build-indexes.js

/**
 * build index files
 */
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 paths = require('metalsmith-paths')
var md = require('./markdown.js')
// get configuration variables
var config = require('./config.js')
var tools = require('./tools.js')
var playlists = require('./playlists.js')
var lessonReadme = require('./lesson-readme.js')

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

// ignore everything except index files
var ignoreOptions = [
  '**',
  '!**/*.md',
  '**/README.md'
]

// collections
var collectionOptions = {}
config.collections.forEach(function (collection) {
  // options for collections
  collectionOptions[collection] = {
    pattern: collection + '/**/*.md'
  }
})
function sortCollections (courses) {
  var out = []
  for (var name in courses) {
    var course = {}
    course.lessons = courses[name]
    course.name = name
    out.push(course)
  }
  out.sort(function (a, b) {
    if (a.lessons.length > b.lessons.length) {
      return -1
    }
    if (a.lessons.length < b.lessons.length) {
      return 1
    }
    return 0
  })
  return out
}

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

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

/**
 * # EXPORT #
 * build-function, calls callback when done
 */
module.exports = function build (callback) {
  // do the building
  Metalsmith(config.lessonRoot)
    .source(config.sourceFolder)
    .clean(false)  // do not delete files, allow gulp tasks in parallel
    .use(lessonReadme())  // before ignore
    .use(playlists({  // before ignore
      collections: Object.keys(collectionOptions)
    }))
    .use(ignore(ignoreOptions))
    // add file.link metadata (files are .md here)
    .use(filepath())
    .use(ignoreIndexedFalse)
    .use(paths())
    // set layout for exercises
    .use(setMetadata(metadataOptions))
    // add relative(path) for use in layouts
    .use(relative())
    // create collections for index
    .use(collections(collectionOptions))
    // remove lessons *after* we have necessary metadata
    .use(ignore(['**', '!**/index.md']))
    .use(tools.removeExternal)
    // convert markdown to html
    .use(md)
    // 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)
    })
}

/**
 * remove files from build which have set indexed: false in frontmatter
 */
function ignoreIndexedFalse (files, _, done) {
  Object.keys(files).forEach(function (key) {
    var file = files[key]
    if (file.indexed === false) {
      delete files[key]
    }
  })
  done()
}