LRT Escalator & Elevator Outages specific controller

src/controllers/lrt-escalator-outages.js

@@ -0,0 +1,135 @@
+const request = require('request-promise-native')
+const uuid = require('uuid/v4')
+
+/**
+ * LRT Escalator & Elevator Outages
+ */
+module.exports = async function(req, res) {
+  console.log('LRT Escalator & Elevator Outages Controller')
+  let key = 'lrt-escalator-outages' // Unique key for dataset storage
+  let url = 'https://data.edmonton.ca/resource/snws-u3zx.json' // The Socrata api endpoint
+  let queryBase = `${url}?$query=`
+
+  let storedData = await req.cache.getLatest(key)
+  let storedTimestamp
+  let filteredStoredColumnValues // The stored/previous column values to be compared to
+  if (storedData) {
+    storedTimestamp = storedData.created_at
+    filteredStoredColumnValues = JSON.parse(storedData.outages).map(device => {
+      return device.device_id
+    })
+  } else {
+    storedTimestamp = '1998-07-25T00:00:00.000Z' // This value is random
+  }
+
+  // Get all the columns (filter it by column later)
+  let getLatestUpdatedQuery = `${queryBase}SELECT lrt_station_name, device_id, lrt_device_location, device_type WHERE :updated_at >= '${storedTimestamp}' ORDER BY :updated_at DESC`
+  let getUpdatedTimestamp = `${queryBase}SELECT :updated_at ORDER BY :updated_at LIMIT 1`
+  let latestTimestamp
+  let latestColumnRows
+  let filteredLatestColumnValues // The current values of the column being monitored
+  try {
+    let rawJsonUpdatedAt = await request(getUpdatedTimestamp)
+    latestTimestamp = JSON.parse(rawJsonUpdatedAt)[0][':updated_at']
+    let rawJsonColumnValues = await request(getLatestUpdatedQuery)
+    latestColumnRows = JSON.parse(rawJsonColumnValues)
+    filteredLatestColumnValues = latestColumnRows.map(row => {
+      return row['device_id']
+    })
+  } catch (e) {
+    e.code = 500
+    throw e
+  }
+  // Ensure that the date is in ISO 8601 time format
+  latestTimestamp = timestampFormat(latestTimestamp)
+
+  let responseValues
+  if (
+    storedData &&
+    compareArr(filteredStoredColumnValues, filteredLatestColumnValues)
+  ) {
+    console.log('Row values not changed. Returning old data')
+    responseValues = await req.cache.getAll(key, req.body['limit'])
+  } else {
+    console.log('Adding new rows')
+    let id = uuid()
+    // The unique difference (does not catch repeat values)
+    let fixed = arrDiffFixed(storedData, filteredLatestColumnValues)
+    let newRows = {
+      id,
+      created_at: latestTimestamp,
+      outages: JSON.stringify(latestColumnRows),
+      fixed: JSON.stringify(fixed),
+      meta: {
+        id,
+        timestamp: Math.round(new Date() / 1000)
+      }
+    }
+    req.cache.add(key, newRows)
+    responseValues = await req.cache.getAll(key, req.body['limit'])
+  }
+
+  res.status(200).send({
+    data: responseValues
+  })
+}
+
+/**
+ * Compares the elements of two arrays and returns TRUE arrays are same or FALSE
+ * if they are different
+ * @param {Array<String|Number>} arr1 The first array to compare
+ * @param {Array<String|Number>} arr2 The second array to compare
+ * @return {Boolean} Returns TRUE if the arrays are the same or FALSE otherwise
+ */
+function compareArr(arr1, arr2) {
+  arr1.sort()
+  arr2.sort()
+  let length
+  if (arr1.length !== arr2.length) {
+    return false
+  } else {
+    length = arr1.length
+  }
+  for (let i = 0; i < length; i++) {
+    if (arr1[i] !== arr2[i]) {
+      return false
+    }
+  }
+  return true
+}
+
+/**
+ * Returns an array of JSON objects of devices that are no longer in the dataset
+ * (devices that are fixed). The IDs that were stored that are no longer in 'latestDeviceIds'
+ * @param {Object} storedData The JSON object that is stored in the Redis cache
+ * @param {Array<String>} latestDeviceIds An array of device IDs representing
+ * escalator/elevator outages
+ */
+function arrDiffFixed(storedData, latestDeviceIds) {
+  let fixed = []
+  if (!storedData) return fixed
+  if (!latestDeviceIds) return stored
+  for (let element of JSON.parse(storedData.outages)) {
+    if (latestDeviceIds.indexOf(element.device_id) == -1) {
+      fixed.push(element)
+    }
+  }
+  return fixed
+}
+
+/**
+ * Converts timestamps to correctly formatted ISO 8601 time (currently only checks for epoch time)
+ * @param {String|Number} timestamp The timestamp to convert
+ * @return {String} The ISO 8601 formatted timestamp string
+ */
+function timestampFormat(timestamp) {
+  if (
+    !timestamp
+      .toString()
+      .match(/[0-9]{4}-[0-9]{2}-[0-9]{2}T[0-9]{2}:[0-9]{2}:[0-9]{2}.[0-9]{3}Z/)
+  ) {
+    // Convert Epoch times to ISO 8601 time format
+    return new Date(timestamp * 1000).toISOString()
+  }
+  return timestamp
+}

src/server.js

@@ -37,6 +37,7 @@ const createAirQualityController = require('./controllers/aqhi-base')
 const status = require('./controllers/status')
 const test = require('./controllers/test-setup')
 const airQualityStations = require('./controllers/air-quality-stations')
+const lrtEscalatorOutages = require('./controllers/lrt-escalator-outages')
 
 // Middleware
 const logger = require('./middleware/logger')
@@ -72,6 +73,8 @@ let edmontonAirHealthIndex = createAirQualityController(req => {
   }
 })
 
+router.post('/triggers/lrt_escalator_outages', lrtEscalatorOutages)
+
 router.post('/triggers/light_the_bridge', lightTheBridge)
 
 // We split the route here to allow for upgrading the API with 0 downtime.