node-asset-pipeline/lib/asset-pipeline.js

Asset pipeline ala rails for node

/*jshint camelcase:false */
/**
 * The bootstrap file.
 *
 */
var grunt    = require('grunt'),
    _        = grunt.util._,
    manifest = require('./asset-manifest'),
    helpers  = require('grunt-ss-helpers'),
    log      = helpers.log,
    util     = require('util'),
    assetIter = require('./asset-itterator'),
    Map       = require('../node_modules/collections/map'),
    pace  = require('pace'),
    when     = require('when');

var assets = module.exports = {
  Map: Map
};


// default throttle of concurent operations
assets.THROTTLE_OPS = 100;

/**
 * [run description]
 * @param  {Array.<Object>} files
 * @param  {Object} options
 * @param  {string} target
 * @return {Object} a promise.
 */
assets.run = function( files, options, target) {
  var task = new assets.Task(files, options, target);

  return task.run();
};

/**
 * [task description]
 * @param  {Array.<Object>} files
 * @param  {Object} options
 * @param  {string} target
 */
assets.Task = function( files, options, target ) {
  assetIter.apply(this, arguments);

  // make a copy of the files array
  this.files = Array.prototype.slice.call(files, 0);
  this.masterDeferred = when.defer();
  this.fileObj = null;

  this.options  = options;
  this.target = target;

  this._assetFiles = [];
  // internal, sanitized parameters
  this._params = {};
  this.destFolder = null;

  this.relPath = '';
  this.prepend = '';

  // progress for scan
  this._paceScan = null;

  // throttle of concurent operations
  this.opThrottle = 100;

  this.debug = false;
};
util.inherits(assets.Task, assetIter);

/**
 * [run description]
 * @return {when.Promise} a promise.
 */
assets.Task.prototype.run = function() {
  var def = when.defer();

  //
  // read or initialize manifest
  //
  if ( !manifest.init( this.options.manifest ) ) {
    return def.reject('No manifest file');
  }

  //
  // Check options
  //
  if ( !this.validateOptions() ) {
    return def.reject('options did not pass validations');
  }

  return when.map(this.files, this.runFileObj.bind(this) );
};


/**
 * Execute the asset task for one fileobject src/dest pair.
 *
 * @param {Object} The grunt file object.
 * @return {when.Promise} a promise.
 */
assets.Task.prototype.runFileObj = function( fileObj ) {
  var def = when.defer();

  //
  // Validate file Object
  //
  if ( !this.validate( fileObj ) ) {
    return def.reject('validation error');
  }

  //
  // expand the source files
  //
  var assetFiles = grunt.file.expand({filter: 'isFile'}, fileObj.src);
  if ( 0 === assetFiles.length ) {
    helpers.log.info('No source files found. Done.');
    return def.resolve('No source files');
  }

  //
  // Go through each file and md5 it...
  //
  log.info('\nStart scanning ' + (assetFiles.length + '').cyan +
    ' files for changes based on m5 hash');

  if (this._progress) { this._paceScan = pace( assetFiles.length ); }

  return this.itterateFiles( assetFiles )
    .then( manifest.save );
};



/**
 * Validates and prepares paths
 *
 * @param  {Object} fileObj grunt file object.
 * @return {boolean} error message yielded in this func.
 */
assets.Task.prototype.validate = function( fileObj ) {

  var dest = fileObj.dest;

  if ( 'string' !== typeof dest ) {
    helpers.log.error('"dest" must be defined, and be of type "string"');
    return false;
  }

  // check if cwd
  if ( 0 <= ['', '.', './', '..', '../'].indexOf(dest) ) {
    helpers.log.error('"dest" cannot be the current working directory');
    return false;
  }

  // check if it exists and create
  if ( !grunt.file.exists(dest) ) {
    grunt.file.mkdir(dest);
  }

  if ( !grunt.file.isDir(dest)) {
    helpers.log.error('"dest" is not a directory: ' + dest);
    return false;
  }

  // good to assign
  this.destFolder = dest;

  return true;
};

/**
 * Perform granular validations on options
 * and define the internal params properties.
 *
 * @return {boolean}
 */
assets.Task.prototype.validateOptions = function() {

  this.debug = !!this.options.debug;

  //
  // cdn url
  //
  var cdnurl = this.options.cdnurl || '';

  manifest.setConf('cdnurl', cdnurl);

  this._progress = !!this.options.progress;

  if ( isNaN(this.opThrottle) ) {
    this.opThrottle = assets.THROTTLE_OPS;
  }

  if ( this.options.rel ) {
    this.relPath = grunt.file.expand({ filter: 'isDirectory' }, this.options.rel )[0];
    if (!_.isString(this.relPath)) {
      log.error('\nRelative path does not exist: '.red + this.options.rel );
      return false;
    }
  }

  this.prepend = this.options.prepend || '';

  return true;
};