using System;
using System.Windows;
using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using HC_APTBS.Models;
using HC_APTBS.Services;
using HC_APTBS.ViewModels.Dialogs;
using HC_APTBS.Views.Dialogs;

namespace HC_APTBS.ViewModels
{
    /// <summary>
    /// ViewModel for manual bench controls: direction toggle, RPM start/stop with
    /// PID ramp, oil pump toggle, and turn downcounter.
    /// Created by <see cref="MainViewModel"/> as a child ViewModel.
    /// </summary>
    public sealed partial class BenchControlViewModel : ObservableObject
    {
        private readonly IBenchService _bench;
        private readonly IConfigurationService _config;

        // ── Direction ─────────────────────────────────────────────────────────────

        /// <summary>True when the bench rotates clockwise (right). False for counter-clockwise (left).</summary>
        [ObservableProperty]
        [NotifyPropertyChangedFor(nameof(IsDirectionLeft))]
        private bool _isDirectionRight = true;

        /// <summary>True when the bench rotates counter-clockwise (left). Computed inverse of <see cref="IsDirectionRight"/>.</summary>
        public bool IsDirectionLeft => !IsDirectionRight;

        // ── Oil pump ──────────────────────────────────────────────────────────────

        /// <summary>True when the oil pump relay is energised.</summary>
        [ObservableProperty] private bool _isOilPumpOn;

        // ── RPM control ───────────────────────────────────────────────────────────

        /// <summary>True when the bench motor is running (last RPM command > 0).</summary>
        [ObservableProperty] private bool _isBenchRunning;

        /// <summary>Controls the RPM quick-select popup visibility.</summary>
        [ObservableProperty] private bool _isRpmPopupOpen;

        /// <summary>Text in the RPM input field.</summary>
        [ObservableProperty] private string _rpmInputText = string.Empty;

        /// <summary>Last RPM setpoint commanded via PID or direct set.</summary>
        [ObservableProperty] private double _targetRpm;

        /// <summary>Last voltage sent to the motor CAN parameter.</summary>
        [ObservableProperty] private double _commandVoltage;

        // ── Counter ───────────────────────────────────────────────────────────────

        /// <summary>Controls the counter popup visibility.</summary>
        [ObservableProperty] private bool _isCounterPopupOpen;

        /// <summary>Text in the counter input field.</summary>
        [ObservableProperty] private string _counterInputText = string.Empty;

        /// <summary>Live counter count-down value read from CAN.</summary>
        [ObservableProperty] private double _benchCounterValue;

        // ── Constructor ───────────────────────────────────────────────────────────

        /// <summary>
        /// Creates the bench control ViewModel and subscribes to service events.
        /// </summary>
        /// <param name="benchService">Bench service for RPM, relay, and parameter operations.</param>
        /// <param name="configService">Configuration service for bench parameters.</param>
        public BenchControlViewModel(IBenchService benchService, IConfigurationService configService)
        {
            _bench  = benchService;
            _config = configService;

            _bench.RpmCommandSent += () =>
                Application.Current.Dispatcher.Invoke(() =>
                {
                    TargetRpm      = _bench.LastTargetRpm;
                    CommandVoltage = _bench.LastCommandVoltage;
                });
        }

        // ── Direction toggle ──────────────────────────────────────────────────────

        partial void OnIsDirectionRightChanged(bool value)
        {
            _bench.SetRelay(RelayNames.DirectionRight, value);
            _bench.SetRelay(RelayNames.DirectionLeft, !value);
        }

        /// <summary>Sets the bench rotation direction to clockwise (right).</summary>
        [RelayCommand]
        private void SetDirectionRight() => IsDirectionRight = true;

        /// <summary>Sets the bench rotation direction to counter-clockwise (left).</summary>
        [RelayCommand]
        private void SetDirectionLeft() => IsDirectionRight = false;

        // ── Oil pump toggle ───────────────────────────────────────────────────────

        partial void OnIsOilPumpOnChanged(bool value)
        {
            // Show confirmation dialog when turning oil pump ON (WAcceptOilTurnOn equivalent).
            if (value)
            {
                var vm  = new OilPumpConfirmViewModel();
                var dlg = new OilPumpConfirmDialog(vm) { Owner = Application.Current.MainWindow };
                dlg.ShowDialog();

                if (!vm.Accepted)
                {
                    // Revert without re-triggering this handler.
                    _isOilPumpOn = false;
                    OnPropertyChanged(nameof(IsOilPumpOn));
                    return;
                }
            }

            _bench.SetRelay(RelayNames.OilPump, value);

            // The dialog's ShowDialog call runs a nested dispatcher message pump.
            // While it was blocking, RefreshFromTick may have fired and written
            // _isOilPumpOn back to the stale relay.State value (false, because
            // SetRelay above hadn't run yet). Re-assert the backing field now
            // that relay.State is committed so IsOilPumpOn reports the correct
            // value to callers downstream (e.g. TestsPageViewModel.StartTestAsync
            // which guards on it right after this setter returns).
            // See docs/gotcha-oil-pump-dialog-race.md.
            if (_isOilPumpOn != value)
            {
                _isOilPumpOn = value;
                OnPropertyChanged(nameof(IsOilPumpOn));
            }
        }

