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

namespace HC_APTBS.ViewModels
{
    /// <summary>
    /// Represents one row in the BIP-STATUS display.
    /// </summary>
    public sealed partial class BipRowViewModel : ObservableObject
    {
        /// <summary>Zero-based index of this BIP definition entry.</summary>
        public int Index { get; init; }

        /// <summary>16-bit nibble pattern from the CFG (displayed as "0xXXXX").</summary>
        public string HexPattern { get; init; } = string.Empty;

        /// <summary>Raw hex value — used to re-resolve the description on language change.</summary>
        public ushort RawHex { get; init; }

        /// <summary>SpecialFunction from the CFG — part of the localization key.</summary>
        public int SpecialFunction { get; init; }

        /// <summary>Original XML text, used as fallback when no resource key matches.</summary>
        public string FallbackDescription { get; init; } = string.Empty;

        /// <summary>Human-readable description shown on match; updated on language switch.</summary>
        [ObservableProperty] private string _description = string.Empty;

        /// <summary>HTML hex colour for the status indicator: green = inactive, red = match detected.</summary>
        [ObservableProperty] private string _color = "#26C200";

        /// <summary>True when this BIP pattern currently matches the captured word.</summary>
        [ObservableProperty] private bool _isActive;
    }

    /// <summary>
    /// ViewModel for the BIP-STATUS display user control.
    ///
    /// <para>
    /// Only populated for PSG5-PI pumps (those whose <see cref="PumpDefinition.BipStatus"/>
    /// is non-null). When <see cref="HasDefinition"/> is false the view hides itself.
    /// </para>
    /// </summary>
    public sealed partial class BipDisplayViewModel : ObservableObject
    {
        private readonly ILocalizationService _loc;

        // ── Properties ────────────────────────────────────────────────────────────

        /// <summary>True when the current pump has BIP definitions; controls view visibility.</summary>
        [ObservableProperty] private bool _hasDefinition;

        /// <summary>Last raw BIP word received from the ECU (displayed as hex for diagnostics).</summary>
        [ObservableProperty] private string _rawValue = "–";

        /// <summary>Ordered rows for the BIP definition table.</summary>
        public ObservableCollection<BipRowViewModel> Rows { get; } = new();

        // ── Construction ──────────────────────────────────────────────────────────

        /// <summary>
        /// Initializes the view model and subscribes to language-change notifications
        /// so that row descriptions update automatically when the operator switches language.
        /// </summary>
        public BipDisplayViewModel(ILocalizationService loc)
        {
            _loc = loc;
            _loc.LanguageChanged += RefreshDescriptions;
        }

        // ── Public API ────────────────────────────────────────────────────────────

        /// <summary>
        /// Loads the BIP definition for the selected pump and resets the display.
        /// Pass <see langword="null"/> to hide the control (non-PSG5-PI pump selected).
        /// Must be called on the UI thread.
        /// </summary>
        public void LoadDefinition(PumpBipDefinition? bipDef)
        {
            Rows.Clear();
            RawValue = "–";

            if (bipDef == null || bipDef.Bits.Count == 0)
            {
                HasDefinition = false;
                return;
            }

            foreach (var d in bipDef.Bits)
            {
                Rows.Add(new BipRowViewModel
                {
                    Index               = d.Index,
                    HexPattern          = $"0x{d.HexPattern:X4}",
                    RawHex              = d.HexPattern,
                    SpecialFunction     = d.SpecialFunction,
                    FallbackDescription = d.Description,
                    Description         = ResolveDescription(d.HexPattern, d.SpecialFunction, d.Description),
                    Color               = "#26C200",
                    IsActive            = false
                });
            }

            HasDefinition = true;
        }

        /// <summary>
        /// Updates the display with a newly captured BIP status word.
        /// Marks matching (and enabled) rows as active.
        /// Must be called on the UI thread.
        /// </summary>
        /// <param name="bipDef">Current pump's BIP definition.</param>
        /// <param name="rawWord">Raw 16-bit value read from ECU RAM 0x0106.</param>
        public void UpdateBipWord(PumpBipDefinition bipDef, ushort rawWord)
        {
            RawValue = $"0x{rawWord:X4}";

            for (int i = 0; i < Rows.Count && i < bipDef.Bits.Count; i++)
            {
                var def = bipDef.Bits[i];
                var row = Rows[i];

                // Bitmask match: all pattern bits must be set in rawWord.
                bool matches = def.Enabled && (rawWord & def.HexPattern) == def.HexPattern;
                row.IsActive = matches;
                row.Color    = matches ? "#FF1E1E" : "#26C200";
            }
        }

        /// <summary>Resets all rows to inactive / green without clearing the definitions.</summary>
        public void Reset()
        {
            foreach (var row in Rows)
            {
                row.IsActive = false;
                row.Color    = "#26C200";
            }
            RawValue = "–";
        }

        // ── Helpers ───────────────────────────────────────────────────────────────

        /// <summary>
        /// Returns the localized description for a BIP entry keyed by (hex, specialFunction),
        /// falling back to the raw XML text when no resource key is found.
        /// </summary>
        private static string ResolveDescription(ushort hex, int sf, string fallback)
        {
            var key = $"Pump.Bip.Desc.{hex:X4}.{sf}";
            return Application.Current.Resources[key]?.ToString() ?? fallback;
        }

        /// <summary>
        /// Re-resolves all row descriptions against the now-active resource dictionary.
        /// Called by <see cref="ILocalizationService.LanguageChanged"/>.
        /// </summary>
        private void RefreshDescriptions()
        {
            foreach (var row in Rows)
                row.Description = ResolveDescription(row.RawHex, row.SpecialFunction, row.FallbackDescription);
        }
    }
}