# EnergyKit Extended Patterns

Overflow reference for the `energykit` skill. Contains advanced patterns
that exceed the main skill file's scope.

## Contents

- [Full App Architecture](#full-app-architecture)
- [EV Charging Session Manager](#ev-charging-session-manager)
- [HVAC Control Manager](#hvac-control-manager)
- [SwiftUI Energy Dashboard](#swiftui-energy-dashboard)
- [Insight Data Visualization](#insight-data-visualization)
- [Error Handling Strategies](#error-handling-strategies)
- [Venue Discovery Flow](#venue-discovery-flow)

## Full App Architecture

An `@Observable` manager that ties together guidance, venues, and load events.

```swift
import EnergyKit
import SwiftUI

@Observable
@MainActor
final class EnergyManager {
    var venues: [EnergyVenue] = []
    var selectedVenue: EnergyVenue?
    var currentGuidance: ElectricityGuidance?
    var guidanceValues: [ElectricityGuidance.Value] = []
    var isLoading = false
    var errorMessage: String?

    private var guidanceTask: Task<Void, Never>?

    func loadVenues() async {
        isLoading = true
        errorMessage = nil

        do {
            venues = try await EnergyVenue.venues()
            selectedVenue = venues.first
            if let venue = selectedVenue {
                startObservingGuidance(for: venue.id)
            }
        } catch let error as EnergyKitError {
            errorMessage = handleError(error)
        } catch {
            errorMessage = error.localizedDescription
        }

        isLoading = false
    }

    func startObservingGuidance(for venueID: UUID) {
        guidanceTask?.cancel()
        guidanceTask = Task { [weak self] in
            let query = ElectricityGuidance.Query(suggestedAction: .shift)
            let service = ElectricityGuidance.sharedService

            do {
                for try await guidance in service.guidance(using: query, at: venueID) {
                    await MainActor.run {
                        self?.currentGuidance = guidance
                        self?.guidanceValues = guidance.values
                    }
                }
            } catch {
                await MainActor.run {
                    self?.errorMessage = error.localizedDescription
                }
            }
        }
    }

    func stopObserving() {
        guidanceTask?.cancel()
        guidanceTask = nil
    }

    var bestWindow: ElectricityGuidance.Value? {
        guidanceValues.min(by: { $0.rating < $1.rating })
    }

    var hasRatePlan: Bool {
        currentGuidance?.options.contains(.locationHasRatePlan) ?? false
    }

    var usesRatePlan: Bool {
        currentGuidance?.options.contains(.guidanceIncorporatesRatePlan) ?? false
    }

    // EnergyKitError cases -- verify against Xcode 26 SDK
    private func handleError(_ error: EnergyKitError) -> String {
        switch error {
        case .unsupportedRegion:
            return "Energy guidance is not available in your region."
        case .guidanceUnavailable:
            return "Grid guidance data is currently unavailable."
        case .venueUnavailable:
            return "No energy venue found. Set up your home in the Home app."
        case .permissionDenied:
            return "Permission to access energy data was denied."
        case .serviceUnavailable:
            return "The energy service is temporarily unavailable."
        case .rateLimitExceeded:
            return "Too many requests. Please try again later."
        case .invalidLoadEvent:
            return "The load event data was invalid."
        case .inProgress:
            return "A request is already in progress."
        case .locationServicesDenied:
            return "Location services are required for energy guidance."
        @unknown default:
            return "An unknown error occurred."
        }
    }
}
```

