using System.Collections.Generic;
using Unity.Collections;
using Unity.Jobs;
using Unity.Mathematics;
using UnityEngine;
using Random = Unity.Mathematics.Random;

namespace DanieleMarotta.RiversongCodeShowcase
{
    public abstract class GrassChunkMeshGeneratorBase<T> : ChunkMeshGenerator where T : unmanaged, IGrassTileMask
    {
        protected GrassChunkMeshGeneratorBase(World world, GameConfig config) : base(world, config)
        {
        }

        protected override void InitializeChunk(TerrainChunk chunk, int lod, GameObject gameObject, Mesh mesh, Renderer renderer)
        {
            renderer.enabled = false;
        }

        protected override void OnCompleted(int lod, List<TerrainChunk> chunks)
        {
            foreach (var chunk in chunks)
            {
                var renderer = GetRenderer(chunk, lod);
                renderer.sharedMaterial = GetMaterial(lod);
            }
        }

        protected abstract Renderer GetRenderer(TerrainChunk chunk, int lod);

        protected abstract Material GetMaterial(int lod);

        protected override JobHandle ScheduleJob(ChunkGenerationJobState jobState, NativeArray<int2> chunkCoords)
        {
            var randomArray = new NativeArray<Random>(chunkCoords.Length, Allocator.Persistent);
            for (var i = 0; i < randomArray.Length; i++) randomArray[i] = Random.CreateFromIndex((uint)(World.Seed + i));

            var jobHandle = ScheduleJob(jobState, chunkCoords, randomArray);

            randomArray.Dispose(jobHandle);

            return jobHandle;
        }

        protected abstract JobHandle ScheduleJob(ChunkGenerationJobState jobState, NativeArray<int2> chunkCoords, NativeArray<Random> randomArray);

        protected void PrepareJob(ChunkGenerationJobState jobState, NativeArray<int2> chunkCoords, NativeArray<Random> randomArray, int lod, ref GenerateGrassChunkJob<T> job)
        {
            var grassGenerationConfig = GetGrassGenerationConfig();

            job.WorldSize = World.Size;
            job.ChunkCoordsArray = chunkCoords;
            job.ChunkSize = Config.WorldGen.ChunkSize;
            job.Mask = GetMask();
            job.Heightmap = World.Heightmap.GetNativeArray();
            job.MeshDataArray = jobState.MeshDataArray;
            job.RandomArray = randomArray;
            job.Density = GetDensityForLOD(lod);
            job.NoiseScale = grassGenerationConfig.NoiseScale;
            job.DiscardThreshold = grassGenerationConfig.NoiseDiscardThreshold;
            job.BladeWidth = grassGenerationConfig.BladeWidth;
            job.BladeHeightRange = grassGenerationConfig.BladeHeightRange;
        }

        protected abstract GameConfig.WorldGenConfig.GrassConfig GetGrassGenerationConfig();

        protected abstract T GetMask();

        protected abstract int GetDensityForLOD(int lod);
    }
}