const { exec } = require("child_process");
const fs = require('fs');

class Server {
  constructor(dir) {
    this.rootDir = dir;
    this.name = dir.split('/').at(-1);
    this.pidFilePath = this.rootDir + '/pid.txt';

    // read version file
    var versionFilePath = this.rootDir + '/current_version.txt';
    if (fs.existsSync(versionFilePath)) {
      this.version = fs.readFileSync(versionFilePath, {encoding:'utf8', flag:'r'});      
    }
  }

  start() {
    console.log(`Starting server ${this.name}...`);

    // create shell command and execute it
    let cmd = `${this.rootDir}/start.sh`;
    exec(cmd, (err, stdout, stderr) => {
      if (err) {
        console.log(`Error while starting server: ${error.message}`);
      }

      console.log(`Server ${this.name} has been started.`);
    });
  }

  stop() {
    console.log(`Stopping server ${this.name}...`);
  }

  getStatus() {
    if (fs.existsSync(this.pidFilePath)) {
      let pid = fs.readFileSync(this.pidFilePath, {encoding: 'utf8', flag: 'r'});
      try {
        return process.kill(pid, 0);
      } catch (err) {
        // ESRCH error means the process doesn't exist, so should return false
        if (err.code !== 'ESRCH') {
          console.error(err);
          return err.code === 'EPERM';
        } else {
          // delete pid.txt so we don't have to worry about checking it again
          fs.unlinkSync(this.pidFilePath);
        }
      }
    }

    return false
  }

  getPid() {
    if (fs.existsSync(this.pidFilePath)) {
      return fs.readFileSync(this.pidFilePath, {encoding:'utf8', flag:'r'})
    }

    return -1;
  }
}

exports.Server = Server;