library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.NUMERIC_STD.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;

entity Digital_Clock is
    Port (
              clock_1s  : in   STD_LOGIC;
              clock_ns  : in     STD_LOGIC;
              clock     : in     STD_LOGIC;
           buttons  : in     STD_LOGIC_VECTOR (3 downto 0);
           disp_1   : out  STD_LOGIC_VECTOR (3 downto 0);
           disp_2       : out  STD_LOGIC_VECTOR (3 downto 0);
           disp_3   : out  STD_LOGIC_VECTOR (3 downto 0);
           disp_4       : out  STD_LOGIC_VECTOR (3 downto 0);
           LEDs         : out  STD_LOGIC_VECTOR (7 downto 0)
              );
end Digital_Clock;

architecture Behavioral of Digital_Clock is

type statetype is
    (S_Digital_Clock, S_Stop_Watch, S_Alarm_Set);
    signal Current_State, Next_State : statetype;

signal seconds              : integer range 0 to 60;
signal minutes_one          : std_logic_vector(3 downto 0) := "0000";
signal minutes_ten          : std_logic_vector(3 downto 0) := "0000";
signal hours_one                : std_logic_vector(3 downto 0) := "0000";
signal hours_ten                : std_logic_vector(3 downto 0) := "0000";
signal alarm_minutes_one    : std_logic_vector(3 downto 0) := "0000";
signal alarm_minutes_ten    : std_logic_vector(3 downto 0) := "0000";
signal alarm_hours_one      : std_logic_vector(3 downto 0) := "0010";
signal alarm_hours_ten      : std_logic_vector(3 downto 0) := "0001";
signal sw_seconds_one       : std_logic_vector(3 downto 0) := "0000";
signal sw_seconds_ten       : std_logic_vector(3 downto 0) := "0000";
signal sw_nanos_one         : std_logic_vector(3 downto 0) := "0000";
signal sw_nanos_ten         : std_logic_vector(3 downto 0) := "0000";
signal stop                     : std_logic := '0';
signal addOne                   : std_logic := '1';
signal addHour                  : std_logic := '0';
signal reset                    : std_logic := '0';

begin

process(clock_1s,addOne,addHour)
begin
if (addOne = '1') then
    seconds <= 0;
    minutes_one <= minutes_one + 1;
elsif(addHour = '1') then
    seconds <= 0;
    hours_one <= hours_one + 1;
elsif rising_edge(clock_1s) then
    seconds <= seconds + 1;
    if(seconds = 60) then
        seconds <= 0;
        minutes_one <= minutes_one + 1;
        if(minutes_one = "1010") then
            minutes_ten <= minutes_ten + 1;
            minutes_one <= "0000";
            if(minutes_ten = "0110") then
                hours_one <= hours_one + 1;
                minutes_ten <= "0000";
                if(hours_one = "1010") then
                    hours_ten <= hours_ten + 1;
                    hours_one <= "0000";
                    if(hours_ten = "0010" and hours_one = "0100") then
                        hours_ten <= "0000";
                        hours_one <= "0000";
    end if;end if;end if;end if;end if;
end if;
end process;

process(clock_ns,reset,stop)
begin
    if(reset = '1') then
        sw_nanos_one <= "0000";
        sw_nanos_ten <= "0000";
        sw_seconds_one <= "0000";
        sw_seconds_ten <= "0000";
    else
        if(stop = '0') then
            if rising_edge(clock_ns) then
                sw_nanos_one <= sw_nanos_one + 1;
                if(sw_nanos_one = "1010") then
                    sw_nanos_one <= "0000";
                    sw_nanos_ten <= sw_nanos_ten + 1;
                    if(sw_nanos_ten = "1010") then
                        sw_nanos_ten <= "0000";
                        sw_seconds_one <= sw_seconds_one + 1;
                        if(sw_seconds_one = "1010") then
                            sw_seconds_one <= "0000";
                            sw_seconds_ten <= sw_seconds_ten + 1;
                            if(sw_seconds_ten = "0110") then
                                sw_seconds_ten <= "0000";
            end if;end if;end if;end if;end if;
        else
            sw_nanos_one <= sw_nanos_one;
            sw_nanos_ten <= sw_nanos_ten;
            sw_seconds_one <= sw_seconds_one;
            sw_seconds_ten <= sw_seconds_ten;
        end if;
    end if;
end process;

