//

//  ChargerStandbyPowerWizardView.swift

//  USB Meter

//

//  Created by Codex on 13/04/2026.

//

import SwiftUI

struct ChargerStandbyPowerWizardView: View {

    @EnvironmentObject private var appData: AppData

    @State private var chargerLibraryVisibility = false

    @State private var discardConfirmationVisibility = false

    @State private var selectedMeterMACAddress: String?

    @State private var selectedChargerID: UUID?

    let preferredMeterMACAddress: String?

    let preferredChargerID: UUID?

    let locksChargerSelection: Bool

    init(

        preferredMeterMACAddress: String? = nil,

        preferredChargerID: UUID? = nil,

        locksChargerSelection: Bool = false

    ) {

        self.preferredMeterMACAddress = preferredMeterMACAddress

        self.preferredChargerID = preferredChargerID

        self.locksChargerSelection = locksChargerSelection

        _selectedMeterMACAddress = State(initialValue: nil)

        _selectedChargerID = State(initialValue: preferredChargerID)

    }

    var body: some View {

        ScrollView {

            VStack(spacing: 18) {

                if let session = activeSession {

                    activeMeasurementCard(session)

                    liveSessionCard(session)

                } else {

                    newMeasurementWizardCard

                }

            }

            .padding()

        }

        .background(

            LinearGradient(

                colors: [.orange.opacity(0.16), Color.clear],

                startPoint: .topLeading,

                endPoint: .bottomTrailing

            )

            .ignoresSafeArea()

        )

        .navigationTitle(navigationTitleText)

            ChargedDeviceLibrarySheetView(

                meterMACAddress: selectedMeterSummary?.macAddress ?? "",

                meterTint: selectedMeter?.color ?? .orange,

                mode: .charger

            )

            .environmentObject(appData)

        }

        .confirmationDialog(

            "Discard the current standby measurement?",

            isPresented: $discardConfirmationVisibility,

            titleVisibility: .visible

        ) {

            Button("Discard", role: .destructive) {

                if let activeSession {

                    _ = appData.finishChargerStandbyMeasurement(for: activeSession.meterMACAddress, save: false)

                }

            }

            Button("Cancel", role: .cancel) {}

        } message: {

            Text("The current sample set will be removed and nothing will be saved for this charger.")

        }

    }

    private var liveMeterSummaries: [AppData.MeterSummary] {

        appData.meterSummaries.filter { $0.meter != nil }

    }

    private var availableChargers: [ChargedDeviceSummary] {

        appData.chargerSummaries

    }

    private var preferredChargerMeterMACAddress: String? {

        preferredChargerID.flatMap { appData.chargedDeviceSummary(id: $0)?.lastAssociatedMeterMAC }

    }

    private var activeSession: ChargerStandbyPowerMonitorSession? {

        let candidateMACAddresses = [

            selectedMeterMACAddress ?? "",

            preferredMeterMACAddress ?? "",

            preferredChargerMeterMACAddress ?? ""

        ]

        .filter { $0.isEmpty == false }

        for macAddress in candidateMACAddresses {

            if let session = appData.chargerStandbyMeasurementSession(for: macAddress) {

                return session

            }

        }

        for meterSummary in liveMeterSummaries {

            if let session = appData.chargerStandbyMeasurementSession(for: meterSummary.macAddress) {

                return session

            }

        }

        return nil

    }

    private var suggestedMeterSummary: AppData.MeterSummary? {

        if let preferredMeterMACAddress {

            return liveMeterSummaries.first(where: { $0.macAddress == preferredMeterMACAddress })

        }

        if let preferredChargerMeterMACAddress {

            return liveMeterSummaries.first(where: { $0.macAddress == preferredChargerMeterMACAddress })

        }

        return liveMeterSummaries.count == 1 ? liveMeterSummaries.first : nil

    }

    private var selectedMeterSummary: AppData.MeterSummary? {

        if let activeSession {

            return liveMeterSummaries.first(where: { $0.macAddress == activeSession.meterMACAddress })

        }

        guard let selectedMeterMACAddress else {

            return nil

        }

        return liveMeterSummaries.first(where: { $0.macAddress == selectedMeterMACAddress })

    }

    private var selectedMeter: Meter? {

        selectedMeterSummary?.meter

    }

    private var isChargerSelectionLocked: Bool {

        locksChargerSelection || preferredChargerID != nil

    }

    private var meterSelectionBinding: Binding<String?> {

        Binding(

            get: { selectedMeterMACAddress },

            set: { selectedMeterMACAddress = $0 }

        )

