const express = require('express')
const multiparty = require('multiparty')
const path = require('path')
const fsa = require('fs')
const fs = fsa.promises
const sqlite = require('sqlite')
const crypto = require('crypto')
const URL = require('url')

const router = express.Router()
const cfgLoader = require(path.join('..', '..', 'config-loader'))(path.join(__dirname, 'config.json'), {
  database: 'index.db',
  root: './files',
  expiry: 2246400,
  gateway: 'https://distributed.icynet.eu',
  shortener: {
    url: 'https://go.lunasqu.ee',
    bytes: 2,
  },
  tokens: {}
})

function asyncForm (req, form) {
  return new Promise(function (resolve, reject) {
    form.parse(req, function(err, fields, files) {
      if (err) return reject(err)
      resolve({ fields, files })
    })
  })
}

async function clearDatabase (config, dbPromise) {
  let db = await dbPromise

  // Remove expired files
  let files = await db.all('SELECT * FROM File WHERE upload < ?', new Date() - (config.expiry * 1000))
  if (files.length > 0) {
    for (let i in files) {
      let f = files[i]
      try {
        await fs.unlink(path.join(config.root, f.path))
      } catch (e) {}
      await db.run('DELETE FROM File WHERE path = ?', f.path)
    }
  }

  // IPFS hashes
  let hashes = await db.all('SELECT * FROM Translation WHERE timeat < ?', new Date() - (config.expiry * 1000))
  if (hashes.length > 0) {
    for (let i in hashes) {
      await db.run('DELETE FROM Translation WHERE file_hash = ?', hashes[i].file_hash)
    }
  }

  console.log('Database was cleared of %d files and %d IPFS hashes.', files.length, hashes.length)
}

async function init () {
  // Load configuration
  let config = await cfgLoader
  let root = path.resolve(config.root)

  // Check for root directory
  await fs.access(root, fsa.constants.F_OK)

  // Initialize database
  const dbPromise = Promise.resolve()
    .then(() => sqlite.open(path.join(__dirname, config.database), { Promise, cache: true }))
    .then(db => db.migrate({ migrationsPath: path.join(__dirname, 'migrations') }))

  await clearDatabase(config, dbPromise)

  // Upload a file or publish a hash
  router.post('/publish', async (req, res, next) => {
    let ip = req.ip
    let token = req.header('token') || req.body.token
    if (!token || !config.tokens[token]) return res.status(402).send('Forbidden')
    let baseurl = config.tokens[token]

    // Handle IPFS hash
    let hash = req.query.hash || req.body.hash
    if (hash) {
      let filename = req.query.filename || req.body.filename
      if (!filename) filename = crypto.randomBytes(8).toString('hex')

      let db = await dbPromise
      await db.run('INSERT INTO Translation (translation,file_hash,timeat) VALUES (?,?,?)', filename, hash, new Date())

      return res.send(baseurl + filename)
    }

    // Handle multipart data
    let form = new multiparty.Form()
    let { fields, files } = await asyncForm(req, form)

    // Detect all files
    let allFiles = []
    for (let i in files) {
      for (let j in files[i]) {
        allFiles.push(files[i][j])
      }
    }

    if (!allFiles.length) return res.status(400).send('Invalid request')

    console.log('[%s] from %s request to upload %d file(s)', new Date(), ip, allFiles.length)

    // Handle all files provided
    let db = await dbPromise
    let uploadedFiles = []
    for (let i in allFiles) {
      let file = allFiles[i]
      let fname = file.originalFilename
      let target = path.join(root, fname)

      // Handle already exists case (overwrite)
      try {
        await fs.access(target, fsa.constants.F_OK)
        await fs.unlink(target)
        await fs.copyFile(file.path, target)
        await fs.unlink(file.path)

        await db.run('UPDATE File SET ip = ?, upload = ? WHERE path = ?', ip, new Date(), fname)

        uploadedFiles.push(baseurl + fname)
        continue
      } catch (e) {
        if (e.code !== 'ENOENT') throw e
      }

      // Copy to target and unlink temporary file
      await fs.copyFile(file.path, target)
      await fs.unlink(file.path)

      await db.run('INSERT INTO File (path,ip,upload) VALUES (?,?,?)', fname, ip, new Date())
      uploadedFiles.push(baseurl + fname)
    }

    if (uploadedFiles.length === 0) return res.status(400).send('No files were uploaded')

    res.send(uploadedFiles.join('\n'))
  })

  router.get('/shorten', async (req, res) => {
    res.send('<h1>Basic URL Shortener</h1><form action="" method="post"> \
      <input type="url" name="url" placeholder="URL to shorten"/><input type="submit" value="Go!"/></form>')
  })

  router.post('/shorten', async (req, res) => {
    let ip = req.ip
    let url = req.body.url

    // Simple URL validator
    try {
      let a = new URL.URL(url)
      if (a.protocol.indexOf('http') !== 0 && a.protocol.indexOf('ftp') !== -1) {
        throw new Error('Unsupported protocol')
      }
    } catch (e) {
      throw new Error('Invalid URL!')
    }

    let db = await dbPromise

    // Get a hash that isnt in use
    let use
    for (let i = 0; i < 8; i++) {
      let add = Math.floor(i / 2)
      let hash = crypto.randomBytes((config.shortener.bytes || 2) + add).toString('hex')
      let exists = await db.get('SELECT timeat FROM Short WHERE hash = ?', hash)
      if (!exists) {
        use = hash
        break
      }
    }

    if (!use) throw new Error('Server could not find a proper hash for some reason')

    await db.run('INSERT INTO Short (url,hash,timeat,ip) VALUES (?,?,?,?)', url, use, Date.now(), ip)

    let ua = req.get('User-Agent')
    let reqRaw = false
    if (!reqRaw && ua && (ua.match(/curl\//i) != null || ua.match(/wget\//i) != null)) reqRaw = true
    let resp = config.shortener.url + '/' + use
    if (!reqRaw) resp = '<a href="' + resp + '" rel="nofollow">' + resp + '</a>'
    res.send(resp)
  })

  router.get('/shorten/:hash', async (req, res) => {
    let hash = req.params.hash
    let db = await dbPromise
    let get = await db.get('SELECT url FROM Short WHERE hash = ?', hash)
    if (!get) throw new Error('No such hash exists in the database.')
    res.redirect(get.url)
  })

  // Serve a file or a hash
  // Files should be served from an external web server (such as nginx) whenever possible.
  router.get('/:hash', async (req, res, next) => {
    if (!req.params.hash) return res.status(400).send('Invalid request')

    let db = await dbPromise
    let file = await db.get('SELECT * FROM File WHERE path = ?', req.params.hash)
    let translation = await db.get('SELECT * FROM Translation WHERE translation = ?', req.params.hash)
    if (!file && !translation) return res.status(404).end()

    res.header('Cache-Control', 'max-age=' + 7 * 24 * 60 * 60 * 1000)

    if (translation) {
      return res.redirect(config.gateway + '/ipfs/' + translation.file_hash)
    }

    res.sendFile(path.join(root, file.path))
  })

  return router
}

module.exports = init