filesafe/controllers/utilsController.js

const { promisify } = require('util')
const fetch = require('node-fetch')
const ffmpeg = require('fluent-ffmpeg')
const path = require('path')
const sharp = require('sharp')
const si = require('systeminformation')
const paths = require('./pathsController')
const perms = require('./permissionController')
const config = require('./../config')
const logger = require('./../logger')
const db = require('knex')(config.database)

const self = {
  clamscan: {
    instance: null,
    version: null,
    groupBypass: config.uploads.scan.groupBypass || null,
    whitelistExtensions: (Array.isArray(config.uploads.scan.whitelistExtensions) &&
      config.uploads.scan.whitelistExtensions.length)
      ? config.uploads.scan.whitelistExtensions
      : null,
    maxSize: (parseInt(config.uploads.scan.maxSize) * 1e6) || null
  },
  gitHash: null,
  idSet: null,

  idMaxTries: config.uploads.maxTries || 1,

  imageExts: ['.gif', '.jpeg', '.jpg', '.png', '.svg', '.tif', '.tiff', '.webp'],
  videoExts: ['.3g2', '.3gp', '.asf', '.avchd', '.avi', '.divx', '.evo', '.flv', '.h264', '.h265', '.hevc', '.m2p', '.m2ts', '.m4v', '.mk3d', '.mkv', '.mov', '.mp4', '.mpeg', '.mpg', '.mxf', '.ogg', '.ogv', '.ps', '.qt', '.rmvb', '.ts', '.vob', '.webm', '.wmv'],
  audioExts: ['.flac', '.mp3', '.wav', '.wma'],

  thumbsSize: config.uploads.generateThumbs.size || 200,
  ffprobe: promisify(ffmpeg.ffprobe),

  albumsCache: {},
  timezoneOffset: new Date().getTimezoneOffset()
}

const statsData = {
  system: {
    title: 'System',
    cache: null,
    generating: false,
    generatedAt: 0
  },
  fileSystems: {
    title: 'File Systems',
    cache: null,
    generating: false,
    generatedAt: 0
  },
  uploads: {
    title: 'Uploads',
    cache: null,
    generating: false,
    generatedAt: 0
  },
  users: {
    title: 'Users',
    cache: null,
    generating: false,
    generatedAt: 0
  },
  albums: {
    title: 'Albums',
    cache: null,
    generating: false,
    generatedAt: 0
  }
}

const cloudflareAuth = config.cloudflare && config.cloudflare.zoneId &&
  (config.cloudflare.apiToken || config.cloudflare.userServiceKey ||
  (config.cloudflare.apiKey && config.cloudflare.email))

self.mayGenerateThumb = extname => {
  return (config.uploads.generateThumbs.image && self.imageExts.includes(extname)) ||
    (config.uploads.generateThumbs.video && self.videoExts.includes(extname))
}

// Expand if necessary (must be lower case); for now only preserves some known tarballs
const extPreserves = ['.tar.gz', '.tar.z', '.tar.bz2', '.tar.lzma', '.tar.lzo', '.tar.xz']

self.extname = filename => {
  // Always return blank string if the filename does not seem to have a valid extension
  // Files such as .DS_Store (anything that starts with a dot, without any extension after) will still be accepted
  if (!/\../.test(filename)) return ''

  let lower = filename.toLowerCase() // due to this, the returned extname will always be lower case
  let multi = ''
  let extname = ''

  // check for multi-archive extensions (.001, .002, and so on)
  if (/\.\d{3}$/.test(lower)) {
    multi = lower.slice(lower.lastIndexOf('.') - lower.length)
    lower = lower.slice(0, lower.lastIndexOf('.'))
  }

  // check against extensions that must be preserved
  for (const extPreserve of extPreserves) {
    if (lower.endsWith(extPreserve)) {
      extname = extPreserve
      break
    }
  }

  if (!extname) {
    extname = lower.slice(lower.lastIndexOf('.') - lower.length) // path.extname(lower)
  }

  return extname + multi
}

self.escape = string => {
  // MIT License
  // Copyright(c) 2012-2013 TJ Holowaychuk
  // Copyright(c) 2015 Andreas Lubbe
  // Copyright(c) 2015 Tiancheng "Timothy" Gu

  if (!string) return string

  const str = String(string)
  const match = /["'&<>]/.exec(str)