    }

    private var selectedCharger: ChargedDeviceSummary? {

        if let activeSession {

            return appData.chargedDeviceSummary(id: activeSession.chargerID)

        }

        guard let selectedChargerID else {

            return nil

        }

        return appData.chargedDeviceSummary(id: selectedChargerID)

    }

    private var chargerSelectionBinding: Binding<UUID?> {

        Binding(

            get: { selectedChargerID },

            set: { selectedChargerID = $0 }

        )

    }

    private var preferredChargerSummary: ChargedDeviceSummary? {

        guard let preferredChargerID else {

            return nil

        }

        return appData.chargedDeviceSummary(id: preferredChargerID)

    }

    private var navigationTitleText: String {

        "New Standby Consumption Measurement"

    }

    private var wizardCardTitle: String {

        if let selectedMeterSummary {

            return selectedMeterSummary.displayName

        }

        if let suggestedMeterSummary {

            return suggestedMeterSummary.displayName

        }

        return "Use Meter"

    }

    private var newMeasurementWizardCard: some View {

        MeterInfoCardView(

            title: wizardCardTitle,

            tint: .orange

        ) {

            if liveMeterSummaries.isEmpty {

                Text("Connect a live meter first. Standby measurement uses a live feed, so meter selection happens here in the wizard.")

                    .font(.footnote)

                    .foregroundColor(.secondary)

                    .frame(maxWidth: .infinity, alignment: .leading)

            } else {

                VStack(alignment: .leading, spacing: 12) {

                    if isChargerSelectionLocked == false {

                        HStack(spacing: 8) {

                            Text("Charger")

                                .font(.subheadline.weight(.semibold))

                            ContextInfoButton(

                                title: "Charger",

                                message: "Choose the charger whose standby consumption you want to measure in this run."

                            )

                        }

                        if availableChargers.isEmpty {

                            Text("No charger available yet. Open the charger library to create one first.")

                                .font(.caption)

                                .foregroundColor(.secondary)

                        } else {

                            Picker("Charger", selection: chargerSelectionBinding) {

                                Text("Select Charger").tag(Optional<UUID>.none)

                                ForEach(availableChargers) { charger in

                                    Text(charger.name).tag(Optional(charger.id))

                                }

                            }

                            .pickerStyle(.menu)

                        }

                    }

                    HStack(spacing: 8) {

                        Text("Use Meter")

                            .font(.subheadline.weight(.semibold))

                        ContextInfoButton(

                            title: "Use Meter",

                            message: "Choose the live meter explicitly. Standby consumption can vary with the upstream source or when the charger is connected to a computer, so re-run after setup changes."

                        )

                    }

                    Picker("Use Meter", selection: meterSelectionBinding) {

                        Text("Select Meter").tag(Optional<String>.none)

                        ForEach(liveMeterSummaries) { meterSummary in

                            Text(meterSummary.displayName).tag(Optional(meterSummary.macAddress))

                        }

                    }

                    .pickerStyle(.menu)

                    .disabled(activeSession != nil)

                    if activeSession == nil, let suggestedMeterSummary, selectedMeterSummary == nil {

                        Text("Suggested from the current context: \(suggestedMeterSummary.displayName). Select it explicitly if this is the meter you want to use.")

                            .font(.caption)

                            .foregroundColor(.secondary)

                    }

                    HStack(spacing: 12) {

                        if isChargerSelectionLocked == false {

                            Button("Manage Charger Library") {

                                chargerLibraryVisibility = true

                            }

                            .disabled(selectedMeter == nil)

                        }

                        Button("Start Measurement") {

                            startMeasurement()

                        }

                        .disabled(selectedCharger == nil || selectedMeter == nil)

                    }

                    .buttonStyle(.borderedProminent)

                }

            }

            if selectedMeter == nil {

                Text("Choose the live meter explicitly before starting. The wizard no longer auto-confirms a suggested meter.")

                    .font(.caption)

                    .foregroundColor(.secondary)

            } else if activeSession == nil, selectedCharger == nil {

                Text("Select the charger you want to measure, then start the run.")

                    .font(.caption)

                    .foregroundColor(.secondary)

            } else if activeSession == nil, selectedMeter?.operationalState != .dataIsAvailable {

                Text("The wizard can start now, but samples will only be captured while live meter data is available.")

