using System;
using UnityEngine;
using System.Collections;
using System.Collections.Generic;

namespace PvpGame
{
  public class GridValue
	{
		public enum EntityType
		{
			None,
			Tree,
			Rock
		}

		public string id;
		public Vector3 position;
		public EntityType entityType;
		public GameObject go;
	}
	
	public class Grid
	{
		public static Dictionary<string, Grid> grids = new Dictionary<string, Grid> ();
		private Dictionary<int, Dictionary<string, GridValue>> cells = new Dictionary<int, Dictionary<string, GridValue>> ();
		private Dictionary<string, GridValue> objectIndex = new Dictionary<string, GridValue> ();
		private Dictionary<string, int> cellsIndex = new Dictionary<string, int> ();

		public static float coordOffset = 5000f;

		private int max;
		private int cellSize = 0;
		private float convFactor;
		private int width;
		private int cellCount;

		public Grid (int max, int cellSize)
		{
			this.max = max;
			this.cellSize = cellSize;
			this.convFactor = 1.0f / this.cellSize;
			this.width = (int)(this.max / this.cellSize);
			this.cellCount = this.width * this.width;
		}

		public int Count ()
		{
			return objectIndex.Count;
		}

		public static Grid FindOrCreate (string id, int max, int cellSize)
		{
			if (!grids.ContainsKey (id)) {
				grids [id] = new Grid (max, cellSize);
			}
			return grids [id];
		}

		public HashSet<int> CellsWithinBounds (float x, float z)
		{
			x += coordOffset;
			z += coordOffset;

			HashSet<int> mcells = new HashSet<int> ();
			
			int offset = this.cellSize;
			
			int startX = (int)(x - offset);
			int startZ = (int)(z - offset);

			int endX = (int)(x + offset);
			int endZ = (int)(z + offset);
			
			for (int rowNum = startX; rowNum <= endX; rowNum += offset) {
				for (int colNum = startZ; colNum <= endZ; colNum += offset) {
					if (rowNum >= 0 && colNum >= 0) {
						mcells.Add (Hash (rowNum, colNum));
					}
				}
			}
			return mcells;
		}

		public List<GridValue> Neighbors (float x, float z, GridValue.EntityType entityType)
		{
			List<GridValue> result = new List<GridValue> ();
			
			ICollection<GridValue> gridValues;
			HashSet<int> cells = CellsWithinBounds (x, z);
			foreach (int cell in cells) {
				gridValues = GridValuesInCell (cell);
				if (gridValues == null) {
					continue;
				}
				foreach (GridValue gridValue in gridValues) {
					if (gridValue != null) {
						if (entityType == GridValue.EntityType.None) {
							result.Add (gridValue);
						} else if (gridValue.entityType == entityType) {
							result.Add (gridValue);
						}
					}
				}
			}
			return result;
		}

		public ICollection<GridValue>  GridValuesInCell (int cell)
		{
			if (cells.ContainsKey (cell)) {
				return cells [cell].Values;
			} else {
				return null;
			}
		}

		public void Set (GridValue gridValue)
		{
			bool hasExisting = false;
			int oldCellValue = -1;
			string id = gridValue.id;
			
			if (objectIndex.ContainsKey (id)) {
				hasExisting = true;
				oldCellValue = cellsIndex [id];
			}
			
			int cell = Hash (gridValue.position.x + coordOffset, gridValue.position.z + coordOffset);

			Dictionary<string, GridValue> cellGridValues;

			if (hasExisting && oldCellValue != cell) {
				if (cells.ContainsKey (oldCellValue)) {
					cellGridValues = cells [oldCellValue];
					if (cellGridValues.ContainsKey (id)) {
						cellGridValues.Remove (id);
					}
					if (cellGridValues.Count == 0) {
						cells.Remove (oldCellValue);
					}
				}
			}
			cellsIndex [id] = cell;
			objectIndex [id] = gridValue;



			if (cells.ContainsKey (cell)) {
				cellGridValues = cells [cell];
				cellGridValues [id] = gridValue;
			} else {
				cellGridValues = new Dictionary<string, GridValue> ();
				cellGridValues [id] = gridValue;
				cells [cell] = cellGridValues;
			}
		}

		public int Hash (float x, float z)
		{
			return (int)((x * this.convFactor)) + (int)((z * this.convFactor)) * this.width;
		}
	}
}