library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;

entity kr_leds is
	port(	clk, reset, obj_ahead, stop 		: in std_logic;
			intensity 			: in std_logic_vector(7 downto 0);
			left_right, fwd_back	: in std_logic_vector(3 downto 0);
			led_out				: buffer std_logic_vector(7 downto 0)
	);
end kr_leds;

architecture behavioural of kr_leds is
--constant max_count: std_logic_vector(13 downto 0) := "00000000000010"; --"10011100010000";
TYPE STATE_TYPE IS (led0, led1, led2, led3, led4, led5, led6, led7);

signal count : std_logic_vector(13 downto 0);
signal max_count : std_logic_vector(13 downto 0);
signal counted, go_left, back : std_logic;
signal state : state_type;
signal normal_out: std_logic_vector(7 downto 0);
signal obj_ahead_out: std_logic_vector(7 downto 0);
signal stop_out, back_out: std_logic_vector(7 downto 0);
signal sample: std_logic_vector(2 downto 0);


begin
	--the max_count is inversely propotional to the intensity of light
	-- plus an offset value
	max_count <= (not intensity) & "111111";
	
	-- assign output for stop mode
	stop_out <= "11111111";

	-- process to do counting to determine when to change states
	counting: process(clk, reset)
	begin
		if reset = '0' then
			count <= (others =>'0');
		elsif rising_edge(clk) then
			if count >= max_count then
				count <= (others => '0');
				counted <= '1';
			else
				count <= count + 1;
				counted <= '0';
			end if;
		end if;
	end process counting;

-- if object ahead
	-- blinking 
	blinking: process(clk)
	begin
		if rising_edge(clk) then
			if fwd_back > "0111" then
				back <= '1';
			else
				back <= '0';
			end if;
			if counted = '1' then
				obj_ahead_out <= not obj_ahead_out;
			end if;
		end if;
	end process blinking;

--	if no object ahead	
--	 process to for the leds to light from left/right
	direction: process(clk)
	begin
		if rising_edge(clk) then
			if left_right = "0111" then
				if state = led0 then	
					go_left <= '0';
				elsif state = led7 then
					go_left <= '1';
				end if;
			elsif left_right > "0111" then
				go_left <= '0';
			else
				go_left <= '1';
			end if;
		end if;
	end process direction;

--	direction2: process(state)
--	begin
--		if state = led0 then	
--			go_left <= '0';
--		elsif state = led7 then
--			go_left <= '1';
--		end if;
--	end process direction2;


	process(clk, reset)
	begin
		if reset = '0' then
			state <= led0;
			go_left <= '0';
		elsif rising_edge(clk) then
			case state is
			when led0 =>
				if counted = '0' then
					state <= led0;
				elsif counted = '1' then	
					if go_left = '0' then
						state <= led1;
					else
						state <= led7;
					end if;
				end if;
			when led1 =>
				if counted = '0' then
					state <= led1;
				elsif counted = '1' then
					if go_left = '0' then
						state <= led2;
					else
						state <= led0;
					end if;
				end if;
			when led2 =>
				if counted = '0' then
					state <= led2;
				elsif counted = '1' then
					if go_left = '0' then
						state <= led3;
					else
						state <= led1;
					end if;
				end if;
			when led3 =>
				if counted = '0' then
					state <= led3;
				elsif counted = '1' then
					if go_left = '0' then
						state <= led4;
					else
						state <= led2;
					end if;
				end if;
			when led4 =>
				if counted = '0' then
					state <= led4;
				elsif counted = '1' then
					if go_left = '0' then
						state <= led5;
					else
						state <= led3;
					end if;
				end if;
			when led5 =>
				if counted = '0' then
					state <= led5;
				elsif counted = '1' then
					if go_left = '0' then
						state <= led6;
					else
						state <= led4;
					end if;
				end if;
			when led6 =>
				if counted = '0' then
					state <= led6;
				elsif counted = '1' then
					if go_left = '0' then
						state <= led7;
					else
						state <= led5;
					end if;
				end if;
			when led7 =>
				if counted = '0' then
					state <= led7;
				elsif counted = '1' then
					if go_left = '0' then
						state <= led0;
					else
						state <= led6;
					end if;
				end if;
			end case;
		end if;
	end process;
	
		-- assign output of states
	WITH state SELECT
		normal_out	<=	"00000001"	WHEN	led0,
					"00000010"	WHEN	led1,
					"00000100"	WHEN	led2,
					"00001000"	WHEN	led3,
					"00010000" 	WHEN	led4,
					"00100000"	WHEN	led5,
					"01000000"	WHEN	led6,
					"10000000"	WHEN	led7;


	WITH state SELECT
		back_out <= "00000011" WHEN led0,
				"00000011" WHEN led1,
				"00001100" WHEN led2,
				"00001100" WHEN led3,
				"00110000" WHEN led4,
				"00110000" WHEN led5,
				"11000000" WHEN led6,
				"11000000" WHEN led7;
			
	-- assign actual output of the leds
	sample <= obj_ahead & stop & back;
	with sample select
			led_out <= obj_ahead_out when "100",
					stop_out when "010"|"110"|"011"|"111",
					back_out when "001",
					normal_out when others;

end behavioural;