  if (!match) return str

  let escape
  let html = ''
  let index = 0
  let lastIndex = 0

  for (index = match.index; index < str.length; index++) {
    switch (str.charCodeAt(index)) {
      case 34: // "
        escape = '&quot;'
        break
      case 38: // &
        escape = '&amp;'
        break
      case 39: // '
        escape = '&#39;'
        break
      case 60: // <
        escape = '&lt;'
        break
      case 62: // >
        escape = '&gt;'
        break
      default:
        continue
    }

    if (lastIndex !== index) {
      html += str.substring(lastIndex, index)
    }

    lastIndex = index + 1
    html += escape
  }

  return lastIndex !== index
    ? html + str.substring(lastIndex, index)
    : html
}

self.stripIndents = string => {
  if (!string) return
  const result = string.replace(/^[^\S\n]+/gm, '')
  const match = result.match(/^[^\S\n]*(?=\S)/gm)
  const indent = match && Math.min(...match.map(el => el.length))
  if (indent) {
    const regexp = new RegExp(`^.{${indent}}`, 'gm')
    return result.replace(regexp, '')
  }
  return result
}

self.authorize = async (req, res) => {
  // TODO: Improve usage of this function by the other APIs
  const token = req.headers.token
  if (token === undefined) {
    res.status(401).json({ success: false, description: 'No token provided.' })
    return
  }

  try {
    const user = await db.table('users')
      .where('token', token)
      .first()
    if (user) {
      if (user.enabled === false || user.enabled === 0) {
        res.json({ success: false, description: 'This account has been disabled.' })
        return
      }
      return user
    }

    res.status(401).json({ success: false, description: 'Invalid token.' })
  } catch (error) {
    logger.error(error)
    res.status(500).json({ success: false, description: 'An unexpected error occurred. Try again?' })
  }
}

self.generateThumbs = async (name, extname, force) => {
  const thumbname = path.join(paths.thumbs, name.slice(0, -extname.length) + '.png')

  try {
    // Check if thumbnail already exists
    try {
      const lstat = await paths.lstat(thumbname)
      if (lstat.isSymbolicLink()) {
        // Unlink if symlink (should be symlink to the placeholder)
        await paths.unlink(thumbname)
      } else if (!force) {
        // Continue only if it does not exist, unless forced to
        return true
      }
    } catch (error) {
      // Re-throw error
      if (error.code !== 'ENOENT') throw error
    }

    // Full path to input file
    const input = path.join(paths.uploads, name)

    // If image extension
    if (self.imageExts.includes(extname)) {
      const resizeOptions = {
        width: self.thumbsSize,
        height: self.thumbsSize,
        fit: 'contain',
        background: {
          r: 0,
          g: 0,
          b: 0,
          alpha: 0
        }
      }
      const image = sharp(input)
      const metadata = await image.metadata()
      if (metadata.width > resizeOptions.width || metadata.height > resizeOptions.height) {
        await image
          .resize(resizeOptions)
          .toFile(thumbname)
      } else if (metadata.width === resizeOptions.width && metadata.height === resizeOptions.height) {
        await image
          .toFile(thumbname)
      } else {
        const x = resizeOptions.width - metadata.width
        const y = resizeOptions.height - metadata.height
        await image
          .extend({
            top: Math.floor(y / 2),
            bottom: Math.ceil(y / 2),
            left: Math.floor(x / 2),
            right: Math.ceil(x / 2),
            background: resizeOptions.background
          })
          .toFile(thumbname)
      }
    } else if (self.videoExts.includes(extname)) {
      const metadata = await self.ffprobe(input)

      const duration = parseInt(metadata.format.duration)
      if (isNaN(duration)) {
        throw 'Warning: File does not have valid duration metadata'
      }

      const videoStream = metadata.streams && metadata.streams.find(s => s.codec_type === 'video')
      if (!videoStream || !videoStream.width || !videoStream.height) {
        throw 'Warning: File does not have valid video stream metadata'
      }