                    .font(.caption)

                    .foregroundColor(.secondary)

            } else if let activeSession {

                Text(

                    "\(activeSession.readinessDescription) • \(formattedDuration(Date().timeIntervalSince(activeSession.startedAt))) • \(activeSession.sampleCount) samples"

                )

                .font(.caption)

                .foregroundColor(.secondary)

            }

        }

    }

    private func activeMeasurementCard(_ session: ChargerStandbyPowerMonitorSession) -> some View {

        MeterInfoCardView(

            title: "Measurement Running",

            infoMessage: "The run keeps collecting samples while this meter stays live. Save when you are happy with the sample set, or discard to cancel it.",

            tint: .orange

        ) {

            MeterInfoRowView(label: "Meter", value: selectedMeterSummary?.displayName ?? session.meterMACAddress)

            MeterInfoRowView(label: "Charger", value: selectedCharger?.name ?? "Selected charger")

            MeterInfoRowView(label: "Status", value: session.readinessDescription)

            MeterInfoRowView(label: "Samples", value: "\(session.sampleCount)")

            HStack(spacing: 12) {

                Button("Save Result") {

                    _ = appData.finishChargerStandbyMeasurement(for: session.meterMACAddress, save: true)

                }

                .disabled(session.hasSamples == false)

                Button("Discard") {

                    discardConfirmationVisibility = true

                }

                .foregroundColor(.red)

            }

            .buttonStyle(.borderedProminent)

        }

    }

    private func liveSessionCard(_ session: ChargerStandbyPowerMonitorSession) -> some View {

        VStack(spacing: 18) {

            if let statistics = session.statistics {

                stabilityCard(

                    isStable: statistics.isStable,

                    averagePowerWatts: statistics.averagePowerWatts,

                    stabilityDeltaWatts: statistics.stabilityDeltaWatts,

                    stabilityToleranceWatts: statistics.stabilityToleranceWatts,

                    sampleCount: statistics.sampleCount

                )

                projectionCard(

                    averagePowerWatts: statistics.averagePowerWatts,

                    projectedDailyEnergyWh: statistics.projectedDailyEnergyWh,

                    projectedWeeklyEnergyWh: statistics.projectedWeeklyEnergyWh,

                    projectedMonthlyEnergyWh: statistics.projectedMonthlyEnergyWh,

                    projectedYearlyEnergyWh: statistics.projectedYearlyEnergyWh

                )

                    averagePowerWatts: statistics.averagePowerWatts,

                    standardDeviationPowerWatts: statistics.standardDeviationPowerWatts,

                    tint: .orange

                )

                statisticsCard(

                    averagePowerWatts: statistics.averagePowerWatts,

                    medianPowerWatts: statistics.medianPowerWatts,

                    minimumPowerWatts: statistics.minimumPowerWatts,

                    maximumPowerWatts: statistics.maximumPowerWatts,

                    standardDeviationPowerWatts: statistics.standardDeviationPowerWatts,

                    coefficientOfVariation: statistics.coefficientOfVariation,

                    averageCurrentAmps: statistics.averageCurrentAmps,

                    averageVoltageVolts: statistics.averageVoltageVolts

                )

            } else {

                MeterInfoCardView(title: "Live Stats", tint: .orange) {

                    Text("Waiting for the first valid power samples from the meter.")

                        .font(.footnote)

                        .foregroundColor(.secondary)

                }

            }

        }

    }

    private func stabilityCard(

        isStable: Bool,

        averagePowerWatts: Double,

        stabilityDeltaWatts: Double,

        stabilityToleranceWatts: Double,

        sampleCount: Int,

        subtitle: String? = nil

    ) -> some View {

        VStack(alignment: .leading, spacing: 10) {

            HStack {

                VStack(alignment: .leading, spacing: 4) {

                    Text(isStable ? "Enough Samples" : "Still Settling")

                        .font(.headline)

                    Text(subtitle ?? (isStable ? "The running average has stabilised." : "The wizard is still watching the average drift."))

