local modstorage = minetest.get_mod_storage()

local register_on_message = minetest.register_on_sending_chat_message
if minetest.register_on_sending_chat_messages then
	register_on_message = minetest.register_on_sending_chat_messages
end

local function rgb_to_hex(rgb)
	local hexadecimal = '#'

	for key, value in pairs(rgb) do
		local hex = ''

		while(value > 0)do
			local index = math.fmod(value, 16) + 1
			value = math.floor(value / 16)
			hex = string.sub('0123456789ABCDEF', index, index) .. hex			
		end

		if(string.len(hex) == 0)then
			hex = '00'

		elseif(string.len(hex) == 1)then
			hex = '0' .. hex
		end

		hexadecimal = hexadecimal .. hex
	end

	return hexadecimal
end

local function color_from_hue(hue)
	local h = hue / 60
	local c = 255
	local x = (1 - math.abs(h%2 - 1)) * 255

  	local i = math.floor(h);
  	if (i == 0) then
		return rgb_to_hex({c, x, 0})
  	elseif (i == 1) then 
		return rgb_to_hex({x, c, 0})
  	elseif (i == 2) then 
		return rgb_to_hex({0, c, x})
	elseif (i == 3) then
		return rgb_to_hex({0, x, c});
	elseif (i == 4) then
		return rgb_to_hex({x, 0, c});
	else 
		return rgb_to_hex({c, 0, x});
	end
end

register_on_message(function(message)
	if message:sub(1,1) == "/" or modstorage:get_string("color") == "" or modstorage:get_string("color") == "white" then
		return false
	end

	minetest.send_chat_message(minetest.get_color_escape_sequence(modstorage:get_string("color")) .. message)
	return true
end)

minetest.register_chatcommand("set_color", {
	description = minetest.gettext("Change chat color"),
	func = function(colour)
		modstorage:set_string("color", colour)
		return true, "Chat color changed."
	end,
})

minetest.register_chatcommand("rainbow", {
	description = minetest.gettext("rainbow text"),
	func = function(param)
		local step = 360 / param:len()
 		local hue = 0
     		 -- iterate the whole 360 degrees
		local output = ""
      		for i = 1, param:len() do
			local char = param:sub(i,i)
			if char:match("%s") then
				output = output .. char
			else
        			output = output  .. minetest.get_color_escape_sequence(color_from_hue(hue)) .. char 
			end
        		hue = hue + step
		end
		minetest.send_chat_message(output)
		return true
end,
})