build.js

/*
 * # DEPENDENCIES #
 */
var Metalsmith  = require('metalsmith');
var templates   = require('metalsmith-templates');
var collections = require('metalsmith-collections');
var setMetadata = require('metalsmith-filemetadata');
var filepath    = require('metalsmith-filepath');
var pandoc      = require('metalsmith-pandoc');
var ignore      = require('metalsmith-ignore');
var relative    = require('metalsmith-relative');
var define      = require('metalsmith-define');
var marked      = require('marked'); // for md strings in YAML header
var path        = require('path');
var getPlaylists = require('./playlist');
var _           = require('lodash');
var changed     = require('metalsmith-changed');
var paths       = require('metalsmith-paths');
var fs          = require('fs');
// code highlighting
var highlight   = require('metalsmith-code-highlight');
var branch      = require('metalsmith-branch');
// search
var lunr        = require('lunr');
require('lunr-no/lunr.stemmer.support')(lunr);
require('lunr-no')(lunr);
var metlunr     = require('metalsmith-lunr');
// get configuration variables
var config      = require('./config.js');
// read front matter on demand
var matter = require('gray-matter');


/*
 * # SETUP OBJECTS #
 */
// metadata
var metadataOptions = [
  // search
  { pattern: path.join('**', '*.md'),
    metadata: { lunr: true }},
  // template for lessons
  { pattern: path.join('*', '**', '*.md'),
    metadata: { template: 'lesson.jade' }},
  // scratch lesson template
  { pattern: path.join('scratch', '**', '*.md'),
    metadata: { template: 'scratch.jade' }},
  // front page template
  { pattern: path.join('index.md'),
    metadata: { template: 'index.jade' }},
  // lesson index template
  { pattern: path.join('*', 'index.md'),
    metadata: { template: 'lesson-index.jade' }},
];

// search - for is not a stopword in this context
var words = lunr.no.stopWordFilter.stopWords.elements;
words.splice(words.indexOf('for'), 1);

// ignores
var ignoreOptions = [
  path.join('**', 'README.md'),
];

// collections
var collectionOptions = {};
config.collections.forEach(function(collection){
  // options for collections
  collectionOptions[collection] = {
    pattern: path.join(collection, '**', '*.md'),
  };
});

// defines available in template
var defineOptions = {
  marked: marked,
  _: _,
  config: config,
  isFile: isFile,
  matter: frontmatter,
};

/** Returns true if file exists */
function isFile(dir, file){
  var fullPath = path.join(config.sourceRoot, dir, file);
  try {
    fs.statSync(fullPath);
  } catch (e) {
    return false;
  }
  return true;
}

/** read front-matter from file, fail gracefully. */
function frontmatter(filename) {
  var filepath = path.join(config.lessonRoot, config.sourceFolder, filename);
  var m;
  try {
    m = matter.read(filepath);
  } catch (e) {
    return {};
  }
  return m.data;
}

// template
var templateOptions = {
  engine: 'jade',
  directory: path.join(config.builderRoot, 'templates'),
};


/*
 * # EXPORT #
 * build-function which takes a callback
 */
module.exports = function build(callback, options){
  options = options || {};
  var forceBuild = options.force || false;

  // read playlists upon every build
  var playlists = {};
  config.collections.forEach(function(collection){
    // playlists
    var collectionFolder = path.join(config.lessonRoot, config.sourceFolder, collection);
    playlists[collection] = getPlaylists(collectionFolder, config.playlistFolder);
  });
  // make it available in template
  defineOptions.playlists = playlists;

  // do the building
  Metalsmith(config.lessonRoot)
  .source(config.sourceFolder)
  .use(ignore(ignoreOptions))
  .clean(false) // do not delete files, allow gulp tasks in parallel
  .use(paths())
  // set template for exercises
  .use(setMetadata(metadataOptions))
  // add relative(path) for use in templates
  .use(relative())
  // create collections for index
  .use(collections(collectionOptions))
  .use(metlunr({
    fields: {
      contents: 1,
      title: 10,
      tags: 20,
    },
    pipelineFunctions: [
      lunr.no.trimmer,
      lunr.no.stopWordFilter,
      lunr.no.stemmer
    ]
  }))
  // remove files not to build *after* we have set collections metadata
  .use(paths())
  .use(changed({
      force: forceBuild,
      extnames: {
          '.md': '.html',
      },
  }))
  // convert to html
  .use(pandoc({
    to: 'html5',
    args: ['--section-divs', '--smart']
  }))
  // highlight code - exclude scratch code blocks
  .use(branch()
    .pattern(['**/*.html', '!scratch/**/*.html']) // no highlight on scratch blocks
    .use(highlight())
  )
  // add file.link metadata (now files are .html)
  .use(filepath())
  // globals for use in templates
  .use(define(defineOptions))
  // apply templates
  .use(templates(templateOptions))
  //build
  .destination('build')
  .build(function(err){
    if (err) console.log(err);
    // callback when build is done
    callback(err);
  });
};