using OECS;

namespace Game.CardWars;

/// <summary>
/// Calculates each player's battle power, awards the castle to the winner,
/// and checks for game end.
/// </summary>
public class ScoringSystem : ISystem
{
    public void Run(World world)
    {
        var state = world.ReadSingleton<GameState>();
        if (state.Phase != GamePhase.Scoring) return;

        ref var mutable = ref world.GetSingleton<GameState>();

        var players = GameUtil.FindAllEntities<Player>(world);
        if (players.Count == 0) return;

        int bestPower = int.MinValue;
        Entity winner = Entity.Null;
        int winnerIndex = -1;

        for (int i = 0; i < players.Count; i++)
        {
            int idx = (state.StartingPlayerIndex + i) % players.Count;
            var player = players[idx];
            int power = GameUtil.CalculatePower(world, player);

            if (power > bestPower)
            {
                bestPower = power;
                winner = player;
                winnerIndex = idx;
            }
        }

        if (winner != Entity.Null)
        {
            var castles = GameUtil.FindAllEntities<Castle>(world);
            if (castles.Count > 0)
            {
                var castle = castles[0];
                world.AddComponent(castle, new HeldBy { Source = castle, Target = winner });
                world.RemoveComponent<Castle>(castle);
            }

            var colors = new[] { CastleColor.Black, CastleColor.White, CastleColor.Blue,
                CastleColor.Brown, CastleColor.Yellow, CastleColor.Indigo, CastleColor.Gold };
            int colorIdx = Mulberry32.NextInt(ref mutable.Seed, 0, colors.Length - 1);
            var newCastle = world.CreateEntity();
            world.AddComponent(newCastle, new Castle { Color = colors[colorIdx] });
        }

        mutable.Phase = GamePhase.Cleanup;
        world.MarkModified<GameState>(World.SingletonEntity);
    }
}