local DEFAULT_BG_COLOR = "fc05e344"
local DEFAULT_FG_COLOR = "fc059dd0"
local DEFAULT_HL_COLOR = "fc059db0"
if not sparktech then sparktech = {} end
function sparktech.makebar(texture, posx, posy, sizex, sizey, value, maxvalue, direction)
	-- direction = where to cut the texture either from thr right(0), below(1) left(2) or above (3)
	-- default is right(0)
	--texture texture name , no folder required
	--sizex the size to modify
	if direction == nil then direction = 0 end --direction is optional this way
	-- format : image[X,Y;W,H;texture_name]

	local ratio = value / maxvalue
	
	if direction == 0 then
		sizex = ratio * sizex
	elseif direction == 1 then
		sizey = ratio * sizey
	elseif direction == 2 then
		posx = posx + (sizex - (ratio * sizex))
		sizex = ratio * sizex
	elseif direction == 3 then
		posy = posy + (sizey - (ratio * sizey))
		sizey = ratio * sizey
	end

	return "image[" .. posx .. "," .. posy .. ";"  .. sizex .. "," .. sizey .. ";" .. texture .. "]"
end

function verify_hexcolor_or_nil(s)
	if not s or #s ~= 8 or s:find("[^abcdefABCDEF0123456789]") then
		return nil
	end
	return s
end

function sparktech.add_inventory(size_x, size_y, formspec) -- pass an unfinished formspec with minimum size, this function adds an inventory
	local bg_color = verify_hexcolor_or_nil(minetest.settings:get("spark_gui_background")) or DEFAULT_BG_COLOR
	local fg_color = verify_hexcolor_or_nil(minetest.settings:get("spark_gui_foreground")) or DEFAULT_FG_COLOR
	local fg_highlight = verify_hexcolor_or_nil(minetest.settings:get("spark_gui_highlight")) or DEFAULT_HL_COLOR
	local gui_immersive	
	if minetest.settings:get("spark_gui_full") then
		gui_immersive = "true"
	else
		gui_immersive = "false"
	end
	if not size_x or size_x < 13.9 then size_x = 13.9 end
	if not size_y or size_y < 0 then size_y = 0 end
	local l_formspec = "size[" .. tostring(size_x) .. "," .. (size_y + 4.8) .. "]" ..
		"real_coordinates[true]" ..
		"list[current_player;main;0," .. size_y .. ";8,3;8]" ..
		"list[current_player;main;0," .. (size_y + 3.8 ) .. ";8,1;]"..
		"list[current_player;craft;10.4," .. size_y .. ";3,3]" ..
		"list[current_player;craftpreview;10.4," .. (size_y + 3.8) .. ";1,1]" ..
		"listcolors[#" .. fg_color .. ";#" .. fg_highlight .. "]" ..
		"bgcolor[#" .. bg_color .. ";" .. gui_immersive .. "]"
	if not formspec then formspec = "" end
	l_formspec = l_formspec .. formspec
	return l_formspec
end