using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using HarmonyLib;

using Gamecraft.ColourPalette;
using Gamecraft.TimeRunning;
using Gamecraft.Wires;
using RobocraftX.Blocks;
using RobocraftX.Common;
using RobocraftX.Physics;
using RobocraftX.Rendering;
using RobocraftX.Rendering.GPUI;
using Svelto.DataStructures;
using Svelto.ECS;
using Svelto.ECS.Hybrid;
using Techblox.BuildingDrone;
using Unity.Mathematics;

using TechbloxModdingAPI.Engines;
using TechbloxModdingAPI.Utility;

namespace TechbloxModdingAPI.Blocks.Engines
{
	/// <summary>
	/// Engine for executing general block actions
	/// </summary>
	public partial class BlockEngine : IApiEngine
	{
		public string Name { get; } = "TechbloxModdingAPIBlockGameEngine";

		public EntitiesDB entitiesDB { set; private get; }

		public bool isRemovable => false;

		public void Dispose()
		{
		}

		public void Ready()
		{
		}

		public Block[] GetConnectedBlocks(EGID blockID)
		{
			if (!BlockExists(blockID)) return new Block[0];
			Stack<EGID> cubeStack = new Stack<EGID>();
			FasterList<EGID> cubes = new FasterList<EGID>(10);
			var coll = entitiesDB.QueryEntities<GridConnectionsEntityStruct>();
			foreach (var (ecoll, _) in coll)
			{
				var ecollB = ecoll.ToBuffer();
				for(int i = 0; i < ecoll.count; i++)
				{
					ref var conn = ref ecollB.buffer[i];
					conn.isProcessed = false;
				}
			}

			ConnectedCubesUtility.TreeTraversal.GetConnectedCubes(entitiesDB, blockID, cubeStack, cubes,
				(in GridConnectionsEntityStruct g) => { return false; });

			var ret = new Block[cubes.count];
			for (int i = 0; i < cubes.count; i++)
				ret[i] = Block.New(cubes[i]);
			return ret;
		}

		public float4 ConvertBlockColor(byte index) => index == byte.MaxValue
			? new float4(-1f, -1f, -1f, -1f)
			: entitiesDB.QueryEntity<PaletteEntryEntityStruct>(index,
				CommonExclusiveGroups.COLOUR_PALETTE_GROUP).Colour;

		public OptionalRef<T> GetBlockInfoOptional<T>(Block block) where T : unmanaged, IEntityComponent
		{
			return entitiesDB.QueryEntityOptional<T>(block);
		}

		public ref T GetBlockInfo<T>(Block block) where T : unmanaged, IEntityComponent
		{
			return ref entitiesDB.QueryEntityOrDefault<T>(block);
		}

		internal ref T GetBlockInfo<T>(EcsObjectBase obj) where T : unmanaged, IEntityComponent
		{
			return ref entitiesDB.QueryEntityOrDefault<T>(obj);
		}

		public ref T GetBlockInfoViewComponent<T>(Block block) where T : struct, IEntityViewComponent
		{
			return ref entitiesDB.QueryEntityOrDefault<T>(block);
		}

		public void UpdateDisplayedBlock(EGID id)
		{
			if (!BlockExists(id)) return;
			RenderingPatch.UpdateBlocks();
		}

		internal void UpdatePrefab(Block block, byte material, bool flipped)
		{
			var prefabAssetIDOpt = entitiesDB.QueryEntityOptional<PrefabAssetIDComponent>(block);
			uint prefabAssetID = prefabAssetIDOpt
				? prefabAssetIDOpt.Get().prefabAssetID
				: uint.MaxValue;
			if (prefabAssetID == uint.MaxValue)
			{
				if (entitiesDB.QueryEntityOptional<DBEntityStruct>(block)) //The block exists
					throw new BlockException("Prefab asset ID not found for block " + block); //Set by the game
				return;
			}

			uint prefabId =
				PrefabsID.GetOrCreatePrefabID((ushort) prefabAssetID, material, 1, flipped);
			entitiesDB.QueryEntityOrDefault<GFXPrefabEntityStructGPUI>(block).prefabID = prefabId;
			if (block.Exists)
			{
				entitiesDB.PublishEntityChange<CubeMaterialStruct>(block.Id);
				entitiesDB.PublishEntityChange<GFXPrefabEntityStructGPUI>(block.Id);

				ref BuildingActionComponent local =
					ref entitiesDB.QueryEntity<BuildingActionComponent>(BuildingDroneUtility
						.GetLocalBuildingDrone(entitiesDB).ToEGID(entitiesDB));
				local.buildAction = BuildAction.ChangeMaterial;
				local.targetPosition = block.Position;
				this.entitiesDB.PublishEntityChange<BuildingActionComponent>(local.ID);
			}
			//Phyiscs prefab: prefabAssetID, set on block creation from the CubeListData
		}

