'use strict';

/**
 * @file Fork execution related functions
 * @author Alexandre Strzelewicz <as@unitech.io>
 * @project PM2
 */

var log           = require('debug')('pm2:god');
var fs            = require('fs');
var cst           = require('../../constants.js');
var uidNumber     = require('uid-number');
var moment        = require('moment');
var Common        = require('../Common');
/**
 * Description
 * @method exports
 * @param {} God
 * @return
 */
module.exports = function ForkMode(God) {
  /**
   * For all apps - FORK MODE
   * fork the app
   * @method forkMode
   * @param {} pm2_env
   * @param {} cb
   * @return
   */
  God.forkMode = function forkMode(pm2_env, cb) {
    var command, args;

    log('Entering in fork mode');
    var spawn = require('child_process').spawn;

    var interpreter = pm2_env.exec_interpreter || 'node';
    var pidFile     = pm2_env.pm_pid_path;

    if (interpreter !== 'none') {
      command = interpreter;
      args = [pm2_env.pm_exec_path];
    }
    else {
      command = pm2_env.pm_exec_path;
      args = [ ];
    }

    // Concat args if present
    if (pm2_env.args)
      args = args.concat(eval((pm2_env.args)));

    var stdout, stderr;
    var outFile = pm2_env.pm_out_log_path;
    var errFile = pm2_env.pm_err_log_path;

    /**
     * Get the uid and gid number if run_as_user or run_as_group
     * is present
     * @method  getuid
     * @param {function} cb A callback that reveice error, uid and gid
     */
    function getugid(cb) {
      var user = pm2_env.run_as_user  || process.getuid();
      var group = pm2_env.run_as_group || process.getgid();

      uidNumber(user, group, cb);
    }

    /**
     * Description
     * @method startLogging
     * @param {} cb
     * @return
     */
    function startLogging(cb) {
      stdout = fs.createWriteStream(outFile, { flags : 'a' });

      stdout.on('open', function() {
        stderr = fs.createWriteStream(errFile, { flags : 'a' });
        stderr.on('open', function() {
          return cb();
        });
      });
    }

    startLogging(function() {
      getugid(function(e, uid, gid){
        if(e){
          God.logAndGenerateError(e);
          if (cb) return cb(e);
        }

        try {
          var cspr = spawn(command, args, {
            env      : pm2_env,
            detached : true,
            gid      : gid,
            uid      : uid,
            cwd      : pm2_env.pm_cwd || process.cwd(),
            stdio    : ['ipc', null, null]
          });
        } catch(e) {
          God.logAndGenerateError(e);
          if (cb) return cb(e);
        }

        cspr.process = {};
        cspr.process.pid = cspr.pid;
        cspr.pm2_env = pm2_env;
        cspr.pm2_env.status = cst.ONLINE_STATUS;

        cspr.stderr.on('data', function forkErrData(data) {

          var log_data = data.toString();
          if (pm2_env.log_date_format)
            log_data = moment().format(pm2_env.log_date_format) + ': ' + log_data;

          stderr.write(log_data);

          God.bus.emit('log:err', {
            process : cspr,
            data : data.toString()
          });
        });

        cspr.stdout.on('data', function forkOutData(data) {

          var log_data = data.toString();
          if (pm2_env.log_date_format)
            log_data = moment().format(pm2_env.log_date_format) + ': ' + log_data;

          stdout.write(log_data);

          God.bus.emit('log:out', {
            process : cspr,
            data : data.toString()
          });
        });

        cspr.on('message', function forkMessage(data) {
          God.bus.emit(data.type ? data.type : 'process:msg', {
            process : cspr,
            data : data
          });
        });

        fs.writeFileSync(pidFile, cspr.pid);

        cspr.once('close', function forkClose(status) {
          try {
            stderr.close();
            stdout.close();
          } catch(e) { God.logAndGenerateError(e);}
        });

        cspr._reloadLogs = startLogging;

        cspr.unref();

        if (cb) return cb(null, cspr);
        return false;
      });
    });

  };
};