", gap: 12 }}>
            <View style={{ flex: 1 }}>
              <Text variant="h1">{product.name}</Text>
              <Text variant="caption" color={colors.subtle} style={{ marginTop: 4 }}>
                {product.brand} · {product.unit}
              </Text>
            </View>
            <Rating value={product.rating} count={product.reviews} showStars={false} />
          </View>

          <Price
            value={product.price}
            compareAt={product.compareAt}
            size="lg"
            format={formatETB}
          />

          {facts.dosages.length > 0 ? (
            <View>
              <Text variant="label" color={colors.muted} style={{ marginBottom: 8 }}>
                Strength
              </Text>
              <View style={{ flexDirection: "row", flexWrap: "wrap", gap: 8 }}>
                {facts.dosages.map((d) => (
                  <Chip
                    key={d}
                    label={d}
                    selected={dose === d}
                    onPress={() => setDose(d)}
                  />
                ))}
              </View>
            </View>
          ) : null}

          <View
            style={{
              flexDirection: "row",
              alignItems: "center",
              justifyContent: "space-between",
            }}
          >
            <QtyStepper value={qty} onChange={setQty} />
            <StockLabel inStock={product.inStock} count={facts.stockCount} />
          </View>

          <View style={{ gap: 8 }}>
            <View style={{ flexDirection: "row", alignItems: "center", gap: 8 }}>
              <Ionicons name="bicycle-outline" size={16} color={colors.info} />
              <Text variant="bodySm" color={colors.muted}>
                Same-day delivery in Addis Ababa
              </Text>
            </View>
            <View style={{ flexDirection: "row", alignItems: "center", gap: 8 }}>
              <Ionicons name="shield-checkmark-outline" size={16} color={colors.brandText} />
              <Text variant="bodySm" color={colors.muted}>
                Pharmacist-verified · 30-day return policy
              </Text>
            </View>
          </View>

          <Button
            title={t("common.addProduct")}
            icon="bag-add-outline"
            onPress={() => {
              addToCart();
              router.push(routes.cart);
            }}
            disabled={!product.inStock}
          />
        </View>

        <View style={{ paddingHorizontal: gutter, marginTop: 18 }}>
          <View
            style={{
              flexDirection: "row",
              backgroundColor: colors.surfaceAlt,
              borderRadius: radii.pill,
              padding: 4,
            }}
          >
            {(["details", "pharmacy"] as const).map((key) => (
              <Pressable
                key={key}
                onPress={() => setTab(key)}
                style={{
                  flex: 1,
                  alignItems: "center",
                  paddingVertical: 10,
                  borderRadius: radii.pill,
                  backgroundColor: tab === key ? colors.surface : "transparent",
                }}
              >
                <Text variant="h3" color={tab === key ? colors.ink : colors.subtle}>
                  {key === "details" ? "Details" : "Pharmacy"}
                </Text>
              </Pressable>
            ))}
          </View>
        </View>

        {tab === "details" ? (
          <View style={{ paddingHorizontal: gutter, paddingBottom: 20 }}>
            <Section title="Description">
              <Text variant="body" color={colors.muted}>
                {more ? product.description : `${product.description.slice(0, 140)}…`}
              </Text>
              <Pressable onPress={() => setMore(!more)} style={{ marginTop: 6 }}>
                <Text variant="label" color={colors.brandText}>
                  {more ? "Show less" : "Read more"}
                </Text>
              </Pressable>
            </Section>

            <Section title="Drug facts">
              <Card elevated={false}>
                <InfoRow label="Generic name" value={facts.genericName} />
                <InfoRow label="Brand names" value={facts.brandNames} />
                <InfoRow label="Drug class" value={facts.drugClass} last />
              </Card>
            </Section>

            <Section title="Side effects">
              <Text variant="caption" color={colors.subtle} style={{ marginBottom: 8 }}>
                Common (mild)
              </Text>
              <View style={{ flexDirection: "row", flexWrap: "wrap", gap: 8 }}>
                {facts.sideEffects.mild.map((s) => (
                  <Badge key={s} label={s} tone="neutral" icon="remove-outline" />
                ))}
              </View>
              {facts.sideEffects.severe.length > 0 ? (
                <>
                  <Text
                    variant="caption"
                    color={colors.subtle}
                    style={{ marginTop: 14, marginBottom: 8 }}
                  >
                    Severe (rare)
                  </Text>
                  <View style={{ flexDirection: "row", flexWrap: "wrap", gap: 8 }}>
                    {facts.sideEffects.severe.map((s) => (
                      <Badge key={s} label={s} tone="danger" icon="alert-outline" />
                    ))}
                  </View>
                </>
              ) : null}
            </Section>

            <Section title="Storage">
              <View style={{ gap: 10 }}>
                {facts.storage.map((note) => (
                  <Card key={note.title} elevated={false}>
                    <View style={{ flexDirection: "row", gap: 12, alignItems: "flex-start" }}>
                      <View
                        style={{
                          width: 36,
                          height: 36,
                          borderRadius: 12,
                          backgroundColor: colors.brandSoft,
                          alignItems: "center",
                          justifyContent: "center",
                        }}
                      >
                        <Ionicons name={note.icon} size={18} color={colors.brandText} />
                      </View>
                      <View style={{ flex: 1 }}>
                        <Text variant="h3">{note.title}</Text>
                        <Text variant="bodySm" color={colors.muted} style={{ marginTop: 2 }}>
                          {note.body}
                        </Text>
                      </View>
                    </View>
                  </Card>
                ))}
              </View>
            </Section>

