import { Injectable, Logger, OnModuleInit } from '@nestjs/common';
import { Cron } from '@nestjs/schedule';
import { InjectRepository } from '@nestjs/typeorm';
import { IsNull, Not, Repository } from 'typeorm';
import { AgrarmonitorService } from './agrarmonitor.service';
import { PaperlessService } from '../paperless/paperless.service';
import { Setting } from '../database/entities/setting.entity';
import { Client } from '../database/entities/client.entity';
import { CorrespondentSetting } from '../database/entities/correspondent-setting.entity';

const INTERN_BELEGNUMMER_FIELD_ID = 7;
const EINGANGSDATUM_FIELD_ID = 9;
const EXTERN_BELEGNUMMER_FIELD_ID = 3;
const DOCS_PAGE_SIZE = 500;
const AGRARMONITOR_BASE_URL = 'https://admin7.agrarmonitor.de';

export interface PollingResult {
  processed: number;
  updated: number;
  skipped: number;
  errors: string[];
}

export interface SyncConflict {
  agrarmonitorId: number;
  correspondents: Array<{ id: number; name: string; documentCount: number }>;
}

export interface SyncCorrespondentsResult {
  total: number;
  matched: number;
  unmatched: number;
  autoMerged: number;
  conflicts: SyncConflict[];
}

@Injectable()
export class AgrarmonitorPollingService implements OnModuleInit {
  private readonly logger = new Logger(AgrarmonitorPollingService.name);
  private pollingRunning = false;
  private uploadCheckRunning = false;

  constructor(
    private readonly agrarmonitorService: AgrarmonitorService,
    private readonly paperlessService: PaperlessService,
    @InjectRepository(Setting) private readonly settingRepo: Repository<Setting>,
    @InjectRepository(Client) private readonly clientRepo: Repository<Client>,
    @InjectRepository(CorrespondentSetting) private readonly corrSettingRepo: Repository<CorrespondentSetting>,
  ) {}

  async onModuleInit() {
    await this.upsertSetting('agrarmonitor_tag_fertig', '4');
    await this.upsertSetting('agrarmonitor_tag_verbucht', '9');
    await this.upsertSetting('agrarmonitor_tag_hochgeladen', '');
    await this.upsertSetting('agrarmonitor_link_field', '');
  }

  @Cron(process.env['AGRARMONITOR_POLLING_CRON'] || '0 */30 * * * *')
  async scheduledPolling() {
    if (!process.env['AGRARMONITOR_POLLING_CRON']) return;
    this.runPolling().catch((err) => this.logger.error('Cron-Polling-Fehler:', err));
  }

  @Cron(process.env['AGRARMONITOR_UPLOAD_CHECK_CRON'] || '0 * * * * *')
  async scheduledUploadCheck() {
    if (!process.env['AGRARMONITOR_UPLOAD_CHECK_CRON']) return;
    this.processVerarbeiteteDocuments().catch((err) => this.logger.error('Cron-Upload-Check-Fehler:', err));
  }

  async getPollingConfig(): Promise<{ tagFertig: string; tagVerbucht: string; tagHochgeladen: string; linkField: string }> {
    const [fertig, verbucht, hochgeladen, linkField] = await Promise.all([
      this.settingRepo.findOneBy({ Tag: 'agrarmonitor_tag_fertig' }),
      this.settingRepo.findOneBy({ Tag: 'agrarmonitor_tag_verbucht' }),
      this.settingRepo.findOneBy({ Tag: 'agrarmonitor_tag_hochgeladen' }),
      this.settingRepo.findOneBy({ Tag: 'agrarmonitor_link_field' }),
    ]);
    return {
      tagFertig: fertig?.Wert ?? '4',
      tagVerbucht: verbucht?.Wert ?? '9',
      tagHochgeladen: hochgeladen?.Wert ?? '',
      linkField: linkField?.Wert ?? '',
    };
  }