## EV Charging Session Manager

Manage the full lifecycle of an EV charging session with guidance tracking.

```swift
import EnergyKit

@Observable
@MainActor
final class EVChargingManager {
    var isCharging = false
    var currentSessionID: UUID?
    var stateOfCharge: Int = 0
    var currentPower: Double = 0  // kW
    var totalEnergy: Double = 0   // kWh

    private let deviceID: String
    private var venue: EnergyVenue?
    private var guidanceToken: UUID?

    init(deviceID: String) {
        self.deviceID = deviceID
    }

    func setVenue(_ venue: EnergyVenue) {
        self.venue = venue
    }

    func setGuidanceToken(_ token: UUID) {
        self.guidanceToken = token
    }

    func startCharging(stateOfCharge: Int) async throws {
        guard let venue else { throw EVError.noVenue }

        let sessionID = UUID()
        currentSessionID = sessionID
        self.stateOfCharge = stateOfCharge
        isCharging = true

        let event = makeEvent(
            sessionState: .begin,
            stateOfCharge: stateOfCharge,
            power: 0,
            energy: 0
        )
        try await venue.submitEvents([event])
    }

    func updateCharging(
        stateOfCharge: Int,
        power: Double,
        energy: Double
    ) async throws {
        guard let venue, isCharging else { return }

        self.stateOfCharge = stateOfCharge
        self.currentPower = power
        self.totalEnergy = energy

        let event = makeEvent(
            sessionState: .active,
            stateOfCharge: stateOfCharge,
            power: power,
            energy: energy
        )
        try await venue.submitEvents([event])
    }

    func stopCharging() async throws {
        guard let venue, isCharging else { return }

        let event = makeEvent(
            sessionState: .end,
            stateOfCharge: stateOfCharge,
            power: 0,
            energy: totalEnergy
        )
        try await venue.submitEvents([event])

        isCharging = false
        currentSessionID = nil
    }

    private func makeEvent(
        sessionState: ElectricVehicleLoadEvent.Session.State,
        stateOfCharge: Int,
        power: Double,
        energy: Double
    ) -> ElectricVehicleLoadEvent {
        let guidanceState = ElectricVehicleLoadEvent.Session.GuidanceState(
            wasFollowingGuidance: guidanceToken != nil,
            guidanceToken: guidanceToken ?? UUID()
        )

        let session = ElectricVehicleLoadEvent.Session(
            id: currentSessionID ?? UUID(),
            state: sessionState,
            guidanceState: guidanceState
        )

        let measurement = ElectricVehicleLoadEvent.ElectricalMeasurement(
            stateOfCharge: stateOfCharge,
            direction: .imported,
            power: Measurement(value: power, unit: .kilowatts),
            energy: Measurement(value: energy, unit: .kilowattHours)
        )

        return ElectricVehicleLoadEvent(
            timestamp: Date(),
            measurement: measurement,
            session: session,
            deviceID: deviceID
        )
    }

    enum EVError: Error {
        case noVenue
    }
}
```

## HVAC Control Manager

Track HVAC load events with guidance compliance.

```swift
import EnergyKit

@Observable
@MainActor
final class HVACManager {
    var isRunning = false
    var currentStage: Int = 0
    var sessionID: UUID?

    private let deviceID: String
    private var venue: EnergyVenue?
    private var guidanceToken: UUID?

    init(deviceID: String) {
        self.deviceID = deviceID
    }

    func configure(venue: EnergyVenue, guidanceToken: UUID?) {
        self.venue = venue
        self.guidanceToken = guidanceToken
    }

    func start(stage: Int) async throws {
        guard let venue else { return }
        sessionID = UUID()
        currentStage = stage
        isRunning = true

        let event = makeEvent(state: .begin, stage: stage)
        try await venue.submitEvents([event])
    }

    func updateStage(_ stage: Int) async throws {
        guard let venue, isRunning else { return }
        currentStage = stage

        let event = makeEvent(state: .active, stage: stage)
        try await venue.submitEvents([event])
    }

    func stop() async throws {
        guard let venue, isRunning else { return }

        let event = makeEvent(state: .end, stage: 0)
        try await venue.submitEvents([event])

        isRunning = false
        sessionID = nil
    }

    private func makeEvent(
        state: ElectricHVACLoadEvent.Session.State,
        stage: Int
    ) -> ElectricHVACLoadEvent {
        let guidanceState = ElectricHVACLoadEvent.Session.GuidanceState(
            wasFollowingGuidance: guidanceToken != nil,
            guidanceToken: guidanceToken ?? UUID()
        )

        let session = ElectricHVACLoadEvent.Session(
            id: sessionID ?? UUID(),
            state: state,
            guidanceState: guidanceState
        )

        let measurement = ElectricHVACLoadEvent.ElectricalMeasurement(stage: stage)

        return ElectricHVACLoadEvent(
            timestamp: Date(),
            measurement: measurement,
            session: session,
            deviceID: deviceID
        )
    }
}
```

