import Foundation
import SwiftUI

struct EditOverrideForm: View {
    var override: OverrideStored
    @Environment(\.presentationMode) var presentationMode
    @Environment(\.colorScheme) var colorScheme
    @Environment(AppState.self) var appState
    @Bindable var state: Adjustments.StateModel

    @State private var name: String
    @State private var percentage: Double
    @State private var indefinite: Bool
    @State private var duration: Decimal
    @State private var target: Decimal?
    @State private var advancedSettings: Bool
    @State private var smbIsOff: Bool
    @State private var smbIsScheduledOff: Bool
    @State private var start: Decimal?
    @State private var end: Decimal?
    @State private var isfAndCr: Bool
    @State private var isf: Bool
    @State private var cr: Bool
    @State private var smbMinutes: Decimal?
    @State private var uamMinutes: Decimal?
    @State private var selectedIsfCrOption: IsfAndOrCrOptions
    @State private var selectedDisableSmbOption: DisableSmbOptions
    @State private var hasChanges = false
    @State private var isEditing = false
    @State private var target_override = false
    @State private var percentageStep: Int = 1
    @State private var displayPickerPercentage: Bool = false
    @State private var displayPickerDuration: Bool = false
    @State private var targetStep: Decimal = 1
    @State private var displayPickerTarget: Bool = false
    @State private var displayPickerDisableSmbSchedule: Bool = false
    @State private var displayPickerSmbMinutes: Bool = false

    init(overrideToEdit: OverrideStored, state: Adjustments.StateModel) {
        override = overrideToEdit
        _state = Bindable(wrappedValue: state)
        _name = State(initialValue: overrideToEdit.name ?? "")
        _percentage = State(initialValue: overrideToEdit.percentage)
        _indefinite = State(initialValue: overrideToEdit.indefinite)
        _duration = State(initialValue: overrideToEdit.duration?.decimalValue ?? 0)
        _target = State(initialValue: overrideToEdit.target?.decimalValue)
        _target_override = State(initialValue: overrideToEdit.target != nil && overrideToEdit.target?.decimalValue != 0)
        _advancedSettings = State(initialValue: overrideToEdit.advancedSettings)
        _smbIsOff = State(initialValue: overrideToEdit.smbIsOff)
        _smbIsScheduledOff = State(initialValue: overrideToEdit.smbIsScheduledOff)
        _start = State(initialValue: overrideToEdit.start?.decimalValue)
        _end = State(initialValue: overrideToEdit.end?.decimalValue)
        _isfAndCr = State(initialValue: overrideToEdit.isfAndCr)
        _isf = State(initialValue: overrideToEdit.isf)
        _cr = State(initialValue: overrideToEdit.cr)
        _selectedIsfCrOption = State(
            initialValue: overrideToEdit.isfAndCr ? .isfAndCr
                : (overrideToEdit.isf ? .isf : (overrideToEdit.cr ? .cr : .nothing))
        )
        _selectedDisableSmbOption = State(
            initialValue: overrideToEdit.smbIsScheduledOff ? .disableOnSchedule
                : (overrideToEdit.smbIsOff ? .disable : .dontDisable)
        )
        _smbMinutes = State(initialValue: overrideToEdit.smbMinutes?.decimalValue)
        _uamMinutes = State(initialValue: overrideToEdit.uamMinutes?.decimalValue)
    }

    private var percentageSelection: Binding<Double> {
        Binding<Double>(
            get: {
                let value = floor(percentage / Double(percentageStep)) * Double(percentageStep)
                return max(10, min(value, 200))
            },
            set: {
                percentage = $0
                hasChanges = true
            }
        )
    }

