import Foundation
import SwiftUI

struct AddOverrideForm: View {
    @Environment(\.presentationMode) var presentationMode
    @Environment(\.colorScheme) var colorScheme
    @Environment(\.dismiss) var dismiss
    @Environment(AppState.self) var appState
    @Bindable var state: Adjustments.StateModel
    @State private var selectedIsfCrOption: IsfAndOrCrOptions = .isfAndCr
    @State private var selectedDisableSmbOption: DisableSmbOptions = .dontDisable
    @State private var percentageStep: Int = 5
    @State private var displayPickerPercentage: Bool = false
    @State private var displayPickerDuration: Bool = false
    @State private var targetStep: Decimal = 5
    @State private var displayPickerTarget: Bool = false
    @State private var displayPickerDisableSmbSchedule: Bool = false
    @State private var displayPickerSmbMinutes: Bool = false
    @State private var durationHours = 0
    @State private var durationMinutes = 0
    @State private var overrideTarget = false
    @State private var didPressSave = false

    var body: some View {
        NavigationView {
            List {
                addOverride()
                saveButton
            }
            .listSectionSpacing(10)
            .padding(.top, 30)
            .ignoresSafeArea(edges: .top)
            .scrollContentBackground(.hidden)
            .background(appState.trioBackgroundColor(for: colorScheme))
            .navigationTitle("Add 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")
                        }
                    )
                }
            }
            .onAppear { targetStep = state.units == .mgdL ? 5 : 9 }
            .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 addOverride() -> some View {
        Group {
            Section {
                HStack {
                    Text("Name")
                    Spacer()
                    TextField("(Optional)", text: $state.overrideName).multilineTextAlignment(.trailing)
                }
            }
            .listRowBackground(Color.chart)

            Section(footer: state.percentageDescription(state.overridePercentage)) {
                // Percentage Picker
                HStack {
                    Text("Change Basal Rate by")
                    Spacer()
                    Text("\(state.overridePercentage.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
                                    state.overridePercentage = Adjustments.StateModel.roundOverridePercentageToStep(
                                        state.overridePercentage,
                                        step
                                    )
                                }
                                .padding(.top, 10)
                            }
                        }
                        .frame(maxWidth: .infinity)

                        Spacer()

                        // Picker on the right side
                        Picker(
                            selection: Binding(
                                get: { Int(truncating: state.overridePercentage as NSNumber) },
                                set: { state.overridePercentage = Double($0) }
                            ), label: Text("")
                        ) {
                            ForEach(Array(stride(from: 40, through: 150, by: percentageStep)), id: \.self) { percent in
                                Text("\(percent) %").tag(percent)
                            }
                        }
                        .pickerStyle(WheelPickerStyle())
                        .frame(maxWidth: .infinity)
                    }
                    .frame(maxWidth: .infinity)
                    .listRowSeparator(.hidden, edges: .top)
                }

                // Picker for ISF/CR settings
                Picker("Also Inversely 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:
                        state.isfAndCr = true
                        state.isf = true
                        state.cr = true
                    case .isf:
                        state.isfAndCr = false
                        state.isf = true
                        state.cr = false
                    case .cr:
                        state.isfAndCr = false
                        state.isf = false
                        state.cr = true
                    case .nothing:
                        state.isfAndCr = false
                        state.isf = false
                        state.cr = false
                    }
                }
            }
            .listRowBackground(Color.chart)

            Section {
                Toggle(isOn: $state.shouldOverrideTarget) {
                    Text("Override Target")
                }

                if state.shouldOverrideTarget {
                    let settingsProvider = PickerSettingsProvider.shared
                    let glucoseSetting = PickerSetting(value: 0, step: targetStep, min: 72, max: 270, type: .glucose)
                    TargetPicker(
                        label: "Target Glucose",
                        selection: Binding(
                            get: { state.target },
                            set: { state.target = $0 }
                        ),
                        options: settingsProvider.generatePickerValues(
                            from: glucoseSetting,
                            units: state.units,
                            roundMinToStep: true
                        ),
                        units: state.units,
                        targetStep: $targetStep,
                        displayPickerTarget: $displayPickerTarget,
                        toggleScrollWheel: toggleScrollWheel
                    )
                    .onAppear {
                        if state.target == 0 {
                            state.target = 100
                        }
                    }
                }
            }
            .listRowBackground(Color.chart)

