// To make min/max cube positions scale with screen dimensions, 
// need to change the code to subtract or add min and max to 1/2
// then divide by screen_mul. Not necessary if they stay at 
// their current values, though.

var temp_loc = window.location
var temp_path = temp_loc.pathname
var temp_match = temp_path.split("/")
var temp_length = temp_match.length
var temp_index_1 = temp_path.search("blog")
var temp_index_2 = temp_match[temp_length - 2].search("metricland")
if (temp_index_1 != -1)
	var path_append = '../../../'
else if (temp_index_2 != -1)
	var path_append = './'
else
	var path_append = '../'

var start_idx = -100000
var atom_dim = [97,56]
var units_dim = [atom_dim[0] / 8, atom_dim[1] / 8]
var sprites_dat =
[
	[97,112,path_append + 'images/isometric_cube_01.png',	[1,1,1],  8/16],
	[97,112,path_append + 'images/isometric_pyrd_01.png',	[1,1,1], 13/16],
//	[97,112,path_append + 'images/isometric_icos_02.png',	[2,2,2], 15/16],
	[97,112,path_append + 'images/isometric_cube_02.png',	[2,2,2], 16/16]
]

if (window.innerWidth)
{
	var screen_wid = window.innerWidth
	var screen_hgh = window.innerHeight
}
else if (document.documentElement.clientWidth)
{
	var screen_wid = document.documentElement.clientWidth
	var screen_hgh = document.documentElement.clientHeight
}
else if (document.body.clientWidth)
{
	var screen_wid = document.body.clientWidth
	var screen_hgh = document.body.clientHeight
}

var screen_dim = [screen_wid - atom_dim[0], screen_hgh - atom_dim[1]]
var screen_mul = screen_wid * screen_hgh / 1024 / 768

var grid_table = []
var grid_padding = 8
var grid_dim_x = Math.ceil(screen_wid / units_dim[0] / 2)
var grid_dim_y = Math.ceil(screen_hgh / units_dim[1] / 2)
var grid_size = grid_dim_x + grid_dim_y + grid_padding * 2

var cube_pos = []
var cube_num = 8
var cube_tot = Math.round(screen_mul) * cube_num
/*
var cube_min_lft = 1/6
var cube_max_lft = 2/6
var cube_min_rgt = 5/6
var cube_max_rgt = 6/6
*/
var cube_min_lft = 0/2
var cube_max_lft = 1/2
var cube_min_rgt = 1/2
var cube_max_rgt = 2/2

var snake_seg = 0
var snake_len = 10
var snake_pos = [97,112]
var snake_idx = start_idx + snake_pos[1] / units_dim[1]
var snake_dir = 0
var snake_cll = []
var dir_table =
[
	[-1,-1],
	[+1,-1],
	[+1,+1],
	[-1,+1]
]

function grid_init()
{
	for (var i = 0; i < grid_size; i++)
	{
		grid_table[i] = []
		for (var j = 0; j < grid_size; j++)
		{
			grid_table[i][j] = 0
		}
	}
}

function grid_location(in_coo)
{
	var grid_cll_i = in_coo[0] / units_dim[0]
	var grid_cll_j = in_coo[1] / units_dim[1]
	grid_cll_i = Math.floor((grid_cll_i + grid_cll_j) / 2) + grid_padding + 6
	grid_cll_j = Math.floor((grid_cll_i - grid_cll_j) / 2) + grid_padding - 3 + grid_dim_y
	return [grid_cll_i, grid_cll_j]
}

function cube_init()
{
	for (var iCount = 0; iCount < cube_tot;)
	{
		var pass_bool = true
		if (iCount < cube_tot/2)
			var rand_x = Math.random() * (cube_max_lft - cube_min_lft) + cube_min_lft
		else
			var rand_x = Math.random() * (cube_max_rgt - cube_min_rgt) + cube_min_rgt
		var rand_y = Math.random()
		var coo_x = Math.round(rand_x * screen_dim[0] / atom_dim[0]) * atom_dim[0]
		var coo_y = Math.round(rand_y * screen_dim[1] / atom_dim[1]) * atom_dim[1]
		for (var jCount = 0; jCount < iCount; jCount++)
		{
			if ((coo_x == cube_pos[jCount][0]) && (coo_y == cube_pos[jCount][1]))
			{
				pass_bool = false
				break
			}
		}
		if (pass_bool == true)
		{
			cube_pos[iCount] = [coo_x, coo_y]
			iCount += 1
		}
	}
	cube_pos.sort(cube_sort)
	for (var iCount = 0; iCount < cube_tot; iCount++)
	{
		var coo_this = cube_pos[iCount]
		var img_new = document.createElement('img')
		var img_rand = Math.random()
		var img_this = sprites_dat[0]
		for (var tCount = 0; tCount < sprites_dat.length; tCount++)
		{
			if (img_rand < sprites_dat[tCount][4])
			{
				img_this = sprites_dat[tCount]
				break
			}
		}
		var img_dim = img_this[3]
		var img_buf = Math.max(img_dim[0], img_dim[1]) - 1
		img_new.src = img_this[2]
		img_new.style.width  = img_this[0] + 'px'
		img_new.style.height = img_this[1] + 'px'
		img_new.style.position = 'fixed'
		img_new.style.zIndex = start_idx + coo_this[1] / units_dim[1] + img_buf
		img_new.style.left = coo_this[0] + 'px'
		img_new.style.top  = coo_this[1] + 'px'
		document.body.appendChild(img_new)
		var grid_cll = grid_location(coo_this)
		var grid_cll_i = grid_cll[0]
		var grid_cll_j = grid_cll[1]
		var img_dim_i = img_dim[0]
		var img_dim_j = img_dim[1]
		for (var i = 0; i < img_dim_i; i++)
		{
			for (var j = 0; j < img_dim_j; j++)
			{
				grid_table[grid_cll_i + i][grid_cll_j - j] = 1
			}
		}
	}
}

