printer.js

var Job = require ('./job');
var spawn = require('child_process').spawn;
var spawnSync = require('child_process').spawnSync;
var _ = require ('underscore');
var utils = require('util');
var events = require('events');
utils.inherits(Printer, events.EventEmitter);

/**
 * Describes the parameter options accepted by lp
 *
 * options array specifies the valid option names for the option
 * if expects is blank '' no option value is required for the option
 *
 * This was written according to lp man page
 * http://unixhelp.ed.ac.uk/CGI/man-cgi?lp
 */
var generalOptions = {
  'E': {
    'options': ['E', 'encryption'],
    'description': 'Forces encryption when connecting to the server',
    'expects': '',
    'default': false
  },
  'U': {
    'options': ['U', 'Username', 'username'],
    'description': 'Specifies the username to use when connecting to the server',
    'expects': 'string'
  },
  'c': {
    'options': ['c', 'backwardsCompatibility'],
    'description': 'This option is provided for backwards-compatibility only. On systems  that	support	 it,  this  option forces the print file to be copied to the spool directory before  printing. In CUPS, print files  are always sent to the scheduler via IPP which has the same effect.',
    'expects': '',
    'default': false
  },
  'd': {
    'options': ['d', 'destination'],
    'description': 'Prints files to the named printer',
    'expects': 'string'
  },
  'h': {
    'options': ['h', 'hostname'],
    'description': 'Chooses an alternate server',
    'expects': 'string'
  },
  'i': {
    'options': ['i', 'job-id'],
    'description': 'Specifies an existing job to modify',
    'expects': 'number'
  },
  'm': {
    'options': ['m'],
    'description': 'Sends an email when the job is completed',
    'expects': ''
  },
  'n': {
    'options': ['n', 'copies', 'numCopies'],
    'description': 'Sets the number of copies to print from 1 to 100',
    'expects': 'number',
    'default': 1
  },
  'o': {
    'options': ['o'],
    'description': '"name=value [name=value ...]" Sets one or more job options',
    'expects': 'string',
    'default': ''
  },
  'q': {
    'options': ['q', 'priority'],
    'description': 'Sets the job priority from	1 (lowest) to 100 (highest). The default priority is 50',
    'expects': 'number',
    'default': 1
  },
  's': {
    'options': ['s'],
    'description': 'Do not report the resulting job IDs (silent mode.)',
    'expects': ''
  },
  't': {
    'options': ['t', 'name'],
    'description': 'Sets the job name',
    'expects': 'string'
  },
  'H': {
    'options': ['H', 'when'],
    'description': 'Specifies  when  the  job  should be printed. A value of immediate will print the file immediately, a value of hold will hold the job indefinitely, and a time value (HH:MM) will hold the job until the specified time. Use a value of resume with the -i option to resume a  held job.  Use a value of restart with the -i option to restart a completed job.',
    'default': 'immediate',
    'expects': 'string'

  },
  'P': {
    'options': ['P', 'page-list'],
    'description': 'page-list Specifies which pages to print in the document. The list can  contain a list of numbers and ranges (#-#) separated by commas (e.g. 1,3-5,16).',
    'expects': 'string'
  }
};

/**
 * Describes the parameter options accepted by lp -o option
 *
 * options array specifies the valid option names for the option
 * if expects is blank '' no option value is required for the option
 *
 * This was written according to lp man page
 * http://unixhelp.ed.ac.uk/CGI/man-cgi?lp
 */
var oOptions = {
  'media': {
    'options': ['media'],
    'description': 'Sets  the  page  size  to size. Most printers support at least the size names "a4", "letter", and "legal".',
    'expects': 'string',
    'default': 'a4'
  },
  'landscape': {
    'options': ['landscape'],
    'description': 'landscape',
    'expects': ''
  },
  'orientation-requested': {
    'options': ['orientation-requested'],
    'description': '',
    'expects': 'number'
  },
  'sides': {
    'options': ['sides'],
    'description': 'Prints on one or two sides of the  paper.  The  value  "two-sided-long-edge" is  normally  used  when printing portrait (unrotated) pages, while "two-sided-short-edge" is used for landscape pages.',
    'expects': 'string'
  },
  'fitplot': {
    'options': ['fitplot'],
    'description': 'Scales the print file to fit on the page',
    'expects': '',
    'default': false
  },
  'scaling': {
    'options': ['scaling'],
    'description': 'Scales image files to use up to number percent of the page. Values greater than 100 cause the image file to be printed across multiple pages',
    'expects': 'number'
  },
  'cpi': {
    'options': ['cpi'],
    'description': 'Sets the number of characters per inch to use when printing a text file. The default is 10',
    'expects': 'number'
  },
  'lpi': {
    'options': ['lpi'],
    'description': 'Sets  the  number  of  lines  per inch to use when printing a text file. The default is 6',
    'expects': 'number'
  },
  'page-bottom': {
    'options': ['page-bottom'],
    'description': 'Sets the page margins when printing text files. The values are in points - there are 72 points to the inch',
    'expects': 'number'
  },
  'page-left': {
    'options': ['page-left'],
    'description': 'Sets the page margins when printing text files. The values are in points - there are 72 points to the inch',
    'expects': 'number'
  },
  'page-right': {
    'options': ['page-right'],
    'description': 'Sets the page margins when printing text files. The values are in points - there are 72 points to the inch',
    'expects': 'number'
  },
  'page-top': {
    'options': ['page-top'],
    'description': 'Sets the page margins when printing text files. The values are in points - there are 72 points to the inch',
    'expects': 'number'
  }
};

var optionsFactory = function (options) {

  var selGeneralOptions = {};


