const MarkdownIt = require('markdown-it')
const fs = require('fs')
const path = require('path')
const moment = require('moment')
const jsonfile = require('jsonfile')
const async = require('async')
const fm = require('front-matter')
const config = require('../../config.json')

/**
 * Renders file using MarkdownIt
 */
function render (file) {
  const md = new MarkdownIt({ html: true })
  return md.render(file)
}

/**
 * Extracts file metadata such as parent directory
 */
function fileMetadata (filepath) {
  const paths = filepath.split('/')
  const basename = path.basename(filepath)

  const metadata = {
    basename,
    filename: basename.substr(0, basename.lastIndexOf('.')),
    parrent: paths[paths.length - 2],
    dirname: path.dirname(filepath)
  }

  return metadata
}

/**
 * Compiles file that is a blog post
 */
function compilePost (filepath, data, fileData, callback) {
  const frontMatter = fm(fileData)
  const rendered = render(frontMatter.body)
  const metadata = fileMetadata(filepath)

  if (frontMatter.attributes.draft) {
    callback(null, null)
    return
  }

  let published
  if (frontMatter.attributes.date) {
    published = moment(frontMatter.attributes.date)
  } else {
    published = moment()
  }

  const post = {
    published: published.format('MMMM DD, YYYY'),
    filename: metadata.filename,
    title: frontMatter.attributes.title,
    link: '/post/' + metadata.filename
  }

  const renderedpath = path.join(process.cwd(), config.renderPath, `${metadata.filename}.html`)

  fs.writeFile(renderedpath, rendered, (err) => {
    if (err) callback(err)
    else callback(null, post)
  })
}

/**
 * Compiles other types of files such as resumes, about me and so on.
 */
function compileOther (filepath, data, fileData, callback) {
  const frontMatter = fm(fileData)
  const rendered = render(frontMatter.body)
  const metadata = fileMetadata(filepath)

  const post = {
    filename: metadata.filename
  }

  const renderedpath = path.join(process.cwd(), config.renderPath, `${metadata.filename}.html`)

  fs.writeFile(renderedpath, rendered, (err) => {
    if (err) callback(err)
    else callback(null, post)
  })
}

function Compiler (data) {
  this.data = data
}

/**
 *
 */
Compiler.prototype.addFile = function (filepath, isPost, callback) {
  if (isPost) {
    async.waterfall([
      fs.readFile.bind(fs, filepath, 'utf8'),
      compilePost.bind(compilePost, filepath, this.data)
    ], (err, result) => {
      if (err) throw err

      if (result == null) {
        callback()
      } else {
        this.data.posts.push(result)
        console.log('[Compiler] File %s compiled', filepath)
        callback()
      }
    })
  } else {
    async.waterfall([
      fs.readFile.bind(fs, filepath, 'utf8'),
      compileOther.bind(compileOther, filepath, this.data)
    ], (err, result) => {
      if (err) throw err

      this.data.other.push(result)
      console.log('[Compiler] File %s compiled', filepath)
      callback()
    })
  }
}

/**
 * Writes updated data to the data file
 */
Compiler.prototype.writeData = function (callback) {
  const dataPath = path.join(process.cwd(), 'src/utils/data.json')
  jsonfile.writeFile(dataPath, this.data, callback)
}

module.exports = Compiler