function cube_sort(a, b)
{
	if (a[1] > b[1]) 
		return +1 
	if (a[1] < b[1]) 
		return -1 
	return 0
}

function snake_init()
{
	for (var i = 0; i < snake_len; i++)
	{
		var img_new = document.createElement('img')
//		var img_this = [97,112,'images/isometric_test' + i + '_01.png',	[1,1,1]]
		var img_this = sprites_dat[0]
		img_new.src = img_this[2]
		img_new.id = 'snake' + i
		img_new.style.width  = img_this[0] + 'px'
		img_new.style.height = img_this[1] + 'px'
		img_new.style.position = 'fixed'
		img_new.style.zIndex = snake_idx
		img_new.style.left = snake_pos[0] + 'px'
		img_new.style.top  = snake_pos[1] + 'px'
		document.body.appendChild(img_new)
		snake_cll[i] = [0,0]
	}
	window.setInterval(snake_move, 250)
}

function snake_move()
{
	var old_pos_x = snake_pos[0]
	var old_pos_y = snake_pos[1]
	var allow_dir = [1,1,1,1]
	if (old_pos_x < 0)
	{
		allow_dir[0] = 0
		allow_dir[3] = 0
	}
	else if (old_pos_x >= screen_dim[0])
	{
		allow_dir[1] = 0
		allow_dir[2] = 0
	}
	if (old_pos_y < 0)
	{
		allow_dir[0] = 0
		allow_dir[1] = 0
	}
	else if (old_pos_y >= screen_dim[1])
	{
		allow_dir[2] = 0
		allow_dir[3] = 0
	}
	if (Math.random() < 0.1)
	{
		var rand_sgn = +1
		if (Math.random() < 0.5)
			rand_sgn = -1
		for (var i = 0; i < 4; i++)
		{
			var temp_dir = snake_dir
			if (temp_dir == 0)
				temp_dir = 4
			if (i == 0)
				temp_dir += rand_sgn
			else if (i == 1)
				temp_dir -= rand_sgn
			else if (i == 2)
				temp_dir += 0
			else if (i == 3)
				temp_dir += 2
			temp_dir %= 4
			if (allow_dir[temp_dir] == 0)
				continue
			if (snake_position(temp_dir, 0) == true)
				break
		}
	}
	snake_position(snake_dir, 1)
}

function snake_position(temp_dir, flag)
{
	var old_pos_x = snake_pos[0]
	var old_pos_y = snake_pos[1]
	var new_dir = dir_table[temp_dir]
	var new_pos_i = old_pos_x + units_dim[0] * new_dir[0]
	var new_pos_j = old_pos_y + units_dim[1] * new_dir[1]
	var new_pos = [new_pos_i, new_pos_j]
	var new_cll = grid_location(new_pos)
	var new_cll_i = new_cll[0]
	var new_cll_j = new_cll[1]
	var new_grid = grid_table[new_cll_i][new_cll_j]
	if (new_grid == 0)
	{
		snake_seg -= 1
		if (snake_seg == -1)
			snake_seg = snake_len - 1
		var old_cll_i = snake_cll[snake_seg][0]
		var old_cll_j = snake_cll[snake_seg][1]
		grid_table[old_cll_i][old_cll_j] = 0
//		grid_table[new_cll_i][new_cll_j] = 1		// buggy because the snake can become trapped
		snake_dir = temp_dir
		snake_pos = new_pos
		snake_cll[snake_seg] = new_cll
		snake_idx += new_dir[1]
		var snake_image = document.getElementById('snake' + snake_seg)
		snake_image.style.left = snake_pos[0] + 'px'
		snake_image.style.top  = snake_pos[1] + 'px'
		snake_image.style.zIndex = snake_idx
		return true
	}
	snake_move()
}

function cube_scatter()
{
	grid_init()
	cube_init()
	snake_init()
}