                        .font(.caption)

                        .foregroundColor(.secondary)

                }

                Spacer()

                Text(isStable ? "Ready" : "Live")

                    .font(.caption.weight(.semibold))

                    .padding(.horizontal, 10)

                    .padding(.vertical, 6)

                    .foregroundColor(isStable ? .green : .orange)

                    .meterCard(

                        tint: isStable ? .green : .orange,

                        fillOpacity: 0.10,

                        strokeOpacity: 0.16,

                        cornerRadius: 999

                    )

            }

            Text("\(averagePowerWatts.format(decimalDigits: 3)) W")

                .font(.system(.largeTitle, design: .rounded).weight(.bold))

                .monospacedDigit()

            Text(

                "Recent drift: \((stabilityDeltaWatts * 1000).format(decimalDigits: 2)) mW, tolerance \((stabilityToleranceWatts * 1000).format(decimalDigits: 2)) mW over \(sampleCount) samples."

            )

            .font(.footnote)

            .foregroundColor(.secondary)

        }

        .frame(maxWidth: .infinity, alignment: .leading)

        .padding(18)

        .meterCard(tint: isStable ? .green : .orange, fillOpacity: 0.18, strokeOpacity: 0.24)

    }

    private func projectionCard(

        averagePowerWatts: Double,

        projectedDailyEnergyWh: Double,

        projectedWeeklyEnergyWh: Double,

        projectedMonthlyEnergyWh: Double,

        projectedYearlyEnergyWh: Double

    ) -> some View {

        MeterInfoCardView(

            title: "Consumption Projection",

            infoMessage: "These projections extrapolate only from the measured standby average. They do not say anything about charger behaviour under load.",

            tint: .teal

        ) {

            MeterInfoRowView(label: "Average Power", value: "\(averagePowerWatts.format(decimalDigits: 3)) W")

            MeterInfoRowView(label: "24 Hours", value: standbyEnergyLabel(projectedDailyEnergyWh))

            MeterInfoRowView(label: "7 Days", value: standbyEnergyLabel(projectedWeeklyEnergyWh))

            MeterInfoRowView(label: "30 Days", value: standbyEnergyLabel(projectedMonthlyEnergyWh))

            MeterInfoRowView(label: "1 Year", value: standbyEnergyLabel(projectedYearlyEnergyWh))

        }

    }

    private func statisticsCard(

        averagePowerWatts: Double,

        medianPowerWatts: Double,

        minimumPowerWatts: Double,

        maximumPowerWatts: Double,

        standardDeviationPowerWatts: Double,

        coefficientOfVariation: Double,

        averageCurrentAmps: Double,

        averageVoltageVolts: Double

    ) -> some View {

        MeterInfoCardView(title: "Interesting Stats", tint: .indigo) {

            MeterInfoRowView(label: "Median", value: "\(medianPowerWatts.format(decimalDigits: 3)) W")

            MeterInfoRowView(label: "Minimum", value: "\(minimumPowerWatts.format(decimalDigits: 3)) W")

            MeterInfoRowView(label: "Maximum", value: "\(maximumPowerWatts.format(decimalDigits: 3)) W")

            MeterInfoRowView(label: "Spread σ", value: "\(standardDeviationPowerWatts.format(decimalDigits: 4)) W")

            MeterInfoRowView(label: "Variation", value: "\(Int((coefficientOfVariation * 100).rounded()))%")

            MeterInfoRowView(label: "Mean Current", value: "\(averageCurrentAmps.format(decimalDigits: 3)) A")

            MeterInfoRowView(label: "Mean Voltage", value: "\(averageVoltageVolts.format(decimalDigits: 3)) V")

            MeterInfoRowView(label: "Power Density", value: "\(averagePowerWatts.format(decimalDigits: 3)) W steady")

        }

    }

    private func startMeasurement() {

        guard let selectedCharger, let selectedMeter else {

            return

        }

        _ = appData.startChargerStandbyMeasurement(for: selectedCharger.id, on: selectedMeter)

    }

    private func standbyEnergyLabel(_ wattHours: Double) -> String {

        if wattHours >= 1000 {

            return "\((wattHours / 1000).format(decimalDigits: 3)) kWh"

        }

        return "\(wattHours.format(decimalDigits: 2)) Wh"

    }

    private func formattedDuration(_ duration: TimeInterval) -> String {

        let formatter = DateComponentsFormatter()

        formatter.allowedUnits = duration >= 3600 ? [.hour, .minute, .second] : [.minute, .second]

        formatter.unitsStyle = .abbreviated

        formatter.zeroFormattingBehavior = .pad

        return formatter.string(from: max(duration, 0)) ?? "0s"

