using System.Collections.Generic;

using Gamecraft.Wires;
using RobocraftX.Blocks;
using RobocraftX.Common;
using RobocraftX.GUI.Hotbar.Colours;
using RobocraftX.Physics;
using RobocraftX.Scene.Simulation;
using Svelto.DataStructures;
using Svelto.ECS;

using GamecraftModdingAPI.Engines;
using GamecraftModdingAPI.Utility;

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

		public EntitiesDB entitiesDB { set; private get; }

		public bool isRemovable => false;

		internal bool Synced = true;

		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)
			foreach (ref var conn in ecoll)
				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] = new Block(cubes[i]);
			return ret;
		}

		public void SetBlockColorFromPalette(ref ColourParameterEntityStruct color)
		{
			ref var paletteEntry = ref entitiesDB.QueryEntity<PaletteEntryEntityStruct>(color.indexInPalette,
				CommonExclusiveGroups.COLOUR_PALETTE_GROUP);
			color.paletteColour = paletteEntry.Colour;
		}

		/// <summary>
		/// Get a struct of a block. Can be used to set properties.
		/// Returns a default value if not found.
		/// </summary>
		/// <param name="blockID">The block's ID</param>
		/// <typeparam name="T">The struct to query</typeparam>
		/// <returns>An editable reference to the struct</returns>
		public ref T GetBlockInfo<T>(EGID blockID) where T : struct, IEntityComponent
		{
			if (!Synced)
			{
				Sync();
				Synced = true;
			}
			if (entitiesDB.Exists<T>(blockID))
				return ref entitiesDB.QueryEntity<T>(blockID);
			T[] structHolder = new T[1]; //Create something that can be referenced
			return ref structHolder[0]; //Gets a default value automatically
		}

		/// <summary>
		/// Get a struct of a block. Can be used to set properties.
		/// Returns a default value if not found.
		/// </summary>
		/// <param name="blockID">The block's ID</param>
		/// <param name="exists">Whether the specified struct exists for the block</param>
		/// <typeparam name="T">The struct to query</typeparam>
		/// <returns>An editable reference to the struct</returns>
		public ref T GetBlockInfo<T>(EGID blockID, out bool exists) where T : struct, IEntityComponent
		{
			if (!Synced)
			{
				Sync();
				Synced = true;
			}
			exists = entitiesDB.Exists<T>(blockID);
			if (exists)
				return ref entitiesDB.QueryEntity<T>(blockID);
			T[] structHolder = new T[1];
			return ref structHolder[0];
		}

		public bool BlockExists(EGID id)
		{
			if (!Synced)
            {
                Sync();
                Synced = true;
            }
			return entitiesDB.Exists<DBEntityStruct>(id);
		}

		public bool GetBlockInfoExists<T>(EGID blockID) where T : struct, IEntityComponent
		{
			if (!Synced)
            {
                Sync();
                Synced = true;
            }
			return entitiesDB.Exists<T>(blockID);
		}

		public SimBody[] GetSimBodiesFromID(byte id)
		{
			var ret = new FasterList<SimBody>(4);
			if (!entitiesDB.HasAny<ObjectIdEntityStruct>(CommonExclusiveGroups.BUILD_OBJID_BLOCK_GROUP))
				return new SimBody[0];
			var oids = entitiesDB.QueryEntities<ObjectIdEntityStruct>(CommonExclusiveGroups.BUILD_OBJID_BLOCK_GROUP);
			var connections = entitiesDB.QueryMappedEntities<GridConnectionsEntityStruct>(CommonExclusiveGroups.BUILD_OBJID_BLOCK_GROUP);
			foreach (ref ObjectIdEntityStruct oid in oids)
			{
				if (oid.objectId != id) continue;
				var rid = connections.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 ObjectIdentifier[] GetObjectIDsFromID(byte id, bool sim)
		{
			var ret = new FasterList<ObjectIdentifier>(4);
			if (!entitiesDB.HasAny<ObjectIdEntityStruct>(CommonExclusiveGroups.BUILD_OBJID_BLOCK_GROUP))
				return new ObjectIdentifier[0];
			var oids = entitiesDB.QueryEntities<ObjectIdEntityStruct>(CommonExclusiveGroups.BUILD_OBJID_BLOCK_GROUP);
			foreach (ref ObjectIdEntityStruct oid in oids)
				if (sim ? oid.simObjectId == id : oid.objectId == id)
					ret.Add(new ObjectIdentifier(oid.ID));
			return ret.ToArray();
		}

		public SimBody[] GetConnectedSimBodies(uint id)
		{
			var joints = entitiesDB.QueryEntities<JointEntityStruct>(MachineSimulationGroups.JOINTS_GROUP);
			var list = new FasterList<SimBody>(4);
			foreach (var joint in joints)
			{
				if (joint.jointState == JointState.Broken) 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 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;
		}

		/// <summary>
		/// Synchronize newly created entity components with entities DB.
		/// This forces a partial game tick, so it may be slow.
		/// This also has the potential to make Gamecraft unstable.
		/// Use this sparingly.
		/// </summary>
		private static void Sync()
		{
			DeterministicStepCompositionRootPatch.SubmitEntitiesNow();
		}

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