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

namespace DanieleMarotta.RiversongCodeShowcase
{
    public class TerrainGeneratorOperation : IWorldGeneratorOperation
    {
        [InjectService]
        private GameConfig _config;

        [InjectService]
        private IScene _scene;

        [InjectService]
        private WorldRenderingState _renderingState;

        public async UniTask Execute(World world)
        {
            var generators = new List<ChunkMeshGenerator>
            {
                new TerrainChunkMeshGenerator(world, _config),
                new GrassChunkMeshGenerator(world, _config),
                new CropsChunkMeshGenerator(world, _config)
            };

            var chunkSize = _config.WorldGen.ChunkSize;
            var horizontalResolution = Mathf.CeilToInt((float)world.Size.x / chunkSize);
            var verticalResolution = Mathf.CeilToInt((float)world.Size.y / chunkSize);

            for (var x = 0; x < horizontalResolution; x++)
            for (var y = 0; y < verticalResolution; y++)
            {
                var chunk = CreateChunk(x, y);

                foreach (var generator in generators) generator.InitializeChunk(chunk);

                _renderingState.AddTerrainChunk(chunk);
            }

            await UniTask.NextFrame();

            var batch = new List<TerrainChunk>(_config.WorldGen.ChunkGenerationBatchCount);
            var count = 0;

            while (count < _renderingState.TerrainChunks.Count)
            {
                batch.Clear();
                for (var i = 0; i < _config.WorldGen.ChunkGenerationBatchCount; i++)
                {
                    batch.Add(_renderingState.TerrainChunks[count]);
                    if (++count >= _renderingState.TerrainChunks.Count) break;
                }

                foreach (var generator in generators) generator.BeginGeneratingChunks(batch);

                foreach (var generator in generators) await generator.Wait();

                foreach (var generator in generators)
                {
                    generator.EndGeneratingChunks();
                    await UniTask.NextFrame();
                }
            }
        }

        private TerrainChunk CreateChunk(int x, int y)
        {
            var chunk = new TerrainChunk
            {
                Coords = new int2(x, y),
                Root = new GameObject($"Chunk_{x}_{y}")
            };

            chunk.Root.transform.SetParent(_scene.SceneFolders.TerrainChunks);
            chunk.GrassLODs = new TerrainChunk.RenderData[_config.Terrain.GrassLODs.Length];
            chunk.CropsLODs = new TerrainChunk.RenderData[_config.Terrain.CropsLODs.Length];

            return chunk;
        }
    }
}