    }

}

private struct StandbyPowerDistributionCard: View {

    let histogram: [ChargerStandbyPowerDistributionBin]

    let averagePowerWatts: Double

    let standardDeviationPowerWatts: Double

    let tint: Color

    var showExport: Bool = false

    private func resolution(for width: CGFloat) -> HistogramResolution {

        if width >= 600 { return .x4 }

        if width >= 360 { return .x2 }

        return .x1

    }

    private func displayedHistogram(width: CGFloat) -> [ChargerStandbyPowerDistributionBin] {

        let factor = HistogramResolution.x4.rawValue / resolution(for: width).rawValue

        return ChargerStandbyPowerMeasurementAnalyzer.downsample(histogram, factor: factor)

    }

    private var csvString: String {

        var lines = ["Bin,Lower Bound (W),Upper Bound (W),Count,Relative Frequency (%)"]

        for bin in histogram {

            lines.append(

                "\(bin.index + 1),"

                + String(format: "%.6f", bin.lowerBoundWatts) + ","

                + String(format: "%.6f", bin.upperBoundWatts) + ","

                + "\(bin.count),"

                + String(format: "%.4f", bin.relativeFrequency * 100)

            )

        }

        return lines.joined(separator: "\n")

    }

    var body: some View {

        MeterInfoCardView(

            title: "Value Spread",

            infoMessage: "Bars show how often each power interval appeared. The curve overlays a normal approximation around the observed mean and standard deviation.",

            tint: tint,

            trailingActions: {

                if showExport {

                    if #available(iOS 16, *) {

                        ShareLink(

                            item: DistributionCSVExport(content: csvString),

                            preview: SharePreview("distribution.csv")

                        ) {

                            Image(systemName: "square.and.arrow.up")

                                .font(.subheadline.weight(.medium))

                                .foregroundStyle(.secondary)

                        }

                    } else {

                        Button {

                            exportCSVLegacy(csvString)

                        } label: {

                            Image(systemName: "square.and.arrow.up")

                                .font(.subheadline.weight(.medium))

                                .foregroundStyle(.secondary)

                        }

                    }

                }

            }

        ) {

            GeometryReader { proxy in

                let bins = displayedHistogram(width: proxy.size.width)

                StandbyPowerHistogramView(

                    histogram: bins,

                    averagePowerWatts: averagePowerWatts,

                    standardDeviationPowerWatts: standardDeviationPowerWatts,

                    tint: tint

                )

                if let firstBin = bins.first, let lastBin = bins.last {

                    let midpointWatts = (firstBin.lowerBoundWatts + lastBin.upperBoundWatts) / 2

                    VStack {

                        Spacer()

                        HStack {

                            Text("\(firstBin.lowerBoundWatts.format(decimalDigits: 3)) W")

                            Spacer()

                            Text("\(midpointWatts.format(decimalDigits: 3)) W")

                            Spacer()

                            Text("\(lastBin.upperBoundWatts.format(decimalDigits: 3)) W")

                        }

                        .font(.caption)

                        .foregroundColor(.secondary)

                        .monospacedDigit()

                    }

                }

            }

            .frame(height: 240)

        }

    }

    private func exportCSVLegacy(_ csv: String) {

        guard let windowScene = UIApplication.shared.connectedScenes

            .compactMap({ $0 as? UIWindowScene }).first,

              let rootVC = windowScene.windows.first?.rootViewController else { return }

        let activityVC = UIActivityViewController(

            activityItems: [csv],

            applicationActivities: nil

        )

        rootVC.present(activityVC, animated: true)

    }

}

@available(iOS 16, *)

struct DistributionCSVExport: Transferable {

    let content: String

    static var transferRepresentation: some TransferRepresentation {

        DataRepresentation(exportedContentType: .commaSeparatedText) { export in

            Data(export.content.utf8)

        }

        .suggestedFileName("distribution")

    }

}

// MARK: - Histogram bars + Gaussian curve

    let histogram: [ChargerStandbyPowerDistributionBin]

    let averagePowerWatts: Double

    let standardDeviationPowerWatts: Double

    let tint: Color

    var body: some View {

        GeometryReader { proxy in

            let maxCount = max(Double(histogram.map(\.count).max() ?? 1), 1)

            ZStack {

                HStack(alignment: .bottom, spacing: 6) {

                    ForEach(histogram) { bin in

                        RoundedRectangle(cornerRadius: 8, style: .continuous)

                            .fill(tint.opacity(0.24))

                            .overlay(

                                RoundedRectangle(cornerRadius: 8, style: .continuous)

