import * as plugins from './smartmetrics.plugins';
import * as interfaces from './smartmetrics.interfaces';
import { Cipher } from 'crypto';

export class SmartMetrics {
  public started = false;
  public sourceNameArg: string;
  public logger: plugins.smartlog.Smartlog;
  public registry: plugins.promClient.Registry;

  public async setup() {
    const collectDefaultMetrics = plugins.promClient.collectDefaultMetrics;
    this.registry = new plugins.promClient.Registry();
    collectDefaultMetrics({ register: this.registry });
  }

  constructor(loggerArg: plugins.smartlog.Smartlog, sourceNameArg: string) {
    this.logger = loggerArg;
    this.sourceNameArg = sourceNameArg;
    this.setup();
  }

  public start() {
    const unattendedStart = async () => {
      if (this.started) {
        return;
      }
      this.started = true;
      while (this.started) {
        this.logger.log('info', `sending heartbeat for ${this.sourceNameArg} with metrics`, {
          eventType: 'heartbeat',
          metrics: await this.getMetrics(),
        });
        await plugins.smartdelay.delayFor(10000, null, true);
      }
    };
    unattendedStart();
  }

  public formatBytes(bytes: number, decimals = 2) {
    if (bytes === 0) return '0 Bytes';

    const k = 1024;
    const dm = decimals < 0 ? 0 : decimals;
    const sizes = ['Bytes', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'];

    const i = Math.floor(Math.log(bytes) / Math.log(k));

    return parseFloat((bytes / Math.pow(k, i)).toFixed(dm)) + ' ' + sizes[i];
  }

  public async getMetrics() {
    const originalMetrics = await this.registry.getMetricsAsJSON();
    const pids = await plugins.pidtree(process.pid);
    const stats = await plugins.pidusage([process.pid, ...pids]);

    // lets compute cpu usage
    let cpuPercentage = 0;
    for (const stat of Object.keys(stats)) {
      if (!stats[stat]) continue;
      cpuPercentage += stats[stat].cpu / 100;
    }
    let cpuUsageText = `${cpuPercentage * 100} %`;

    // lets compute memory usage
    let memoryUsageBytes = 0;
    for (const stat of Object.keys(stats)) {
      if (!stats[stat]) continue;
      memoryUsageBytes += stats[stat].memory;
    }
    let memoryUsageText = this.formatBytes(memoryUsageBytes);
    let memoryPercentage = Math.round((memoryUsageBytes / plugins.os.totalmem()) * 100) / 100;

    const returnMetrics: interfaces.IMetricsSnapshot = {
      originalMetrics,
      process_cpu_seconds_total: (
        originalMetrics.find((metricSet) => metricSet.name === 'process_cpu_seconds_total') as any
      ).values[0].value,
      nodejs_active_handles_total: (
        originalMetrics.find((metricSet) => metricSet.name === 'nodejs_active_handles_total') as any
      ).values[0].value,
      nodejs_active_requests_total: (
        originalMetrics.find(
          (metricSet) => metricSet.name === 'nodejs_active_requests_total'
        ) as any
      ).values[0].value,
      nodejs_heap_size_total_bytes: (
        originalMetrics.find(
          (metricSet) => metricSet.name === 'nodejs_heap_size_total_bytes'
        ) as any
      ).values[0].value,
      cpuPercentage,
      cpuUsageText,
      memoryPercentage,
      memoryUsageBytes,
      memoryUsageText,
    };
    return returnMetrics;
  }

  public stop() {
    this.started = false;
  }
}