import 'server-only';
import type { SupabaseClient } from '@supabase/supabase-js';

import type { Database } from '@kit/supabase/database';

export function createEventExportService(client: SupabaseClient<Database>) {
  return new EventExportService(client);
}

class EventExportService {
  constructor(private readonly client: SupabaseClient<Database>) {}

  async exportRegistrationsCsv(eventId: string): Promise<string> {
    const { data: registrations, error } = await this.client
      .from('event_registrations')
      .select('*')
      .eq('event_id', eventId)
      .order('last_name');

    if (error) throw error;
    if (!registrations?.length) return '';

    const headers = [
      'Vorname',
      'Nachname',
      'E-Mail',
      'Telefon',
      'Geburtsdatum',
      'Status',
      'Anmeldedatum',
    ];

    const rows = registrations.map((r) =>
      [
        r.first_name,
        r.last_name,
        r.email ?? '',
        r.phone ?? '',
        r.date_of_birth ?? '',
        r.status,
        r.created_at ?? '',
      ]
        .map((v) => `"${String(v).replace(/"/g, '""')}"`)
        .join(';'),
    );

    return [headers.join(';'), ...rows].join('\n');
  }

  async exportEventsCsv(
    accountId: string,
    filters?: { status?: string },
  ): Promise<string> {
    let query = this.client
      .from('events')
      .select('*')
      .eq('account_id', accountId)
      .order('event_date', { ascending: false });

    if (filters?.status) {
      query = query.eq('status', filters.status as any);
    }

    const { data: events, error } = await query;
    if (error) throw error;
    if (!events?.length) return '';

    const headers = ['Name', 'Status', 'Datum', 'Ort', 'Kapazitat'];

    const rows = events.map((e) =>
      [
        e.name,
        e.status,
        e.event_date ?? '',
        e.location ?? '',
        e.capacity?.toString() ?? '',
      ]
        .map((v) => `"${String(v).replace(/"/g, '""')}"`)
        .join(';'),
    );

    return [headers.join(';'), ...rows].join('\n');
  }
}