using System.Collections.Generic;
using InfiniteWorld.VoxelWorld.Contracts;
using UnityEngine;
using UnityEngine.AI;

namespace InfiniteWorld.VoxelWorld.NavMesh
{
    internal static class NavBuildSourceCollector
    {
        public static bool CollectBuildSources(
            IChunkNavSourceReader chunkNavSourceReader,
            Bounds coverageBounds,
            List<Vector2Int> loadedChunkCoords,
            List<NavMeshBuildSource> results)
        {
            loadedChunkCoords.Clear();
            chunkNavSourceReader.GetLoadedChunkCoords(loadedChunkCoords);

            bool hasSources = false;
            for (int i = 0; i < loadedChunkCoords.Count; i++)
            {
                Vector2Int chunkCoord = loadedChunkCoords[i];
                if (!NavMeshBoundsUtility.IntersectsXZ(GetChunkWorldBounds(chunkNavSourceReader, chunkCoord), coverageBounds))
                {
                    continue;
                }

                if (!chunkNavSourceReader.TryGetChunkNavSourceSnapshot(chunkCoord, out ChunkNavSourceSnapshot snapshot) || snapshot.Sources == null || snapshot.Sources.Length == 0)
                {
                    continue;
                }

                hasSources = true;
                AppendBuildSources(snapshot.Sources, results);
            }

            return hasSources;
        }

        public static Bounds GetChunkWorldBounds(IChunkNavSourceReader chunkNavSourceReader, Vector2Int chunkCoord)
        {
            float chunkSize = Mathf.Max(1f, chunkNavSourceReader.ChunkWorldSize);
            Vector3 min = new Vector3(chunkCoord.x * chunkSize, -500f, chunkCoord.y * chunkSize);
            Vector3 size = new Vector3(chunkSize, 1000f, chunkSize);
            return new Bounds(min + new Vector3(chunkSize * 0.5f, 0f, chunkSize * 0.5f), size);
        }

        public static Bounds ExpandCoverageBounds(IChunkNavSourceReader chunkNavSourceReader, Bounds bounds, int chunkMargin)
        {
            return ExpandChunkBounds(chunkNavSourceReader, bounds, chunkMargin);
        }

        public static Bounds ExpandChunkBounds(IChunkNavSourceReader chunkNavSourceReader, Bounds bounds, int chunkMargin)
        {
            float chunkSize = Mathf.Max(1f, chunkNavSourceReader.ChunkWorldSize);
            float horizontalPadding = chunkMargin * chunkSize;
            bounds.Expand(new Vector3(horizontalPadding * 2f, 0f, horizontalPadding * 2f));
            return bounds;
        }

        private static void AppendBuildSources(ChunkNavBuildSourceDescriptor[] descriptors, List<NavMeshBuildSource> results)
        {
            for (int i = 0; i < descriptors.Length; i++)
            {
                ChunkNavBuildSourceDescriptor descriptor = descriptors[i];
                if (descriptor.Shape == NavMeshBuildSourceShape.Mesh && descriptor.Mesh == null)
                {
                    continue;
                }

                NavMeshBuildSource source = new NavMeshBuildSource
                {
                    area = descriptor.Area,
                    shape = descriptor.Shape,
                    transform = descriptor.Transform,
                    size = descriptor.Size,
                    sourceObject = descriptor.Shape == NavMeshBuildSourceShape.Mesh ? descriptor.Mesh : null
                };

                results.Add(source);
            }
        }
    }
}