perf: adds cache to reduce api requests

Fixes #16, resolves #5

.gitignore

@@ -1 +1,2 @@
 dist
+.track.json

package.json

@@ -24,6 +24,7 @@
     "@semantic-release/release-notes-generator": "^7.3.5",
     "@types/chalk": "^2.2.0",
     "@types/date-fns": "^2.6.0",
+    "@types/fs-extra": "^8.0.1",
     "@types/hapi__joi": "^16.0.3",
     "@types/jest": "^24.0.22",
     "@types/node": "^12.12.14",
@@ -46,6 +47,7 @@
     "@sentry/node": "^5.9.0",
     "axios": "^0.19.0",
     "chalk": "^2.4.2",
-    "date-fns": "^2.8.1"
+    "date-fns": "^2.8.1",
+    "fs-extra": "^8.1.0"
   }
 }

readme.md

@@ -55,7 +55,7 @@ Variable | Default | Description
 `ACTIVE_HOURS_END` | `18` | The hour of the day to stop updating your Slack status
 `UPDATE_INTERVAL` | `1` | The time in minutes to wait until updating your Slack Status
 `UPDATE_WEEKENDS` | `undefined` | Provide any value to enable status updates during the weekend
-`UPDATE_EXPIRATION` | `15` | The time in minutes to use as a default status expiration length
+`UPDATE_EXPIRATION` | `10` | The time in minutes to use as a default status expiration length
 `SENTRY_DSN` | `undefined` | Optionally provide a Sentry DSN to enable error reporting
 
 ## Hosting

src/config.ts

@@ -9,6 +9,7 @@ const {
   ACTIVE_HOURS_START = '8',
   ACTIVE_HOURS_END = '18',
   UPDATE_INTERVAL = '1',
+  UPDATE_EXPIRATION = '10',
   UPDATE_WEEKENDS,
   SENTRY_DSN
 } = process.env
@@ -38,4 +39,7 @@ export const sentryDsn = SENTRY_DSN
 export const updateInterval = Number(UPDATE_INTERVAL)
 export const updateWeekends = !!UPDATE_WEEKENDS
 
+/** Time in minutes to use as a default expiration time */
+export const updateExpiration = Number(UPDATE_EXPIRATION)
+
 export const tz = TZ

src/index.ts

@@ -9,38 +9,57 @@ import {
 import {
   getLastFmTrack,
   getNowPlaying,
-  getRecentLastFmTracks
+  getRecentLastFmTracks,
+  trackIsEqual
 } from './utils/lastFm'
+import {
+  deleteTrackJSON,
+  readTrackJSON,
+  writeTrackJSON
+} from './utils/cache'
 import { handleError, enableErrorTracking } from './utils/errors'
 import { log } from './utils/log'
 import { validateConfig } from './utils/validation'
 
+/** Clears the slack status if the cached track has no duration */
+async function clearSlackStatus (cached: LastFM.Track | undefined) {
+  if (cached && cached.duration === '0') {
+    log('Cached track has no duration, clearing Slack status', 'slack')
+    await setSlackStatus('')
+  }
+}
+
 async function main () {
+  const cachedTrack = await readTrackJSON()
+
   // Time restrictions
   const currentTime = getTime(new Date())
   const currentHour = getHours(currentTime)
 
   const { start, end } = config.activeHours
   if (currentHour < start || currentHour >= end) {
-    log(`Outside active hours (${start}-${end}), skipping`)
+    log(`Outside active hours (${start}-${end})`)
+    await clearSlackStatus(cachedTrack)
     return
   }
 
   if (!config.updateWeekends && isWeekend(currentTime)) {
     log('Weekend updates not enabled, skipping')
+    await clearSlackStatus(cachedTrack)
     return
   }
 
   // Status restrictions
   const currentPresence = await getSlackPresence()
   if (currentPresence === 'away') {
-    log('User presence is "away", skipping')
+    log('User presence is "away"')
+    await clearSlackStatus(cachedTrack)
     return
   }
 
   const currentProfile = await getSlackProfile()
   if (!shouldSetStatus(currentProfile)) {
-    log('Custom status detected, skipping')
+    log('Custom status detected')
     return
   }
 
