module Brick_Escape
	(
		CLOCK_50,						//	On Board 50 MHz
		// Your inputs and outputs here
        KEY,
        SW,
		// The ports below are for the VGA output.  Do not change.
		VGA_CLK,   						//	VGA Clock
		VGA_HS,							//	VGA H_SYNC
		VGA_VS,							//	VGA V_SYNC
		VGA_BLANK_N,						//	VGA BLANK
		VGA_SYNC_N,						//	VGA SYNC
		VGA_R,   						//	VGA Red[9:0]
		VGA_G,	 						//	VGA Green[9:0]
		VGA_B   						//	VGA Blue[9:0]
	);

	input			CLOCK_50;				//	50 MHz
	input   [9:0]   SW;
	input   [3:0]   KEY;

	// Declare your inputs and outputs here
	// Do not change the following outputs
	output			VGA_CLK;   				//	VGA Clock
	output			VGA_HS;					//	VGA H_SYNC
	output			VGA_VS;					//	VGA V_SYNC
	output			VGA_BLANK_N;				//	VGA BLANK
	output			VGA_SYNC_N;				//	VGA SYNC
	output	[9:0]	VGA_R;   				//	VGA Red[9:0]
	output	[9:0]	VGA_G;	 				//	VGA Green[9:0]
	output	[9:0]	VGA_B;   				//	VGA Blue[9:0]

	wire resetn;
	assign resetn = ~SW[0];

	// Create the colour, x, y and writeEn wires that are inputs to the controller.
	wire [2:0] colour;
	wire [6:0] x;
	wire [6:0] y;

	// writeEn will always be high
	wire writeEn = 1'b1;

	// Create an Instance of a VGA controller - there can be only one!
	// Define the number of colours as well as the initial background
	// image file (.MIF) for the controller.
	vga_adapter VGA(
			.resetn(resetn),
			.clock(CLOCK_50),
			.colour(colour),
			.x(x),
			.y(y),
			.plot(writeEn),
			/* Signals for the DAC to drive the monitor. */
			.VGA_R(VGA_R),
			.VGA_G(VGA_G),
			.VGA_B(VGA_B),
			.VGA_HS(VGA_HS),
			.VGA_VS(VGA_VS),
			.VGA_BLANK(VGA_BLANK_N),
			.VGA_SYNC(VGA_SYNC_N),
			.VGA_CLK(VGA_CLK));
		defparam VGA.RESOLUTION = "160x120";
		defparam VGA.MONOCHROME = "FALSE";
		defparam VGA.BITS_PER_COLOUR_CHANNEL = 1;
		defparam VGA.BACKGROUND_IMAGE = "black.mif";

	 // RATE DIVIDER TO SLOW DOWN THE UPDATE PROCESS FOR PLAYER AND ENEMIES
	 wire update;		// Will be used to update position of player and enemies
	 rateDivider ratedivider(CLOCK_50, update);


	 // PLAYER PROPERTIES /////////////////////////////////////////////////////////////////
	 wire [6:0] playerx;		// x position of the player
	 wire [6:0] playery;		// y position of the player

	 Player player(update, resetn, playerx, playery, KEY);



	 // ENEMIES PROPERTIES ////////////////////////////////////////////////////////////////
	 wire [6:0] enemyx[0:1];			// x position of the enemies
	 wire [6:0] enemyy[0:1];			// y position of the enemies
	 reg [6:0] enemyx_init[0:1];		// initial x position of the enemies
	 reg [6:0] enemyy_init[0:1];		// initial y position of the enemies
	 reg left_and_right[0:1];			// Determines whether the enemy will move up and down, or left and right

	 // Initializes the enemy's starting position and other properties
	 initial
	 begin
		enemyx_init[0] = 7'd100;
		enemyx_init[1] = 7'd150;

		enemyy_init[0] = 7'd100;
		enemyy_init[1] = 7'd150;

		left_and_right[0] = 1'd0;
		left_and_right[1] = 1'd1;
	 end

	 // Instantiates multiple enemies
	 genvar index;
	 generate
	 for (index = 0; index < 2; index = index + 1)
		begin: create_enemies
			Enemy enemy(update, resetn, enemyx[index], enemyy[index], left_and_right[index], enemyx_init[index], enemyy_init[index]);
		end
	 endgenerate

