using Cysharp.Threading.Tasks;
using Unity.Mathematics;
using UnityEngine;
using Random = Unity.Mathematics.Random;

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

        [InjectService]
        private ITileSpace _tileSpace;

        public async UniTask Execute(World world)
        {
            await GenerateTreesAsync(world);
        }

        private async UniTask GenerateTreesAsync(World world)
        {
            var config = _config.WorldGen;
            var treeDefinition = await config.Trees.TreeDefinition.LoadAssetAsync<ResourceNodeDefinition>();

            var horizontalResolution = Mathf.FloorToInt(world.Size.x / config.Trees.Spacing);
            var verticalResolution = Mathf.FloorToInt(world.Size.y / config.Trees.Spacing);

            var random = new Random((uint)world.Seed);
            var noiseSalt = world.Seed % ushort.MaxValue * 37;

            for (var x = 0; x < horizontalResolution; x++)
            for (var z = 0; z < verticalResolution; z++)
            {
                var treePosition = new Vector3((x + 0.5f) * config.Trees.Spacing, 0, (z + 0.5f) * config.Trees.Spacing);
                if (z % 2 == 0) treePosition.x += 0.5f * config.Trees.Spacing;

                treePosition.x += Mathf.Lerp(config.Trees.OffsetRange.x, config.Trees.OffsetRange.y, random.NextFloat());
                treePosition.z += Mathf.Lerp(config.Trees.OffsetRange.x, config.Trees.OffsetRange.y, random.NextFloat());

                var tile = _tileSpace.WorldToTile(treePosition);

                if (!EnoughSpaceAround(world, tile)) continue;

                var h = world.Heightmap.GetValue(tile);
                if (h == 0) continue;

                treePosition.y = h;

                var noiseSamplePos = new float2(h * 997 + x, noiseSalt + z) * config.Trees.NoiseScale;
                var n = noise.snoise(noiseSamplePos);
                if (n < 1 - config.Trees.Coverage && random.NextFloat() < 1 - config.Trees.RandomTreeChance) continue;

                world.RawResources.AddResourceNode(
                    new ResourceNode
                    {
                        Id = 1 + world.RawResources.Count,
                        DefinitionId = treeDefinition.RuntimeId,
                        Position = treePosition,
                        Tile = tile,
                        Elevation = _tileSpace.GetElevation(treePosition.y),
                        CanBeDeleted = true
                    });

                world.BlockMap.AddReason(tile, BlockReason.RawResource);
            }
        }

        private static bool EnoughSpaceAround(World world, int2 center)
        {
            const int radius = 1;

            for (var x = -radius; x <= radius; x++)
            for (var y = -radius; y <= radius; y++)
            {
                var p = center + new int2(x, y);

                if (!world.Contains(p)) continue;

                if (world.Fertility.GetValue(p).MaxFertility > 0) return false;
            }

            return true;
        }
    }
}