7th day timezone hotfix (#327)

backend/dependencies/nodejs/models/pacific_power_recent.js

@@ -2,26 +2,49 @@ const DB = require('/opt/nodejs/sql-access.js')
 
 class PacificPowerRecent {
   async get() {
-    // Get Unix TimeStamp for 11:59:59 PM GMT of 7 days ago
     await DB.connect()
-    const currentDate = new Date()
-    const date = new Date(currentDate)
-    date.setUTCHours(0)
-    date.setUTCMinutes(0)
-    date.setUTCSeconds(0)
-    date.setUTCMilliseconds(0)
-    const endTimestamp = Math.floor(date.getTime() / 1000) // End of today in seconds
 
-    date.setDate(date.getDate() - 7)
-    const startTimestamp = Math.floor(date.getTime() / 1000) // 7 days ago in seconds
+    // see automated-jobs/SEC/readSEC.js for original function
+    // Automatically detects the timezone difference of US Pacific vs GMT-0 (7 or 8 depending on daylight savings)
+    // https://stackoverflow.com/questions/20712419/get-utc-offset-from-timezone-in-javascript
+    const getOffset = timeZone => {
+      const timeZoneName = Intl.DateTimeFormat('ia', {
+        timeZoneName: 'shortOffset',
+        timeZone
+      })
+        .formatToParts()
+        .find(i => i.type === 'timeZoneName').value
+      const offset = timeZoneName.slice(3)
+      if (!offset) return 0
+
+      const matchData = offset.match(/([+-])(\d+)(?::(\d+))?/)
+      if (!matchData) throw `cannot parse timezone name: ${timeZoneName}`
+
+      const [, sign, hour, minute] = matchData
+      let result = parseInt(hour) * 60
+      if (sign === '+') result *= -1
+      if (minute) result += parseInt(minute)
+
+      return result
+    }
+
+    // Get Unix TimeStamp for 11:59:59 PM GMT of 7 days ago
+    const dateObjUnix = new Date(
+      // (days * hours * minutes * seconds * ms)
+      new Date().getTime() - (7 * 24 * 60 * 60 * 1000 + getOffset('US/Pacific') * 60 * 1000)
+    )
+
+    dateObjUnix.setUTCHours(23, 59, 59, 0)
+
+    const timestamp7DaysAgo = Math.floor(dateObjUnix.getTime() / 1000) // Convert milliseconds to seconds
 
     return DB.query(
       `SELECT MAX(time) as time, MAX(time_seconds) as time_seconds, pacific_power_meter_id 
       FROM pacific_power_data
-      WHERE time_seconds >= ? AND time_seconds <= ?
+      WHERE time_seconds >= ?
       GROUP BY pacific_power_meter_id, DATE(FROM_UNIXTIME(time_seconds))
       ORDER BY pacific_power_meter_id, time_seconds ASC;`,
-      [startTimestamp, endTimestamp]
+      [timestamp7DaysAgo]
     )
   }
 }