import { useMemo, useState } from "react";
import { Alert, ScrollView, View } from "react-native";
import { useTranslation } from "react-i18next";
import { Badge } from "@/components/ui/Badge";
import { Button } from "@/components/ui/Button";
import { Card } from "@/components/ui/Card";
import { Chip, Segmented } from "@/components/ui/Chip";
import { Field } from "@/components/ui/Field";
import { AppHeader } from "@/components/ui/Header";
import { Screen } from "@/components/ui/Screen";
import { Text } from "@/components/ui/Text";
import { products } from "@/lib/data/products";
import { useFamilyStore } from "@/lib/stores/familyStore";
import { useLocationStore, type Fulfillment, type PaymentMethod } from "@/lib/stores/locationStore";
import { useSubscriptionStore } from "@/lib/stores/subscriptionStore";
import { colors, gutter } from "@/lib/theme";

const FREQUENCIES = [
  { days: 7, label: "Weekly" },
  { days: 14, label: "Every 2 weeks" },
  { days: 30, label: "Monthly" },
  { days: 60, label: "Every 2 months" },
  { days: 90, label: "Every 3 months" },
];

export default function SubscriptionsScreen() {
  const { t } = useTranslation();
  const items = useSubscriptionStore((s) => s.items);
  const add = useSubscriptionStore((s) => s.add);
  const pause = useSubscriptionStore((s) => s.pause);
  const resume = useSubscriptionStore((s) => s.resume);
  const cancel = useSubscriptionStore((s) => s.cancel);
  const paymentPref = useLocationStore((s) => s.paymentPreference);
  const fulfillmentPref = useLocationStore((s) => s.fulfillment);
  const members = useFamilyStore((s) => s.members);

  const refillCandidates = useMemo(
    () =>
      products.filter(
        (p) =>
          p.requiresPrescription ||
          p.category === "diabetic" ||
          p.category === "vitamins" ||
          p.badge === "bestseller"
      ),
    []
  );

  const [showCreate, setShowCreate] = useState(false);
  const [productId, setProductId] = useState(refillCandidates[0]?.id ?? products[0].id);
  const [qty, setQty] = useState("1");
  const [frequencyDays, setFrequencyDays] = useState(30);
  const [fulfillment, setFulfillment] = useState<Fulfillment>(fulfillmentPref);
  const [payment, setPayment] = useState<PaymentMethod>(
    paymentPref === "pay_at_branch" && fulfillmentPref === "delivery"
      ? "chapa"
      : paymentPref
  );
  const [memberId, setMemberId] = useState<string | null>(null);
  const [query, setQuery] = useState("");

  const filtered = refillCandidates.filter(
    (p) =>
      !query ||
      p.name.toLowerCase().includes(query.toLowerCase()) ||
      p.brand.toLowerCase().includes(query.toLowerCase())
  );
  const selected = products.find((p) => p.id === productId) ?? products[0];

  return (
    <Screen>
      <AppHeader
        title={t("common.subscriptions")}
        subtitle="Auto-refill chronic medicines on a schedule"
      />
      <ScrollView contentContainerStyle={{ paddingHorizontal: gutter, paddingBottom: 40, gap: 12 }}>
        {!showCreate ? (
          <Button
            title="Create refill subscription"
            icon="add-circle-outline"
            onPress={() => setShowCreate(true)}
          />
        ) : (
          <Card elevated={false}>
            <Text variant="h3" style={{ marginBottom: 12 }}>
              New subscription
            </Text>
            <Field
              label="Search product"
              value={query}
              onChangeText={setQuery}
              placeholder="Metformin, Vitamin C…"
              icon="search-outline"
            />
            <ScrollView
              horizontal
              showsHorizontalScrollIndicator={false}
              style={{ marginTop: 12 }}
              contentContainerStyle={{ gap: 8 }}
            >
              {filtered.slice(0, 12).map((p) => (
                <Chip
                  key={p.id}
                  label={p.name}
                  selected={productId === p.id}
                  onPress={() => setProductId(p.id)}
                />
              ))}
            </ScrollView>
            <Text variant="caption" color={colors.subtle} style={{ marginTop: 8 }}>
              Selected: {selected.name} · {selected.unit}
            </Text>

