Refactor Bolus recommendation code (#708)

* Refactor Bolus Recommendation

Make Bolus recommendation part of Loop update and don't allow
external calls to it.  The data doesn't change in any case and
update() is called in all places where we want a Bolus
recommendation.

This is in preparation of automated Bolus code, which needs
consistent Bolus and Basal data.

* Remove recommendBolus function from LoopState

The recommendedBolus variable contains the same information.

Loop/Managers/LoopDataManager.swift

@@ -293,7 +293,7 @@ final class LoopDataManager {
                     do {
                         try self.update()
 
-                        completion(.success(try self.recommendBolus()))
+                        completion(.success(self.recommendedBolus?.recommendation))
                     } catch let error {
                         completion(.failure(error))
                     }
@@ -580,7 +580,7 @@ final class LoopDataManager {
 
         if predictedGlucose == nil {
             do {
-                try updatePredictedGlucoseAndRecommendedBasal()
+                try updatePredictedGlucoseAndRecommendedBasalAndBolus()
             } catch let error {
                 logger.error(error)
 
@@ -719,6 +719,7 @@ final class LoopDataManager {
     fileprivate var predictedGlucose: [GlucoseValue]? {
         didSet {
             recommendedTempBasal = nil
+            recommendedBolus = nil
         }
     }
     fileprivate var retrospectivePredictedGlucose: [GlucoseValue]? {
@@ -728,6 +729,8 @@ final class LoopDataManager {
     }
     fileprivate var recommendedTempBasal: (recommendation: TempBasalRecommendation, date: Date)?
 
+    fileprivate var recommendedBolus: (recommendation: BolusRecommendation, date: Date)?
+
     fileprivate var carbsOnBoard: CarbValue?
 
     fileprivate var lastTempBasal: DoseEntry?
@@ -843,7 +846,7 @@ final class LoopDataManager {
     ///     - LoopError.glucoseTooOld
     ///     - LoopError.missingDataError
     ///     - LoopError.pumpDataTooOld
-    private func updatePredictedGlucoseAndRecommendedBasal() throws {
+    private func updatePredictedGlucoseAndRecommendedBasalAndBolus() throws {
         dispatchPrecondition(condition: .onQueue(dataAccessQueue))
 
         guard let glucose = glucoseStore.latestGlucose else {
@@ -881,14 +884,25 @@ final class LoopDataManager {
             let glucoseTargetRange = settings.glucoseTargetRangeSchedule,
             let insulinSensitivity = insulinSensitivitySchedule,
             let basalRates = basalRateSchedule,
+            let maxBolus = settings.maximumBolus,
             let model = insulinModelSettings?.model
         else {
             throw LoopError.configurationError("Check settings")
         }
+
+        let pendingInsulin = try self.getPendingInsulin()
 
-        guard
-            lastRequestedBolus == nil,  // Don't recommend changes if a bolus was just set
-            let tempBasal = predictedGlucose.recommendedTempBasal(
+        guard lastRequestedBolus == nil
+        else {
+            // Don't recommend changes if a bolus was just requested.
+            // Sending additional pump commands is not going to be
+            // successful in any case.
+            recommendedBolus = nil
+            recommendedTempBasal = nil
+            return
+        }
+
+        let tempBasal = predictedGlucose.recommendedTempBasal(
                 to: glucoseTargetRange,
                 suspendThreshold: settings.suspendThreshold?.quantity,
                 sensitivity: insulinSensitivity,
@@ -897,42 +911,13 @@ final class LoopDataManager {
                 maxBasalRate: maxBasal,
                 lastTempBasal: lastTempBasal
             )
-        else {
+
+        if let temp = tempBasal {
+            recommendedTempBasal = (recommendation: temp, date: startDate)
+        } else {
             recommendedTempBasal = nil
-            return
-        }
-
-        recommendedTempBasal = (recommendation: tempBasal, date: Date())
-    }
-
-    /// - Returns: A bolus recommendation from the current data
-    /// - Throws: 
-    ///     - LoopError.configurationError
-    ///     - LoopError.glucoseTooOld
-    ///     - LoopError.missingDataError
-    fileprivate func recommendBolus() throws -> BolusRecommendation {
-        dispatchPrecondition(condition: .onQueue(dataAccessQueue))
-
-        guard
-            let predictedGlucose = predictedGlucose,
-            let maxBolus = settings.maximumBolus,
-            let glucoseTargetRange = settings.glucoseTargetRangeSchedule,
-            let insulinSensitivity = insulinSensitivitySchedule,
-            let model = insulinModelSettings?.model
-        else {
-            throw LoopError.configurationError("Check Settings")
-        }
-
-        guard let glucoseDate = predictedGlucose.first?.startDate else {
-            throw LoopError.missingDataError(details: "No glucose data found", recovery: "Check your CGM source")
         }
-
-        guard abs(glucoseDate.timeIntervalSinceNow) <= recencyInterval else {
-            throw LoopError.glucoseTooOld(date: glucoseDate)
-        }
-
-        let pendingInsulin = try self.getPendingInsulin()
-
+
         let recommendation = predictedGlucose.recommendedBolus(
             to: glucoseTargetRange,
             suspendThreshold: settings.suspendThreshold?.quantity,
@@ -941,8 +926,7 @@ final class LoopDataManager {
             pendingInsulin: pendingInsulin,
             maxBolus: maxBolus
         )
-
-        return recommendation
+        recommendedBolus = (recommendation: recommendation, date: startDate)
     }
 
