using System.Collections.Generic;
using Cysharp.Threading.Tasks;
using Unity.Mathematics;
using Random = Unity.Mathematics.Random;

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

        [InjectService]
        private ITileSpace _tileSpace;

        public async UniTask Execute(World world)
        {
            return; // Temporarily disabled
            
            var blockMap = world.BlockMap;
            var resourcesState = world.RawResources;

            var config = _config.WorldGen.Stone;
            var stoneDefinition = await config.StoneDefinition.LoadAssetAsync<ResourceNodeDefinition>();

            var random = new Random((uint)world.Seed);
            var count = random.NextInt(config.Count.x, config.Count.y + 1);

            var candidates = new List<(int2, int2, Directions)>();
            foreach (var tile in TileRange.From(1, world.Size - 2))
                if (ValidateCandidate(world, tile, out var side, out var orientation))
                    candidates.Add((tile, side, orientation));

            var current = new List<int2>(count);
            while (candidates.Count > 0 && current.Count < count)
            {
                var i = random.NextInt(candidates.Count);
                var (tile, side, orientation) = candidates[i];
                candidates[i] = candidates[^1];
                candidates.RemoveAt(candidates.Count - 1);

                if (TooCloseToOtherResources(tile, current, config.Spacing)) continue;

                current.Add(tile);

                var position = _tileSpace.TileToWorld(tile);
                resourcesState.AddResourceNode(
                    new ResourceNode
                    {
                        Id = 1 + resourcesState.Count,
                        DefinitionId = stoneDefinition.RuntimeId,
                        Position = position,
                        Tile = tile,
                        Orientation = orientation,
                        Elevation = _config.GeneralSettings.BaseElevation
                    });

                blockMap.AddReason(tile, BlockReason.RawResource);
                blockMap.AddReason(tile + side, BlockReason.RawResource);
                blockMap.AddReason(tile - side, BlockReason.RawResource);
            }
        }

        private bool ValidateCandidate(World world, int2 tile, out int2 side, out Directions orientation)
        {
            side = default;
            orientation = default;
            return world.Heightmap.GetValue(tile) == _config.GeneralSettings.BaseElevation &&
                   !world.BlockMap.IsBlocked(tile) &&
                   NextToCliff(world, tile, out side, out orientation);
        }

        private bool NextToCliff(World world, int2 tile, out int2 side, out Directions orientation)
        {
            side = new int2(0, 1);

            if (NextToCliff(world, tile, new int2(1, 0), side))
            {
                orientation = Directions.East;
                return true;
            }

            if (NextToCliff(world, tile, new int2(-1, 0), side))
            {
                orientation = Directions.West;
                return true;
            }

            side = new int2(1, 0);

            if (NextToCliff(world, tile, new int2(0, 1), side))
            {
                orientation = Directions.North;
                return true;
            }

            if (NextToCliff(world, tile, new int2(0, -1), side))
            {
                orientation = Directions.South;
                return true;
            }

            orientation = default;
            return false;
        }

        private bool NextToCliff(World world, int2 bottomTile, int2 direction, int2 side)
        {
            var topTile = bottomTile + direction;
            var baseElevation = _config.GeneralSettings.BaseElevation;

            return world.Heightmap.GetValue(bottomTile + side) == baseElevation &&
                   world.Heightmap.GetValue(bottomTile - side) == baseElevation &&
                   world.Heightmap.GetValue(topTile) > baseElevation &&
                   world.Heightmap.GetValue(topTile + side) > baseElevation &&
                   world.Heightmap.GetValue(topTile - side) > baseElevation;
        }

        private static bool TooCloseToOtherResources(int2 tile, List<int2> alreadyPlaced, int spacing)
        {
            foreach (var other in alreadyPlaced)
                if (TileMath.StepCount(tile, other) < spacing)
                    return true;
            return false;
        }
    }
}