    var body: some View {
        NavigationView {
            List {
                editOverride()
                saveButton
            }
            .listSectionSpacing(10)
            .padding(.top, 30)
            .ignoresSafeArea(edges: .top)
            .scrollContentBackground(.hidden)
            .background(appState.trioBackgroundColor(for: colorScheme))
            .navigationTitle("Edit Override")
            .navigationBarTitleDisplayMode(.inline)
            .toolbar {
                ToolbarItem(placement: .topBarLeading) {
                    Button(action: {
                        presentationMode.wrappedValue.dismiss()
                    }, label: {
                        Text("Cancel")
                    })
                }
                ToolbarItem(placement: .topBarTrailing) {
                    Button(
                        action: {
                            state.isHelpSheetPresented.toggle()
                        },
                        label: {
                            Image(systemName: "questionmark.circle")
                        }
                    )
                }
            }
            .onDisappear {
                if !hasChanges {
                    // Reset UI changes
                    resetValues()
                }
            }
            .sheet(isPresented: $state.isHelpSheetPresented) {
                NavigationStack {
                    List {
                        VStack(alignment: .leading, spacing: 10) {
                            VStack(alignment: .leading, spacing: 0) {
                                Text("This feature can be used to override these therapy settings for a chosen length of time:")
                                    .fixedSize(horizontal: false, vertical: true)
                                Text("• Basal Rate")
                                Text("  ◦ Insulin Sensitivity")
                                Text("  ◦ Carb Ratio")
                                Text("• Glucose Target")
                            }
                            Text(
                                "There are also options to override your Max SMB Minutes and Max UAM SMB Minutes, as well as to disable SMBs."
                            )
                            Text(
                                "Select \"Start Override\" to immediately start using the Override, or select \"Save as Preset\" to be able to easily start the Override at a later time."
                            )
                            Text(
                                "If an active override preset is edited, the changes will also apply to the currently running override. However, if you edit the currently running override directly, the preset stays unchanged."
                            )
                            Text(
                                "If using Dynamic ISF (without Sigmoid), overriding your ISF will only adjust the limits of the ISF the algorithm is allowed to set."
                            )
                            Text(
                                "If using Dynamic ISF (with Sigmoid), overriding your ISF will adjust the ISF used at your glucose target which extends to the ISF used at other glucose. Overriding your glucose target will change glucose level your ISF will be set to your profile ISF. Both of these can be combined in a single Override."
                            )
                        }
                    }
                    .padding(.trailing, 10)
                    .navigationBarTitle("Help", displayMode: .inline)

                    Button { state.isHelpSheetPresented.toggle() }
                    label: { Text("Got it!").frame(maxWidth: .infinity, alignment: .center) }
                        .buttonStyle(.bordered)
                        .padding(.top)
                }
                .padding()
                .presentationDetents(
                    [.fraction(0.9), .large],
                    selection: $state.helpSheetDetent
                )
            }
        }
    }

    @ViewBuilder private func editOverride() -> some View {
        Group {
            if override.name != nil {
                Section {
                    HStack {
                        Text("Name")
                        Spacer()
                        TextField("Name", text: $name)
                            .onChange(of: name) { hasChanges = true }
                            .multilineTextAlignment(.trailing)
                    }
                }
                .listRowBackground(Color.chart)
            }

            // Percentage Picker
            Section(footer: state.percentageDescription(percentage)) {
                HStack {
                    Text("Change Basal Rate by")
                    Spacer()
                    Text("\(percentage.formatted(.number)) %")
                        .foregroundColor(!displayPickerPercentage ? .primary : .accentColor)
                        .onTapGesture {
                            displayPickerPercentage = toggleScrollWheel(displayPickerPercentage)
                        }
                }

                if displayPickerPercentage {
                    HStack {
                        // Radio buttons and text on the left side
                        VStack(alignment: .leading) {
                            // Radio buttons for step iteration
                            ForEach([1, 5], id: \.self) { step in
                                RadioButton(isSelected: percentageStep == step, label: "\(step) %") {
                                    percentageStep = step
                                    percentage = Adjustments.StateModel.roundOverridePercentageToStep(percentage, step)
                                }
                                .padding(.top, 10)
                            }
                        }
                        .frame(maxWidth: .infinity)

                        Spacer()

                        // Picker on the right side
                        Picker(
                            selection: percentageSelection,
                            label: Text("")
                        ) {
                            ForEach(
                                Array(stride(from: 40.0, through: 150.0, by: Double(percentageStep))),
                                id: \.self
                            ) { percent in
                                Text("\(Int(percent)) %").tag(percent)
                            }
                        }
                        .pickerStyle(WheelPickerStyle())
                        .frame(maxWidth: .infinity)
                    }
                    .listRowSeparator(.hidden, edges: .top)
                }

                // Picker for ISF/CR settings
                Picker("Also Change", selection: $selectedIsfCrOption) {
                    ForEach(IsfAndOrCrOptions.allCases, id: \.self) { option in
                        Text(option.rawValue).tag(option)
                    }
                }
                .pickerStyle(MenuPickerStyle())
                .onChange(of: selectedIsfCrOption) { _, newValue in
                    switch newValue {
                    case .isfAndCr:
                        isfAndCr = true
                        isf = false
                        cr = false
                    case .isf:
                        isfAndCr = false
                        isf = true
                        cr = false
                    case .cr:
                        isfAndCr = false
                        isf = false
                        cr = true
                    case .nothing:
                        isfAndCr = false
                        isf = false
                        cr = false
                    }
                    hasChanges = true
                }
            }
            .listRowBackground(Color.chart)