     /// *This method should only be called from the `dataAccessQueue`*
@@ -999,6 +983,8 @@ protocol LoopState {
     /// The recommended temp basal based on predicted glucose
     var recommendedTempBasal: (recommendation: TempBasalRecommendation, date: Date)? { get }
 
+    var recommendedBolus: (recommendation: BolusRecommendation, date: Date)? { get }
+
     /// The retrospective prediction over a recent period of glucose samples
     var retrospectivePredictedGlucose: [GlucoseValue]? { get }
 
@@ -1010,15 +996,6 @@ protocol LoopState {
     /// - Returns: An timeline of predicted glucose values
     /// - Throws: LoopError.missingDataError if prediction cannot be computed
     func predictGlucose(using inputs: PredictionInputEffect) throws -> [GlucoseValue]
-
-    /// Calculates a recommended bolus based on predicted glucose
-    ///
-    /// - Returns: A bolus recommendation
-    /// - Throws: An error describing why a bolus couldnʼt be computed
-    ///     - LoopError.configurationError
-    ///     - LoopError.glucoseTooOld
-    ///     - LoopError.missingDataError
-    func recommendBolus() throws -> BolusRecommendation
 }
 
 
@@ -1066,6 +1043,11 @@ extension LoopDataManager {
             dispatchPrecondition(condition: .onQueue(loopDataManager.dataAccessQueue))
             return loopDataManager.recommendedTempBasal
         }
+
+        var recommendedBolus: (recommendation: BolusRecommendation, date: Date)? {
+            dispatchPrecondition(condition: .onQueue(loopDataManager.dataAccessQueue))
+            return loopDataManager.recommendedBolus
+        }
 
         var retrospectivePredictedGlucose: [GlucoseValue]? {
             dispatchPrecondition(condition: .onQueue(loopDataManager.dataAccessQueue))
@@ -1075,10 +1057,6 @@ extension LoopDataManager {
         func predictGlucose(using inputs: PredictionInputEffect) throws -> [GlucoseValue] {
             return try loopDataManager.predictGlucose(using: inputs)
         }
-
-        func recommendBolus() throws -> BolusRecommendation {
-            return try loopDataManager.recommendBolus()
-        }
     }
 
     /// Executes a closure with access to the current state of the loop.
@@ -1120,6 +1098,7 @@ extension LoopDataManager {
                 "predictedGlucose: \(state.predictedGlucose ?? [])",
                 "retrospectivePredictedGlucose: \(state.retrospectivePredictedGlucose ?? [])",
                 "recommendedTempBasal: \(String(describing: state.recommendedTempBasal))",
+                "recommendedBolus: \(String(describing: state.recommendedBolus))",
                 "lastBolus: \(String(describing: manager.lastRequestedBolus))",
                 "lastGlucoseChange: \(String(describing: manager.lastGlucoseChange))",
                 "retrospectiveGlucoseChange: \(String(describing: manager.retrospectiveGlucoseChange))",

Loop/Managers/NightscoutDataManager.swift

@@ -43,15 +43,7 @@ final class NightscoutDataManager {
             var loopError = state.error
             let recommendedBolus: Double?
 
-            do {
-                recommendedBolus = try state.recommendBolus().amount
-            } catch let error {
-                recommendedBolus = nil
-
-                if loopError == nil {
-                    loopError = error
-                }
-            }
+            recommendedBolus = state.recommendedBolus?.recommendation.amount
 
             let carbsOnBoard = state.carbsOnBoard
             let predictedGlucose = state.predictedGlucose

Loop/Managers/WatchDataManager.swift

@@ -125,7 +125,7 @@ final class WatchDataManager: NSObject, WCSessionDelegate {
                 context.reservoir = reservoir?.unitVolume
 
                 context.loopLastRunDate = state.lastLoopCompleted
-                context.recommendedBolusDose = try? state.recommendBolus().amount
+                context.recommendedBolusDose = state.recommendedBolus?.recommendation.amount
                 context.maxBolus = manager.settings.maximumBolus
 
                 if let glucoseTargetRangeSchedule = manager.settings.glucoseTargetRangeSchedule {

Loop/View Controllers/BolusViewController+LoopDataManager.swift

@@ -20,7 +20,7 @@ extension BolusViewController {
             if let recommendation = recommendation {
                 bolusRecommendation = recommendation
             } else {
-                bolusRecommendation = try? state.recommendBolus()
+                bolusRecommendation = state.recommendedBolus?.recommendation
             }
 
             manager.doseStore.insulinOnBoard(at: Date()) { (result) in