      await new Promise((resolve, reject) => {
        ffmpeg(input)
          .on('error', error => reject(error))
          .on('end', () => resolve())
          .screenshots({
            folder: paths.thumbs,
            filename: name.slice(0, -extname.length) + '.png',
            timestamps: ['20%'],
            size: videoStream.width >= videoStream.height
              ? `${self.thumbsSize}x?`
              : `?x${self.thumbsSize}`
          })
      })
        .catch(error => error) // Error passthrough
        .then(async error => {
          // FFMPEG would just warn instead of exiting with errors when dealing with incomplete files
          // Sometimes FFMPEG would throw errors but actually somehow succeeded in making the thumbnails
          // (this could be a fallback mechanism of fluent-ffmpeg library instead)
          // So instead we check if the thumbnail exists to really make sure
          try {
            await paths.lstat(thumbname)
            return true
          } catch (err) {
            if (err.code === 'ENOENT') {
              throw error || 'Warning: FFMPEG exited with empty output file'
            } else {
              throw error || err
            }
          }
        })
    } else {
      return false
    }
  } catch (error) {
    logger.error(`[${name}]: ${error.toString().trim()}`)
    try {
      await paths.symlink(paths.thumbPlaceholder, thumbname)
      return true
    } catch (err) {
      logger.error(err)
      return false
    }
  }

  return true
}

self.stripTags = async (name, extname) => {
  const fullpath = path.join(paths.uploads, name)

  if (self.imageExts.includes(extname)) {
    const tmpfile = path.join(paths.uploads, `tmp-${name}`)
    await paths.rename(fullpath, tmpfile)

    try {
      await sharp(tmpfile)
        .toFile(fullpath)
      await paths.unlink(tmpfile)
    } catch (error) {
      await paths.unlink(tmpfile)
      // Re-throw error
      throw error
    }
  } else if (config.uploads.stripTags.video && self.videoExts.includes(extname)) {
    const tmpfile = path.join(paths.uploads, `tmp-${name}`)
    await paths.rename(fullpath, tmpfile)

    try {
      await new Promise((resolve, reject) => {
        ffmpeg(tmpfile)
          .output(fullpath)
          .outputOptions([
            // Experimental.
            '-c copy',
            '-map_metadata:g -1:g',
            '-map_metadata:s:v -1:g',
            '-map_metadata:s:a -1:g'
          ])
          .on('error', error => reject(error))
          .on('end', () => resolve(true))
          .run()
      })
      await paths.unlink(tmpfile)
    } catch (error) {
      await paths.unlink(tmpfile)
      // Re-throw error
      throw error
    }
  }

  return true
}

self.unlinkFile = async (filename, predb) => {
  try {
    await paths.unlink(path.join(paths.uploads, filename))
  } catch (error) {
    // Return true if file does not exist
    if (error.code !== 'ENOENT') throw error
  }

  const identifier = filename.split('.')[0]

  // Do not remove from identifiers cache on pre-db-deletion
  // eslint-disable-next-line curly
  if (!predb && self.idSet) {
    self.idSet.delete(identifier)
    // logger.log(`Removed ${identifier} from identifiers cache (deleteFile)`)
  }

  const extname = self.extname(filename)
  if (self.imageExts.includes(extname) || self.videoExts.includes(extname)) {
    try {
      await paths.unlink(path.join(paths.thumbs, `${identifier}.png`))
    } catch (error) {
      if (error.code !== 'ENOENT') throw error
    }
  }
}

self.bulkDeleteFromDb = async (field, values, user) => {
  // Always return an empty array on failure
  if (!user || !['id', 'name'].includes(field) || !values.length) return []

  // SQLITE_LIMIT_VARIABLE_NUMBER, which defaults to 999
  // Read more: https://www.sqlite.org/limits.html
  const MAX_VARIABLES_CHUNK_SIZE = 999
  const chunks = []
  while (values.length) {
    chunks.push(values.splice(0, MAX_VARIABLES_CHUNK_SIZE))
  }

  const failed = []
  const ismoderator = perms.is(user, 'moderator')

  try {
    const unlinkeds = []
    const albumids = []

    await Promise.all(chunks.map(async chunk => {
      const files = await db.table('files')
        .whereIn(field, chunk)
        .where(function () {
          if (!ismoderator) {
            this.where('userid', user.id)
          }
        })

      // Push files that could not be found in db
      failed.push(...chunk.filter(value => !files.find(file => file[field] === value)))

      // Unlink all found files
      const unlinked = []

      await Promise.all(files.map(async file => {
        try {
          await self.unlinkFile(file.name, true)
          unlinked.push(file)
        } catch (error) {
          logger.error(error)
          failed.push(file[field])
        }
      }))

      if (!unlinked.length) return

      // Delete all unlinked files from db
      await db.table('files')
        .whereIn('id', unlinked.map(file => file.id))
        .del()
      self.invalidateStatsCache('uploads')

      if (self.idSet) {
        unlinked.forEach(file => {
          const identifier = file.name.split('.')[0]
          self.idSet.delete(identifier)
          // logger.log(`Removed ${identifier} from identifiers cache (bulkDeleteFromDb)`)
        })
      }