	 // CONTROL AND DATAPATH PROPERTIES ///////////////////////////////////
	 wire go_next, clear_screen, update_player, update_enemy, wait_screen;	// ENABLE SIGNALS

	 Controller controller(CLOCK_50, resetn, go_next, clear_screen, update_player, update_enemy, wait_screen);

	 Datapath datapath(CLOCK_50, resetn, go_next, clear_screen, update_player, update_enemy, wait_screen, playerx, playery, enemyx[0], enemyy[0], x, y, colour);

endmodule

module Datapath(clk, resetn, go_next, clear_screen, update_player, update_enemy, wait_screen, playerx, playery, enemyx, enemyy, x, y, colour);
	input clk;
	input resetn;
	input clear_screen;
	input update_player;
	input update_enemy;
	input wait_screen;
	input [6:0] playerx;
	input [6:0] playery;
	input [6:0] enemyx;
	input [6:0] enemyy;
	reg [30:0] wait_screen_counter;
	reg [6:0] clear_screen_x;
	reg [6:0] clear_screen_y;
	output reg go_next;
	output reg [6:0] x;
	output reg [6:0] y;
	output reg [2:0] colour;

	always@(posedge clk)
		begin
			if(~resetn)		// Basic reset functionality
				begin
					clear_screen_x = 1'd0;
					clear_screen_y = 1'd0;
					go_next = 1'd0;
					x = 1'd0;
					y = 1'd0;
					colour = 3'b000;
				end
			else
				begin
					/* This will fully clear the screen, in other words this part of the datapath will go
						through each pixel on the vga screen and place a black pixel on the current
						pixel and will continue to do so until iterates through the whole screen.
					*/
					if(clear_screen)
					begin
						go_next = 1'd0;
						x = clear_screen_x;
						y = clear_screen_y;
						colour = 3'b000;
						clear_screen_x = clear_screen_x + 1'd1;	// Continue onto the next pixel to the right
						if(clear_screen_x > 7'd126)	// Iteration reaches the far right of the screen
							begin
								clear_screen_x = 1'd0;	// Restart the iteration back to the beginning (far left of the screen)
								clear_screen_y = clear_screen_y + 1'd1;	// Go one pixel down
							end
						else if(clear_screen_x == 7'd126 && clear_screen_y == 7'd126)	// Iteration reaches the end of the screen (bottom-right corner)
							begin
								go_next = 1'd1;	// Go to the next state
								clear_screen_x = 1'd0;	// Reset the iteration for future iterations
								clear_screen_y = 1'd0;
							end
					end
					/* This will re-display the updated x and y position of the player
					*/
					if(update_player)
					begin
						go_next = 1'd0;
						x = playerx;
						y = playery;
						colour = 3'b111;
						go_next = 1'd1;
					end
					/* This will re-display the updated x and y position of each enemy
					*/
					if(update_enemy)
					begin
						go_next = 1'd0;
						x = enemyx;
						y = enemyy;
						colour = 3'b011;
						go_next = 1'd1;
					end
					/* Acts as the end of the refresh
					*/
					if(wait_screen)
					begin
						go_next = 1'd1;
					end
				end
		end
endmodule

module Controller(clk, resetn, go_next, clear_screen, update_player, update_enemy, wait_screen);
	input clk;
	input resetn;
	input go_next;
	output reg clear_screen;
	output reg update_player;
	output reg update_enemy;
	output reg wait_screen;

	reg [1:0] current_state, next_state;

	// Represents the different states of the finite state machine
	localparam	S_CLEAR_SCREEN		= 2'd0,
					S_UPDATE_PLAYER	= 2'd1,
					S_UPDATE_ENEMY		= 2'd2,
					S_WAIT_SCREEN		= 2'd3;

	always @(*)
		begin: state_table
			case (current_state)
				S_CLEAR_SCREEN: 	next_state = go_next ? S_UPDATE_PLAYER :	S_CLEAR_SCREEN;
				S_UPDATE_PLAYER: 	next_state = go_next ? S_UPDATE_ENEMY	:	S_UPDATE_PLAYER;
				S_UPDATE_ENEMY:	next_state = go_next ? S_WAIT_SCREEN	:	S_UPDATE_ENEMY;
				S_WAIT_SCREEN:		next_state = go_next ? S_CLEAR_SCREEN	:	S_WAIT_SCREEN;
				default: next_state = S_UPDATE_PLAYER;
			endcase
		end

