box-nestjs-monorepo/libs/common/src/cache/cache-builder.ts

import { Logger } from '@nestjs/common';
import { RedisService } from '@box/db/redis/redis.service';
import { MongoPrismaService } from '@box/db/prisma/mongo-prisma.service';

/**
 * Base class for cache builders that read from MongoDB and publish JSON into Redis.
 */
export abstract class BaseCacheBuilder {
  protected readonly logger: Logger;

  protected constructor(
    protected readonly redis: RedisService,
    protected readonly mongoPrisma: MongoPrismaService,
    loggerContext?: string,
  ) {
    this.logger = new Logger(loggerContext ?? new.target.name);
  }

  /** Build every cache item managed by this builder. */
  abstract buildAll(): Promise<void>;

  /**
   * Convert Prisma BigInt timestamps to numbers for JSON payloads.
   * Falls back to the original number when already numeric.
   */
  protected toMillis(value?: bigint | number | null): number | null {
    if (value === null || value === undefined) return null;
    return typeof value === 'bigint' ? Number(value) : value;
  }
}