import { EmptyState } from "@/src/components/ui/EmptyState";
import { ModalHeader } from "@/src/components/ui/ModalHeader";
import { TAB_COLORS } from "@/src/constants/colors";
import {
  useTrips,
  useCreateTrip,
  type Trip,
  type CreateTripInput,
} from "@/src/hooks/useTrips";
import { formatEur } from "@/src/utils/format";
import { Ionicons } from "@expo/vector-icons";
import { useRouter } from "expo-router";
import { useState } from "react";
import { useTranslation } from "react-i18next";
import {
  ActivityIndicator,
  FlatList,
  Modal,
  Pressable,
  ScrollView,
  Text,
  TextInput,
  View,
} from "react-native";
import { useSafeAreaInsets } from "react-native-safe-area-context";

const ACCENT = TAB_COLORS.shopping; // green #16A34A

// ── Helpers ───────────────────────────────────────────────────────────────────

function formatDateRange(startDate: string, endDate: string): string {
  const fmt = (d: string) => {
    const parts = d.split("-");
    return `${parts[2]}.${parts[1]}.${parts[0]?.slice(2)}`;
  };
  return `${fmt(startDate)} – ${fmt(endDate)}`;
}

function getBudgetColor(remaining: number, budget: number): string {
  if (remaining <= 0) return "#dc2626"; // red
  if (remaining < budget * 0.1) return "#ea580c"; // orange
  return ACCENT; // green
}

// ── Progress Bar ──────────────────────────────────────────────────────────────

function ProgressBar({
  spent,
  budget,
  color,
}: {
  spent: number;
  budget: number;
  color: string;
}) {
  const ratio = budget > 0 ? Math.min(spent / budget, 1) : 0;
  return (
    <View className="h-1.5 bg-gray-100 rounded-full overflow-hidden mt-2">
      <View
        style={{ width: `${ratio * 100}%`, backgroundColor: color }}
        className="h-full rounded-full"
      />
    </View>
  );
}

// ── Active Trip Card ──────────────────────────────────────────────────────────

function ActiveTripCard({ trip, onPress }: { trip: Trip; onPress: () => void }) {
  const { t } = useTranslation();
  const remaining = trip.budget - trip.spent;
  const color = getBudgetColor(remaining, trip.budget);
  const isOver = remaining <= 0;

  return (
    <Pressable
      onPress={onPress}
      className="mx-4 mb-3 bg-white rounded-2xl p-4 active:opacity-80"
      style={{ borderWidth: 1, borderColor: "#f3f4f6" }}
    >
      <View className="flex-row items-start justify-between mb-1">
        <View className="flex-1 mr-2">
          <Text className="text-base font-semibold text-gray-900">{trip.name}</Text>
          {trip.destination && (
            <Text className="text-xs text-gray-400 mt-0.5">{trip.destination}</Text>
          )}
        </View>
        <View
          className="px-2 py-0.5 rounded-full"
          style={{ backgroundColor: `${ACCENT}18` }}
        >
          <Text className="text-xs font-medium" style={{ color: ACCENT }}>
            {t("trips.active")}
          </Text>
        </View>
      </View>

      <Text className="text-xs text-gray-400 mb-2">
        {formatDateRange(trip.startDate, trip.endDate)}
      </Text>

      <ProgressBar spent={trip.spent} budget={trip.budget} color={color} />

      <View className="flex-row justify-between mt-2">
        <Text className="text-xs text-gray-400">
          {t("trips.spent")}: {formatEur(trip.spent)}
        </Text>
        {isOver ? (
          <Text className="text-xs font-semibold" style={{ color: "#dc2626" }}>
            {t("trips.overBudget", { amount: formatEur(Math.abs(remaining)) })}
          </Text>
        ) : (
          <Text className="text-xs font-semibold" style={{ color }}>
            {t("trips.remaining")}: {formatEur(remaining)}
          </Text>
        )}
      </View>

      <View className="flex-row justify-between mt-1">
        <Text className="text-xs text-gray-300">{t("trips.budget")}: {formatEur(trip.budget)}</Text>
      </View>
    </Pressable>
  );
}

