store 8 last points when loading data

Author: mackuba

SmogWatch WatchKit Extension/DataStore.swift

@@ -8,9 +8,15 @@
 
 import Foundation
 
-private let CurrentLevelKey = "CurrentLevel"
-private let LastMeasurementDate = "LastMeasurementDate"
-private let LastUpdateDate = "LastUpdateDate"
+private let savedPointsKey = "SavedPoints"
+private let lastUpdateDateKey = "LastUpdateDate"
+
+private let pointsCount = 8
+
+struct DataPoint {
+    let date: Date
+    let value: Double
+}
 
 class DataStore {
     let defaults = UserDefaults.standard
@@ -19,28 +25,51 @@ class DataStore {
 
     var currentLevel: Double? {
         get {
-            return defaults.object(forKey: CurrentLevelKey) as? Double
+            return points.last?.value
         }
-        set {
-            defaults.set(newValue, forKey: CurrentLevelKey)
+    }
+
+    var lastMeasurementDate: Date? {
+        get {
+            return points.last?.date
         }
     }
 
     var lastUpdateDate: Date? {
         get {
-            return defaults.object(forKey: LastUpdateDate) as? Date
+            return defaults.object(forKey: lastUpdateDateKey) as? Date
         }
         set {
-            defaults.set(newValue, forKey: LastUpdateDate)
+            defaults.set(newValue, forKey: lastUpdateDateKey)
         }
     }
 
-    var lastMeasurementDate: Date? {
+    var points: [DataPoint] {
         get {
-            return defaults.object(forKey: LastMeasurementDate) as? Date
-        }
-        set {
-            defaults.set(newValue, forKey: LastMeasurementDate)
+            guard let tuples = defaults.object(forKey: savedPointsKey) as? [[Any]] else {
+                return []
+            }
+
+            return tuples.compactMap { t in
+                if t.count == 2, let date = t[0] as? Date, let value = t[1] as? Double {
+                    return DataPoint(date: date, value: value)
+                } else {
+                    return nil
+                }
+            }
         }
     }
+
+    func addPoints(_ newPoints: [DataPoint]) {
+        var pointMap: [Date:DataPoint] = [:]
+
+        self.points.forEach { p in pointMap[p.date] = p }
+        newPoints.forEach { p in pointMap[p.date] = p }
+
+        let allPoints = pointMap.keys.sorted().map { date in pointMap[date]! }
+        let recentPoints = Array(allPoints.suffix(pointsCount))
+        let encodedData = recentPoints.map { p in [p.date, p.value ]}
+
+        defaults.set(encodedData, forKey: savedPointsKey)
+    }
 }

SmogWatch WatchKit Extension/KrakowPiosDataLoader.swift

@@ -106,12 +106,13 @@ class KrakowPiosDataLoader {
             if let data = data {
                 if let response = try? JSONDecoder().decode(Response.self, from: data) {
                     if let series = response.data.series.first {
-                        if let point = series.points.last {
-                            self.dataStore.currentLevel = point.value
-                            self.dataStore.lastMeasurementDate = point.date
+                        if let lastPoint = series.points.last {
+                            self.dataStore.addPoints(
+                                series.points.map({ DataPoint(date: $0.date, value: $0.value )})
+                            )
                             self.dataStore.lastUpdateDate = Date()
 
-                            NSLog("KrakowPiosDataLoader: saving data: %.0f at %@", point.value, "\(point.date)")
+                            NSLog("KrakowPiosDataLoader: saving data: %.0f at %@", lastPoint.value, "\(lastPoint.date)")
 
                             success = true
                         }