import { useLocalSearchParams, useRouter } from "expo-router";
import { useState } from "react";
import { useTranslation } from "react-i18next";
import {
  ActivityIndicator,
  Alert,
  Pressable,
  ScrollView,
  Text,
  TextInput,
  View,
} from "react-native";
import { useSafeAreaInsets } from "react-native-safe-area-context";
import { Ionicons } from "@expo/vector-icons";
import { useSettlementV2 } from "@/src/hooks/useFixedCosts";
import { useHouseholdSettings } from "@/src/hooks/useHouseholdSettings";
import { useCloseMonth } from "@/src/hooks/useMonthStatus";
import { useAuthStore } from "@/src/stores/auth.store";
import { monthLabel } from "@/src/utils/date";
import { formatEur } from "@/src/utils/format";

const ACCENT = "#2563EB";

export default function CloseMonthScreen() {
  const insets = useSafeAreaInsets();
  const router = useRouter();
  const { t } = useTranslation();
  const { month } = useLocalSearchParams<{ month: string }>();
  const userId = useAuthStore((s) => s.user?.id);

  const { data: settlement, isLoading: settlementLoading } = useSettlementV2(month);
  const { data: hhSettings } = useHouseholdSettings();
  const { mutate: closeMonth, isPending } = useCloseMonth(month);

  const remaining = settlement?.remaining ?? 0;
  const [amountStr, setAmountStr] = useState<string | null>(null);
  const [notes, setNotes] = useState("");

  // Lazy-init amount from settlement once loaded
  const displayAmount = amountStr ?? (remaining > 0 ? remaining.toFixed(2).replace(".", ",") : "0,00");

  const others = (settlement?.members ?? []).filter((m) => m.userId !== userId);
  const otherName = hhSettings?.partnerName ?? others[0]?.name ?? "Partner";
  const otherUserId = others[0]?.userId ?? "";

  function handleAmountChange(text: string) {
    // Allow only digits and one comma
    const cleaned = text.replace(/[^0-9,]/g, "");
    const parts = cleaned.split(",");
    if (parts.length > 2) return;
    if (parts[1] !== undefined && parts[1].length > 2) return;
    setAmountStr(cleaned);
  }

  function handleClose() {
    const amount = parseFloat(displayAmount.replace(",", ".")) || 0;

    Alert.alert(
      t('monthClose.closeConfirmTitle', { month: monthLabel(month) }),
      t('monthClose.closeConfirmMessage'),
      [
        { text: t('common.cancel'), style: "cancel" },
        {
          text: t('monthClose.closeConfirmAction'),
          style: "destructive",
          onPress: () => {
            closeMonth(
              { finalAmount: amount, toUserId: otherUserId, notes: notes.trim() || undefined },
              {
                onSuccess: () => router.back(),
                onError: (err) =>
                  Alert.alert(t('common.error'), err.message ?? "Abschluss fehlgeschlagen"),
              },
            );
          },
        },
      ],
    );
  }

  if (settlementLoading) {
    return (
      <View className="flex-1 bg-gray-50 items-center justify-center">
        <ActivityIndicator size="large" color={ACCENT} />
      </View>
    );
  }

  const s = settlement;

  return (
    <View className="flex-1 bg-gray-50">
      {/* Header */}
      <View
        className="bg-white border-b border-gray-100"
        style={{ paddingTop: insets.top }}
      >
        <View className="flex-row items-center px-4 py-3">
          <Pressable onPress={() => router.back()} className="mr-3 p-1">
            <Ionicons name="chevron-back" size={22} color="#374151" />
          </Pressable>
          <Text className="text-base font-semibold text-gray-900 flex-1">
            {t('monthClose.title', { month: monthLabel(month) })}
          </Text>
        </View>
      </View>

      <ScrollView
        className="flex-1"
        contentContainerStyle={{ padding: 16, paddingBottom: insets.bottom + 80 }}
        keyboardShouldPersistTaps="handled"
      >
        {/* Overview card */}
        {s && (
          <View className="bg-white rounded-2xl p-4 mb-4" style={{ borderWidth: 1, borderColor: "#f3f4f6" }}>
            <Text className="text-xs font-medium uppercase text-gray-400 mb-3">{t('monthClose.overview')}</Text>