  _.each(generalOptions, function(generalOption, generalOptionId) { // for each of lp available options
    _.each(generalOption.options, function(option) { // for each option possible name
      if(typeof options[option] !== 'undefined') { // check of the method options contains the value
        if(generalOption.expects === '') { // when expects is empty, ommit the options defined value, just add
          if(options[option]) {
            selGeneralOptions[generalOptionId] = true;
          }
        } else {
          selGeneralOptions[generalOptionId] = options[option];
        }
      }
    });
    if(typeof generalOption.default != 'undefined') { // if method options does not contains the value, use default if available
      if(typeof selGeneralOptions[generalOptionId] == 'undefined') {
        selGeneralOptions[generalOptionId] = generalOption.default;
      }
    }
  });

  var selOOptions = {};

  _.each(oOptions, function(oOption, oOptionId) { // for each of lp available options
    _.each(oOption.options, function(option) { // for each option possible name
      if(typeof options[option] !== 'undefined') { // check of the method options contains the value
        if(oOption.expects === '') { // when expects is empty, ommit the options defined value, just add
          if(options[option]) {
            selOOptions[oOptionId] = true;
          }
        } else {
          selOOptions[oOptionId] = options[option];
        }
      } else if(typeof oOption.default != 'undefined') { // if method options does not contains the value, use default if available
        selOOptions[oOptionId] = oOption.default;
      }
    });
    if(typeof oOption.default != 'undefined') { // if method options does not contains the value, use default if available
      if(typeof selOOptions[oOptionId] == 'undefined') {
        selOOptions[oOptionId] = oOption.default;
      }
    }
  });

  if(!_.isEmpty(selOOptions)) {
    var selOoptionsString = '';
    _.each(selOOptions, function(oOption, oOptionId) {
      if(oOptions[oOptionId].expects === '') {
        if(oOption) {
          selOoptionsString = selOoptionsString + ' ' + oOptionId;
        }
      } else {
        selOoptionsString = selOoptionsString + ' ' + oOptionId + '=' + oOption;
      }
    });
    if(typeof selGeneralOptions.o == 'string') {
      selGeneralOptions.o = selGeneralOptions.o + selOoptionsString;
    } else {
      selGeneralOptions.o = selOoptionsString;
    }
  }

  return selGeneralOptions;
};

var argsFactory = function(options) {
  var args = [];
  _.each(options, function(optionValue, optionKey) {
    if(generalOptions[optionKey].expects === '') {
      if(optionValue) {
        args.push('-' + optionKey);
      }
    } else {
      args.push('-' + optionKey + optionValue);
    }

  });
  return args;
};

var buildArgs = function(options) {
  if (!options) return [];
  options = optionsFactory(options);
  return argsFactory(options);
};

var parseStdout = function(data) {
  if (!Buffer.isBuffer(data)) return [];
  return data.toString()
    .replace(/\n$/, '')
    .split('\n');
};

function Printer(name) {
  var self = this;
  if (!Printer.match(name)) {
    console.error(
      name + ' printer does not exist ; installed printers are ' + Printer.list()
      );
    throw new Error('Printer ' + name + ' does not exist on your system.');
  }
  self.name = name;
  self.jobs = [];
  self.watch();
}

Printer.list = function() {
  return parseStdout(spawnSync('lpstat', ['-e']).stdout);
};

Printer.match = function(name) {
  return Boolean(Printer.list().filter(function(printer) {
    return name === printer;
  }).length);
};

Printer.prototype.watch = function() {
  var self = this;
  var args = ['-P', this.name];

  var lpq = spawn('lpq', args);

  lpq.stdout.on('data', function(data) {
    var parsedData = parseStdout(data)
      .slice(2)
      .map(function(line) {
        line = line.split(/[ ]{2,}/);
        return {
          rank: (line[0] === 'active' ? line[0] : parseInt(line[0].slice(0, -2))),
          owner: line[1],
          identifier: parseInt(line[2]),
          files: line[3],
          totalSize: line[4]
        };
      });

    self.jobs.map(function(job) {
      var status = parsedData.filter(function(status) {
        if (status.identifier === job.identifier) return status;
      })[0];

      if (status) {
        job.update(status);
      } else {
        job.unqueue();
      }
    });
  });

  lpq.on('exit', function() {
    self.watch();
  });
};

Printer.prototype.findJob = function(jobId) {
  return this.jobs.filter(function(job) {
    if (job.identifier === jobId) return job;
  })[0];
};

Printer.prototype.printBuffer = function(data, options) {
  var self = this;
  var args = buildArgs(options);
  args.push('-d', self.name);

  var lp = spawn('lp', args);

  lp.stdin.write(data);
  lp.stdin.end();

  var job = new Job(lp);
  job.on('sent', function() {
    self.jobs.push(job);
  });

  job.on('completed', function() {
    self.jobs.splice(self.jobs.indexOf(job), 1);
  });

  return job;
};

Printer.prototype.printText = Printer.prototype.printBuffer;

Printer.prototype.printFile = function(filePath, options) {
  var self = this;
  var args = buildArgs(options);
  args.push('-d', self.name);

  args.push('--');
  args.push(filePath);

  var lp = spawn('lp', args);

  var job = new Job(lp);
  job.on('sent', function() {
    self.jobs.push(job);
  });

  job.on('completed', function() {
    self.jobs.splice(self.jobs.indexOf(job), 1);
  });

  return job;
};

module.exports = Printer;