using OECS;

namespace Game.CardWars;

/// <summary>
/// Discards field cards, clears tokens, draws new hands, checks game over.
/// </summary>
public class CleanupSystem : ISystem
{
    public void Run(World world)
    {
        var state = world.ReadSingleton<GameState>();
        if (state.Phase != GamePhase.Cleanup) return;

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

        var players = GameUtil.FindAllEntities<Player>(world);
        var publicDeck = GameUtil.FindEntity<PublicDeck>(world);

        foreach (var player in players)
        {
            GameUtil.DiscardField(world, player, publicDeck);

            // Clear tokens on banners.
            var banner = CardEffectHelpers.GetBanner(world, player);
            if (banner != Entity.Null)
            {
                var tokens = world.GetSources<PlacedOn>(banner).ToList();
                foreach (var token in tokens)
                    world.DestroyEntity(token);
            }
        }

        // Draw 2 public cards per player.
        foreach (var player in players)
        {
            for (int i = 0; i < 2; i++)
                GameUtil.DrawCard(world, publicDeck, player);
        }

        // Check game over.
        int maxScore = 0;
        foreach (var player in players)
        {
            var castles = world.GetSources<HeldBy>(player)
                .Where(c => world.HasComponent<Castle>(c))
                .ToList();
            maxScore = Math.Max(maxScore, castles.Count);
        }

        if (maxScore >= 4)
        {
            mutable.Phase = GamePhase.GameOver;
        }
        else
        {
            mutable.Phase = GamePhase.PlayPhase;
            mutable.RoundNumber++;
            mutable.CurrentPlayerIndex = (mutable.StartingPlayerIndex + 1) % mutable.PlayerCount;
            mutable.StartingPlayerIndex = mutable.CurrentPlayerIndex;
            mutable.PlayPhaseEnded = false;
        }

        world.MarkModified<GameState>(World.SingletonEntity);
    }
}