process(Current_State,buttons,hours_ten,hours_one,minutes_ten,minutes_one,alarm_hours_ten,alarm_hours_one,alarm_minutes_one,alarm_minutes_ten,sw_seconds_ten,sw_seconds_one,sw_nanos_ten,sw_nanos_one)
begin
    case Current_State is
        when S_Digital_Clock        =>
            disp_1 <= hours_ten;
            disp_2 <= hours_one;
            disp_3 <= minutes_ten;
            disp_4 <= minutes_one;
            if (buttons(3) = '1') then
                disp_1 <= alarm_hours_ten;
                disp_2 <= alarm_hours_one;
                disp_3 <= alarm_minutes_ten;
                disp_4 <= alarm_minutes_one;
            else
                disp_1 <= hours_ten;
                disp_2 <= hours_one;
                disp_3 <= minutes_ten;
                disp_4 <= minutes_one;
            end if;

            if(buttons(1) = '1') then
                addOne <= '1';
            else
                addOne <= '0';
            end if;

            if(buttons(2) = '1') then
                addHour <= '1';
            else
                addHour <= '0';
            end if;

            if(buttons(0) = '1') then
                Next_State <= S_Stop_Watch;
            else
                Next_State <= S_Digital_Clock;
            end if;

            when S_Stop_Watch =>
                disp_1 <= sw_seconds_ten;
                disp_2 <= sw_seconds_one;
                disp_3 <= sw_nanos_ten;
                disp_4 <= sw_nanos_one;

                if(buttons(3) = '1') then
                    reset <= '1';
                else
                    reset <= '0';
                end if;

                if(buttons(2) = '1') then
                    stop <= NOT stop;
                else
                    stop <= stop;
                end if;

                if(buttons(1) = '1') then
                    Next_State <= S_Digital_Clock;
                else
                    Next_State <= S_Stop_Watch;
                end if;

                if(buttons(0) = '1') then
                    Next_State <= S_Alarm_Set;
                else
                    Next_State <= S_Stop_Watch;
                end if;

            when S_Alarm_Set  =>
                disp_1 <= alarm_hours_ten;
                disp_2 <= alarm_hours_one;
                disp_3 <= alarm_minutes_ten;
                disp_4 <= alarm_minutes_one;

                if(buttons(3) = '1') then
                    Next_State <= S_Stop_Watch;
                else
                    Next_State <= S_Alarm_Set;
                end if;

                if(buttons(2) = '1') then
                    alarm_hours_one <= alarm_hours_one + 1;
                    alarm_minutes_ten <= "0000";
                    if(alarm_hours_one = "1010") then
                        alarm_hours_one <= "0000";
                        alarm_hours_ten <= alarm_hours_ten + 1;
                        if(alarm_hours_ten = "0010" and hours_one = "0100") then
                            alarm_hours_ten <= "0000";
                            alarm_hours_one <= "0000";
                    end if;end if;
                else
                    alarm_minutes_one <= alarm_minutes_one;
                    alarm_minutes_ten <= alarm_minutes_ten;
                    alarm_hours_one <= alarm_hours_one;
                    alarm_hours_ten <= alarm_hours_ten;
                end if;

                if(buttons(1) = '1') then
                alarm_minutes_one <= alarm_minutes_one + 1;
                    if(alarm_minutes_one = "1010") then
                        alarm_minutes_ten <= alarm_minutes_ten + 1;
                        alarm_minutes_one <= "0000";
                        if(alarm_minutes_ten = "1010") then
                        alarm_hours_one <= alarm_hours_one + 1;
                        alarm_minutes_ten <= "0000";
                        if(alarm_hours_one = "1010") then
                            alarm_hours_one <= "0000";
                            alarm_hours_ten <= alarm_hours_ten + 1;
                            if(alarm_hours_ten = "0010" and hours_one = "0100") then
                                alarm_hours_ten <= "0000";
                                alarm_hours_one <= "0000";
                        end if;end if;end if;end if;
                else
                    alarm_minutes_one <= alarm_minutes_one;
                    alarm_minutes_ten <= alarm_minutes_ten;
                    alarm_hours_one <= alarm_hours_one;
                    alarm_hours_ten <= alarm_hours_ten;
                end if;
                if(buttons(0) = '1') then
                    Next_State <= S_Digital_Clock;
                else
                    Next_State <= S_Alarm_Set;
                end if;
            end case;
end process;

StateReg    :   process(clock)
begin
    if rising_edge(clock)then
        Current_State <= Next_State;
    end if;
end process StateReg;

end Behavioral;