import { Controller, Get, Res } from '@nestjs/common';
import { ApiExcludeController } from '@nestjs/swagger';
import { PrismaService } from '../prisma/prisma.service';
import * as express from 'express';

@ApiExcludeController()
@Controller('metrics')
export class MetricsController {
  private static requestCount = 0;

  constructor(private readonly prisma: PrismaService) {}

  public static incrementRequestCount() {
    this.requestCount++;
  }

  @Get()
  async getMetrics(@Res() res: express.Response) {
    const memory = process.memoryUsage();
    const cpu = process.cpuUsage();
    
    let dbStatus = 1;
    try {
      await this.prisma.$queryRaw`SELECT 1`;
    } catch (e) {
      dbStatus = 0;
    }

    const uptime = process.uptime();

    const responseText = `# HELP node_memory_rss_bytes Resident set size in bytes.
# TYPE node_memory_rss_bytes gauge
node_memory_rss_bytes ${memory.rss}

# HELP node_memory_heap_used_bytes Heap used in bytes.
# TYPE node_memory_heap_used_bytes gauge
node_memory_heap_used_bytes ${memory.heapUsed}

# HELP node_memory_heap_total_bytes Heap total in bytes.
# TYPE node_memory_heap_total_bytes gauge
node_memory_heap_total_bytes ${memory.heapTotal}

# HELP node_cpu_user_time_microseconds CPU user time in microseconds.
# TYPE node_cpu_user_time_microseconds counter
node_cpu_user_time_microseconds ${cpu.user}

# HELP node_cpu_system_time_microseconds CPU system time in microseconds.
# TYPE node_cpu_system_time_microseconds counter
node_cpu_system_time_microseconds ${cpu.system}

# HELP node_app_uptime_seconds Application uptime in seconds.
# TYPE node_app_uptime_seconds gauge
node_app_uptime_seconds ${uptime}

# HELP canino_db_connected Database connection status (1 = connected, 0 = disconnected).
# TYPE canino_db_connected gauge
canino_db_connected ${dbStatus}

# HELP canino_http_requests_total Total HTTP requests processed.
# TYPE canino_http_requests_total counter
canino_http_requests_total ${MetricsController.requestCount}
`;

    res.set('Content-Type', 'text/plain; version=0.0.4; charset=utf-8');
    res.end(responseText);
  }
}