import { Injectable } from '@nestjs/common';
import { PrismaService } from '../prisma/prisma.service';
import { LogService } from '../log/log.service';
import { ObatService } from '../obat/obat.service';
import { RekammedisService } from '../rekammedis/rekammedis.service';
import { TindakanDokterService } from '../tindakandokter/tindakandokter.service';
import { sha256 } from '@api/common/crypto/hash';
import type {
  AuditEvent,
  resultStatus as ResultStatus,
} from '@dist/generated/prisma';

type AuditRecordPayload = {
  id: string;
  event: AuditEvent;
  payload: string;
  timestamp: Date;
  user_id: bigint;
  last_sync: Date;
  result: ResultStatus;
};

@Injectable()
export class AuditService {
  constructor(
    private readonly prisma: PrismaService,
    private readonly logService: LogService,
    private readonly obatService: ObatService,
    private readonly rekamMedisService: RekammedisService,
    private readonly tindakanDokterService: TindakanDokterService,
  ) {}

  async getAuditTrails(pageSize: number, bookmark: string) {
    const auditLogs = await this.prisma.audit.findMany({
      take: pageSize,
      skip: bookmark ? 1 : 0,
      cursor: bookmark ? { id: bookmark } : undefined,
      orderBy: { timestamp: 'asc' },
    });

    return auditLogs;
  }

  async storeAuditTrail() {
    console.log('Storing audit trail...');
    const BATCH_SIZE = 25;
    let bookmark = '';
    let processedCount = 0;

    try {
      while (true) {
        const pageResults = await this.logService.getLogsWithPagination(
          BATCH_SIZE,
          bookmark,
        );

        const logs: any[] = Array.isArray(pageResults?.logs)
          ? pageResults.logs
          : [];
        const nextBookmark: string = pageResults?.bookmark ?? '';

        if (
          logs.length === 0 &&
          (nextBookmark === '' || nextBookmark === bookmark)
        ) {
          break;
        }

        const records = (
          await Promise.all(
            logs.map((logEntry) => this.buildAuditRecord(logEntry)),
          )
        ).filter((record): record is AuditRecordPayload => record !== null);

        if (records.length > 0) {
          await this.prisma.$transaction(
            records.map((record) =>
              this.prisma.audit.upsert({
                where: { id: record.id },
                create: record,
                update: {
                  event: record.event,
                  payload: record.payload,
                  timestamp: record.timestamp,
                  user_id: record.user_id,
                  last_sync: record.last_sync,
                  result: record.result,
                },
              }),
            ),
          );
          processedCount += records.length;
        }

        if (nextBookmark === '' || nextBookmark === bookmark) {
          break;
        }

        bookmark = nextBookmark;
      }
    } catch (error) {
      console.error('Error storing audit trail:', error);
      throw error;
    }
  }

  private async buildAuditRecord(
    logEntry: any,
  ): Promise<AuditRecordPayload | null> {
    if (!logEntry?.value) {
      return null;
    }

    const { value } = logEntry;
    const logId: string | undefined = value.id;

    if (!logId) {
      return null;
    }

    const now = new Date();
    const timestamp = this.parseTimestamp(value.timestamp) ?? now;
    const userId = value.user_id;
    const blockchainHash: string | undefined = value.payload;

    if (!blockchainHash) {
      return null;
    }

    let dbHash: string | null = null;

    try {
      if (logId.startsWith('OBAT_')) {
        const obatId = this.extractNumericId(logId);
        if (obatId !== null) {
          const obat = await this.obatService.getObatById(obatId);
          if (obat) {
            dbHash = this.obatService.createHashingPayload({
              obat: obat.obat,
              jumlah_obat: obat.jumlah_obat,
              aturan_pakai: obat.aturan_pakai,
            });
          }
        }
      } else if (logId.startsWith('REKAM')) {
        const rekamMedisId = this.extractStringId(logId);
        if (rekamMedisId) {
          const rekamMedis =
            await this.rekamMedisService.getRekamMedisById(rekamMedisId);
          if (rekamMedis) {
            dbHash = this.rekamMedisService.createHashingPayload({
              dokter_id: 123,
              visit_id: rekamMedis.id_visit ?? '',
              anamnese: rekamMedis.anamnese ?? '',
              jenis_kasus: rekamMedis.jenis_kasus ?? '',
              tindak_lanjut: rekamMedis.tindak_lanjut ?? '',
            });
          }
        }
      } else if (logId.startsWith('TINDAKAN')) {
        const tindakanId = this.extractNumericId(logId);
        if (tindakanId !== null) {
          const tindakanDokter =
            await this.tindakanDokterService.getTindakanDokterById(tindakanId);
          if (tindakanDokter) {
            dbHash = this.tindakanDokterService.createHashingPayload({
              id_visit: tindakanDokter.id_visit,
              tindakan: tindakanDokter.tindakan,
              kategori_tindakan: tindakanDokter.kategori_tindakan,
              kelompok_tindakan: tindakanDokter.kelompok_tindakan,
            });
          }
        }
      } else {
        return null;
      }
    } catch (err) {
      console.warn(`Failed to resolve related data for log ${logId}:`, err);
    }

    const isNotTampered = dbHash
      ? await this.compareData(blockchainHash, dbHash)
      : false;

    const result: ResultStatus = isNotTampered ? 'non_tampered' : 'tampered';

    return {
      id: logId,
      event: value.event as AuditEvent,
      payload: blockchainHash,
      timestamp,
      user_id: userId,
      last_sync: now,
      result,
    };
  }

  private parseTimestamp(rawTimestamp?: string) {
    if (!rawTimestamp) {
      return null;
    }

    const parsed = new Date(rawTimestamp);
    if (Number.isNaN(parsed.getTime())) {
      return null;
    }

    return parsed;
  }

  private extractNumericId(rawId: string): number | null {
    const [, numericPart] = rawId.split('_');
    const parsed = parseInt(numericPart, 10);
    return Number.isNaN(parsed) ? null : parsed;
  }

  private extractStringId(rawId: string): string | null {
    const parts = rawId.split('_');
    return parts.length > 1 ? parts[1] : null;
  }

  async compareData(blockchainHash: string, postgreHash: string) {
    return blockchainHash === postgreHash;
  }
}