using System.Collections.ObjectModel;
using System.Linq;
using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using HC_APTBS.Models;
using HC_APTBS.Services;

namespace HC_APTBS.ViewModels
{
    /// <summary>
    /// Represents one test type section (e.g. "F", "DFI", "SVME") containing
    /// a header with metadata and a horizontal list of <see cref="PhaseCardViewModel"/> cards.
    /// </summary>
    public sealed partial class TestSectionViewModel : ObservableObject
    {
        private readonly ILocalizationService _loc;

        /// <summary>Initialises a new test section with a localization service.</summary>
        public TestSectionViewModel(ILocalizationService loc) => _loc = loc;

        // ── Suppress cascade guard ────────────────────────────────────────────────

        private bool _suppressCascade;

        // ── Identity / metadata ───────────────────────────────────────────────────

        /// <summary>Test type identifier (e.g. "F", "DFI", "SVME").</summary>
        [ObservableProperty] private string _testName = string.Empty;

        /// <summary>Human-readable description of the test type.</summary>
        [ObservableProperty] private string _description = string.Empty;

        /// <summary>WPF-UI SymbolIcon name to show in the card header (Fluent Tests page).</summary>
        [ObservableProperty] private string _iconSymbol = "Beaker24";

        /// <summary>Conditioning time in seconds.</summary>
        [ObservableProperty] private int _conditioningTimeSec;

        /// <summary>Measurement time in seconds.</summary>
        [ObservableProperty] private int _measurementTimeSec;

        /// <summary>Measurements per second during the measurement window.</summary>
        [ObservableProperty] private double _measurementsPerSecond;

        // ── UI state ──────────────────────────────────────────────────────────────

        /// <summary>Whether this section's expander is open.</summary>
        [ObservableProperty] private bool _isExpanded = true;

        /// <summary>True when any phase in this test section is currently executing.</summary>
        [ObservableProperty] private bool _isActiveTest;

        /// <summary>
        /// Bidirectional check state for all phases.  Setting this cascades down to
        /// all child <see cref="PhaseCardViewModel.IsEnabled"/> properties; child changes
        /// cascade back up to recalculate this value.
        /// </summary>
        [ObservableProperty] private bool _allPhasesChecked = true;

        // ── Phases ────────────────────────────────────────────────────────────────

        /// <summary>Phase cards shown in the horizontal scroll area.</summary>
        public ObservableCollection<PhaseCardViewModel> Phases { get; } = new();

        // ── Back-reference ────────────────────────────────────────────────────────

        /// <summary>Back-reference to the source model.</summary>
        internal TestDefinition? Source { get; set; }

        // ── Cascade: parent → children ────────────────────────────────────────────

        partial void OnAllPhasesCheckedChanged(bool value)
        {
            if (_suppressCascade) return;

            _suppressCascade = true;
            try
            {
                foreach (var phase in Phases)
                    phase.IsEnabled = value;
            }
            finally
            {
                _suppressCascade = false;
            }
        }

        // ── Commands ──────────────────────────────────────────────────────────────

        /// <summary>Inverts <see cref="AllPhasesChecked"/>. Bound to the section card's click gesture.</summary>
        [RelayCommand]
        private void ToggleAllPhases() => AllPhasesChecked = !AllPhasesChecked;

        // ── Cascade: child → parent ──────────────────────────────────────────────

        /// <summary>
        /// Called by a child <see cref="PhaseCardViewModel"/> when its
        /// <see cref="PhaseCardViewModel.IsEnabled"/> changes.
        /// Recalculates <see cref="AllPhasesChecked"/> without re-cascading.
        /// </summary>
        internal void OnChildEnabledChanged(PhaseCardViewModel _)
        {
            if (_suppressCascade) return;

            _suppressCascade = true;
            try
            {
                AllPhasesChecked = Phases.All(p => p.IsEnabled);
            }
            finally
            {
                _suppressCascade = false;
            }
        }

        // ── Factory ───────────────────────────────────────────────────────────────

        /// <summary>
        /// Creates a <see cref="TestSectionViewModel"/> from a <see cref="TestDefinition"/> model,
        /// populating all child <see cref="PhaseCardViewModel"/> instances.
        /// </summary>
        /// <param name="test">Source test definition.</param>
        /// <param name="showValues">Initial show-operation-values state.</param>
        /// <param name="loc">Localization service for user-facing strings.</param>
        public static TestSectionViewModel FromDefinition(TestDefinition test, bool showValues, ILocalizationService loc)
        {
            var section = new TestSectionViewModel(loc)
            {
                TestName              = test.Name,
                Description           = loc.GetString(MapDescriptionKey(test.Name)),
                IconSymbol            = MapIconSymbol(test.Name),
                ConditioningTimeSec   = test.ConditioningTimeSec,
                MeasurementTimeSec    = test.MeasurementTimeSec,
                MeasurementsPerSecond = test.MeasurementsPerSecond,
                Source                = test
            };

            foreach (var phaseDef in test.Phases)
            {
                var card = new PhaseCardViewModel(loc)
                {
                    Name                 = phaseDef.Name,
                    IsCritical           = phaseDef.IsCritical,
                    IsEnabled            = phaseDef.Enabled,
                    ResultText           = phaseDef.Enabled ? "\u2013" : loc.GetString("Common.Disabled"),
                    ShowOperationValues  = showValues,
                    Source               = phaseDef,
                    EnabledChanged       = section.OnChildEnabledChanged
                };

                // Populate operation values from Sends.
                foreach (var tp in phaseDef.Sends)
                    card.OperationValues.Add(new OperationValueViewModel { Name = tp.Name, Value = tp.Value });

                // Populate readiness conditions from Readies.
                foreach (var tp in phaseDef.Readies)
                    card.ReadyValues.Add(new OperationValueViewModel { Name = tp.Name, Value = tp.Value });

                // Populate graphic result indicators from Receives.
                foreach (var tp in phaseDef.Receives)
                {
                    card.ResultIndicators.Add(new GraphicIndicatorViewModel
                    {
                        ParameterName = tp.Name,
                        ExpectedValue = tp.Value,
                        Tolerance     = tp.Tolerance
                    });
                }

                section.Phases.Add(card);
            }

            section.AllPhasesChecked = section.Phases.All(p => p.IsEnabled);
            return section;
        }

        /// <summary>
        /// Maps a test type identifier to a localization resource key.
        /// Returns the test name itself for unknown types (fail-visible).
        /// </summary>
        private static string MapDescriptionKey(string testName) => testName switch
        {
            TestType.Wl    => "TestType.Warmup",
            TestType.Dfi   => "TestType.Adjustment",
            TestType.F     => "TestType.Flow",
            TestType.Svme  => "TestType.ServoValve",
            TestType.Up    => "TestType.Upstroke",
            TestType.Pfp   => "TestType.PreInjection",
            _              => testName
        };

        /// <summary>
        /// Maps a test type identifier to a WPF-UI SymbolIcon name used in the
        /// Fluent Tests page card header.
        /// </summary>
        private static string MapIconSymbol(string testName) => testName switch
        {
            TestType.Wl    => "Temperature24",
            TestType.Dfi   => "WrenchScrewdriver24",
            TestType.F     => "Drop24",
            TestType.Svme  => "Timeline24",
            TestType.Up    => "ArrowTrendingLines24",
            TestType.Pfp   => "Gauge24",
            _              => "Beaker24"
        };
    }
}