                                    .stroke(tint.opacity(0.22), lineWidth: 1)

                            )

                            .frame(height: max(10, (Double(bin.count) / maxCount) * proxy.size.height))

                    }

                }

                .frame(maxWidth: .infinity, maxHeight: .infinity, alignment: .bottom)

                gaussianCurve(in: proxy.size)

                    .stroke(tint, style: StrokeStyle(lineWidth: 2.5, lineCap: .round, lineJoin: .round))

                meanMarker(in: proxy.size)

                    .stroke(tint.opacity(0.9), style: StrokeStyle(lineWidth: 1.5, dash: [6, 4]))

            }

        }

    }

    private func gaussianCurve(in size: CGSize) -> Path {

        guard histogram.count > 1,

              standardDeviationPowerWatts > 0,

              let firstBin = histogram.first,

              let lastBin = histogram.last else {

            return Path()

        }

        let minimum = firstBin.lowerBoundWatts

        let maximum = lastBin.upperBoundWatts

        let span = max(maximum - minimum, 0.000_001)

        let sampleCount = 48

        let peakDensity = 1 / (standardDeviationPowerWatts * sqrt(2 * .pi))

        return Path { path in

            for index in 0...sampleCount {

                let progress = Double(index) / Double(sampleCount)

                let value = minimum + (span * progress)

                let zScore = (value - averagePowerWatts) / standardDeviationPowerWatts

                let density = exp(-0.5 * zScore * zScore) / (standardDeviationPowerWatts * sqrt(2 * .pi))

                let normalizedHeight = density / peakDensity

                let x = progress * size.width

                let y = size.height - (normalizedHeight * (Double(size.height) * 0.92))

                let point = CGPoint(x: x, y: y)

                if index == 0 {

                    path.move(to: point)

                } else {

                    path.addLine(to: point)

                }

            }

        }

    }

    private func meanMarker(in size: CGSize) -> Path {

        guard let firstBin = histogram.first, let lastBin = histogram.last else {

            return Path()

        }

        let minimum = firstBin.lowerBoundWatts

        let maximum = lastBin.upperBoundWatts

        let span = max(maximum - minimum, 0.000_001)

        let normalizedX = min(max((averagePowerWatts - minimum) / span, 0), 1)

        let x = normalizedX * size.width

        return Path { path in

            path.move(to: CGPoint(x: x, y: 0))

            path.addLine(to: CGPoint(x: x, y: size.height))

        }

    }

}

struct ChargerStandbyPowerMeasurementsView: View {

    @EnvironmentObject private var appData: AppData

    let chargerID: UUID

    var body: some View {

        Group {

            if let charger = appData.chargedDeviceSummary(id: chargerID) {

                Text("This charger is no longer available.")

                    .foregroundColor(.secondary)

                    .navigationTitle("Saved Measurements")

        }

    }

    private func measurementsList(for charger: ChargedDeviceSummary) -> some View {

        let content = List(selection: $selectedMeasurementIDs) {

            if charger.standbyPowerMeasurements.isEmpty {

                Text("No standby measurements saved yet.")

                    .foregroundColor(.secondary)

            } else {

                ForEach(charger.standbyPowerMeasurements) { measurement in

                    NavigationLink(

                        destination: ChargerStandbyPowerMeasurementDetailView(

                            chargerID: charger.id,

                            measurementID: measurement.id

                        )

                    ) {

                        VStack(alignment: .leading, spacing: 6) {

                            HStack {

                                Text(measurement.endedAt.format())

                                    .font(.subheadline.weight(.semibold))

                                Spacer()

                                Text("\(measurement.averagePowerWatts.format(decimalDigits: 3)) W")

                                    .font(.subheadline.weight(.bold))

                                    .monospacedDigit()

                            }

                            Text(

                                "\(formattedDuration(measurement.duration)) • \(measurement.sampleCount) samples • \(standbyEnergyLabel(measurement.projectedYearlyEnergyWh)) / year"

                            )

                            .font(.caption)

                            .foregroundColor(.secondary)

                        }

                        .frame(maxWidth: .infinity, alignment: .leading)

                    }

                    .tag(measurement.id)

                }

                .onDelete { offsets in

                    let measurements = charger.standbyPowerMeasurements

                    for index in offsets {

                        guard measurements.indices.contains(index) else { continue }

                        let measurement = measurements[index]

                        _ = appData.deleteChargerStandbyMeasurement(

                            id: measurement.id,

                            chargerID: charger.id

                        )