            <Row label={t('monthClose.householdTotal')} value={`-${formatEur(s.householdExpenses)}`} />
            {s.householdIncome > 0 && (
              <Row label={t('monthClose.householdIncome')} value={`+${formatEur(s.householdIncome)}`} color="#16a34a" />
            )}
            <Row
              label={t('monthClose.yourShare', { percent: s.memberCount > 0 ? Math.round(100 / s.memberCount) : 50 })}
              value={`-${formatEur(s.perMemberShare)}`}
              bold
            />

            {s.lineItems.length > 0 && (
              <>
                <View className="h-px bg-gray-100 my-2" />
                {s.lineItems.map((li) => (
                  <Row key={li.id} label={li.label} value={`-${formatEur(li.amount)}`} />
                ))}
              </>
            )}

            <View className="h-px bg-gray-200 my-3" />
            <Row label={t('monthClose.totalTransfer')} value={`-${formatEur(s.totalOwed)}`} bold />
            <Row label={t('monthClose.alreadyTransferred')} value={`-${formatEur(s.alreadyTransferred)}`} />
          </View>
        )}

        {/* Remaining amount hero */}
        <View
          className="rounded-2xl p-4 mb-4 items-center"
          style={{ backgroundColor: remaining > 0.01 ? "#fff7ed" : "#f0fdf4", borderWidth: 1, borderColor: remaining > 0.01 ? "#fed7aa" : "#bbf7d0" }}
        >
          <Text className="text-xs text-gray-500 mb-1">
            {remaining > 0.01 ? t('monthClose.receives', { name: otherName }) : remaining < -0.01 ? t('monthClose.youReceive') : t('monthClose.settled')}
          </Text>
          <Text
            className="text-3xl font-bold"
            style={{ color: remaining > 0.01 ? "#ea580c" : remaining < -0.01 ? "#16a34a" : "#6b7280" }}
          >
            {formatEur(Math.abs(remaining))}
          </Text>
        </View>

        {/* Amount adjustment */}
        <View className="bg-white rounded-2xl p-4 mb-4" style={{ borderWidth: 1, borderColor: "#f3f4f6" }}>
          <Text className="text-sm font-medium text-gray-700 mb-2">
            {t('monthClose.adjustAmount')}
          </Text>
          <Text className="text-xs text-gray-400 mb-3">
            {t('monthClose.adjustHint')}
          </Text>
          <View className="flex-row items-center bg-gray-50 border border-gray-200 rounded-xl px-4 py-3">
            <Text className="text-base text-gray-400 mr-2">€</Text>
            <TextInput
              className="flex-1 text-base text-gray-900"
              value={displayAmount}
              onChangeText={handleAmountChange}
              keyboardType="decimal-pad"
              selectTextOnFocus
            />
          </View>
        </View>

        {/* Notes */}
        <View className="bg-white rounded-2xl p-4 mb-6" style={{ borderWidth: 1, borderColor: "#f3f4f6" }}>
          <Text className="text-sm font-medium text-gray-700 mb-2">{t('monthClose.note')}</Text>
          <TextInput
            className="bg-gray-50 border border-gray-200 rounded-xl px-4 py-3 text-base text-gray-900"
            placeholder={t('monthClose.notePlaceholder')}
            value={notes}
            onChangeText={setNotes}
            multiline
          />
        </View>

        {/* CTA */}
        <Pressable
          onPress={handleClose}
          disabled={isPending}
          className="rounded-2xl py-4 items-center active:opacity-80 mb-3"
          style={{ backgroundColor: "#dc2626" }}
        >
          {isPending ? (
            <ActivityIndicator color="#fff" />
          ) : (
            <View className="flex-row items-center gap-2">
              <Ionicons name="lock-closed-outline" size={18} color="#fff" />
              <Text className="text-base font-semibold text-white">{t('monthClose.closeButton')}</Text>
            </View>
          )}
        </Pressable>

        <Pressable
          onPress={() => router.back()}
          className="py-3 items-center active:opacity-50"
        >
          <Text className="text-sm text-gray-400">{t('common.cancel')}</Text>
        </Pressable>
      </ScrollView>
    </View>
  );
}

function Row({
  label,
  value,
  bold,
  color,
}: {
  label: string;
  value: string;
  bold?: boolean;
  color?: string;
}) {
  return (
    <View className="flex-row justify-between items-center py-1.5">
      <Text className={`text-sm ${bold ? "font-semibold text-gray-800" : "text-gray-500"}`}>
        {label}
      </Text>
      <Text
        className={`text-sm ${bold ? "font-semibold text-gray-800" : "text-gray-700"}`}
        style={color ? { color } : undefined}
      >
        {value}
      </Text>
    </View>
  );
}