            Section {
                Toggle(isOn: $target_override) {
                    Text("Override Target")
                }
                .onChange(of: target_override) {
                    hasChanges = true
                }
                // Target Glucose Picker
                if target_override {
                    let settingsProvider = PickerSettingsProvider.shared
                    let glucoseSetting = PickerSetting(value: 0, step: targetStep, min: 72, max: 270, type: .glucose)

                    TargetPicker(
                        label: "Target Glucose",
                        selection: Binding(
                            get: { target ?? 100 },
                            set: { target = $0 }
                        ),
                        options: settingsProvider.generatePickerValues(
                            from: glucoseSetting,
                            units: state.units,
                            roundMinToStep: true
                        ),
                        units: state.units,
                        hasChanges: $hasChanges,
                        targetStep: $targetStep,
                        displayPickerTarget: $displayPickerTarget,
                        toggleScrollWheel: toggleScrollWheel
                    )
                    .onAppear {
                        if target == 0 || target == nil {
                            target = 100
                        }
                    }
                }
            }
            .listRowBackground(Color.chart)

            Section {
                // Picker for Disable SMB settings
                Picker("Disable SMBs", selection: $selectedDisableSmbOption) {
                    ForEach(DisableSmbOptions.allCases, id: \.self) { option in
                        Text(option.rawValue).tag(option)
                    }
                }
                .pickerStyle(MenuPickerStyle())
                .onChange(of: selectedDisableSmbOption) { _, newValue in
                    switch newValue {
                    case .dontDisable:
                        smbIsOff = false
                        smbIsScheduledOff = false
                    case .disable:
                        smbIsOff = true
                        smbIsScheduledOff = false
                    case .disableOnSchedule:
                        smbIsOff = false
                        smbIsScheduledOff = true
                    }
                    hasChanges = true
                }

                if smbIsScheduledOff {
                    // First Hour SMBs Are Disabled
                    HStack {
                        Text("From")
                        Spacer()
                        Text(
                            state.is24HourFormat() ? state.format24Hour(Int(truncating: start! as NSNumber)) + ":00" :
                                state.convertTo12HourFormat(Int(truncating: start! as NSNumber))
                        )
                        .foregroundColor(!displayPickerDisableSmbSchedule ? .primary : .accentColor)
                        .onTapGesture {
                            displayPickerDisableSmbSchedule = toggleScrollWheel(displayPickerDisableSmbSchedule)
                        }

                        Spacer()

                        Divider().frame(width: 1, height: 20)

                        Spacer()

                        Text("To")
                        Spacer()
                        Text(
                            state.is24HourFormat() ? state.format24Hour(Int(truncating: end! as NSNumber)) + ":00" :
                                state.convertTo12HourFormat(Int(truncating: end! as NSNumber))
                        )
                        .foregroundColor(!displayPickerDisableSmbSchedule ? .primary : .accentColor)
                        .onTapGesture {
                            displayPickerDisableSmbSchedule = toggleScrollWheel(displayPickerDisableSmbSchedule)
                        }
                    }

                    if displayPickerDisableSmbSchedule {
                        HStack {
                            Picker(selection: Binding(
                                get: { Int(truncating: start! as NSNumber) },
                                set: {
                                    start = Decimal($0)
                                    hasChanges = true
                                }
                            ), label: Text("")) {
                                if state.is24HourFormat() {
                                    ForEach(0 ..< 24, id: \.self) { hour in
                                        Text(state.format24Hour(hour) + ":00").tag(hour)
                                    }
                                } else {
                                    ForEach(0 ..< 24, id: \.self) { hour in
                                        Text(state.convertTo12HourFormat(hour)).tag(hour)
                                    }
                                }
                            }
                            .pickerStyle(WheelPickerStyle())
                            .frame(maxWidth: .infinity)