  async updatePollingConfig(
    tagFertig: string,
    tagVerbucht: string,
    tagHochgeladen: string,
    linkField: string,
  ): Promise<{ tagFertig: string; tagVerbucht: string; tagHochgeladen: string; linkField: string }> {
    await Promise.all([
      this.settingRepo.update({ Tag: 'agrarmonitor_tag_fertig' }, { Wert: tagFertig }),
      this.settingRepo.update({ Tag: 'agrarmonitor_tag_verbucht' }, { Wert: tagVerbucht }),
      this.settingRepo.update({ Tag: 'agrarmonitor_tag_hochgeladen' }, { Wert: tagHochgeladen }),
      this.settingRepo.update({ Tag: 'agrarmonitor_link_field' }, { Wert: linkField }),
    ]);
    return { tagFertig, tagVerbucht, tagHochgeladen, linkField };
  }

  async runPolling(): Promise<PollingResult> {
    if (this.pollingRunning) {
      this.logger.warn('Polling läuft bereits, überspringe');
      return { processed: 0, updated: 0, skipped: 0, errors: ['Polling bereits aktiv'] };
    }
    this.pollingRunning = true;

    const result: PollingResult = { processed: 0, updated: 0, skipped: 0, errors: [] };
    this.logger.log('Starte Agrarmonitor-Polling');

    try {
      const [tagFertigSetting, tagVerbuchtSetting] = await Promise.all([
        this.settingRepo.findOneBy({ Tag: 'agrarmonitor_tag_fertig' }),
        this.settingRepo.findOneBy({ Tag: 'agrarmonitor_tag_verbucht' }),
      ]);
      const tagFertigId = parseInt(tagFertigSetting?.Wert ?? '4', 10);
      const tagVerbuchtId = parseInt(tagVerbuchtSetting?.Wert ?? '9', 10);

      if (isNaN(tagFertigId) || isNaN(tagVerbuchtId)) {
        const msg = 'Tag-IDs ungültig (keine Zahlen)';
        this.logger.error(msg);
        return { ...result, errors: [msg] };
      }

      let amClient: Awaited<ReturnType<typeof this.agrarmonitorService.getClient>>;
      try {
        amClient = await this.agrarmonitorService.getClient();
      } catch (err: unknown) {
        const msg = `Connector-Fehler: ${err instanceof Error ? err.message : 'unbekannt'}`;
        this.logger.error(msg);
        return { ...result, errors: [msg] };
      }

      let customers: Awaited<ReturnType<typeof amClient.fetchCustomers>>;
      try {
        customers = await amClient.fetchCustomers();
      } catch (err: unknown) {
        const msg = `Kunden-Abruf fehlgeschlagen: ${err instanceof Error ? err.message : 'unbekannt'}`;
        this.logger.error(msg);
        return { ...result, errors: [msg] };
      }

      for (const customer of customers.filter(
        (c) => Number(c['ist_lieferant']) === 1 && Number(c['ist_aktiv']) === 1,
      )) {
        try {
          await this.getOrCreateCorrespondent(customer);
        } catch (err: unknown) {
          this.logger.warn(`Korrespondenten-Sync fehlgeschlagen: ${err instanceof Error ? err.message : err}`);
        }
      }

      const docsResponse = await this.paperlessService.getDocuments({
        page: 1,
        page_size: DOCS_PAGE_SIZE,
        truncate_content: true,
        tags__id__all: tagFertigId,
      });
      const docs: any[] = docsResponse?.results ?? [];
      if ((docsResponse?.count ?? 0) > DOCS_PAGE_SIZE) {
        this.logger.warn(`Mehr als ${DOCS_PAGE_SIZE} Dokumente bereit — nur erste ${DOCS_PAGE_SIZE} werden verarbeitet`);
      }
      this.logger.log(`${docs.length} Dokumente fertig in Agrarmonitor`);

      for (const doc of docs) {
        result.processed++;

        const interneBelegnummer =
          ((doc.custom_fields as any[]) ?? []).find(
            (cf: any) => cf.field === INTERN_BELEGNUMMER_FIELD_ID,
          )?.value as string ?? '';

