import { useCallback, useEffect, useMemo, useState } from 'react';
import { ActivityIndicator, Pressable, RefreshControl, ScrollView, StyleSheet, Text, View } from 'react-native';
import { useLocalSearchParams } from 'expo-router';
import * as WebBrowser from 'expo-web-browser';

import { HistorySection } from '@/components/history-section';
import { CalendarEvent, fetchEventById } from '@/src/lib/api';
import { useAuth } from '@/src/providers/auth-provider';

const PRIMARY = '#69c350';

function formatDateTime(value: unknown): string {
  if (!value) return '-';
  const date = new Date(String(value));
  if (Number.isNaN(date.getTime())) return String(value);
  return date.toLocaleString('de-DE', {
    weekday: 'short',
    day: '2-digit',
    month: '2-digit',
    year: 'numeric',
    hour: '2-digit',
    minute: '2-digit',
  });
}

function relationName(value: unknown): string {
  if (!value) return '-';
  if (typeof value === 'object') {
    const relation = value as { id?: number | string; name?: string };
    return String(relation.name || relation.id || '-');
  }
  return String(value);
}

export default function EventDetailScreen() {
  const params = useLocalSearchParams<{ id?: string }>();
  const eventId = Number(params.id);
  const { token } = useAuth();
  const [event, setEvent] = useState<CalendarEvent | null>(null);
  const [loading, setLoading] = useState(true);
  const [refreshing, setRefreshing] = useState(false);
  const [error, setError] = useState<string | null>(null);
  const validId = useMemo(() => Number.isFinite(eventId) && eventId > 0, [eventId]);

  const load = useCallback(async (showSpinner = true) => {
    if (!token || !validId) return;
    if (showSpinner) setLoading(true);
    setError(null);
    try {
      setEvent(await fetchEventById(token, eventId));
    } catch (err) {
      setError(err instanceof Error ? err.message : 'Der Termin konnte nicht geladen werden.');
    } finally {
      setLoading(false);
      setRefreshing(false);
    }
  }, [eventId, token, validId]);

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

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

  async function openLink() {
    if (!event?.link) return;
    const raw = String(event.link).trim();
    const url = /^https?:\/\//i.test(raw) ? raw : `https://${raw}`;
    await WebBrowser.openBrowserAsync(url, { controlsColor: PRIMARY, showTitle: true });
  }

  const rows = event
    ? [
        { label: 'Beginn', value: formatDateTime(event.startDate) },
        { label: 'Ende', value: formatDateTime(event.endDate) },
        { label: 'Projekt', value: relationName(event.project) },
        { label: 'Kunde', value: relationName(event.customer) },
        { label: 'Status', value: String(event.state || '-') },
        { label: 'Wiederholung', value: String(event.repeatInterval || '-') },
      ]
    : [];

  return (
    <ScrollView
      contentContainerStyle={styles.container}
      refreshControl={<RefreshControl refreshing={refreshing} onRefresh={onRefresh} />}>
      {error ? <Text style={styles.error}>{error}</Text> : null}
      {loading ? (
        <View style={styles.loadingBox}><ActivityIndicator /><Text style={styles.loadingText}>Termin wird geladen...</Text></View>
      ) : null}
      {!loading && event ? (
        <>
          <View style={styles.card}>
            <View style={styles.headingRow}>
              <View style={[styles.colorMark, { backgroundColor: event.color || PRIMARY }]} />
              <Text style={styles.title}>{event.name}</Text>
            </View>
            <View style={styles.table}>
              {rows.map((row) => (
                <View key={row.label} style={styles.row}>
                  <Text style={styles.label}>{row.label}</Text>
                  <Text style={styles.value}>{row.value}</Text>
                </View>
              ))}
            </View>
            {event.notes ? <View style={styles.notesBox}><Text style={styles.notesLabel}>Notizen</Text><Text style={styles.notes}>{event.notes}</Text></View> : null}
            {event.link ? <Pressable style={styles.linkButton} onPress={openLink}><Text style={styles.linkButtonText}>Link öffnen</Text></Pressable> : null}
          </View>
          <HistorySection resource="events" resourceId={eventId} />
        </>
      ) : null}
    </ScrollView>
  );
}

const styles = StyleSheet.create({
  container: { padding: 16, gap: 12, backgroundColor: '#f9fafb' },
  card: { backgroundColor: '#ffffff', borderRadius: 12, borderWidth: 1, borderColor: '#e5e7eb', padding: 12, gap: 10 },
  headingRow: { flexDirection: 'row', alignItems: 'center', gap: 9 },
  colorMark: { width: 6, height: 28, borderRadius: 3 },
  title: { flex: 1, color: '#111827', fontSize: 19, fontWeight: '700' },
  table: { borderWidth: 1, borderColor: '#e5e7eb', borderRadius: 10, overflow: 'hidden' },
  row: { borderBottomWidth: 1, borderBottomColor: '#e5e7eb', paddingHorizontal: 10, paddingVertical: 8, gap: 2 },
  label: { color: '#6b7280', fontSize: 12, textTransform: 'uppercase', fontWeight: '600' },
  value: { color: '#111827', fontSize: 14, fontWeight: '500' },
  notesBox: { borderWidth: 1, borderColor: '#e5e7eb', borderRadius: 10, padding: 10, backgroundColor: '#fafafa', gap: 4 },
  notesLabel: { color: '#6b7280', fontSize: 12, fontWeight: '600', textTransform: 'uppercase' },
  notes: { color: '#374151', fontSize: 14 },
  linkButton: { backgroundColor: PRIMARY, borderRadius: 9, minHeight: 40, alignItems: 'center', justifyContent: 'center' },
  linkButtonText: { color: '#ffffff', fontWeight: '700' },
  loadingBox: { paddingVertical: 24, alignItems: 'center', gap: 8 },
  loadingText: { color: '#6b7280' },
  error: { color: '#dc2626', fontSize: 13 },
});