build.js

/*
 * # DEPENDENCIES #
 */
var Metalsmith = require('metalsmith')
var layouts = require('metalsmith-layouts')
var collections = require('metalsmith-collections')
var setMetadata = require('metalsmith-filemetadata')
var filepath = require('metalsmith-filepath')
var ignore = require('metalsmith-ignore')
var relative = require('metalsmith-relative')
var define = require('metalsmith-define')
var _ = require('lodash')
var changed = require('metalsmith-changed')
var paths = require('metalsmith-paths')
var md = require('./markdown.js')
// get configuration variables
var config = require('./config.js')
var tools = require('./tools.js')
var lessonReadme = require('./lesson-readme.js')

/*
 * # SETUP OBJECTS #
 */
// metadata
var metadataOptions = [
  // scratch lesson layout
  {
    pattern: '**/*.md',
    metadata: { layout: 'lesson.jade' }
  },
  // scratch lesson layout
  {
    pattern: 'scratch/**/*.md',
    metadata: { layout: 'scratch.jade' }
  }
]

// ignores
var ignoreOptions = [
  'index.md',
  '*/index.md'
]

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

// defines available in layout
var defineOptions = {
  markdown: md.parser,
  _: _,
  config: config,
  isFile: tools.isFile,
  matter: tools.frontmatter
}

// layout
var layoutOptions = {
  engine: 'jade',
  directory: config.builderRoot + '/layouts'
}

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

  // do the building
  Metalsmith(config.lessonRoot)
    .source(config.sourceFolder)
    .clean(false) // do not delete files, allow gulp tasks in parallel
    .use(changed({
      force: forceBuild
    }))
    .use(lessonReadme())
    .use(ignore(ignoreOptions))
    .use(paths())
    // set layout for exercises
    .use(setMetadata(metadataOptions))
    // add relative(path) for use in layouts
    .use(relative())
    // create collections
    .use(collections(collectionOptions))
    // convert markdown to html
    .use(md)
    // add file.link metadata (now files are .html)
    .use(filepath())
    // globals for use in layouts
    .use(define(defineOptions))
    // apply layouts
    .use(layouts(layoutOptions))
    // build
    .destination('build')
    .build(function (err) {
      if (err) console.log(err)
      // callback when build is done
      callback(err)
    })
}