        if (!interneBelegnummer) {
          this.logger.log(`Dokument ${doc.id as number} hat keine interne Belegnummer`);
          result.skipped++;
          await this.delay(500);
          continue;
        }

        let amResults: Awaited<ReturnType<typeof amClient.eingangsrechnungenLivesearch>>;
        try {
          amResults = await amClient.eingangsrechnungenLivesearch(interneBelegnummer);
        } catch (err: unknown) {
          const status = (err as any)?.response?.status;
          if (status === 401 || status === 403) {
            this.agrarmonitorService.clearClient();
            const msg = `Session abgelaufen (${status}) — Polling abgebrochen, nächster Lauf meldet sich neu an`;
            this.logger.warn(msg);
            result.errors.push(msg);
            break;
          }
          const msg = `${interneBelegnummer}: Livesearch-Fehler`;
          this.logger.error(`${msg}: ${err instanceof Error ? err.message : err}`);
          result.errors.push(msg);
          await this.delay(500);
          continue;
        }

        if (amResults.length === 0) {
          this.logger.log(`${interneBelegnummer} nicht in Agrarmonitor gefunden`);
          result.skipped++;
          await this.delay(500);
          continue;
        }

        if (amResults.length > 1) {
          const msg = `${interneBelegnummer}: Mehrfach gefunden`;
          this.logger.error(msg);
          result.errors.push(msg);
          await this.delay(500);
          continue;
        }

        const amDoc = amResults[0];

        if (!amDoc.interneBelegNummer && interneBelegnummer) {
          try {
            await amClient.setLieferscheinNummer(amDoc.eingangId, interneBelegnummer);
          } catch (err: unknown) {
            this.logger.warn(`${interneBelegnummer}: Lieferscheinnummer setzen fehlgeschlagen: ${err instanceof Error ? err.message : err}`);
          }
        }

        if (!amDoc.eingangsDatum) {
          const eingangsdatumField = ((doc.custom_fields as any[]) ?? []).find(
            (cf: any) => cf.field === EINGANGSDATUM_FIELD_ID,
          );
          if (eingangsdatumField?.value) {
            const eingangsdatum = new Date(eingangsdatumField.value as string);
            if (!isNaN(eingangsdatum.getTime())) {
              await amClient.setEingangsdatum(amDoc.eingangId, eingangsdatum);
              this.logger.log(`Eingangsdatum für ${interneBelegnummer} gesetzt`);
            }
          }
          result.skipped++;
        } else if (amDoc.buchungsDatum) {
          try {
            let correspondentId: number | undefined;
            const customer = customers.find((c) => Number(c.id) === amDoc.kundenId);
            if (customer) {
              const corr = await this.getOrCreateCorrespondent(customer);
              if (corr) correspondentId = corr.id as number;
            }

            let ownerId: number | undefined;
            const matchedClient = await this.clientRepo.findOneBy({
              AgrarmonitorBetriebId: amDoc.betriebId,
            });
            if (matchedClient) ownerId = matchedClient.PaperlessUserId;

            const currentTags: number[] = (doc.tags as number[]) ?? [];
            const newTags = [...new Set(currentTags.filter((t) => t !== tagFertigId).concat([tagVerbuchtId]))];

            const updateData: Record<string, any> = { tags: newTags };
            if (correspondentId !== undefined) updateData.correspondent = correspondentId;
            if (ownerId !== undefined) updateData.owner = ownerId;

            await this.paperlessService.updateDocument(doc.id as number, updateData);
            this.logger.log(`Beleg ${interneBelegnummer} gebucht`);
            result.updated++;
          } catch (err: unknown) {
            const msg = `${interneBelegnummer}: Update-Fehler`;
            this.logger.error(`${msg}: ${err instanceof Error ? err.message : err}`);
            result.errors.push(msg);
          }
        } else {
          result.skipped++;
        }