            Section {
                // Picker for ISF/CR 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:
                        state.smbIsOff = false
                        state.smbIsScheduledOff = false
                    case .disable:
                        state.smbIsOff = true
                        state.smbIsScheduledOff = false
                    case .disableOnSchedule:
                        state.smbIsOff = false
                        state.smbIsScheduledOff = true
                    }
                }

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

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

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

            if !state.smbIsOff {
                Section {
                    Toggle(isOn: $state.advancedSettings) {
                        Text("Override Max SMB Minutes")
                    }

                    if state.advancedSettings {
                        // SMB Minutes Picker
                        HStack {
                            Text("SMB")
                            Spacer()
                            Text("\(state.smbMinutes.formatted(.number)) min")
                                .foregroundColor(!displayPickerSmbMinutes ? .primary : .accentColor)
                                .onTapGesture {
                                    displayPickerSmbMinutes = toggleScrollWheel(displayPickerSmbMinutes)
                                }
                            Spacer()
                            Divider().frame(width: 1, height: 20)
                            Spacer()
                            Text("UAM")
                            Spacer()
                            Text("\(state.uamMinutes.formatted(.number)) min")
                                .foregroundColor(!displayPickerSmbMinutes ? .primary : .accentColor)
                                .onTapGesture {
                                    displayPickerSmbMinutes = toggleScrollWheel(displayPickerSmbMinutes)
                                }
                        }

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

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

            Section {
                Toggle(isOn: $state.indefinite) {
                    Text("Enable Indefinitely")
                }

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

                    if displayPickerDuration {
                        HStack {
                            Picker("Hours", selection: $durationHours) {
                                ForEach(0 ..< 24) { hour in
                                    Text("\(hour) hr").tag(hour)
                                }
                            }
                            .pickerStyle(WheelPickerStyle())
                            .frame(maxWidth: .infinity)
                            .onChange(of: durationHours) {
                                state.overrideDuration = state.convertToMinutes(durationHours, durationMinutes)
                            }

                            Picker("Minutes", selection: $durationMinutes) {
                                ForEach(Array(stride(from: 0, through: 55, by: 5)), id: \.self) { minute in
                                    Text("\(minute) min").tag(minute)
                                }
                            }
                            .pickerStyle(WheelPickerStyle())
                            .frame(maxWidth: .infinity)
                            .onChange(of: durationMinutes) {
                                state.overrideDuration = state.convertToMinutes(durationHours, durationMinutes)
                            }
                        }
                        .listRowSeparator(.hidden, edges: .top)
                    }
                }
            }
            .listRowBackground(Color.chart)
        }
    }

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

        return Group {
            Section(
                header:
                HStack {
                    Spacer()
                    Text(errorMessage ?? "").textCase(nil)
                        .foregroundColor(colorScheme == .dark ? .orange : .accentColor)
                    Spacer()
                },
                content: {
                    Button(action: {
                        Task {
                            if state.indefinite { state.overrideDuration = 0 }
                            state.isEnabled.toggle()
                            await state.saveCustomOverride()
                            await state.resetStateVariables()
                            dismiss()
                        }
                    }, label: {
                        Text("Start Override")
                    })
                        .disabled(isInvalid)
                        .frame(maxWidth: .infinity, alignment: .center)
                        .tint(.white)
                }
            ).listRowBackground(isInvalid ? Color(.systemGray4) : Color(.systemBlue))

            Section {
                Button(action: {
                    Task {
                        await state.saveOverridePreset()
                        dismiss()
                    }
                }, label: {
                    Text("Save as Preset")

                })
                    .disabled(isInvalid)
                    .frame(maxWidth: .infinity, alignment: .center)
                    .tint(.white)
            }
            .listRowBackground(
                isInvalid ? Color(.systemGray4) : Color.secondary
            )
        }
    }

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

    private func isOverrideInvalid() -> (Bool, String?) {
        let noDurationSpecified = !state.indefinite && state.overrideDuration == 0
        let targetZeroWithOverride = state.shouldOverrideTarget && state.target == 0
        let allSettingsDefault = state.overridePercentage == 100 && !state.shouldOverrideTarget &&
            !state.advancedSettings && !state.smbIsOff && !state.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.")
        }

        return (false, nil)
    }
}