            <Section title="Directions of use">
              <View style={{ gap: 0, paddingLeft: 8 }}>
                {facts.directions.map((step, index) => (
                  <View key={step.title} style={{ flexDirection: "row", gap: 14 }}>
                    <View style={{ alignItems: "center", width: 22 }}>
                      <View
                        style={{
                          width: 22,
                          height: 22,
                          borderRadius: 11,
                          backgroundColor: colors.brand,
                          alignItems: "center",
                          justifyContent: "center",
                        }}
                      >
                        <Text variant="micro" color={colors.ink}>
                          {index + 1}
                        </Text>
                      </View>
                      {index < facts.directions.length - 1 ? (
                        <View
                          style={{
                            width: 2,
                            flex: 1,
                            minHeight: 28,
                            backgroundColor: colors.brandBorder,
                          }}
                        />
                      ) : null}
                    </View>
                    <View style={{ flex: 1, paddingBottom: 16 }}>
                      <Text variant="h3">{step.title}</Text>
                      <Text variant="bodySm" color={colors.muted} style={{ marginTop: 2 }}>
                        {step.body}
                      </Text>
                    </View>
                  </View>
                ))}
              </View>
            </Section>

            <Section title="Reviews">
              <Card elevated={false}>
                <View style={{ flexDirection: "row", alignItems: "flex-end", gap: 8 }}>
                  <Text variant="display">{product.rating.toFixed(1)}</Text>
                  <Text variant="bodySm" color={colors.subtle} style={{ marginBottom: 6 }}>
                    {product.reviews} reviews
                  </Text>
                </View>
                <View style={{ marginTop: 14, gap: 8 }}>
                  {reviews.map((row) => {
                    const max = reviews[0]?.count || 1;
                    return (
                      <View
                        key={row.stars}
                        style={{ flexDirection: "row", alignItems: "center", gap: 8 }}
                      >
                        <Text variant="caption" color={colors.muted} style={{ width: 14 }}>
                          {row.stars}
                        </Text>
                        <View
                          style={{
                            flex: 1,
                            height: 6,
                            borderRadius: 3,
                            backgroundColor: colors.surfaceAlt,
                            overflow: "hidden",
                          }}
                        >
                          <View
                            style={{
                              width: `${Math.round((row.count / max) * 100)}%`,
                              height: "100%",
                              backgroundColor: colors.brand,
                            }}
                          />
                        </View>
                      </View>
                    );
                  })}
                </View>
              </Card>
            </Section>

            <Card tone="brand" elevated={false} style={{ marginTop: 8 }}>
              <Text variant="h3">Pharmacist tip</Text>
              <Text variant="bodySm" color={colors.muted} style={{ marginTop: 6 }}>
                {facts.advice}
              </Text>
            </Card>
          </View>
        ) : (
          <View style={{ paddingHorizontal: gutter, paddingBottom: 20 }}>
            <Section title="Available at">
              {branches.slice(0, 4).map((branch, index) => (
                <Card
                  key={branch.id}
                  onPress={() => router.push(routes.branches)}
                  style={{ marginTop: index === 0 ? 0 : 10 }}
                >
                  <View
                    style={{
                      flexDirection: "row",
                      justifyContent: "space-between",
                      alignItems: "flex-start",
                      gap: 12,
                    }}
                  >
                    <View style={{ flex: 1 }}>
                      <Text variant="h3">{branch.name}</Text>
                      <Text variant="bodySm" color={colors.muted} style={{ marginTop: 4 }}>
                        {branch.area}
                      </Text>
                      <Text variant="caption" color={colors.subtle} style={{ marginTop: 4 }}>
                        {branch.hours}
                        {branch.pickupAvailable ? " · Pickup available" : ""}
                      </Text>
                    </View>
                    {index === 0 ? (
                      <StockLabel inStock={product.inStock} count={facts.stockCount} />
                    ) : (
                      <Badge
                        label={product.inStock ? "In stock" : "Call"}
                        tone={product.inStock ? "brand" : "warn"}
                      />
                    )}
                  </View>
                </Card>
              ))}
              <Button
                title="View all branches"
                variant="outline"
                onPress={() => router.push(routes.branches)}
                style={{ marginTop: 14 }}
              />
            </Section>
          </View>
        )}
      </ScrollView>

      <StickyBar floating>
        <View style={{ flex: 1 }}>
          <Text variant="caption" color="rgba(255,255,255,0.7)" numberOfLines={1}>
            {product.name}
          </Text>
          <Text variant="h3" color={colors.surface}>
            {formatETB(product.price * qty)}
          </Text>
        </View>
        <Button
          title="Add"
          size="md"
          fullWidth={false}
          icon="bag-add-outline"
          onPress={addToCart}
          disabled={!product.inStock}
          style={{ minWidth: 110 }}
        />
      </StickyBar>
    </View>
  );
}