<?php

/* This file will contain the much wanted create_hex_graph file. */

class create_hex_graph
{
    protected $hex_graph = array();



/* The constructor takes an x, y coordinate as well as the number of layers to return to
 * the page that requested it. */
    function __construct($coord_x, $coord_y, $layer_min, $layer_max)
    {
	$i = $layer_min;
	$start_marker = 1;

	while($i <= $layer_max)
	{
	    /* The start marker is needed otherwise the array_merge function will try to combine
	     * a non-existant array with an existing array. The $i in this case is the layer number that
	     * this function wants. */
	    if($start_marker == 1)
	    {
		$hex_graph = $this->create_hex_layer($coord_x, $coord_y, $i);
		$start_marker = 0;
	    }

	    else
	    {
		$pre_hex_graph = $this->create_hex_layer($coord_x, $coord_y, $i);

		$hex_graph = array_merge($hex_graph, $pre_hex_graph);
	    }

	    
	    $i++;
	}

	$this->hex_graph = $hex_graph;

    }


/* This function creates a linear array (0 -> size_of_array) that contains two values, the
 * x and y coordinates of a hex that can  be found of a specific hex that is $layer_level layers
 * away from the starting hex 
 *
 * IMPORTANT NOTES: In some while loops you will see if(!($cursor_x & 1)) instead of if($cursor_x & 1).
 * This is because hexes work a bit differently when going from right to left than left to right.
 * To fix this we have some while loops do an if-not check instead of an if check. */
    function create_hex_layer($coord_x, $coord_y, $layer_level)
    {
	$cursor_x = $coord_x;
	$cursor_y = $coord_y;
	$cursor_y = $cursor_y + $layer_level;
	$layer_graph_cursor = 0;

	/* This if clause is here because it is asking for the 0th level, which would be the starting hex. */
	$i = 0;
	if($layer_level == 0)
	{
	    $layer_graph[$layer_graph_cursor]['x'] = $cursor_x;
	    $layer_graph[$layer_graph_cursor]['y'] = $cursor_y;
	    $layer_graph_cursor++;
	}


	/* Now we are working clockwise around the layer. If we are getting level two this is
	 * where we would be right now. Layers 0 and 1 are only used for reference, they do
	 * not exist or are inserted into the array. This is just for level 2. The arrays are
	 * combined in the constructor.
	 *      
	 *        2  <-
	 *
	 *        1
	 *    1       1
	 *        0
	 *    1       1
	 *        1
	 *
	 *        
	 * What the while loop does is add in more hexes like so:
	 *
	 *        2    _______
	 *            2       |<- Inserted into array
	 *        1       2___|
	 *    1       1
	 *        0
	 *    1       1
	 *        1
	 *
	 *        */
	while($i < $layer_level)
	{
	    $layer_graph[$layer_graph_cursor]['x'] = $cursor_x;
	    $layer_graph[$layer_graph_cursor]['y'] = $cursor_y;

            /* The if clause goes after the x is incremented. In other while loops
	     * it goes before the x is incremented. Be careful of this! */
	    $cursor_x++;
	    if($cursor_x & 1)
	    {
		$cursor_y--;
	    }

	    $i++;
	    $layer_graph_cursor++;
	}


	/*
	 *
	 *        2
	 *            2
	 *        1       2
	 *    1       1    _____
	 *        0       2     |
	 *    1       1         |<- These values are inserted.
	 *        1       2_____|
	 *
	 *   */
	$i = 0;
	while($i < $layer_level)
	{
	    $layer_graph[$layer_graph_cursor]['x'] = $cursor_x;
	    $layer_graph[$layer_graph_cursor]['y'] = $cursor_y;

	    $cursor_y--;

	    $i++;
	    $layer_graph_cursor++;
	}


	/*
	 *
	 *        2
	 *            2
	 *        1       2
	 *    1       1
	 *        0       2
	 *    1       1
	 *        1    ___2_
	 *            2     |<- these values are inserted
	 *        2_________|
	 *
	 *        */
	$i = 0;
	while($i < $layer_level)
	{
	    $layer_graph[$layer_graph_cursor]['x'] = $cursor_x;
	    $layer_graph[$layer_graph_cursor]['y'] = $cursor_y;



	    $cursor_x--;
	    if($cursor_x & 1)
	    {
		$cursor_y--;
	    }

	    $i++;
	    $layer_graph_cursor++;
	}


	/*
	 *
	 *          2
	 *              2
	 *          1       2
	 *      1       1
	 *          0       2
	 *      1       1
	 *  2       1       2
	 * |    2       2     
	 * |_____|  2
	 *   |
	 *These values are inserted
	 *        */
	$i = 0;
	while($i < $layer_level)
	{
	    $layer_graph[$layer_graph_cursor]['x'] = $cursor_x;
	    $layer_graph[$layer_graph_cursor]['y'] = $cursor_y;

	    $cursor_x--;
	    if(!($cursor_x & 1))
	    {
		$cursor_y++;
	    }

	    $i++;
	    $layer_graph_cursor++;
	}


	/*
	 *
	 *          2
	 * _             2
	 *| 2       1       2
	 *|     1       1
	 *|_2       0       2
	 *      1       1
	 *  2       1       2
	 *      2       2     
	 *          2
	 *
	 *
	 *        */
	$i = 0;
	while($i < $layer_level)
	{
	    $layer_graph[$layer_graph_cursor]['x'] = $cursor_x;
	    $layer_graph[$layer_graph_cursor]['y'] = $cursor_y;

	    $cursor_y++;

	    $i++;
	    $layer_graph_cursor++;
	}


	/*    Inserted
	 *      |
	 *     \_/    2
	 *      2        2
	 *  2       1       2
	 *      1       1
	 *  2       0       2
	 *      1       1
	 *  2       1       2
	 *      2       2     
	 *          2
	 *
	 *
	 *        */
	$i = 0;
	while($i < $layer_level)
	{
	    $layer_graph[$layer_graph_cursor]['x'] = $cursor_x;
	    $layer_graph[$layer_graph_cursor]['y'] = $cursor_y;


	    $cursor_x++;
	    if(!($cursor_x & 1))
	    {
		$cursor_y++;
	    }


	    $i++;
	    $layer_graph_cursor++;
	}

	return $layer_graph;
    }

    function get_hex_graph()
    {
	$result = $this->hex_graph;
	return $result;
    }
}