const path = require('path')
const https = require('https')
const Stream = require('stream').Transform
const hasha = require('hasha')
const md = require('markdown-it')()
const {httpsGetAsync, parseJSONData} = require('../../lib/request')

const GLITCH_API_ROOT = '/ghost/api/v0.1/'

// Retrieve ghost access token
const getToken = config => {
  return new Promise((resolve, reject) => {
    const tokenReqData = `grant_type=password&username=${config.ghost.username}&password=${config.ghost.password}&client_id=${config.ghost.id}&client_secret=${config.ghost.secret}`
    const tokenReqOptions = {
      host: config.ghost.host,
      path: `${GLITCH_API_ROOT}authentication/token`,
      method: 'POST',
      headers: {
        'Content-Type': 'application/x-www-form-urlencoded',
        'Content-Length': Buffer.byteLength(tokenReqData, 'utf8')}}
    const collectToken = https.request(tokenReqOptions, res => {
      const data = new Stream()
      res.on('data', chunk => data.push(chunk))
      res.on('end', parseJSONData.bind(null, data, resolve, reject))
    })
    collectToken.write(tokenReqData)
    collectToken.end()
    collectToken.on('error', error => reject(error))
  })
}

const download = (image, config) => {
  return new Promise(async (resolve, reject) => {
    const src = `https://${config.ghost.host}${image}`
    const dest = path.join(config.basepath, config.image_path, image)
    const data = new Stream()
    const res = await httpsGetAsync(src)
    res.on('data', chunk => data.push(chunk))
    res.on('end', () => {
      const buf = data.read()
      resolve({src, dest, hash: hasha(buf), original: buf, optimized: null, responsive: []})
    })
  })
}

// download images
const downloadImages = async (posts, config) => {
  let images = []
  posts.posts.forEach((post, idx) => {
    let postImages = []
    if (post.image) postImages.push(post.image)
    // parse inline images
    md.parse(post.markdown).forEach(token => {
      if (token.type === 'image') postImages.push(token.attrs[0][1])
      if (Array.isArray(token.children)) {
        token.children.forEach(async child => {
          if (child.type === 'image') postImages.push(child.attrs[0][1])
        })
      }
    })
    images.push(Promise.all(postImages.map(image => download(image, config))))
  })
  return Promise.all(images)
}

const mapPostPages = async (posts, images, config) => {
  const postsWithMappedImages = posts.posts.map((post, idx) => Object.assign({}, post, {image: images[idx].pop()}, {images: images[idx]}))
  const postsWithMappedFields = postsWithMappedImages.map(post => {
    return {
      id: post.id,
      uuid: post.uuid,
      title: post.title,
      slug: post.slug,
      url: post.url,
      article: !post.page,
      status: post.status,
      language: post.language,
      visibility: post.visibility,
      meta_title: post.meta_title || post.title,
      meta_description: post.meta_description,
      created_at: new Date(post.created_at),
      created_by: post.created_by,
      updated_at: new Date(post.updated_at),
      updated_by: post.updated_by,
      published_at: new Date(post.published_at),
      published_by: post.published_by,
      tags: post.tags,
      author: post.author,
      image: post.image,
      images: post.images,
      markdown: post.markdown
    }
  })
  return postsWithMappedFields
}

// fetch ghost posts
const getPosts = async config => {
  const loadPosts = () => {
    return new Promise(async (resolve, reject) => {
      const token = await getToken(config)
      const postsReqOptions = {
        host: config.ghost.host,
        path: `${GLITCH_API_ROOT}posts/?status=all&staticPages=all&include=tags&limit=30`,
        headers: {
          'authorization': `Bearer ${token.access_token}`,
          'accept': 'application/json'}}
      const data = new Stream()
      const res = await httpsGetAsync(postsReqOptions)
      res.on('data', chunk => data.push(chunk))
      res.on('end', parseJSONData.bind(null, data, resolve, reject))
    })
  }
  const posts = await loadPosts()
  const images = await downloadImages(posts, config)
  return mapPostPages(posts, images, config)
}

module.exports.getPosts = getPosts