                            Picker(selection: Binding(
                                get: { Int(truncating: end! as NSNumber) },
                                set: {
                                    end = Decimal($0)
                                    hasChanges = true
                                }
                            ), label: Text("")) {
                                if state.is24HourFormat() {
                                    ForEach(0 ..< 24, id: \.self) { hour in
                                        Text(state.format24Hour(hour) + ":00").tag(hour)
                                    }
                                } else {
                                    ForEach(0 ..< 24, id: \.self) { hour in
                                        Text(state.convertTo12HourFormat(hour)).tag(hour)
                                    }
                                }
                            }
                            .pickerStyle(WheelPickerStyle())
                            .frame(maxWidth: .infinity)
                        }
                        .listRowSeparator(.hidden, edges: .top)
                    }
                }
            }
            .listRowBackground(Color.chart)

            if !smbIsOff {
                Section {
                    Toggle(isOn: $advancedSettings) {
                        Text("Change Max SMB Minutes")
                    }
                    .onChange(of: advancedSettings) { hasChanges = true }

                    if advancedSettings {
                        // SMB Minutes Picker
                        HStack {
                            Text("SMB")
                            Spacer()
                            Text("\(smbMinutes?.formatted(.number) ?? "\(state.defaultSmbMinutes)") min")
                                .foregroundColor(!displayPickerSmbMinutes ? .primary : .accentColor)
                                .onTapGesture {
                                    displayPickerSmbMinutes = toggleScrollWheel(displayPickerSmbMinutes)
                                }

                            Spacer()

                            Divider().frame(width: 1, height: 20)

                            Spacer()

                            Text("UAM")
                            Spacer()
                            Text("\(uamMinutes?.formatted(.number) ?? "\(state.defaultUamMinutes)") min")
                                .foregroundColor(!displayPickerSmbMinutes ? .primary : .accentColor)
                                .onTapGesture {
                                    displayPickerSmbMinutes = toggleScrollWheel(displayPickerSmbMinutes)
                                }
                        }

                        if displayPickerSmbMinutes {
                            HStack {
                                Picker(
                                    selection: Binding(
                                        get: { smbMinutes ?? state.defaultSmbMinutes },
                                        set: {
                                            smbMinutes = $0
                                            hasChanges = true
                                        }
                                    ),
                                    label: Text("")
                                ) {
                                    ForEach(Array(stride(from: 0, through: 180, by: 5)), id: \.self) { minute in
                                        Text("\(minute) min").tag(Decimal(minute))
                                    }
                                }
                                .pickerStyle(WheelPickerStyle())
                                .frame(maxWidth: .infinity)

                                Picker(
                                    selection: Binding(
                                        get: { uamMinutes ?? state.defaultUamMinutes },
                                        set: {
                                            uamMinutes = $0
                                            hasChanges = true
                                        }
                                    ),
                                    label: Text("")
                                ) {
                                    ForEach(Array(stride(from: 0, through: 180, by: 5)), id: \.self) { minute in
                                        Text("\(minute) min").tag(Decimal(minute))
                                    }
                                }
                                .pickerStyle(WheelPickerStyle())
                                .frame(maxWidth: .infinity)
                            }
                            .listRowSeparator(.hidden, edges: .top)
                        }
                    }
                }
                .listRowBackground(Color.chart)
            }

            Section {
                Toggle(isOn: $indefinite) { Text("Enable Indefinitely") }
                    .onChange(of: indefinite) { hasChanges = true }

                if !indefinite {
                    HStack {
                        Text("Duration")
                        Spacer()
                        Text(state.formatHrMin(Int(truncating: duration as NSNumber)))
                            .foregroundColor(!displayPickerDuration ? .primary : .accentColor)
                            .onTapGesture {
                                displayPickerDuration = toggleScrollWheel(displayPickerDuration)
                            }
                    }

                    if displayPickerDuration {
                        HStack {
                            Picker(
                                selection: Binding(
                                    get: {
                                        Int(truncating: duration as NSNumber) / 60
                                    },
                                    set: {
                                        let minutes = Int(truncating: duration as NSNumber) % 60
                                        let totalMinutes = $0 * 60 + minutes
                                        duration = Decimal(totalMinutes)
                                        hasChanges = true
                                    }
                                ),
                                label: Text("")
                            ) {
                                ForEach(0 ..< 24) { hour in
                                    Text("\(hour) hr").tag(hour)
                                }
                            }
                            .pickerStyle(WheelPickerStyle())
                            .frame(maxWidth: .infinity)