// ── Past Trip Row ─────────────────────────────────────────────────────────────

function PastTripRow({ trip, onPress }: { trip: Trip; onPress: () => void }) {
  const { t } = useTranslation();

  const hasSettlement =
    trip.settlementAmount !== null && trip.settlementAmount > 0.01;
  const isBalanced =
    trip.settlementAmount !== null && trip.settlementAmount <= 0.01;

  return (
    <Pressable
      onPress={onPress}
      className="flex-row items-center px-4 py-3 bg-white active:opacity-80"
      style={{ borderBottomWidth: 1, borderBottomColor: "#f9fafb" }}
    >
      <View className="flex-1">
        <Text className="text-sm font-medium text-gray-700">{trip.name}</Text>
        {trip.destination && (
          <Text className="text-xs text-gray-400">{trip.destination}</Text>
        )}
        {hasSettlement && (
          <Text className="text-xs text-gray-400 mt-0.5">
            {t("trips.settlement.closedBanner")} · {formatEur(trip.settlementAmount ?? 0)}
          </Text>
        )}
        {isBalanced && (
          <Text className="text-xs mt-0.5" style={{ color: "#16a34a" }}>
            {t("trips.settlement.balanced")}
          </Text>
        )}
      </View>
      <View className="items-end mr-3">
        <Text className="text-sm font-semibold text-gray-600">{formatEur(trip.spent)}</Text>
        <Text className="text-xs text-gray-400">{formatDateRange(trip.startDate, trip.endDate)}</Text>
      </View>
      <View
        className="px-2 py-0.5 rounded-full"
        style={{ backgroundColor: "#f3f4f6" }}
      >
        <Text className="text-xs text-gray-500">{t("trips.completed")}</Text>
      </View>
    </Pressable>
  );
}

// ── Create Trip Modal ─────────────────────────────────────────────────────────

function CreateTripModal({ onClose }: { onClose: () => void }) {
  const { t } = useTranslation();
  const { mutate: createTrip, isPending } = useCreateTrip();

  const [name, setName] = useState("");
  const [destination, setDestination] = useState("");
  const [budgetStr, setBudgetStr] = useState("");
  const [startDate, setStartDate] = useState("");
  const [endDate, setEndDate] = useState("");

  const canSave =
    name.trim().length > 0 &&
    parseFloat(budgetStr.replace(",", ".")) > 0 &&
    startDate.length === 10 &&
    endDate.length === 10;

  function handleSave() {
    const budget = parseFloat(budgetStr.replace(",", "."));
    if (!canSave || isNaN(budget)) return;

    const input: CreateTripInput = {
      name: name.trim(),
      budget,
      startDate,
      endDate,
      ...(destination.trim() ? { destination: destination.trim() } : {}),
    };

    createTrip(input, { onSuccess: onClose });
  }

  return (
    <Modal visible animationType="slide" presentationStyle="pageSheet" onRequestClose={onClose}>
      <View className="flex-1 bg-white">
        <ModalHeader
          title={t("trips.new")}
          onClose={onClose}
          closeLabel={t("common.cancel")}
          onSave={handleSave}
          saveLabel={t("common.create")}
          saveDisabled={!canSave}
          saveLoading={isPending}
          saveColor={ACCENT}
        />

        <ScrollView className="flex-1 px-4 pt-4" keyboardShouldPersistTaps="handled">
          {/* Name */}
          <Text className="text-xs font-medium text-gray-500 mb-1 uppercase tracking-wide">
            {t("trips.name")} *
          </Text>
          <TextInput
            className="bg-gray-50 border border-gray-200 rounded-xl px-4 py-3 text-base text-gray-900 mb-4"
            placeholder="z.B. Sommerurlaub Italien"
            placeholderTextColor="#9ca3af"
            value={name}
            onChangeText={setName}
            autoFocus
          />

          {/* Destination */}
          <Text className="text-xs font-medium text-gray-500 mb-1 uppercase tracking-wide">
            {t("trips.destination")}
          </Text>
          <TextInput
            className="bg-gray-50 border border-gray-200 rounded-xl px-4 py-3 text-base text-gray-900 mb-4"
            placeholder="z.B. Rom, Italien"
            placeholderTextColor="#9ca3af"
            value={destination}
            onChangeText={setDestination}
          />

          {/* Budget */}
          <Text className="text-xs font-medium text-gray-500 mb-1 uppercase tracking-wide">
            {t("trips.budget")} (€) *
          </Text>
          <TextInput
            className="bg-gray-50 border border-gray-200 rounded-xl px-4 py-3 text-base text-gray-900 mb-4"
            placeholder="z.B. 2000"
            placeholderTextColor="#9ca3af"
            value={budgetStr}
            onChangeText={setBudgetStr}
            keyboardType="decimal-pad"
          />

          {/* Start Date */}
          <Text className="text-xs font-medium text-gray-500 mb-1 uppercase tracking-wide">
            {t("trips.startDate")} *
          </Text>
          <TextInput
            className="bg-gray-50 border border-gray-200 rounded-xl px-4 py-3 text-base text-gray-900 mb-4"
            placeholder="YYYY-MM-DD"
            placeholderTextColor="#9ca3af"
            value={startDate}
            onChangeText={setStartDate}
            keyboardType="numbers-and-punctuation"
            maxLength={10}
          />