        await this.delay(500);
      }

      this.logger.log(
        `Polling abgeschlossen: ${result.processed} verarbeitet, ${result.updated} aktualisiert, ` +
        `${result.skipped} übersprungen, ${result.errors.length} Fehler`,
      );
    } finally {
      this.pollingRunning = false;
    }

    return result;
  }

  async processVerarbeiteteDocuments(): Promise<PollingResult> {
    if (this.uploadCheckRunning) {
      this.logger.warn('Upload-Check läuft bereits, überspringe');
      return { processed: 0, updated: 0, skipped: 0, errors: ['Upload-Check bereits aktiv'] };
    }
    this.uploadCheckRunning = true;

    const result: PollingResult = { processed: 0, updated: 0, skipped: 0, errors: [] };
    this.logger.log('Starte Upload-Check');

    try {
      const [hochgeladenSetting, fertigSetting, linkFieldSetting] = await Promise.all([
        this.settingRepo.findOneBy({ Tag: 'agrarmonitor_tag_hochgeladen' }),
        this.settingRepo.findOneBy({ Tag: 'agrarmonitor_tag_fertig' }),
        this.settingRepo.findOneBy({ Tag: 'agrarmonitor_link_field' }),
      ]);

      const tagHochgeladenId = parseInt(hochgeladenSetting?.Wert ?? '', 10);
      const tagFertigId = parseInt(fertigSetting?.Wert ?? '4', 10);
      const linkFieldId = parseInt(linkFieldSetting?.Wert ?? '', 10);

      if (isNaN(tagHochgeladenId)) {
        this.logger.warn('Tag "hochgeladen" nicht konfiguriert — Upload-Check übersprungen');
        return { ...result, errors: ['Tag "hochgeladen" nicht konfiguriert'] };
      }

      let amClient: Awaited<ReturnType<typeof this.agrarmonitorService.getClient>>;
      try {
        amClient = await this.agrarmonitorService.getClient();
      } catch (err: unknown) {
        const msg = `Connector-Fehler: ${err instanceof Error ? err.message : 'unbekannt'}`;
        this.logger.error(msg);
        return { ...result, errors: [msg] };
      }

      const docsResponse = await this.paperlessService.getDocuments({
        page: 1,
        page_size: DOCS_PAGE_SIZE,
        truncate_content: true,
        tags__id__all: tagHochgeladenId,
      });
      const docs: any[] = docsResponse?.results ?? [];
      if ((docsResponse?.count ?? 0) > DOCS_PAGE_SIZE) {
        this.logger.warn(`Mehr als ${DOCS_PAGE_SIZE} Dokumente hochgeladen — nur erste ${DOCS_PAGE_SIZE} werden geprüft`);
      }
      this.logger.log(`${docs.length} Dokumente laut Paperless im Dateieingang`);

      for (const doc of docs) {
        result.processed++;

        const interneBelegnummer =
          ((doc.custom_fields as any[]) ?? []).find(
            (cf: any) => cf.field === INTERN_BELEGNUMMER_FIELD_ID,
          )?.value as string ?? '';

        if (!interneBelegnummer) {
          this.logger.log(`Dokument ${doc.id as number} hat keine interne Belegnummer`);
          result.skipped++;
          await this.delay(500);
          continue;
        }

        let vorhanden: boolean;
        try {
          vorhanden = await amClient.eingangsrechnungVorhanden(interneBelegnummer);
        } catch (err: unknown) {
          const status = (err as any)?.response?.status;
          if (status === 401 || status === 403) {
            this.agrarmonitorService.clearClient();
            const msg = `Session abgelaufen (${status}) — Upload-Check abgebrochen`;
            this.logger.warn(msg);
            result.errors.push(msg);
            break;
          }
          const msg = `${interneBelegnummer}: Vorhanden-Check fehlgeschlagen`;
          this.logger.error(`${msg}: ${err instanceof Error ? err.message : err}`);
          result.errors.push(msg);
          await this.delay(500);
          continue;
        }