            <View style={{ marginTop: 14, gap: 12 }}>
              <Field
                label="Quantity"
                value={qty}
                onChangeText={setQty}
                keyboardType="number-pad"
              />
              <Text variant="label" color={colors.muted}>
                Frequency
              </Text>
              <View style={{ flexDirection: "row", flexWrap: "wrap", gap: 8 }}>
                {FREQUENCIES.map((f) => (
                  <Chip
                    key={f.days}
                    label={f.label}
                    selected={frequencyDays === f.days}
                    onPress={() => setFrequencyDays(f.days)}
                  />
                ))}
              </View>

              <Text variant="label" color={colors.muted}>
                Fulfillment
              </Text>
              <Segmented
                value={fulfillment}
                onChange={(v) => {
                  setFulfillment(v);
                  if (v === "delivery" && payment === "pay_at_branch") setPayment("chapa");
                }}
                options={[
                  { value: "delivery", label: "Delivery" },
                  { value: "pickup", label: "Pickup" },
                ]}
              />

              <Text variant="label" color={colors.muted} style={{ marginTop: 4 }}>
                Payment
              </Text>
              <View style={{ flexDirection: "row", flexWrap: "wrap", gap: 8 }}>
                {(
                  [
                    "chapa",
                    "telebirr",
                    "mpesa",
                    ...(fulfillment === "pickup" ? (["pay_at_branch"] as const) : []),
                  ] as PaymentMethod[]
                ).map((m) => (
                  <Chip
                    key={m}
                    label={m}
                    selected={payment === m}
                    onPress={() => setPayment(m)}
                  />
                ))}
              </View>

              <Text variant="label" color={colors.muted}>
                For family member (optional)
              </Text>
              <View style={{ flexDirection: "row", flexWrap: "wrap", gap: 8 }}>
                <Chip label="Me" selected={!memberId} onPress={() => setMemberId(null)} />
                {members
                  .filter((m) => m.status === "accepted")
                  .map((m) => (
                    <Chip
                      key={m.id}
                      label={m.name}
                      selected={memberId === m.id}
                      onPress={() => setMemberId(m.id)}
                    />
                  ))}
              </View>

              <Button
                title="Start subscription"
                onPress={() => {
                  add({
                    productId: selected.id,
                    productName: selected.name,
                    quantity: Math.max(1, Number(qty) || 1),
                    frequencyDays,
                    fulfillment,
                    paymentMethod: payment,
                    memberId,
                  });
                  setShowCreate(false);
                  Alert.alert(
                    "Subscription active",
                    `${selected.name} every ${frequencyDays} days via ${fulfillment}.`
                  );
                }}
              />
              <Button title="Cancel" variant="ghost" onPress={() => setShowCreate(false)} />
            </View>
          </Card>
        )}

        {items.map((s) => (
          <Card key={s.id}>
            <View style={{ flexDirection: "row", justifyContent: "space-between", gap: 12 }}>
              <View style={{ flex: 1 }}>
                <Text variant="h3">{s.productName}</Text>
                <Text variant="caption" color={colors.subtle} style={{ marginTop: 4 }}>
                  Every {s.frequencyDays} days · Qty {s.quantity} · {s.fulfillment}
                </Text>
                <Text variant="bodySm" color={colors.muted} style={{ marginTop: 6 }}>
                  Next: {new Date(s.nextFulfillmentAt).toLocaleDateString()} · {s.paymentMethod}
                  {s.memberId
                    ? ` · ${members.find((m) => m.id === s.memberId)?.name ?? "Family"}`
                    : ""}
                </Text>
              </View>
              <Badge
                label={s.status}
                tone={
                  s.status === "active" ? "brand" : s.status === "paused" ? "warn" : "danger"
                }
              />
            </View>
            <View style={{ flexDirection: "row", gap: 10, marginTop: 14 }}>
              {s.status === "active" ? (
                <Button title="Pause" size="sm" variant="outline" fullWidth={false} onPress={() => pause(s.id)} />
              ) : s.status === "paused" ? (
                <Button title="Resume" size="sm" fullWidth={false} onPress={() => resume(s.id)} />
              ) : null}
              {s.status !== "cancelled" ? (
                <Button
                  title="Cancel"
                  size="sm"
                  variant="ghost"
                  fullWidth={false}
                  onPress={() => cancel(s.id)}
                />
              ) : null}
            </View>
          </Card>
        ))}
      </ScrollView>
    </Screen>
  );
}