          {/* End Date */}
          <Text className="text-xs font-medium text-gray-500 mb-1 uppercase tracking-wide">
            {t("trips.endDate")} *
          </Text>
          <TextInput
            className="bg-gray-50 border border-gray-200 rounded-xl px-4 py-3 text-base text-gray-900 mb-4"
            placeholder="YYYY-MM-DD"
            placeholderTextColor="#9ca3af"
            value={endDate}
            onChangeText={setEndDate}
            keyboardType="numbers-and-punctuation"
            maxLength={10}
          />
        </ScrollView>
      </View>
    </Modal>
  );
}

// ── Main Screen ───────────────────────────────────────────────────────────────

type SectionItem =
  | { type: "header"; label: string }
  | { type: "active-trip"; trip: Trip }
  | { type: "past-trip"; trip: Trip }
  | { type: "empty" };

export default function UrlaubScreen() {
  const insets = useSafeAreaInsets();
  const router = useRouter();
  const { t } = useTranslation();
  const { data: trips = [], isLoading, refetch, isRefetching } = useTrips();
  const [showCreate, setShowCreate] = useState(false);

  const activeTrips = trips.filter((t) => t.status === "active");
  const pastTrips = trips.filter((t) => t.status === "completed");

  // Build flat list items for sectioned rendering
  const listItems: SectionItem[] = [];

  if (activeTrips.length > 0) {
    listItems.push({ type: "header", label: t("trips.active") });
    activeTrips.forEach((trip) => listItems.push({ type: "active-trip", trip }));
  }

  if (pastTrips.length > 0) {
    listItems.push({ type: "header", label: t("trips.past") });
    pastTrips.forEach((trip) => listItems.push({ type: "past-trip", trip }));
  }

  if (trips.length === 0 && !isLoading) {
    listItems.push({ type: "empty" });
  }

  function renderItem({ item }: { item: SectionItem }) {
    if (item.type === "header") {
      return (
        <Text className="text-xs font-semibold text-gray-400 uppercase tracking-wide px-4 pt-4 pb-2">
          {item.label}
        </Text>
      );
    }

    if (item.type === "active-trip") {
      return (
        <ActiveTripCard
          trip={item.trip}
          onPress={() =>
            router.push({
              pathname: "/(app)/urlaub/[id]",
              params: { id: item.trip.id },
            })
          }
        />
      );
    }

    if (item.type === "past-trip") {
      return (
        <PastTripRow
          trip={item.trip}
          onPress={() =>
            router.push({
              pathname: "/(app)/urlaub/[id]",
              params: { id: item.trip.id },
            })
          }
        />
      );
    }

    // empty state
    return (
      <EmptyState
        icon="airplane-outline"
        title={t("trips.noTrips")}
        subtitle={t("trips.noTripsHint")}
      />
    );
  }

  return (
    <View className="flex-1 bg-gray-50">
      {/* Header */}
      <View
        style={{
          backgroundColor: "#fff",
          paddingTop: insets.top + 12,
          borderBottomWidth: 1,
          borderBottomColor: "#f3f4f6",
        }}
        className="px-4 pb-3 flex-row items-center justify-between"
      >
        <View className="flex-row items-center gap-2">
          <Pressable onPress={() => router.push("/(app)/mehr")} className="mr-1 p-1">
            <Ionicons name="chevron-back" size={22} color="#374151" />
          </Pressable>
          <Text className="text-xl font-bold text-gray-900">{t("trips.title")}</Text>
        </View>
        <Pressable
          onPress={() => setShowCreate(true)}
          className="w-9 h-9 rounded-full items-center justify-center active:opacity-70"
          style={{ backgroundColor: ACCENT }}
        >
          <Ionicons name="add" size={22} color="#fff" />
        </Pressable>
      </View>

      {isLoading ? (
        <View className="flex-1 items-center justify-center">
          <ActivityIndicator size="large" color={ACCENT} />
        </View>
      ) : (
        <FlatList
          data={listItems}
          keyExtractor={(item, index) => {
            if (item.type === "header") return `header-${item.label}`;
            if (item.type === "active-trip" || item.type === "past-trip")
              return item.trip.id;
            return `empty-${index}`;
          }}
          renderItem={renderItem}
          contentContainerStyle={
            trips.length === 0
              ? { flex: 1, paddingBottom: insets.bottom + 16 }
              : { paddingBottom: insets.bottom + 16, paddingTop: 4 }
          }
          refreshing={isRefetching}
          onRefresh={() => void refetch()}
        />
      )}

      {showCreate && <CreateTripModal onClose={() => setShowCreate(false)} />}
    </View>
  );
}