                    }

                }

            }

        }

            ToolbarItem(placement: .primaryAction) {

                    if editMode.isEditing {

                        editMode = .inactive

                        selectedMeasurementIDs.removeAll()

                    } else {

                        editMode = .active

                    }

                }

        }

        if selectedMeasurementIDs.isEmpty {

            content

        } else {

            content.toolbar {

                ToolbarItem(placement: .destructiveAction) {

                    Button(role: .destructive) {

                        deleteMeasurements(

                            ids: selectedMeasurementIDs,

                            for: charger.id

                        )

                    } label: {

                        Image(systemName: "trash")

                    }

                }

            }

        }

    }

        if wattHours >= 1000 {

            return "\((wattHours / 1000).format(decimalDigits: 3)) kWh"

        }

        return "\(wattHours.format(decimalDigits: 2)) Wh"

    }

    private func formattedDuration(_ duration: TimeInterval) -> String {

        let formatter = DateComponentsFormatter()

        formatter.allowedUnits = duration >= 3600 ? [.hour, .minute, .second] : [.minute, .second]

        formatter.unitsStyle = .abbreviated

        formatter.zeroFormattingBehavior = .pad

        return formatter.string(from: max(duration, 0)) ?? "0s"

    }

    private func deleteMeasurements(ids: Set<UUID>, for chargerID: UUID) {

        for id in ids {

            _ = appData.deleteChargerStandbyMeasurement(id: id, chargerID: chargerID)

        }

        selectedMeasurementIDs.removeAll()

struct ChargerStandbyPowerMeasurementDetailView: View {

    @EnvironmentObject private var appData: AppData

    @State private var deleteConfirmationVisibility = false

    let chargerID: UUID

    let measurementID: UUID

    var body: some View {

        Group {

            if let charger = appData.chargedDeviceSummary(id: chargerID),

               let measurement = charger.standbyPowerMeasurements.first(where: { $0.id == measurementID }) {

                ScrollView {

                    VStack(spacing: 18) {

                        MeterInfoCardView(title: charger.name, tint: .orange) {

                            MeterInfoRowView(label: "Saved", value: measurement.endedAt.format())

                            MeterInfoRowView(label: "Average", value: "\(measurement.averagePowerWatts.format(decimalDigits: 3)) W")

                            MeterInfoRowView(label: "Samples", value: "\(measurement.sampleCount)")

                            MeterInfoRowView(label: "Duration", value: formattedDuration(measurement.duration))

                        }

                        ChargerStandbyPowerMeasurementSnapshotView(measurement: measurement)

                    }

                    .padding()

                }

                .background(

                    LinearGradient(

                        colors: [.orange.opacity(0.16), Color.clear],

                        startPoint: .topLeading,

                        endPoint: .bottomTrailing

                .ignoresSafeArea()

                .navigationTitle("Measurement")

                    ToolbarItem(placement: .primaryAction) {

                        Button(role: .destructive) {

                            deleteConfirmationVisibility = true

                        } label: {

                            Label("Delete Measurement", systemImage: "trash")

                        }

                    }

                }

                .confirmationDialog(

                    "Delete this measurement?",

                    isPresented: $deleteConfirmationVisibility,

                    titleVisibility: .visible

                ) {

                    Button("Delete", role: .destructive) {

                        let didDelete = appData.deleteChargerStandbyMeasurement(

                            id: measurement.id,

                            chargerID: charger.id

                        )

                        if didDelete {

                            dismiss()

                        }

                    }

                    Button("Cancel", role: .cancel) {}

                } message: {

                    Text("This removes the saved standby measurement from the charger history and iCloud sync.")

                }

                Text("This measurement is no longer available.")

                    .foregroundColor(.secondary)

                    .navigationTitle("Measurement")

        }

    }

    private func formattedDuration(_ duration: TimeInterval) -> String {

        let formatter = DateComponentsFormatter()

        formatter.allowedUnits = duration >= 3600 ? [.hour, .minute, .second] : [.minute, .second]

        formatter.unitsStyle = .abbreviated

        formatter.zeroFormattingBehavior = .pad

        return formatter.string(from: max(duration, 0)) ?? "0s"

