const get = require("lodash.get") 
const isEqual = require("lodash.isequal")

// Parse hostname from URL to generate feedLinks below
// You can make GET requests to /rss, /json, or /atom
// to retrieve these feeds
const hostname = new URL(event.url).hostname
this.rssFeedLink = `https://${hostname}/rss`
this.jsonFeedLink = `https://${hostname}/json`
this.atomFeedLink = `https://${hostname}/atom`

// We only add the required options here, but you can add
// any of the options from https://www.npmjs.com/package/feed
// See https://validator.w3.org/feed/docs/rss2.html for a
// full description of each element
const { title, description, link } = params

const feedOptions = {
  title,
  description,
  link,
  id: link,
  feedLinks: {
    rss: this.rssFeedLink,
    json: this.jsonFeedLink,
    atom: this.atomFeedLink, 
  },
}

// If feedOptions has changed (e.g. if you changed Feed Title), 
// save to workflow state.
const savedFeedOptions = get($checkpoint, "feedOptions")
if (!isEqual(savedFeedOptions, feedOptions)) {
  // If this is our first time running the workflow,
  // $checkpoint will be undefined. Instantiate it to be an object
  if (!$checkpoint) $checkpoint = {}
  $checkpoint.feedOptions = feedOptions
}

this.feedOptions = feedOptions

const get = require("lodash.get")

// Send an HTTP POST request to add a new item to the feed
// From the RSS spec (https://validator.w3.org/feed/docs/rss2.html):
// "All elements of an item are optional, however at least one of title or description must be present."

// The body of the request must match the properties the feed package 
// expects in the addItem method: https://www.npmjs.com/package/feed
if (event.method === "POST") {
  // Require secret is present on requests to add items to the feed
  if (params.secret !== event.headers.secret) {
    $end("Invalid secret")
  }

  // Get any items stored in state
  // This keeps the last MAX_ITEMS items POSTed to this feed
  MAX_ITEMS = 15
  
  const items = get($checkpoint, "items", [])
  if (items.length > MAX_ITEMS) {
    items.shift()
  }
  items.push(event.body)

  if (!$checkpoint) $checkpoint = {}
  $checkpoint.items = items

  $respond({
    body: {
      success: true,
      msg: "Saved new item to feed"
    }
  })
  
  $end("Saved new item to feed")
}

const Feed = require('feed').Feed; 
const get = require("lodash.get")

// Build feed object from channel metadata generated above
const feed = new Feed(steps.rss_channel_metadata.feedOptions)

const items = get($checkpoint, "items", [])
for (const item of items) {
  feed.addItem(item)
}

// Did the user issue a GET request to retrieve feed data?
if (event.method === "GET") {
  this.pathname = new URL(event.url).pathname
  let body
  switch (this.pathname) {
    case '/rss':
      body = feed.rss2()
      break
    case '/json':
      body = feed.json1()
      break
    case '/atom':
      body = feed.atom1()
      break
    default:
      body = feed.rss2()
  }

  $respond({
    headers: {
      "Content-Type": "application/xml",
    },
    body,
  })

  $end(`Retrieved ${this.pathname} feed`)
}