const axios = require('axios')
const allSettled = require('promise.allsettled')
const get = require("lodash.get")
const { WebClient } = require('@slack/web-api')

// Keywords are comma-separated, so we convert into an array
const { keywords, channel } = params
var KEYWORDS = keywords.split(",").map(k => k.trim())

const HN_BASE_URL = "https://hacker-news.firebaseio.com/v0/"

// Fetch all top HN stories, filtering by keywords,
const topStories = (await axios.get(`${HN_BASE_URL}/topstories.json`)).data
if (!topStories) {
  $end("No top stories found")
}

const responses = await allSettled(
  topStories.map(topStory => 
    axios.get(`${HN_BASE_URL}/item/${topStory}.json`)
  )
)

// Pull previously-posted stories from this.$checkpoint.
// See https://docs.pipedream.com/workflows/steps/code/#step-level-state-this-checkpoint
const previouslyPostedStories = get(this, '$checkpoint', [])

const matchingStories = []
for (response of responses) {
  const story = response.value.data
  for (keyword of KEYWORDS) {
    const re = new RegExp(keyword, 'gi')
    if (story.title.match(re) && !previouslyPostedStories.includes(story.id)) {
      console.log(`MATCHING TITLE: ${story.title}`)
      matchingStories.push(story)
    }
  }
}

if (!matchingStories.length) {
  $end("No new stories matching keywords")
}

// Send to Slack
const web = new WebClient(auths.slack.token)

for (story of matchingStories) {
  const storyURL = story.url ? story.url : `https://news.ycombinator.com/item?id=${story.id}`
  const text = `New Story on HN matching your keywords: <${storyURL}|${story.title}> (<https://news.ycombinator.com/item?id=${story.id}|comments>)`
  await web.chat.postMessage({
    channel,
    text,
  })
}

// Finally, store the processed stories in state so we don't process them next time
this.$checkpoint = previouslyPostedStories.concat(matchingStories.map(s => s.id))