        if (!vorhanden) {
          result.skipped++;
          await this.delay(500);
          continue;
        }

        this.logger.log(`Dokument ${interneBelegnummer} ist bereits verarbeitet, aktualisiere Paperless`);

        let amResults: Awaited<ReturnType<typeof amClient.eingangsrechnungenLivesearch>>;
        try {
          amResults = await amClient.eingangsrechnungenLivesearch(interneBelegnummer);
        } catch (err: unknown) {
          const status = (err as any)?.response?.status;
          if (status === 401 || status === 403) {
            this.agrarmonitorService.clearClient();
            const msg = `Session abgelaufen (${status}) — Upload-Check abgebrochen`;
            this.logger.warn(msg);
            result.errors.push(msg);
            break;
          }
          const msg = `${interneBelegnummer}: Livesearch-Fehler`;
          this.logger.error(`${msg}: ${err instanceof Error ? err.message : err}`);
          result.errors.push(msg);
          await this.delay(500);
          continue;
        }

        if (amResults.length > 1) {
          this.logger.log(`Dokument ${interneBelegnummer} ist doppelt vorhanden`);
          result.skipped++;
          await this.delay(500);
          continue;
        }

        const amDoc = amResults[0];

        try {
          // Kundendaten abrufen
          const customer = await amClient.getCustomerById(amDoc.kundenId);
          const lieferantennummer = (customer['lieferantennummer'] as string) ?? '';
          if (!lieferantennummer) {
            this.logger.log(`Kunde ${amDoc.kundenId} hat keine Lieferantennummer — Dokument wird übersprungen`);
            result.skipped++;
            await this.delay(500);
            continue;
          }

          // Korrespondent ermitteln oder anlegen
          const corr = await this.getOrCreateCorrespondent(customer);

          // Owner aus Client-Tabelle
          let ownerId: number | undefined;
          const matchedClient = await this.clientRepo.findOneBy({ AgrarmonitorBetriebId: amDoc.betriebId });
          if (matchedClient) ownerId = matchedClient.PaperlessUserId;

          // Tags: hochgeladen entfernen, fertig hinzufügen
          const currentTags: number[] = (doc.tags as number[]) ?? [];
          const newTags = [...new Set(currentTags.filter((t) => t !== tagHochgeladenId).concat([tagFertigId]))];

          // Custom fields aufbauen: bestehende behalten, extern + link setzen
          const existingFields: any[] = ((doc.custom_fields as any[]) ?? []).map((f: any) => ({ ...f }));
          this.setCustomField(existingFields, EXTERN_BELEGNUMMER_FIELD_ID, amDoc.belegNummer);
          if (!isNaN(linkFieldId)) {
            this.setCustomField(
              existingFields,
              linkFieldId,
              `${AGRARMONITOR_BASE_URL}/rechnungen/detail/${amDoc.eingangId}`,
            );
          }

          const updateData: Record<string, any> = {
            title: (amDoc.dokumentTyp === 0 ? 'ERG ' : 'EGU ') + amDoc.belegNummer,
            document_type: amDoc.dokumentTyp === 0 ? 1 : 2,
            tags: newTags,
            custom_fields: existingFields,
          };
          if (amDoc.belegDatum) updateData.created = amDoc.belegDatum.toISOString().slice(0, 10);
          if (corr) updateData.correspondent = corr.id as number;
          if (ownerId !== undefined) updateData.owner = ownerId;

          await this.paperlessService.updateDocument(doc.id as number, updateData);
          await this.paperlessService.addNote(
            doc.id as number,
            `Beleg in Agrarmonitor verarbeitet: ${new Date().toLocaleString('de-DE')}`,
          );
          this.logger.log(`Beleg ${interneBelegnummer} auf AMfertig gesetzt`);
          result.updated++;
        } catch (err: unknown) {
          const msg = `${interneBelegnummer}: Update-Fehler`;
          this.logger.error(`${msg}: ${err instanceof Error ? err.message : err}`);
          result.errors.push(msg);
        }

