import { useCallback, useEffect, useMemo, useState } from 'react';
import {
  ActivityIndicator,
  Pressable,
  RefreshControl,
  ScrollView,
  StyleSheet,
  Text,
  TextInput,
  View,
} from 'react-native';
import { router } from 'expo-router';

import { EventCreateModal } from '@/components/event-create-modal';
import { CalendarEvent, fetchEvents, fetchProjects, Project } from '@/src/lib/api';
import { useAuth } from '@/src/providers/auth-provider';

const PRIMARY = '#69c350';

function formatEventDate(event: CalendarEvent): string {
  const start = new Date(event.startDate);
  const end = event.endDate ? new Date(event.endDate) : null;
  if (Number.isNaN(start.getTime())) return String(event.startDate || '-');

  const date = start.toLocaleDateString('de-DE', { weekday: 'short', day: '2-digit', month: '2-digit', year: 'numeric' });
  const startTime = start.toLocaleTimeString('de-DE', { hour: '2-digit', minute: '2-digit' });
  const endTime = end && !Number.isNaN(end.getTime())
    ? end.toLocaleTimeString('de-DE', { hour: '2-digit', minute: '2-digit' })
    : null;
  return `${date} · ${startTime}${endTime ? `–${endTime}` : ''}`;
}

function projectName(event: CalendarEvent): string | null {
  if (!event.project) return null;
  if (typeof event.project === 'object') return event.project.name || (event.project.id ? `Projekt #${event.project.id}` : null);
  return `Projekt #${event.project}`;
}

export default function EventsScreen() {
  const { token } = useAuth();
  const [events, setEvents] = useState<CalendarEvent[]>([]);
  const [projects, setProjects] = useState<Project[]>([]);
  const [search, setSearch] = useState('');
  const [showPast, setShowPast] = useState(false);
  const [createOpen, setCreateOpen] = useState(false);
  const [loading, setLoading] = useState(true);
  const [refreshing, setRefreshing] = useState(false);
  const [error, setError] = useState<string | null>(null);

  const load = useCallback(async (showSpinner = true) => {
    if (!token) return;
    if (showSpinner) setLoading(true);
    setError(null);
    try {
      const [eventRows, projectRows] = await Promise.all([fetchEvents(token), fetchProjects(token)]);
      setEvents(eventRows);
      setProjects(projectRows);
    } catch (err) {
      setError(err instanceof Error ? err.message : 'Termine konnten nicht geladen werden.');
    } finally {
      setLoading(false);
      setRefreshing(false);
    }
  }, [token]);

  useEffect(() => {
    void load(true);
  }, [load]);

  const visibleEvents = useMemo(() => {
    const now = Date.now();
    const terms = search.trim().toLowerCase().split(/\s+/).filter(Boolean);
    return events
      .filter((event) => showPast || new Date(event.endDate || event.startDate).getTime() >= now)
      .filter((event) => {
        if (terms.length === 0) return true;
        const haystack = [event.name, event.notes, event.eventtype, projectName(event)]
          .map((value) => String(value || '').toLowerCase())
          .join(' ');
        return terms.every((term) => haystack.includes(term));
      })
      .sort((a, b) => new Date(a.startDate).getTime() - new Date(b.startDate).getTime());
  }, [events, search, showPast]);

  async function onRefresh() {
    setRefreshing(true);
    await load(false);
  }

  return (
    <View style={styles.screen}>
      <View style={styles.toolbar}>
        <TextInput
          placeholder="Termine suchen"
          placeholderTextColor="#9ca3af"
          style={styles.searchInput}
          value={search}
          onChangeText={setSearch}
        />
        <View style={styles.toolbarActions}>
          <Pressable
            style={[styles.filterButton, showPast ? styles.filterButtonActive : null]}
            onPress={() => setShowPast((value) => !value)}>
            <Text style={[styles.filterButtonText, showPast ? styles.filterButtonTextActive : null]}>Vergangene anzeigen</Text>
          </Pressable>
          <Pressable style={styles.calendarButton} onPress={() => router.push('/more/calendar' as any)}>
            <Text style={styles.calendarButtonText}>Kalender</Text>
          </Pressable>
        </View>
      </View>