      // Push album ids
      unlinked.forEach(file => {
        if (file.albumid && !albumids.includes(file.albumid)) {
          albumids.push(file.albumid)
        }
      })

      // Push unlinked files
      unlinkeds.push(...unlinked)
    }))

    if (unlinkeds.length) {
      // Update albums if necessary, but do not wait
      if (albumids.length) {
        db.table('albums')
          .whereIn('id', albumids)
          .update('editedAt', Math.floor(Date.now() / 1000))
          .catch(logger.error)
        self.invalidateAlbumsCache(albumids)
      }

      // Purge Cloudflare's cache if necessary, but do not wait
      if (config.cloudflare.purgeCache) {
        self.purgeCloudflareCache(unlinkeds.map(file => file.name), true, true)
          .then(results => {
            for (const result of results) {
              if (result.errors.length) {
                result.errors.forEach(error => logger.error(`[CF]: ${error}`))
              }
            }
          })
      }
    }
  } catch (error) {
    logger.error(error)
  }

  return failed
}

self.purgeCloudflareCache = async (names, uploads, thumbs) => {
  const errors = []
  if (!cloudflareAuth) {
    errors.push('Cloudflare auth is incomplete or missing')
  }
  if (!Array.isArray(names) || !names.length) {
    errors.push('Names array is invalid or empty')
  }
  if (errors.length) {
    return [{ success: false, files: [], errors }]
  }

  let domain = config.domain
  if (!uploads) domain = config.homeDomain

  const thumbNames = []
  names = names.map(name => {
    if (uploads) {
      const url = `${domain}/${name}`
      const extname = self.extname(name)
      if (thumbs && self.mayGenerateThumb(extname)) {
        thumbNames.push(`${domain}/thumbs/${name.slice(0, -extname.length)}.png`)
      }
      return url
    } else {
      return name === 'home' ? domain : `${domain}/${name}`
    }
  })
  names.push(...thumbNames)

  // Split array into multiple arrays with max length of 30 URLs
  // https://api.cloudflare.com/#zone-purge-files-by-url
  const MAX_LENGTH = 30
  const MAX_TRIES = 3 // only for rate limit and unexpected errors
  const chunks = []
  while (names.length) {
    chunks.push(names.splice(0, MAX_LENGTH))
  }

  const url = `https://api.cloudflare.com/client/v4/zones/${config.cloudflare.zoneId}/purge_cache`
  const results = []

  await Promise.all(chunks.map(async chunk => {
    const result = {
      success: false,
      files: chunk,
      errors: []
    }

    const headers = {
      'Content-Type': 'application/json'
    }
    if (config.cloudflare.apiToken) {
      headers.Authorization = `Bearer ${config.cloudflare.apiToken}`
    } else if (config.cloudflare.userServiceKey) {
      headers['X-Auth-User-Service-Key'] = config.cloudflare.userServiceKey
    } else if (config.cloudflare.apiKey && config.cloudflare.email) {
      headers['X-Auth-Key'] = config.cloudflare.apiKey
      headers['X-Auth-Email'] = config.cloudflare.email
    }

    for (let i = 0; i < MAX_TRIES; i++) {
      const _log = message => {
        let prefix = `[CF]: ${i + 1}/${MAX_TRIES}: ${path.basename(chunk[0])}`
        if (chunk.length > 1) prefix += ',\u2026'
        logger.log(`${prefix}: ${message}`)
      }

      try {
        const purge = await fetch(url, {
          method: 'POST',
          body: JSON.stringify({ files: chunk }),
          headers
        })
        const response = await purge.json()

        const hasErrorsArray = Array.isArray(response.errors) && response.errors.length
        if (hasErrorsArray) {
          const rateLimit = response.errors.find(error => /rate limit/i.test(error.message))
          if (rateLimit && i < MAX_TRIES - 1) {
            _log(`${rateLimit.code}: ${rateLimit.message}. Retrying in a minute\u2026`)
            await new Promise(resolve => setTimeout(resolve, 60000))
            continue
          }
        }