                            Picker(
                                selection: Binding(
                                    get: {
                                        Int(truncating: duration as NSNumber) %
                                            60 // Convert Decimal to Int for modulus operation
                                    },
                                    set: {
                                        duration = Decimal((Int(truncating: duration as NSNumber) / 60) * 60 + $0)
                                        hasChanges = true
                                    }
                                ),
                                label: Text("")
                            ) {
                                ForEach(Array(stride(from: 0, through: 55, by: 5)), id: \.self) { minute in
                                    Text("\(minute) min").tag(minute)
                                }
                            }
                            .pickerStyle(WheelPickerStyle())
                            .frame(maxWidth: .infinity)
                        }
                        .listRowSeparator(.hidden, edges: .top)
                    }
                }
            }
            .listRowBackground(Color.chart)
        }
    }

    private var saveButton: some View {
        let (isInvalid, errorMessage) = isOverrideInvalid()

        return Section(
            header:
            HStack {
                Spacer()
                Text(errorMessage ?? "").textCase(nil)
                    .foregroundColor(colorScheme == .dark ? .orange : .accentColor)
                Spacer()
            },
            content: {
                Button(action: {
                    saveChanges()

                    do {
                        guard let moc = override.managedObjectContext else { return }
                        guard moc.hasChanges else { return }
                        try moc.save()
                        Task {
                            await state.nightscoutManager.uploadProfiles()
                        }
                        // Disable previous active Override
                        if let currentActiveOverride = state.currentActiveOverride {
                            Task {
                                await state.disableAllActiveOverrides(
                                    except: currentActiveOverride.objectID,
                                    createOverrideRunEntry: false
                                )
                                // Update View
                                state.updateLatestOverrideConfiguration()
                            }
                        }

                        hasChanges = false
                        presentationMode.wrappedValue.dismiss()
                    } catch {
                        debugPrint("\(DebuggingIdentifiers.failed) \(#file) \(#function) Failed to edit Override")
                    }
                }, label: {
                    Text("Save Override")
                })
                    .disabled(isInvalid) // Disable button if changes are invalid
                    .frame(maxWidth: .infinity, alignment: .center)
                    .tint(.white)
            }
        )
        .listRowBackground(isInvalid ? Color(.systemGray4) : Color(.systemBlue))
    }

    private func isOverrideInvalid() -> (Bool, String?) {
        let noDurationSpecified = !indefinite && duration == 0
        let targetZeroWithOverride = target_override && (target ?? 0 < 72 || target ?? 0 > 270)
        let allSettingsDefault = percentage == 100 && !target_override && !advancedSettings &&
            !smbIsOff && !smbIsScheduledOff

        if noDurationSpecified {
            return (true, "Enable indefinitely or set a duration.")
        }

        if targetZeroWithOverride {
            return (true, "Target glucose is out of range (\(state.units == .mgdL ? "72-270" : "4-14")).")
        }

        if allSettingsDefault {
            return (true, "All settings are at default values.")
        }

        if !hasChanges {
            return (true, nil)
        }

        return (false, nil)
    }

    private func saveChanges() {
        if !override.isPreset, hasChanges, name == (override.name ?? "") {
            override.name = "Custom Override"
        } else {
            override.name = name
        }
        override.percentage = percentage
        override.indefinite = indefinite
        override.duration = NSDecimalNumber(decimal: duration)
        override.target = target_override ? NSDecimalNumber(decimal: target ?? 100) : nil
        override.advancedSettings = advancedSettings
        override.smbIsOff = smbIsOff
        override.smbIsScheduledOff = smbIsScheduledOff
        override.start = start.map { NSDecimalNumber(decimal: $0) }
        override.end = end.map { NSDecimalNumber(decimal: $0) }
        override.isfAndCr = isfAndCr
        override.isf = isf
        override.cr = cr
        override.smbMinutes = smbMinutes.map { NSDecimalNumber(decimal: $0) }
        override.uamMinutes = uamMinutes.map { NSDecimalNumber(decimal: $0) }
        override.isUploadedToNS = false
    }

    private func resetValues() {
        name = override.name ?? ""
        percentage = override.percentage
        indefinite = override.indefinite
        duration = override.duration?.decimalValue ?? 0
        target = override.target?.decimalValue
        advancedSettings = override.advancedSettings
        smbIsOff = override.smbIsOff
        smbIsScheduledOff = override.smbIsScheduledOff
        start = override.start?.decimalValue
        end = override.end?.decimalValue
        isfAndCr = override.isfAndCr
        isf = override.isf
        cr = override.cr
        smbMinutes = override.smbMinutes?.decimalValue ?? state.defaultSmbMinutes
        uamMinutes = override.uamMinutes?.decimalValue ?? state.defaultUamMinutes
    }

    private func toggleScrollWheel(_ toggle: Bool) -> Bool {
        displayPickerDuration = false
        displayPickerPercentage = false
        displayPickerTarget = false
        displayPickerDisableSmbSchedule = false
        displayPickerSmbMinutes = false
        return !toggle
    }
}