import {
  Controller,
  Get,
  Inject,
  ServiceUnavailableException,
} from '@nestjs/common';
import { InjectConnection } from '@nestjs/mongoose';
import {
  ApiOkResponse,
  ApiOperation,
  ApiServiceUnavailableResponse,
  ApiTags,
} from '@nestjs/swagger';
import { Public } from '@task-stream/api/identity/presenters';
import { REDIS_CLIENT } from '@task-stream/api/shared/infrastructure';
import Redis from 'ioredis';
import { Connection } from 'mongoose';
import { DataSource } from 'typeorm';

@ApiTags('Health')
@Controller('health')
export class HealthController {
  constructor(
    private readonly postgres: DataSource,
    @InjectConnection() private readonly mongo: Connection,
    @Inject(REDIS_CLIENT) private readonly redis: Redis,
  ) {}

  @Public()
  @Get()
  @ApiOperation({ summary: 'API and databases status' })
  @ApiOkResponse({
    schema: {
      example: { status: 'ok', postgres: 'up', mongo: 'up', redis: 'up' },
    },
  })
  @ApiServiceUnavailableResponse({ description: 'A database is down' })
  async check() {
    const checks = await Promise.allSettled([
      this.postgres.query('SELECT 1'),
      this.mongo.db?.admin().ping(),
      this.redis.ping(),
    ]);
    const [postgres, mongo, redis] = checks.map((c) =>
      c.status === 'fulfilled' ? 'up' : 'down',
    );
    const result = { status: 'ok', postgres, mongo, redis };
    if (checks.some((c) => c.status === 'rejected')) {
      throw new ServiceUnavailableException({ ...result, status: 'degraded' });
    }
    return result;
  }
}