		public bool BlockExists(EGID blockID)
		{
			return entitiesDB.Exists<DBEntityStruct>(blockID);
		}

		public SimBody[] GetSimBodiesFromID(byte id)
		{
			var ret = new FasterList<SimBody>(4);
			var oide = entitiesDB.QueryEntities<ObjectIdEntityStruct>();
			EGIDMapper<GridConnectionsEntityStruct>? connections = null;
			foreach (var ((oids, count), _) in oide)
			{
				for (int i = 0; i < count; i++)
				{	
					ref ObjectIdEntityStruct oid = ref oids[i];
					if (oid.objectId != id) continue;
					if (!connections.HasValue) //Would need reflection to get the group from the build group otherwise
						connections = entitiesDB.QueryMappedEntities<GridConnectionsEntityStruct>(oid.ID.groupID);
					var rid = connections.Value.Entity(oid.ID.entityID).machineRigidBodyId;
					foreach (var rb in ret)
					{
						if (rb.Id.entityID == rid)
							goto DUPLICATE; //Multiple Object Identifiers on one rigid body
					}

					ret.Add(new SimBody(rid));
					DUPLICATE: ;
				}
			}

			return ret.ToArray();
		}

		public SimBody[] GetConnectedSimBodies(uint id)
		{
			var joints = entitiesDB.QueryEntities<JointEntityStruct>(MachineSimulationGroups.JOINTS_GROUP).ToBuffer();
			var list = new FasterList<SimBody>(4);
			for (int i = 0; i < joints.count; i++)
			{
				ref var joint = ref joints.buffer[i];
				if (joint.isBroken) continue;
				if (joint.connectedEntityA == id) list.Add(new SimBody(joint.connectedEntityB));
				else if (joint.connectedEntityB == id) list.Add(new SimBody(joint.connectedEntityA));
			}

			return list.ToArray();
		}

		public SimBody[] GetClusterBodies(uint cid)
		{
			var groups = entitiesDB.QueryEntities<GridConnectionsEntityStruct>();
			var bodies = new HashSet<uint>();
			foreach (var (coll, _) in groups)
			{
				var array = coll.ToBuffer().buffer;
				for (var index = 0; index < array.capacity; index++)
				{
					var conn = array[index];
					if (conn.clusterId == cid)
						bodies.Add(conn.machineRigidBodyId);
				}
			}

			return bodies.Select(id => new SimBody(id, cid)).ToArray();
		}

		public EGID? FindBlockEGID(uint id)
		{
			var groups = entitiesDB.FindGroups<DBEntityStruct>();
			foreach (ExclusiveGroupStruct group in groups)
			{
				if (entitiesDB.Exists<DBEntityStruct>(id, group))
					return new EGID(id, group);
			}

			return null;
		}

		public Cluster GetCluster(uint sbid)
		{
			var groups = entitiesDB.QueryEntities<GridConnectionsEntityStruct>();
			foreach (var (coll, _) in groups)
			{
				var array = coll.ToBuffer().buffer;
				for (var index = 0; index < array.capacity; index++)
				{
					var conn = array[index];
					//Static blocks don't have a cluster ID but the cluster destruction manager should have one
					if (conn.machineRigidBodyId == sbid && conn.clusterId != uint.MaxValue)
						return new Cluster(conn.clusterId);
				}
			}

			return null;
		}

		public Block[] GetBodyBlocks(uint sbid)
		{
			var groups = entitiesDB.QueryEntities<GridConnectionsEntityStruct>();
			var set = new HashSet<Block>();
			foreach (var (coll, _) in groups)
			{
				var array = coll.ToBuffer().buffer;
				for (var index = 0; index < array.capacity; index++)
				{
					var conn = array[index];
					if (conn.machineRigidBodyId == sbid)
						set.Add(Block.New(conn.ID));
				}
			}

			return set.ToArray();
		}

#if DEBUG
		public EntitiesDB GetEntitiesDB()
		{
			return entitiesDB;
		}
#endif

		[HarmonyPatch]
		public static class RenderingPatch
		{
			private static ComputeRenderingEntitiesMatricesEngine Engine;

			public static void Postfix(ComputeRenderingEntitiesMatricesEngine __instance)
			{
				Engine = __instance;
			}

			public static MethodBase TargetMethod()
			{
				return typeof(ComputeRenderingEntitiesMatricesEngine).GetConstructors()[0];
			}

			public static void UpdateBlocks()
			{
				var data = new RenderingDataStruct();
				Engine.Add(ref data, new EGID(0, CommonExclusiveGroups.BUTTON_BLOCK_GROUP));
			}
		}
	}
}