import { BadRequestException, Injectable, Logger } from '@nestjs/common';
import { PaginatedResponse } from '@edr/types';

import { AuditLog } from './entities/audit-log.entity';
import { AuditLogRepository } from './audit-log.repository';
import { AuditLogQueryDto } from './dto/audit-log-query.dto';
import {
  buildPaginationMeta,
  normalizePagination,
} from '../../common/utils/pagination.util';

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

  constructor(private readonly auditLogRepository: AuditLogRepository) {}

  /**
   * Persist one audit row, swallowing any failure.
   *
   * An audit write must never turn a successful business action into an error
   * for the user: if this table is full, misconfigured or mid-migration,
   * contract approvals still need to work. Failures are logged so the gap is
   * visible in application logs rather than silent.
   */
  async record(entry: Partial<AuditLog>): Promise<void> {
    try {
      await this.auditLogRepository.record(entry);
    } catch (error) {
      this.logger.error(
        `Failed to write audit log for ${entry.method} ${entry.routePath}: ${
          error instanceof Error ? error.message : String(error)
        }`,
      );
    }
  }

  /** Paginated, filtered audit history, newest first. */
  async search(query: AuditLogQueryDto): Promise<PaginatedResponse<AuditLog>> {
    const { page, pageSize, skip, take } = normalizePagination(query);

    const from = query.from ? new Date(query.from) : undefined;
    const to = query.to ? new Date(query.to) : undefined;

    // A reversed range silently returns zero rows, which reads as "nothing
    // happened" rather than "your filter is wrong" — reject it explicitly.
    if (from && to && from > to) {
      throw new BadRequestException('`from` must be earlier than `to`');
    }

    const [items, total] = await this.auditLogRepository.search({
      type: query.type,
      userId: query.userId,
      method: query.method,
      resourceId: query.resourceId,
      isSuccess:
        query.isSuccess === undefined ? undefined : query.isSuccess === 'true',
      from,
      to,
      skip,
      take,
    });

    return { items, meta: buildPaginationMeta(total, page, pageSize) };
  }

  /** Distinct entity types, for the filter dropdown on the audit screen. */
  async listTypes(): Promise<string[]> {
    return this.auditLogRepository.distinctTypes();
  }
}