@@ -49,23 +68,34 @@ async function main () {
   const nowPlaying = getNowPlaying(recentTracks.track)
 
   if (nowPlaying === undefined) {
-    log('Nothing playing, skipping')
+    log('Nothing playing')
+    await clearSlackStatus(cachedTrack)
+    await deleteTrackJSON()
+    return
+  }
+
+  // Equality restriction, don't update if it's not necessary
+  if (trackIsEqual(nowPlaying, cachedTrack)) {
+    log('Now playing track is cached, no update necessary')
     return
   }
 
   const track = await getLastFmTrack(nowPlaying.name, nowPlaying.artist['#text'])
+  let duration = 60 * (config.updateExpiration * 1000)
+  let status = `${nowPlaying.name} ${config.slack.separator} ${nowPlaying.artist['#text']}`
 
   if (track !== undefined) {
-    const status = `${track.name} ${config.slack.separator} ${track.artist.name}`
-    log(`Setting status to "${status}"`, 'slack')
-    await setSlackStatus(status, Number(track.duration))
-    return
+    await writeTrackJSON(track)
+
+    status = `${track.name} ${config.slack.separator} ${track.artist.name}`
+    duration = track.duration !== '0' ? Number(track.duration) : duration
+  } else {
+    log('No detailed track info found, falling back to recent track', 'lastfm')
+    await deleteTrackJSON()
   }
 
-  log('Unable to find detailed track info, falling back to recent track', 'lastfm')
-  const status = `${nowPlaying.name} ${config.slack.separator} ${nowPlaying.artist['#text']}`
   log(`Setting status to "${status}"`, 'slack')
-  await setSlackStatus(status)
+  await setSlackStatus(status, duration)
 }
 
 async function loop () {

src/utils/cache.ts

@@ -0,0 +1,27 @@
+import * as path from 'path'
+import * as fs from 'fs-extra'
+
+const cachePath = path.join('.', '.track.json')
+
+export async function writeTrackJSON (obj?: LastFM.Track) {
+  if (obj === undefined) return undefined
+  return fs.writeJSON(cachePath, obj)
+}
+
+export async function readTrackJSON (): Promise<LastFM.Track | undefined> {
+  try {
+    const track: LastFM.Track = await fs.readJSON(cachePath)
+    return track
+  } catch (error) {
+    // this is fine, I promise
+    return undefined
+  }
+}
+
+export async function deleteTrackJSON () {
+  try {
+    await fs.remove(cachePath)
+  } catch (error) {
+    // this is okay
+  }
+}

src/utils/lastFm.ts

@@ -63,3 +63,9 @@ export async function getLastFmTrack (track: string, artist: string): Promise<La
 export function getNowPlaying (tracks: LastFM.RecentTrack[]) {
   return tracks.find(track => track['@attr']?.nowplaying === 'true')
 }
+
+/** Determines if the recent track is equal to the cached track */
+export function trackIsEqual (recent: LastFM.RecentTrack, cached?: LastFM.Track) {
+  if (cached === undefined) return false
+  return recent.name === cached.name && recent.artist['#text'] === cached.artist.name
+}

src/utils/slack.ts

@@ -18,7 +18,7 @@ export function calcExpiration (duration: number) {
  * [API Doc](https://api.slack.com/methods/users.profile.set)
  *
  * @param status The status text to set
- * @param duration The time in seconds to keep the state
+ * @param duration The time in milliseconds to keep the state
  *
  */
 export async function setSlackStatus (status: string, duration?: number) {
@@ -29,7 +29,7 @@ export async function setSlackStatus (status: string, duration?: number) {
     profile: {
       status_text: status,
       status_emoji: status !== '' ? config.slack.emoji : '',
-      status_expiration: duration ? calcExpiration(duration) : 0
+      status_expiration: duration !== undefined ? calcExpiration(duration) : 0
     }
   }