    }

}

private struct ChargerStandbyPowerMeasurementSnapshotView: View {

    let measurement: ChargerStandbyPowerMeasurementSummary

    var body: some View {

        VStack(spacing: 18) {

            stabilityCard

            projectionCard

            distributionCard

            statisticsCard

        }

    }

    private var stabilityCard: some View {

        VStack(alignment: .leading, spacing: 10) {

            HStack {

                VStack(alignment: .leading, spacing: 4) {

                    Text(measurement.isStable ? "Enough Samples" : "Still Settling")

                        .font(.headline)

                    Text("Saved \(measurement.endedAt.format())")

                        .font(.caption)

                        .foregroundColor(.secondary)

                }

                Spacer()

                Text(measurement.isStable ? "Ready" : "Live")

                    .font(.caption.weight(.semibold))

                    .padding(.horizontal, 10)

                    .padding(.vertical, 6)

                    .foregroundColor(measurement.isStable ? .green : .orange)

                    .meterCard(

                        tint: measurement.isStable ? .green : .orange,

                        fillOpacity: 0.10,

                        strokeOpacity: 0.16,

                        cornerRadius: 999

                    )

            }

            Text("\(measurement.averagePowerWatts.format(decimalDigits: 3)) W")

                .font(.system(.largeTitle, design: .rounded).weight(.bold))

                .monospacedDigit()

            Text(

                "Recent drift: \((measurement.stabilityDeltaWatts * 1000).format(decimalDigits: 2)) mW, tolerance \((measurement.stabilityToleranceWatts * 1000).format(decimalDigits: 2)) mW over \(measurement.sampleCount) samples."

            )

            .font(.footnote)

            .foregroundColor(.secondary)

        }

        .frame(maxWidth: .infinity, alignment: .leading)

        .padding(18)

        .meterCard(

            tint: measurement.isStable ? .green : .orange,

            fillOpacity: 0.18,

            strokeOpacity: 0.24

        )

    }

    private var projectionCard: some View {

        MeterInfoCardView(

            title: "Consumption Projection",

            infoMessage: "These projections extrapolate only from the measured standby average. They do not say anything about charger behaviour under load.",

            tint: .teal

        ) {

            MeterInfoRowView(label: "Average Power", value: "\(measurement.averagePowerWatts.format(decimalDigits: 3)) W")

            MeterInfoRowView(label: "24 Hours", value: standbyEnergyLabel(measurement.projectedDailyEnergyWh))

            MeterInfoRowView(label: "7 Days", value: standbyEnergyLabel(measurement.projectedWeeklyEnergyWh))

            MeterInfoRowView(label: "30 Days", value: standbyEnergyLabel(measurement.projectedMonthlyEnergyWh))

            MeterInfoRowView(label: "1 Year", value: standbyEnergyLabel(measurement.projectedYearlyEnergyWh))

        }

    }

    private var distributionCard: some View {

            histogram: measurement.storedHistogram,

            averagePowerWatts: measurement.averagePowerWatts,

            standardDeviationPowerWatts: measurement.standardDeviationPowerWatts,

            tint: .orange,

            showExport: true

        )

    private var statisticsCard: some View {

        MeterInfoCardView(title: "Interesting Stats", tint: .indigo) {

            MeterInfoRowView(label: "Median", value: "\(measurement.medianPowerWatts.format(decimalDigits: 3)) W")

            MeterInfoRowView(label: "Minimum", value: "\(measurement.minimumPowerWatts.format(decimalDigits: 3)) W")

            MeterInfoRowView(label: "Maximum", value: "\(measurement.maximumPowerWatts.format(decimalDigits: 3)) W")

            MeterInfoRowView(label: "Spread σ", value: "\(measurement.standardDeviationPowerWatts.format(decimalDigits: 4)) W")

            MeterInfoRowView(label: "Variation", value: "\(Int((measurement.coefficientOfVariation * 100).rounded()))%")

            MeterInfoRowView(label: "Mean Current", value: "\(measurement.averageCurrentAmps.format(decimalDigits: 3)) A")

            MeterInfoRowView(label: "Mean Voltage", value: "\(measurement.averageVoltageVolts.format(decimalDigits: 3)) V")

            MeterInfoRowView(label: "Power Density", value: "\(measurement.averagePowerWatts.format(decimalDigits: 3)) W steady")

        }

    }

    private func standbyEnergyLabel(_ wattHours: Double) -> String {

        if wattHours >= 1000 {

            return "\((wattHours / 1000).format(decimalDigits: 3)) kWh"

        }

        return "\(wattHours.format(decimalDigits: 2)) Wh"

    }

}