        result.success = response.success
        result.errors = hasErrorsArray
          ? response.errors.map(error => `${error.code}: ${error.message}`)
          : []
      } catch (error) {
        const errorString = error.toString()
        if (i < MAX_TRIES - 1) {
          _log(`${errorString}. Retrying in 5 seconds\u2026`)
          await new Promise(resolve => setTimeout(resolve, 5000))
          continue
        }

        result.errors = [errorString]
      }

      results.push(result)
      break
    }
  }))

  return results
}

self.bulkDeleteExpired = async (dryrun, verbose) => {
  const timestamp = Date.now() / 1000
  const fields = ['id']
  if (verbose) fields.push('name')
  const sudo = { username: 'root' }

  const result = {}
  result.expired = await db.table('files')
    .where('expirydate', '<=', timestamp)
    .select(fields)

  if (!dryrun) {
    // Make a shallow copy
    const field = fields[0]
    const values = result.expired.slice().map(row => row[field])
    result.failed = await self.bulkDeleteFromDb(field, values, sudo)
  }

  return result
}

self.invalidateAlbumsCache = albumids => {
  for (const albumid of albumids) {
    delete self.albumsCache[albumid]
    delete self.albumsCache[`${albumid}-nojs`]
  }
}

self.invalidateStatsCache = type => {
  if (!['albums', 'users', 'uploads'].includes(type)) return
  statsData[type].cache = null
}

self.stats = async (req, res, next) => {
  const user = await self.authorize(req, res)
  if (!user) return

  const isadmin = perms.is(user, 'admin')
  if (!isadmin) return res.status(403).end()

  try {
    const hrstart = process.hrtime()
    const stats = {}
    Object.keys(statsData).forEach(key => {
      // Pre-assign object keys to fix their display order
      stats[statsData[key].title] = {}
    })

    const os = await si.osInfo()
    await Promise.all([
      (async () => {
        // System info
        const data = statsData.system

        if (!data.cache && data.generating) {
          stats[data.title] = false
        } else if (((Date.now() - data.generatedAt) <= 1000) || data.generating) {
          // Use cache for 1000 ms (1 second)
          stats[data.title] = data.cache
        } else {
          data.generating = true
          data.generatedAt = Date.now()

          const currentLoad = await si.currentLoad()
          const mem = await si.mem()
          const time = si.time()
          const nodeUptime = process.uptime()

          if (self.clamscan.instance) {
            try {
              self.clamscan.version = await self.clamscan.instance.get_version().then(s => s.trim())
            } catch (error) {
              logger.error(error)
              self.clamscan.version = 'Errored when querying version.'
            }
          }

          stats[data.title] = {
            Platform: `${os.platform} ${os.arch}`,
            Distro: `${os.distro} ${os.release}`,
            Kernel: os.kernel,
            Scanner: self.clamscan.version || 'N/A',
            'CPU Load': `${currentLoad.currentload.toFixed(1)}%`,
            'CPUs Load': currentLoad.cpus.map(cpu => `${cpu.load.toFixed(1)}%`).join(', '),
            'System Memory': {
              value: {
                used: mem.active,
                total: mem.total
              },
              type: 'byteUsage'
            },
            'Memory Usage': {
              value: process.memoryUsage().rss,
              type: 'byte'
            },
            'System Uptime': {
              value: time.uptime,
              type: 'uptime'
            },
            'Node.js': `${process.versions.node}`,
            'Service Uptime': {
              value: Math.floor(nodeUptime),
              type: 'uptime'
            }
          }

          // Update cache
          data.cache = stats[data.title]
          data.generating = false
        }
      })(),
      (async () => {
        // File systems
        const data = statsData.fileSystems

        if (!data.cache && data.generating) {
          stats[data.title] = false
        } else if (((Date.now() - data.generatedAt) <= 60000) || data.generating) {
          // Use cache for 60000 ms (60 seconds)
          stats[data.title] = data.cache
        } else {
          data.generating = true
          data.generatedAt = Date.now()

          stats[data.title] = {}

          const fsSize = await si.fsSize()
          for (const fs of fsSize) {
            stats[data.title][`${fs.fs} (${fs.type}) on ${fs.mount}`] = {
              value: {
                total: fs.size,
                used: fs.used
              },
              type: 'byteUsage'
            }
          }

