app.js

const express = require('express')
const cron = require('node-cron')
const cors=require("cors")
const {getTopStoryIds, getAllTopStories, getItem, getComments, getImagePreviewForStory} = require("./modules/hackernews");
const {data} = require("./modules/data");
const {ellipsis, removeHttp} = require("./utilities/string");
const chalk = require("chalk");

const app = express()
const port = process.env.PORT || 5000

let topStoriesHaveBeenFetched = false
let cronJobIsRunning = false

const fetchPreview = async (story, silent=true) => {
  if (story.url) {
    const formattedUrl = removeHttp(ellipsis(story.url, 50))
    if (!silent)
      console.log(`Fetching preview for url: ${formattedUrl}`)
    try {
      story["preview"] = await getImagePreviewForStory(story.url)
    } catch(e) {
      if (!silent)
        console.log(`Error while fetching story preview from url: ${formattedUrl}. \n !!! Message: ${ellipsis(e.toString(), 50)}`)
    }
  }

  return story
}

const epochToDay = (epochTime) => {
  const date = new Date(0)
  date.setUTCSeconds(epochTime)
  return date
}

const fetchTopStories = async (ids, compareAgainstState=true, amount=ids.length) => {
  console.log(`Ids for the top stories have been fetched, found ${chalk.green(ids.length)} ids\n`)
  const stories = await getAllTopStories(ids, compareAgainstState, amount)

  console.log(`Collected ${chalk.green(stories.length)} stories. Processing...`)
  console.log('--------------------------------------------------------------------')

  const sortedStories = stories.sort((x, y) => y.time - x.time)

  for (let i = 0; i < sortedStories.length; i++) {
    if (stories[i].url)
      stories[i] = await fetchPreview(stories[i])

    if (!data.topStories.includes(stories[i])) {
      console.log(`${chalk.green("Pushing story")}: ${ellipsis(stories[i].title, 50)}`)

      data.topStories.push(stories[i]) // Add new story

      // The typical maximum of stories; if more that the max, pop.
      if (data.topStories.length > 500) {
        const archivedStory = data.topStories[data.topStories.length - 1]
        console.log(`${chalk.yellow("Popping story from memory")}: ${ellipsis(archivedStory.title, 50)}`)

        data.archives.push(archivedStory)
        data.topStories.pop()
      }
    } else {
      console.log(chalk.red(`Cannot add story as it is already stored]: ${stories[i].id}`))
    }
  }

  console.log("\nAll stories have been processed!")

  topStoriesHaveBeenFetched = true
}

const corsOptions = {
  origin:'*',
  credentials:true,
  optionSuccessStatus:200,
}

app.use(cors(corsOptions))
app.use(express.json())
app.listen(port, async () => {
  console.log(`Starting the ${chalk.cyan("HackerCrust")} backend on port: ${chalk.blue(port)}`)

  const request = await getTopStoryIds()
  data.topStoryIds = await request.json()

  await fetchTopStories(data.topStoryIds, false)

  console.log(`The ${chalk.cyan("HackerCrust")} backend is ready for use.`)
})

app.get("/", (req, res) => {
  res.send("Hacker Crust API is up and running.")
})

app.post("/comments", async (req, res) => {
  const comments = await getComments(req.body.ids)
  res.json({comments: comments})
})

app.get("/storyids", async(req, res) => {
  const request = await getTopStoryIds()
  res.send(await request.json())
})

app.get("/topstories", async (req, res) => {
  console.log("Request to /topstories")
  res.send(data.topStories)
})

app.get("/item/:id", async (req, res) => {
  console.log(req.params)
  const item = await getItem(req.params.id)

  if (item) {
    console.log(`Found story: ${req.params.id}`)
  } else {
    console.log(`Could not find: ${req.params.id}`)
  }

  res.send(await fetchPreview(await item.json()))
})

app.get("/topstories/page/:page/amount/:amount/increaseBy/:increaseBy", async (req, res) => {
  console.log("Request to /topstories")
  console.log(req.params)
  const filters = {
    currentPage: req.params.page,
    amount: req.params.amount,
    increaseBy: req.params.increaseBy
  }

  let stories = []

  let minStoriesToGet = (filters.currentPage - 1) * filters.increaseBy
  const maxStoriesToGet = filters.currentPage * filters.increaseBy

  for (let i = minStoriesToGet; i < maxStoriesToGet; i++) {
    const story = await data.topStories[i]
    if (story) {

      if (!story.returnId)
        story.returnId = 0

      story.returnId = i
      stories.push(story)
    }
  }

  console.log(`Returning stories ${minStoriesToGet} to ${maxStoriesToGet}.`)
  console.log(`Number of stories: ${stories.length}`)

  res.send(stories)
})

cron.schedule(`30 * * * *`, async () => {
  console.log("Starting CRON job & fetching more stories...")
  if (topStoriesHaveBeenFetched && !cronJobIsRunning) {
    cronJobIsRunning = true
    console.log("Cron job running.\n Fetching stories...")
    const request = await getTopStoryIds()
    const stories = await request.json()

    // WHY?? I don't remember
    if (stories === []) {
      cronJobIsRunning = false
      return
    }

    await fetchTopStories(stories, true)
    cronJobIsRunning = false
  } else {
    console.log(`Original fetch has not ran or Cron job has not finished... exiting job.`)
  }
})