      <ScrollView
        style={styles.list}
        contentContainerStyle={styles.listContent}
        refreshControl={<RefreshControl refreshing={refreshing} onRefresh={onRefresh} />}>
        {error ? <Text style={styles.error}>{error}</Text> : null}
        {loading ? (
          <View style={styles.loadingBox}>
            <ActivityIndicator />
            <Text style={styles.loadingText}>Termine werden geladen...</Text>
          </View>
        ) : null}
        {!loading && visibleEvents.length === 0 ? <Text style={styles.empty}>Keine Termine gefunden.</Text> : null}
        {!loading
          ? visibleEvents.map((event) => (
              <Pressable
                key={String(event.id)}
                style={({ pressed }) => [styles.eventRow, pressed ? styles.eventRowPressed : null]}
                onPress={() => router.push(`/more/event/${event.id}` as any)}>
                <View style={[styles.colorBar, { backgroundColor: event.color || PRIMARY }]} />
                <View style={styles.eventMain}>
                  <Text style={styles.eventName}>{event.name}</Text>
                  <Text style={styles.eventDate}>{formatEventDate(event)}</Text>
                  {projectName(event) ? <Text style={styles.eventProject}>{projectName(event)}</Text> : null}
                  {event.notes ? <Text style={styles.eventNotes} numberOfLines={2}>{String(event.notes)}</Text> : null}
                </View>
                <Text style={styles.arrow}>›</Text>
              </Pressable>
            ))
          : null}
      </ScrollView>

      <Pressable style={styles.fab} onPress={() => setCreateOpen(true)}>
        <Text style={styles.fabText}>+</Text>
      </Pressable>

      <EventCreateModal
        visible={createOpen}
        projects={projects}
        onClose={() => setCreateOpen(false)}
        onCreated={() => load(false)}
      />
    </View>
  );
}

const styles = StyleSheet.create({
  screen: { flex: 1, backgroundColor: '#ffffff' },
  toolbar: { padding: 14, gap: 10, borderBottomWidth: 1, borderBottomColor: '#e5e7eb' },
  searchInput: {
    borderWidth: 1,
    borderColor: '#d1d5db',
    borderRadius: 10,
    paddingHorizontal: 12,
    paddingVertical: 10,
    fontSize: 15,
    color: '#111827',
  },
  toolbarActions: { flexDirection: 'row', justifyContent: 'space-between', gap: 8 },
  filterButton: { borderWidth: 1, borderColor: '#d1d5db', borderRadius: 999, paddingHorizontal: 10, paddingVertical: 7 },
  filterButtonActive: { borderColor: PRIMARY, backgroundColor: '#eff9ea' },
  filterButtonText: { color: '#374151', fontSize: 12, fontWeight: '600' },
  filterButtonTextActive: { color: '#3d7a30' },
  calendarButton: { borderRadius: 8, backgroundColor: PRIMARY, paddingHorizontal: 13, paddingVertical: 7 },
  calendarButtonText: { color: '#ffffff', fontSize: 13, fontWeight: '700' },
  list: { flex: 1 },
  listContent: { paddingBottom: 96 },
  eventRow: { minHeight: 82, flexDirection: 'row', alignItems: 'stretch', borderBottomWidth: 1, borderBottomColor: '#e5e7eb' },
  eventRowPressed: { backgroundColor: '#f3f4f6' },
  colorBar: { width: 5 },
  eventMain: { flex: 1, paddingHorizontal: 12, paddingVertical: 11, gap: 2 },
  eventName: { color: '#111827', fontSize: 15, fontWeight: '700' },
  eventDate: { color: '#374151', fontSize: 13 },
  eventProject: { color: '#3d7a30', fontSize: 12, fontWeight: '600' },
  eventNotes: { color: '#6b7280', fontSize: 12 },
  arrow: { alignSelf: 'center', color: '#9ca3af', fontSize: 25, paddingRight: 12 },
  loadingBox: { paddingVertical: 24, alignItems: 'center', gap: 8 },
  loadingText: { color: '#6b7280' },
  empty: { color: '#6b7280', textAlign: 'center', paddingVertical: 28 },
  error: { color: '#dc2626', fontSize: 13, padding: 14 },
  fab: {
    position: 'absolute',
    right: 18,
    bottom: 20,
    width: 56,
    height: 56,
    borderRadius: 28,
    backgroundColor: PRIMARY,
    alignItems: 'center',
    justifyContent: 'center',
    shadowColor: '#111827',
    shadowOpacity: 0.25,
    shadowRadius: 8,
    shadowOffset: { width: 0, height: 4 },
    elevation: 5,
  },
  fabText: { color: '#ffffff', fontSize: 30, lineHeight: 30, marginTop: -2 },
});