        await this.delay(500);
      }

      this.logger.log(
        `Upload-Check abgeschlossen: ${result.processed} geprüft, ${result.updated} aktualisiert, ` +
        `${result.skipped} übersprungen, ${result.errors.length} Fehler`,
      );
    } finally {
      this.uploadCheckRunning = false;
    }

    return result;
  }

  private setCustomField(fields: any[], fieldId: number, value: any): void {
    const existing = fields.find((f) => f.field === fieldId);
    if (existing) {
      existing.value = value;
    } else {
      fields.push({ field: fieldId, value });
    }
  }

  async syncCorrespondentIds(): Promise<SyncCorrespondentsResult> {
    let amClient: Awaited<ReturnType<typeof this.agrarmonitorService.getClient>>;
    try {
      amClient = await this.agrarmonitorService.getClient();
    } catch (err: unknown) {
      throw new Error(`Connector-Fehler: ${err instanceof Error ? err.message : 'unbekannt'}`);
    }

    const customers = await amClient.fetchCustomers();
    const lieferantMap = new Map<string, number>(); // lieferantennummer → AM-ID
    const kundenMap = new Map<string, number>();     // kundennummer       → AM-ID
    for (const c of customers) {
      const liefNr = String(c['lieferantennummer'] ?? '').trim();
      if (liefNr) lieferantMap.set(liefNr, Number(c.id));
      const kdNr = String(c['kundennummer'] ?? '').trim();
      if (kdNr) kundenMap.set(kdNr, Number(c.id));
    }

    const allCorrespondents: any[] = [];
    let page = 1;
    while (true) {
      const resp = await this.paperlessService.getCorrespondents({ page, page_size: 250 });
      allCorrespondents.push(...(resp.results ?? []));
      if (!resp.next) break;
      page++;
    }

    const lieferantRegex = /\((\d+)\)$/;        // reine Zahl → Lieferantennummer
    const kundenRegex    = /\(KD(\d+)\)$/;      // KD-Prefix  → Kundennummer
    let matched = 0;
    let unmatched = 0;

    for (const corr of allCorrespondents) {
      const name = corr.name as string;
      let amId: number | undefined;

      const kdMatch = kundenRegex.exec(name);
      if (kdMatch) {
        amId = kundenMap.get(kdMatch[1]);
      } else {
        const liefMatch = lieferantRegex.exec(name);
        if (liefMatch) amId = lieferantMap.get(liefMatch[1]);
      }

      if (amId === undefined) { unmatched++; continue; }

      let setting = await this.corrSettingRepo.findOneBy({ CorrespondentId: corr.id as number });
      if (!setting) {
        setting = this.corrSettingRepo.create({ CorrespondentId: corr.id as number, AgrarmonitorId: amId });
      } else {
        setting.AgrarmonitorId = amId;
      }
      await this.corrSettingRepo.save(setting);
      matched++;
    }

    // Duplikate ermitteln: mehrere Paperless-Korrespondenten mit derselben AgrarmonitorId
    const allLinked = await this.corrSettingRepo.find({
      where: { AgrarmonitorId: Not(IsNull()) },
    });
    const byAmId = new Map<number, number[]>();
    for (const s of allLinked) {
      const amId = s.AgrarmonitorId!;
      const ids = byAmId.get(amId) ?? [];
      ids.push(s.CorrespondentId);
      byAmId.set(amId, ids);
    }

    let autoMerged = 0;
    const conflicts: SyncConflict[] = [];

    for (const [amId, corrIds] of byAmId) {
      if (corrIds.length <= 1) continue;

      const corrs = await Promise.all(corrIds.map(id => this.paperlessService.getCorrespondent(id)));
      const uniqueNames = new Set(corrs.map((c: any) => c.name as string));

      if (uniqueNames.size === 1) {
        // Gleicher Name — automatisch zusammenführen
        const withoutDocs = corrs.filter((c: any) => Number(c.document_count) === 0);
        const withDocs = corrs.filter((c: any) => Number(c.document_count) > 0);

