import { Injectable, Logger, ForbiddenException } from '@nestjs/common';
import { InjectRepository } from '@nestjs/typeorm';
import { Repository } from 'typeorm';
import { DocumentType } from '../database/entities/document-type.entity';
import { PaperlessService } from '../paperless/paperless.service';

const FREIGABE_FIELD_ID = 15;
const ZAHLUNG_FIELD_ID = 16;
const FREIGABE_WERT_FREIGEGEBEN = 'freigegeben';

export type ZahlungFilter = 'ausstehend' | 'freigegeben' | 'alle';

@Injectable()
export class ZahlungService {
  private readonly logger = new Logger(ZahlungService.name);

  constructor(
    @InjectRepository(DocumentType)
    private readonly documentTypeRepo: Repository<DocumentType>,
    private readonly paperlessService: PaperlessService,
  ) {}

  async getZahlungDocuments(
    page: number,
    pageSize: number,
    filter: ZahlungFilter,
  ) {
    const docTypes = await this.documentTypeRepo.find({
      where: { FreigabeErforderlich: true as any },
    });

    if (docTypes.length === 0) {
      return { count: 0, results: [] };
    }

    const docTypeIds = docTypes.map((dt) => dt.DocumentTypeId).join(',');

    const params: Record<string, any> = {
      page: 1,
      page_size: 9999,
      document_type__id__in: docTypeIds,
      ordering: '-created',
      truncate_content: true,
    };

    let allDocs: any[];
    try {
      const result = await this.paperlessService.getDocuments(params);
      allDocs = result.results ?? [];
    } catch (err: any) {
      this.logger.warn(
        'Fehler beim Laden der Belege für Zahlung',
        err?.message,
      );
      return { count: 0, results: [] };
    }

    const filtered = this.applyFilter(allDocs, filter);
    const start = (page - 1) * pageSize;
    return {
      count: filtered.length,
      results: filtered.slice(start, start + pageSize),
    };
  }

  private applyFilter(docs: any[], filter: ZahlungFilter): any[] {
    if (filter === 'alle') return docs;

    return docs.filter((doc: any) => {
      const freigabeValue = this.getCfValue(doc, FREIGABE_FIELD_ID);
      const istFreigegeben = freigabeValue === FREIGABE_WERT_FREIGEGEBEN;

      if (filter === 'freigegeben') return istFreigegeben;

      // 'ausstehend': freigegeben aber noch nicht bezahlt
      const zahlungValue = this.getCfValue(doc, ZAHLUNG_FIELD_ID);
      return istFreigegeben && !zahlungValue;
    });
  }

  private getCfValue(doc: any, fieldId: number): string | null {
    const cf = (doc.custom_fields ?? []).find((f: any) => f.field === fieldId);
    if (!cf || cf.value === null || cf.value === undefined || cf.value === '')
      return null;
    if (typeof cf.value === 'object') {
      return (
        String(cf.value?.id ?? cf.value?.value ?? cf.value?.label ?? '') || null
      );
    }
    return String(cf.value);
  }

  async setZahlung(documentId: number, value: string | null) {
    const doc = await this.paperlessService.getDocument(documentId);

    const freigabeValue = this.getCfValue(doc, FREIGABE_FIELD_ID);
    if (freigabeValue !== FREIGABE_WERT_FREIGEGEBEN) {
      throw new ForbiddenException(
        'Zahlung kann nur für freigegebene Belege gesetzt werden',
      );
    }

    const customFields: any[] = [...(doc.custom_fields ?? [])];
    const existing = customFields.find(
      (f: any) => f.field === ZAHLUNG_FIELD_ID,
    );
    if (existing) {
      existing.value = value;
    } else if (value !== null && value !== '') {
      customFields.push({ field: ZAHLUNG_FIELD_ID, value });
    }

    await this.paperlessService.updateDocument(documentId, {
      custom_fields: customFields,
    });
    return { success: true };
  }

  async getZahlungOptions(): Promise<{ id: string; label: string }[]> {
    const fields = await this.paperlessService.getCustomFields();
    const field = fields.find((f: any) => f.id === ZAHLUNG_FIELD_ID);
    if (!field) return [];

    const rawOptions: any[] = field.extra_data?.select_options ?? [];
    return rawOptions
      .filter((o) => o !== null && o !== undefined && o !== '')
      .map((o) => {
        if (typeof o === 'object') {
          return {
            id: String(o.id ?? o.value ?? o.label ?? ''),
            label: String(o.label ?? o.name ?? o.id ?? ''),
          };
        }
        return { id: String(o), label: String(o) };
      })
      .filter((o) => o.id !== '');
  }
}