          // Update cache
          data.cache = stats[data.title]
          data.generating = false
        }
      })(),
      (async () => {
        // Uploads
        const data = statsData.uploads

        if (!data.cache && data.generating) {
          stats[data.title] = false
        } else if (data.cache) {
          // Cache will be invalidated with self.invalidateStatsCache() after any related operations
          stats[data.title] = data.cache
        } else {
          data.generating = true
          data.generatedAt = Date.now()

          stats[data.title] = {
            Total: 0,
            Images: 0,
            Videos: 0,
            Others: 0,
            Temporary: 0,
            'Size in DB': {
              value: 0,
              type: 'byte'
            }
          }

          await Promise.all([
            (async () => {
              const uploads = await db.table('files')
                .select('size')
              stats[data.title].Total = uploads.length
              stats[data.title]['Size in DB'].value = uploads.reduce((acc, upload) => acc + parseInt(upload.size), 0)
            })(),
            (async () => {
              stats[data.title].Images = await db.table('files')
                .where(function () {
                  for (const ext of self.imageExts) {
                    this.orWhere('name', 'like', `%${ext}`)
                  }
                })
                .count('id as count')
                .then(rows => rows[0].count)
            })(),
            (async () => {
              stats[data.title].Videos = await db.table('files')
                .where(function () {
                  for (const ext of self.videoExts) {
                    this.orWhere('name', 'like', `%${ext}`)
                  }
                })
                .count('id as count')
                .then(rows => rows[0].count)
            })(),
            (async () => {
              stats[data.title].Temporary = await db.table('files')
                .whereNotNull('expirydate')
                .count('id as count')
                .then(rows => rows[0].count)
            })()
          ])

          stats[data.title].Others = stats[data.title].Total - stats[data.title].Images - stats[data.title].Videos

          // Update cache
          data.cache = stats[data.title]
          data.generating = false
        }
      })(),
      (async () => {
        // Users
        const data = statsData.users

        if (!data.cache && data.generating) {
          stats[data.title] = false
        } else if (data.cache) {
          // Cache will be invalidated with self.invalidateStatsCache() after any related operations
          stats[data.title] = data.cache
        } else {
          data.generating = true
          data.generatedAt = Date.now()

          stats[data.title] = {
            Total: 0,
            Disabled: 0
          }

          const permissionKeys = Object.keys(perms.permissions).reverse()
          permissionKeys.forEach(p => {
            stats[data.title][p] = 0
          })

          const users = await db.table('users')
          stats[data.title].Total = users.length
          for (const user of users) {
            if (user.enabled === false || user.enabled === 0) {
              stats[data.title].Disabled++
            }

            user.permission = user.permission || 0
            for (const p of permissionKeys) {
              if (user.permission === perms.permissions[p]) {
                stats[data.title][p]++
                break
              }
            }
          }

          // Update cache
          data.cache = stats[data.title]
          data.generating = false
        }
      })(),
      (async () => {
        // Albums
        const data = statsData.albums

        if (!data.cache && data.generating) {
          stats[data.title] = false
        } else if (data.cache) {
          // Cache will be invalidated with self.invalidateStatsCache() after any related operations
          stats[data.title] = data.cache
        } else {
          data.generating = true
          data.generatedAt = Date.now()

          stats[data.title] = {
            Total: 0,
            Disabled: 0,
            Public: 0,
            Downloadable: 0,
            'ZIP Generated': 0
          }

          const albums = await db.table('albums')
          stats[data.title].Total = albums.length
          const identifiers = []
          for (const album of albums) {
            if (!album.enabled) {
              stats[data.title].Disabled++
              continue
            }
            if (album.download) stats[data.title].Downloadable++
            if (album.public) stats[data.title].Public++
            if (album.zipGeneratedAt) identifiers.push(album.identifier)
          }

          await Promise.all(identifiers.map(async identifier => {
            try {
              await paths.access(path.join(paths.zips, `${identifier}.zip`))
              stats[data.title]['ZIP Generated']++
            } catch (error) {
              // Re-throw error
              if (error.code !== 'ENOENT') throw error
            }
          }))

          // Update cache
          data.cache = stats[data.title]
          data.generating = false
        }
      })()
    ])

    return res.json({ success: true, stats, hrtime: process.hrtime(hrstart) })
  } catch (error) {
    logger.error(error)
    // Reset generating state when encountering any errors
    Object.keys(statsData).forEach(key => {
      statsData[key].generating = false
    })
    return res.status(500).json({ success: false, description: 'An unexpected error occurred. Try again?' })
  }
}

module.exports = self