	always @(*)
		begin: enable_signals
			clear_screen = 1'd0;
			update_player = 1'd0;
			update_enemy = 1'd0;
			wait_screen = 1'd0;
			case (current_state)
				S_CLEAR_SCREEN:
					begin
						clear_screen = 1'd1;
					end
				S_UPDATE_PLAYER:
					begin
						update_player = 1'd1;
					end
				S_UPDATE_ENEMY:
					begin
						update_enemy = 1'd1;
					end
				S_WAIT_SCREEN:
					begin
						wait_screen = 1'd1;
					end
			endcase
		end

	always @(posedge clk)
		begin: curr_state_FSM
			if(~resetn)
				current_state <= S_CLEAR_SCREEN;
			else
				current_state <= next_state;
		end

endmodule

module Enemy(update, resetn, enemyx, enemyy, left_and_right, enemyx_init, enemyy_init);

	input update;
	input resetn;
	input left_and_right; // if 0 the enemy will move up and down, if 1 the enemy will move left and right
	input enemyx_init;
	input enemyy_init;
	reg [3:0] movement_position;
	reg left_right;	// if 0 move left, if 1 move right
	reg up_down;		// if 0 move up, if 1 move down
	output reg [6:0] enemyx;
	output reg [6:0] enemyy;

	initial
	begin
		enemyx = enemyx_init;
		enemyy = enemyy_init;
	end

	always @(posedge update)
	begin
		if(~resetn)
		begin
			enemyx = 1'd0;
			enemyy = 1'd0;
		end
		else
		begin
			if(left_and_right)	// Enemy will move left and right
			begin
				if(movement_position == 4'd10)	// Change direction every time it moves 10 pixels left or right
				begin
					left_right = ~left_right;
					movement_position = 1'd0;
				end
				if(left_right == 1'b0)
				begin
					enemyx = enemyx - 1'd1;			// Move enemy to the left by one pixel
				end
				else
				begin
					enemyx = enemyx + 1'd1;			// Move enemy to the right by one pixel
				end
			end
			else		// Enemy will move up and down
			begin
				if(movement_position == 4'd10)	// Change direction everytime it moves 10 pixels up or down
				begin
					up_down = ~up_down;
					movement_position = 1'd0;
				end
				if(up_down == 1'b0)
				begin
					enemyy = enemyy + 1'd1;			// Move enemy down by one pixel
				end
				else
				begin
					enemyy = enemyy - 1'd1;			// Move enemy up by one pixel
				end
			end
			movement_position <= movement_position + 1'b1;	// Iterate how much pixels the enemy has moved by 1
		end
	end
endmodule

module Player(update, resetn, playerx, playery, KEY);

	input update;
	input resetn;
	output reg [6:0] playerx;
	output reg [6:0] playery;
	input [3:0] KEY;

	// Initialize the starting position of the player
	initial
	begin
		playerx = 7'd25;
		playery = 7'd25;
	end

	/* This will constantly check for player input and move the player
		accordingly.
	*/
	always @(posedge update)
	begin
		if(~resetn)
		begin
			playerx = 1'b0;
			playery = 1'b0;
		end
		else
		begin
			if(~KEY[3]) // MOVE PLAYER LEFT
			begin
				playerx = playerx - 1'b1;
			end
			else if(~KEY[2]) // MOVE PLAYER UP
			begin
				playery = playery - 1'b1;
			end
			else if(~KEY[1]) // MOVE PLAYER DOWN
			begin
				playery = playery + 1'b1;
			end
			else if(~KEY[0]) // MOVE PLAYER RIGHT
			begin
				playerx = playerx + 1'b1;
			end
		end
	end
endmodule

module rateDivider(clk, update);
	input clk;
	output reg update;
	reg [25:0] counter;

	always @(posedge clk)
	begin
		counter = counter + 1'd1;
		if(counter > 26'd3124999)
		begin
			counter = 1'd0;
		end
		update = (counter == 1'd0) ? 1 : 0;
	end

endmodule