using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using Cysharp.Threading.Tasks;
using Unity.Mathematics;
using UnityEngine;

namespace DanieleMarotta.RiversongCodeShowcase
{
    [Service(typeof(IAoERenderingService))]
    [GameSystemGroup(typeof(LateGameSystemGroup))]
    public class AoERenderingSystem : GameSystem, IInitializable, IDisposable, IUpdatable, IAoERenderingService
    {
        private const int MaxAoECount = 16;

        private static readonly int AoESourcesPropertyID = Shader.PropertyToID("_AoE_Sources");

        private static readonly int AoECountPropertyID = Shader.PropertyToID("_AoE_Count");

        [InjectService]
        private GameConfig _config;

        [InjectService]
        private IBuildingVisualizationCollection _buildingVisualizationCollection;

        private ComputeBuffer _aoeBuffer;

        private List<AoE> _data = new(MaxAoECount);

        public AoERenderingSystem(IServiceLocator serviceLocator) : base(serviceLocator)
        {
        }

        public UniTask InitializeAsync()
        {
            _aoeBuffer = new ComputeBuffer(MaxAoECount, sizeof(int) + sizeof(float) * 4, ComputeBufferType.Structured, ComputeBufferMode.Dynamic);

            return UniTask.CompletedTask;
        }

        public void Dispose()
        {
            _aoeBuffer.Dispose();
        }

        public void Update()
        {
            _aoeBuffer.SetData(_data);

            var material = _config.Vfx.AoEMaterial;
            material.SetBuffer(AoESourcesPropertyID, _aoeBuffer);
            material.SetInt(AoECountPropertyID, _data.Count);

            _data.Clear();
        }

        public void Add(int layer, TileRect rect)
        {
            _data.Add(
                new AoE
                {
                    Layer = layer,
                    Rect = new float4(rect.Min, rect.Max)
                });
        }

        [StructLayout(LayoutKind.Sequential)]
        private struct AoE
        {
            public int Layer;

            public float4 Rect;
        }
    }
}