## SwiftUI Energy Dashboard

A complete dashboard view showing guidance and insights.

```swift
import SwiftUI
import EnergyKit

struct EnergyDashboardView: View {
    @Environment(EnergyManager.self) private var energyManager

    var body: some View {
        NavigationStack {
            Group {
                if energyManager.isLoading {
                    ProgressView("Loading energy data...")
                } else if let error = energyManager.errorMessage {
                    ContentUnavailableView(
                        "Energy Guidance Unavailable",
                        systemImage: "bolt.slash",
                        description: Text(error)
                    )
                } else {
                    dashboardContent
                }
            }
            .navigationTitle("Energy")
            .task {
                await energyManager.loadVenues()
            }
        }
    }

    private var dashboardContent: some View {
        List {
            if let venue = energyManager.selectedVenue {
                Section("Venue") {
                    LabeledContent("Name", value: venue.name)
                }
            }

            if let best = energyManager.bestWindow {
                Section("Best Time") {
                    VStack(alignment: .leading) {
                        Text("Optimal usage window")
                            .font(.headline)
                        Text(best.interval.start, style: .time)
                        + Text(" - ")
                        + Text(best.interval.end, style: .time)
                        Text("Rating: \(best.rating, specifier: "%.2f")")
                            .foregroundStyle(.secondary)
                    }
                }
            }

            if !energyManager.guidanceValues.isEmpty {
                Section("Timeline") {
                    ForEach(energyManager.guidanceValues, id: \.interval.start) { value in
                        HStack {
                            VStack(alignment: .leading) {
                                Text(value.interval.start, style: .time)
                                Text(value.interval.end, style: .time)
                                    .font(.caption)
                                    .foregroundStyle(.secondary)
                            }
                            Spacer()
                            guidanceRatingView(value.rating)
                        }
                    }
                }
            }

            if energyManager.hasRatePlan {
                Section("Rate Plan") {
                    Label(
                        energyManager.usesRatePlan
                            ? "Guidance incorporates your rate plan"
                            : "Rate plan available but not yet incorporated",
                        systemImage: "dollarsign.circle"
                    )
                }
            }
        }
    }

    private func guidanceRatingView(_ rating: Double) -> some View {
        let color: Color = rating <= 0.3 ? .green : rating <= 0.6 ? .yellow : .red
        let label = rating <= 0.3 ? "Good" : rating <= 0.6 ? "Fair" : "Avoid"

        return Text(label)
            .font(.caption)
            .fontWeight(.medium)
            .padding(.horizontal, 8)
            .padding(.vertical, 4)
            .background(color.opacity(0.15))
            .foregroundStyle(color)
            .clipShape(Capsule())
    }
}
```

## Insight Data Visualization

Prepare insight records for chart display.

```swift
struct InsightDataPoint: Identifiable {
    let id = UUID()
    let date: Date
    let energy: Double  // kWh
    let cleanerEnergy: Double?
    let lessCleanEnergy: Double?
}

func processInsightRecords(
    _ records: [ElectricityInsightRecord<Measurement<UnitEnergy>>]
) -> [InsightDataPoint] {
    records.compactMap { record in
        guard let total = record.totalEnergy else { return nil }

        return InsightDataPoint(
            date: record.range.start,
            energy: total.converted(to: .kilowattHours).value,
            cleanerEnergy: record.dataByGridCleanliness?.cleaner?
                .converted(to: .kilowattHours).value,
            lessCleanEnergy: record.dataByGridCleanliness?.lessClean?
                .converted(to: .kilowattHours).value
        )
    }
}
```

## Error Handling Strategies

Comprehensive error handling with retry logic.

```swift
@Observable
@MainActor
final class ResilientEnergyService {
    private var retryCount = 0
    private let maxRetries = 3

    func fetchGuidanceWithRetry(venueID: UUID) async throws -> ElectricityGuidance? {
        let query = ElectricityGuidance.Query(suggestedAction: .shift)
        let service = ElectricityGuidance.sharedService

        while retryCount < maxRetries {
            do {
                for try await guidance in service.guidance(using: query, at: venueID) {
                    retryCount = 0
                    return guidance
                }
            } catch let error as EnergyKitError {
                switch error {
                case .serviceUnavailable, .rateLimitExceeded:
                    retryCount += 1
                    let delay = UInt64(pow(2.0, Double(retryCount))) * 1_000_000_000
                    try await Task.sleep(nanoseconds: delay)
                case .unsupportedRegion, .permissionDenied, .venueUnavailable:
                    throw error  // Do not retry permanent failures
                default:
                    throw error
                }
            }
        }

        return nil
    }
}
```

## Venue Discovery Flow

Guide users through venue setup if none exist.

```swift
import SwiftUI
import EnergyKit

struct VenueSetupView: View {
    @State private var venues: [EnergyVenue] = []
    @State private var isLoading = true
    @State private var showSetupGuide = false

    var body: some View {
        Group {
            if isLoading {
                ProgressView()
            } else if venues.isEmpty {
                ContentUnavailableView {
                    Label("No Energy Venues", systemImage: "house")
                } description: {
                    Text("Set up your home in the Home app to use energy guidance.")
                } actions: {
                    Button("Learn More") { showSetupGuide = true }
                        .buttonStyle(.borderedProminent)
                }
            } else {
                List(venues, id: \.id) { venue in
                    NavigationLink(value: venue.id) {
                        Label(venue.name, systemImage: "house.fill")
                    }
                }
            }
        }
        .task {
            do {
                venues = try await EnergyVenue.venues()
            } catch {
                venues = []
            }
            isLoading = false
        }
    }
}
```
