using System.Collections.Generic;

namespace CardGames;

/// <summary>
/// Draws the on-table "value" decals beside hands (Blackjack totals, Poker categories, …). Runs locally on
/// every client off the active game's <see cref="CardGame.HandValueDecals"/>; the decals are non-networked
/// children of this component and are reused/updated by key. Mirrors the empty-slot decals on <c>Pile</c>.
/// </summary>
public sealed class HandValueDecalRenderer : Component
{
	private sealed class Entry
	{
		public GameObject Go;
		public Decal Decal;
		public Texture Tex;
	}

	private readonly Dictionary<string, Entry> _decals = new();
	private readonly List<string> _stale = new();

	protected override void OnUpdate()
	{
		if ( Application.IsHeadless ) return; // decals are purely visual

		var game = Scene.Get<CardGame>();
		var deck = game?.Deck;

		var live = new HashSet<string>();
		if ( game is not null && deck is not null )
		{
			foreach ( var d in game.HandValueDecals() )
			{
				if ( string.IsNullOrEmpty( d.Text ) ) continue;
				live.Add( d.Key );
				Apply( d, deck );
			}
		}

		// Drop decals whose hand is gone or whose label emptied (e.g. between rounds).
		_stale.Clear();
		foreach ( var key in _decals.Keys )
			if ( !live.Contains( key ) ) _stale.Add( key );
		foreach ( var key in _stale )
		{
			_decals[key].Go?.Destroy();
			_decals.Remove( key );
		}
	}

	private void Apply( HandValueDecal d, DeckDefinition deck )
	{
		if ( !_decals.TryGetValue( d.Key, out var e ) )
		{
			var go = new GameObject( true, $"HandValue:{d.Key}" );
			go.Parent = GameObject;

			e = new Entry { Go = go, Decal = go.Components.Create<Decal>(), Tex = null };

			float w = CardMesh.Width * 1.6f;
			e.Decal.Size = new Vector2( w, w / HandValueRenderer.Aspect );
			e.Decal.Depth = 8f;
			e.Decal.Rotation = 0f;          // ParticleFloat otherwise defaults to a random spin
			e.Decal.AttenuationAngle = 0f;  // stay visible top-down
			e.Decal.LifeTime = 0f;          // permanent (we manage its lifetime)
			e.Decal.ColorTint = Color.White.WithAlpha( 0.85f ); // mostly opaque so the white-on-black pill reads

			_decals[d.Key] = e;
		}

		// Sit the pill just past the hand, projected straight down onto the felt. Offset only along the hand's
		// toward-dealer axis (no sideways drift for off-centre seats), picking the sign that points toward the
		// table centre - so player pills sit above their near-edge hands and the dealer's sits below its far one.
		var spot = d.Spot;
		var centre = Scene.Get<TableAnchor>()?.WorldPosition ?? spot.Position;
		float sign = Vector3.Dot( centre - spot.Position, spot.Rotation.Left ) < 0f ? -1f : 1f;

		e.Go.WorldRotation = Rotation.LookAt( -spot.Rotation.Up, spot.Rotation.Left );
		e.Go.WorldPosition = spot.Position + spot.Rotation.Left * (sign * CardMesh.Height * 0.7f) + spot.Rotation.Up * 2f;

		// Compare the actual texture, not the text: the build cache clears on hotload and returns a fresh
		// texture, so a style edit (colours, layout) shows live instead of being masked by a per-text guard.
		var tex = HandValueRenderer.BuildLabel( deck, d.Text );
		if ( e.Tex != tex )
		{
			e.Decal.Decals = new List<DecalDefinition>
			{
				new() { ColorTexture = tex, Width = 1f, Height = 1f, ColorMix = 1f }
			};
			e.Tex = tex;
		}
	}
}