        if (withoutDocs.length > 0) {
          for (const toDelete of withoutDocs) {
            await this.paperlessService.deleteCorrespondent(toDelete.id as number);
            await this.corrSettingRepo.delete({ CorrespondentId: toDelete.id as number });
            autoMerged++;
            this.logger.log(`Duplikat gelöscht (keine Dokumente): ${toDelete.name as string} (ID ${toDelete.id as number})`);
          }
        } else {
          // Alle haben Dokumente — in den mit den meisten Dokumenten zusammenführen
          const sorted = [...withDocs].sort((a: any, b: any) => Number(b.document_count) - Number(a.document_count));
          const keep = sorted[0] as any;
          for (const toMerge of sorted.slice(1)) {
            await this.mergeCorrespondents(keep.id as number, toMerge.id as number);
            autoMerged++;
            this.logger.log(`Duplikat zusammengeführt in ${keep.name as string} (ID ${keep.id as number})`);
          }
        }
      } else {
        // Unterschiedliche Namen — Nutzerentscheidung erforderlich
        conflicts.push({
          agrarmonitorId: amId,
          correspondents: corrs.map((c: any) => ({
            id: c.id as number,
            name: c.name as string,
            documentCount: Number(c.document_count),
          })),
        });
      }
    }

    this.logger.log(
      `Korrespondenten-Abgleich: ${matched} zugeordnet, ${unmatched} ohne Treffer, ` +
      `${autoMerged} automatisch zusammengeführt, ${conflicts.length} Konflikte`,
    );
    return { total: allCorrespondents.length, matched, unmatched, autoMerged, conflicts };
  }

  async mergeCorrespondents(keepId: number, deleteId: number): Promise<{ mergedDocuments: number }> {
    let mergedDocuments = 0;
    let page = 1;
    while (true) {
      const resp = await this.paperlessService.getDocuments({
        correspondent__id: deleteId,
        page,
        page_size: 250,
        truncate_content: true,
      });
      const docs: any[] = resp?.results ?? [];
      for (const doc of docs) {
        await this.paperlessService.updateDocument(doc.id as number, { correspondent: keepId });
        mergedDocuments++;
      }
      if (!resp?.next) break;
      page++;
    }
    await this.paperlessService.deleteCorrespondent(deleteId);
    await this.corrSettingRepo.delete({ CorrespondentId: deleteId });
    this.logger.log(`Korrespondent ${deleteId} → ${keepId} zusammengeführt (${mergedDocuments} Dokumente)`);
    return { mergedDocuments };
  }

  private async getOrCreateCorrespondent(customer: Record<string, unknown>): Promise<any> {
    const lieferantennummer = (customer['lieferantennummer'] as string) ?? '';
    const displayName = this.buildCustomerName(customer, lieferantennummer);
    let corr = await this.paperlessService.getCorrespondentByName(displayName);
    if (!corr) {
      corr = await this.paperlessService.addCorrespondent({
        name: displayName,
        match: '',
        matching_algorithm: 0,
        is_insensitive: true,
        owner: null,
      });
    }
    return corr;
  }

  private buildCustomerName(customer: Record<string, unknown>, nummer: string): string {
    const firma = (customer['firma'] as string) ?? '';
    const nachname = (customer['nachname'] as string) ?? '';
    const vorname = (customer['vorname'] as string) ?? '';
    const name = firma || (nachname + (vorname ? ', ' + vorname : ''));
    return `${name} (${nummer})`;
  }

  private delay(ms: number): Promise<void> {
    return new Promise((resolve) => setTimeout(resolve, ms));
  }

  private async upsertSetting(tag: string, defaultValue: string): Promise<void> {
    const existing = await this.settingRepo.findOneBy({ Tag: tag });
    if (!existing) {
      await this.settingRepo.save(
        this.settingRepo.create({ Typ: 1, Wert: defaultValue, Tag: tag }),
      );
    }
  }
}