const fetch = require('node-fetch')
const config = require('./config.js')
const Path = require('path')

let cache = require('./cache.json')
const { JSDOM } = require('jsdom')

let waitingList = new Map()

const handleNitterUser = async user => {
  let data
  let index = 0
  let sources = cache.nitter[user] ?
    [ cache.nitter[user] ].concat(config.sources.nitter) :
    config.sources.nitter

  while(!data && index < sources.length) {
    let source = sources[index]
    let rss = await fetchRss(source, user + '/rss')

    try {
      data = processNitter(rss, user)
    } catch(err) {
      if(err.constructor.name == NoMatchesError.name || err.constructor.name == DOMException.name) {
        console.log(`Failed to fetch ${user} from ${source}`)
        index++
      } else {
        console.error(err)
        break
      }
    }
  }

  console.log(`Found ${user} at ${sources[index]}`)
  cache.nitter[user] = sources[index]
  return data
}

const sleep = delay => new Promise(resolve => setTimeout(() => resolve(), delay) )

class NoMatchesError extends Error {}

const processRss = (rss, reducerCallback, cdata) => {
  let { document } = new JSDOM(rss, {
    contentType: 'text/xml'
  }).window
  let items = document.querySelectorAll('channel item')

  if(items.length == 0) {
    throw new NoMatchesError('Got no matches')
  }

  let posts = []

  for(let item of items) {
    let description = new JSDOM(item.querySelector('description').textContent).window.document
    let dateString = item.querySelector('pubDate').textContent
    let link = item.querySelector('link').textContent

    let post = reducerCallback(item, description, dateString, link)

    if(post) {
      post.date = new Date(dateString).valueOf() ?? 0
      post.link = link

      posts.push(post)
    }
  }

  return posts
}

const fetchRss = async (hostname, path) => {
  let waitFor = waitingList.get(hostname)

  if(waitFor !== 0) {
    await sleep(waitFor)
    waitingList.set(hostname, 0)
  }

  return await fetch(new URL(path, 'https://' + hostname))
    .then(response => {
      waitingList.set(hostname, config.courtesyWait)
      return response.text()
    })
    .catch(console.error)
}

const getImages = (user, description) => {
  let images = description.querySelectorAll('img')

  if(images) {
    let imageUrls = []

    for(let image of images) {
      let { src } = image

      if(!src) {
        let finalSrc = image.srcset.split(', ').pop()

        src = finalSrc.slice(0, finalSrc.indexOf(' ') )
      }
      
      imageUrls.push(src)
    }

    if(imageUrls.length > 0) {
      return {
        images: imageUrls,
        user
      }
    }
  }
}

const processNitter = (rss, user) => {
  return processRss(rss, (item, description) => {
    let creator = item.getElementsByTagName('dc:creator')[0]

    if(creator.innerHTML.slice(1) === user)
      return getImages(user, description)
  }, true)
}

const handleTumblrUser = async (user) => {
  let rss = await fetchRss(user + '.tumblr.com', 'rss')

  console.log('Found ' + user)
  return processTumblr(rss, user)
}

const processTumblr = (rss, user) => {  
  return processRss(rss, (item, description) => {
    let reblog = description.querySelector('p > a.tumblr_blog')

    // If it's a reblog, skip it
    if(reblog && reblog.innerHTML !== user) {
      return
    }

    return getImages(user, description)
  })
}

const oneDay = 1000 * 60 * 60 * 24

const printFeed = async (sources, directory, header) => {
  // Coalate
  let feed = []
  let tooLongAgo = (Date.now() - (Date.now() % oneDay)) - oneDay * config.tooLongAgo
  let missingSources = 0

  for(let source of sources) {
    if(source == undefined) {
      missingSources++
      continue
    }

    for(let post of source) {
      if(tooLongAgo && post.date > tooLongAgo)
        feed.push(post)
    }
  }

  feed = feed.sort((a, b) => a.date < b.date)

  if(missingSources) {
    console.log('Missing ' + missingSources + ' feeds!')
  }

  // Render

  let pages = []

  for(let i = 0; i < Math.ceil(feed.length / config.pageSize); i++) {
    pages.push(feed.slice(i * config.pageSize, (i + 1) * config.pageSize) )
  }

  // Write

  for(let i = 0; i < pages.length; i++) {
    let nextPage = i + 1

    let link = nextPage === pages.length ?
      `<a href="data:text/html,">end</a>` :
      `<a href="${nextPage}.html">next</a>`

    Bun.write(
      Path.join(directory, (i == 0 ? 'index' : i) + '.html'),
      renderPage(`Page ${i + 1}`, pages[i], header, link)
    )
  }
}

const renderPage = (title, posts, header, footer) => {
  let html = `\
<html>
<head>

<title>${title}</title>
<meta name="viewport" content="width=device-width, initial-scale=1">
<style>
  body {
    max-width: 640px;
    float: right;
    font-family: sans-serif;
  }

  p {
    padding: 30px;
  }

  img {
    margin: 10px auto;
    max-width: 100%;
  }

  p a, footer a {
    float: right
  }

  hr {
    clear: both
  }
</style>

</head>
<body>`

  if(header) {
    html += `
<header>
${header}
</header>
`
  }

  for(let post of posts) {
    let date = new Date(post.date)

    html += `
${post.images.map(renderImage).join('\n')}
<p><b>${post.user}</b> ${config.printDate(date)} <a href="${post.link}">open</a></p><hr>`
  }

  if(footer) {
    html += `

<footer>
${footer}
</footer>`
  }

  html += `
</body>
</html>`
  return html
}

const renderImage = image => `\
<a href="${image}"><img src="${image}" loading="lazy"></img></a>`

const main = async () => {
  let feeds = []
  let allSources = []

  for(let feedName in config.feeds) {
    let feed = config.feeds[feedName]
    let sources = []

    const subscribe = (sourcePromise, type, name) =>
      sourcePromise
        .catch(error => console.error(error) )
        .then(source => {
          sources.push(source)
          allSources.push({
            type,
            name,
            link: Path.join(type, name),
            source
          })
        })

    if(feed.nitter) {
      for(let user of feed.nitter) {
        await subscribe(handleNitterUser(user), 'nitter', user)
      }
      console.log('Caching sources...')
      Bun.write('cache.json', JSON.stringify(cache, null, 2))
    }

    if(feed.tumblr) {
      for(let user of feed.tumblr) {
        await subscribe(handleTumblrUser(user), 'tumblr', user)
      }
    }

    let link = feed.main ? '' : feedName

    feeds.push({
      name: feedName,
      main: feed.main,
      sources,
      link
    })
  }

  const buildFeedNav = depth => {
    const buildLink = (page, name = page.link) => {
      let link = '../'.repeat(depth) + page.link

      if(config.linkToIndex)
        link += '/index.html'

      return `<div><a href="${link}">${name}</a></div>`
    }

    return `\
<details>

<summary>Feeds</summary>
<section>
${buildLink({ link: '' }, 'main')}
${feeds.filter(feed => !feed.main).map(feed => buildLink(feed)).join('\n')}
<hr>
${allSources.map(source => buildLink(source)).join('\n')}
</section>

</details>
<hr>`
  }

  console.log('Writing...')
  for(let source of allSources) {
    console.log(source)

    await printFeed([ source.source ], Path.join('out', source.link), buildFeedNav(2))
  }
  for(let feed of feeds) {
    await printFeed(feed.sources, Path.join('out', feed.link), buildFeedNav(feed.main ? 0 : 1))
  }

  console.log('Done!')
}

main()