import { IPtyForkOptions, IWindowsPtyForkOptions, spawn } from 'node-pty';

import { Logger, LogLevel } from '../../common/util/logger.class';

const LOG_LEVEL: LogLevel = (process.env.LOG_LEVEL as LogLevel) || 'INFO';
Logger.logLevel = LOG_LEVEL;

export type MemoryUsage = { used: number; avail: number; unit: string };

export class TopTTY {
  private cpuSubscriber?: (usage: number) => void;
  private ramSubscriber?: (usage: MemoryUsage) => void;

  public subscribe = {
    cpu: (subscriber: (usage: number) => void) => {
      this.cpuSubscriber = subscriber;
    },
    ram: (subscriber: (usage: MemoryUsage) => void) => {
      this.ramSubscriber = subscriber;
    }
  };

  public async runloop() {
    while (true) {
      try {
        await execTTY('top -d 0.5', { cols: 100, rows: 10, env: { LC_ALL: 'C' } }, (line: string) => {
          if (line.includes('Cpu')) {
            line = line.replace(/\u001b(\[|\()([0-9]{1,3}(;[0-9]{1,2};?)?)?[mGKB]/g, ''); // get rid of tty color format codes
            line = line.replace(/:/g, ' ');
            const tokens = line.split(/\s+|,/g).filter(v => !!v); // split by whitespace and colon, omit emties

            const usage = Number(tokens[tokens.length - 14]) + Number(tokens[tokens.length - 16]);
            if (this.cpuSubscriber) this.cpuSubscriber(usage);
          } else if (/^([KMGPT]i)?B\s+Mem\s*:/.test(line)) {
            line = line.replace(/\u001b(\[|\()([0-9]{1,3}(;[0-9]{1,2};?)?)?[mGKB]/g, ''); // get rid of tty color format codes
            line = line.replace(/:/g, ' ');
            const tokens = line.split(/\s+/g).filter(v => !!v); // split by whitespace, omit emties
            const unit = tokens[0];
            const avail = Number(tokens[2]);
            const used = Number(tokens[6]);

            if (this.ramSubscriber) this.ramSubscriber({ unit, avail, used });
          }
        });
      } catch (err) {
        Logger.error('top runloop crashed:', err);
        Logger.info('Restaring top runloop...');
      }
      await new Promise<void>(res => setTimeout(res, 1000));
    }
  }
}

function execTTY(command: string, options: IPtyForkOptions | IWindowsPtyForkOptions, stdout?: (...args: any[]) => void) {
  return new Promise<void>((resolve, reject) => {
    try {
      let stdoutbuf = '';

      // SPAWN PTY PROCESS
      const p = spawn(command.split(' ')[0], command.split(' ').slice(1), options);

      // PIPE STDOUT
      if (typeof stdout === 'function') {
        p.onData(chunk => {
          stdoutbuf += chunk;
          let i = -1;
          while ((i = stdoutbuf.indexOf('\n')) >= 0) {
            const line = stdoutbuf.substring(0, i);
            stdoutbuf = stdoutbuf.substring(i + 1);
            if (typeof stdout === 'function') {
              stdout(line);
            }
          }
        });
        p.onExit(() => resolve());
      }
    } catch (err) {
      reject(err);
    }
  });
}