import { Injectable, OnApplicationShutdown } from '@nestjs/common';
import { PinoLogger } from 'nestjs-pino';

import { RequestContextService } from './request-context.service';

type LogLevel = 'debug' | 'error' | 'info' | 'warn';
type LogContext = Record<string, boolean | number | string | undefined>;

const allowedFields = new Set([
  'attempts',
  'brokerageAccountId',
  'clientRequestId',
  'code',
  'count',
  'durationMs',
  'environment',
  'found',
  'grpcCode',
  'method',
  'operation',
  'requestId',
  'route',
  'service',
  'status',
  'userId',
]);

@Injectable()
export class StructuredLogger implements OnApplicationShutdown {
  constructor(
    private readonly requestContext: RequestContextService,
    private readonly pino: PinoLogger,
  ) {}

  info(message: string, context?: LogContext): void {
    this.write('info', message, context);
  }

  event(level: LogLevel, message: string, context?: LogContext): void {
    this.write(level, message, context);
  }

  onApplicationShutdown(): void {
    this.info('application.stopped');
  }

  private write(
    level: LogLevel,
    message: string,
    context: LogContext = {},
  ): void {
    // eslint-disable-next-line security/detect-object-injection -- The log level is restricted to the internal LogLevel union.
    this.pino[level](
      this.safeContext({ ...this.requestContext.get(), ...context }),
      message,
    );
  }

  private safeContext(context: LogContext): LogContext {
    return Object.fromEntries(
      Object.entries(context).filter(
        ([key, value]) => allowedFields.has(key) && value !== undefined,
      ),
    );
  }
}