library ieee;

use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
use ieee.numeric_std.all;

entity image_generator is
    generic (
        input_clk: integer
    );
    port (
        clk: in std_logic;
        x, y: in std_logic_vector(9 downto 0);
        ctrl_up: in std_logic;
        ctrl_down: in std_logic;

        rgb: out std_logic_vector(23 downto 0)
    );
end image_generator;


architecture logic of image_generator is
    type glyph is array(0 to 7) of std_logic_vector(7 downto 0);
    constant emoji_grin: glyph := (
        "00111100",
        "01000010",
        "10101001",
        "10101001",
        "10000101",
        "10111001",
        "01000010",
        "00111100"
    );

    signal glyph_x: integer range 0 to 7;
    signal glyph_y: integer range 0 to 7;

    signal color: std_logic_vector(23 downto 0);
    signal color_index: integer range 0 to 2;
begin
    glyph_x <= to_integer(unsigned(x(4 downto 1)));
    glyph_y <= to_integer(unsigned(y(4 downto 1)));

    process(clk) is
        variable last_up: std_logic;
        variable last_down: std_logic;
        constant debounce_max: integer := input_clk / 50; -- 20ms
        variable debounce: integer range 0 to debounce_max := 0;
    begin
        if rising_edge(clk) then
            if debounce = 0 then
                if ctrl_up = '1' and last_up = '0' then
                    if color_index /= 2 then
                        color_index <= color_index + 1;
                    end if;
                    debounce := debounce_max;
                end if;
                last_up := ctrl_up;

                if ctrl_down = '1' and last_down = '0' then
                    if color_index /= 0 then
                        color_index <= color_index - 1;
                    end if;
                    debounce := debounce_max;
                end if;
                last_down := ctrl_down;
            else
                debounce := debounce - 1;
            end if;
        end if;
    end process;

    with color_index select color <=
        "111111111111111111111111" when 0,
        "000000000000000011111111" when 1,
        "000101001111111110110100" when 2;

    -- actually currently BRG
    rgb <=
        color when x(4) = y(4) and emoji_grin(glyph_y)(glyph_x) = '1' else
        "000000000000000000000000";
end logic;