        /// <summary>
        /// Energises the oil-pump relay and flags <see cref="IsOilPumpOn"/> without
        /// presenting the leak-check confirmation dialog. Used by the Dashboard
        /// "Connect &amp; Auto Test" flow when the operator has opted in via
        /// <see cref="AppSettings.AutoTestSkipsOilPumpConfirm"/>. Writes the backing
        /// field directly to avoid re-entering <see cref="OnIsOilPumpOnChanged"/>.
        /// </summary>
        public void TurnOilPumpOnSilent()
        {
            if (_isOilPumpOn) return;
            _bench.SetRelay(RelayNames.OilPump, true);
            _isOilPumpOn = true;
            OnPropertyChanged(nameof(IsOilPumpOn));
        }

        // ── RPM commands ──────────────────────────────────────────────────────────

        /// <summary>Opens the RPM quick-select popup.</summary>
        [RelayCommand]
        private void OpenRpmPopup()
        {
            IsRpmPopupOpen = true;
        }

        /// <summary>
        /// Starts the bench motor at the RPM specified in <see cref="RpmInputText"/>.
        /// Shows a safety warning dialog if the oil pump is off.
        /// </summary>
        [RelayCommand]
        private void StartBench()
        {
            if (!int.TryParse(RpmInputText, out int rpm) || rpm <= 0) return;

            // Safety warning if oil pump is not running (WCareOnRpmOn equivalent).
            if (!IsOilPumpOn)
            {
                var vm  = new RpmSafetyWarningViewModel();
                var dlg = new RpmSafetyWarningDialog(vm) { Owner = Application.Current.MainWindow };
                dlg.ShowDialog();

                switch (vm.Result)
                {
                    case RpmSafetyResult.Cancel:
                        return;
                    case RpmSafetyResult.ProceedWithOil:
                        IsOilPumpOn = true;
                        break;
                    case RpmSafetyResult.ProceedWithoutOil:
                        // Operator accepted the risk.
                        break;
                }
            }

            // Ensure direction relays are set.
            _bench.SetRelay(RelayNames.DirectionRight, IsDirectionRight);
            _bench.SetRelay(RelayNames.DirectionLeft, !IsDirectionRight);

            _bench.StartRpmPid(rpm);
            IsBenchRunning = true;
            IsRpmPopupOpen = false;
        }

        /// <summary>
        /// Stops the bench motor via PID stop and clears direction relays.
        /// </summary>
        [RelayCommand]
        private void StopBench()
        {
            _bench.StopRpmPid();
            _bench.SetRelay(RelayNames.DirectionLeft, false);
            _bench.SetRelay(RelayNames.DirectionRight, false);
            IsBenchRunning = false;
        }

        /// <summary>
        /// Applies the RPM value from <see cref="RpmInputText"/> and starts the bench.
        /// Bound to the inline Apply button in <c>BenchRpmCommandCard</c>.
        /// </summary>
        [RelayCommand]
        private void ApplyRpm() => StartBench();

        /// <summary>
        /// Quick-select button handler: sets the RPM input and starts the bench.
        /// </summary>
        /// <param name="rpmString">RPM value as a string from the button content.</param>
        [RelayCommand]
        private void SetQuickRpm(string rpmString)
        {
            RpmInputText = rpmString;
            StartBench();
        }

        // ── Counter commands ──────────────────────────────────────────────────────

        /// <summary>Toggles the counter popup visibility.</summary>
        [RelayCommand]
        private void ToggleCounterPopup()
        {
            IsCounterPopupOpen = !IsCounterPopupOpen;
        }

        /// <summary>
        /// Sends the counter value over CAN and activates the counter relay.
        /// </summary>
        [RelayCommand]
        private void SendCounter()
        {
            if (!int.TryParse(CounterInputText, out int count) || count <= 0) return;

            // Set the counter parameter value and transmit.
            _bench.SetParameter(BenchParameterNames.Counter, count);
            if (_config.Bench.ParametersByName.TryGetValue(
                    BenchParameterNames.Counter, out var counterParam))
            {
                _bench.SendParameters(counterParam.MessageId);
            }

            // Activate the counter relay.
            _bench.SetRelay(RelayNames.Counter, true);
        }

        // ── Refresh (called from MainViewModel timer tick) ────────────────────────

        /// <summary>
        /// Updates live counter readback from CAN, and mirrors the oil-pump relay
        /// state so this VM's <see cref="IsOilPumpOn"/> stays in sync even when the
        /// relay is toggled outside the manual Bench page (e.g. the Dashboard
        /// auto-test orchestrator). Writes through the backing field to avoid
        /// re-triggering the confirmation dialog in <see cref="OnIsOilPumpOnChanged"/>.
        /// Called on the UI thread from <see cref="MainViewModel.OnRefreshTick"/>.
        /// </summary>
        public void RefreshFromTick()
        {
            BenchCounterValue = _bench.ReadBenchParameter(BenchParameterNames.BenchCounter);

            bool relayOn = _config.Bench.Relays.TryGetValue(RelayNames.OilPump, out var oilRelay) && oilRelay.State;
            if (_isOilPumpOn != relayOn)
            {
                _isOilPumpOn = relayOn;
                OnPropertyChanged(nameof(IsOilPumpOn));
            }
        }
    }
}