function hw1_test()

	hold on

	global BOT_UP = 1;
	global BOT_DOWN = 2;
	global BOT_LEFT = 3;
	global BOT_RIGHT = 4;

	agent = struct( "position", [9,9], "direction", BOT_UP );
	% world = struct( "agent", agent, "width", 20, "height", 20, "tiles", round(20 * rand(20,2)), "holes", round(20 * rand(20,2)) );
	world = struct( "agent", agent, "width", 20, "height", 20, "holes", [], "tiles", round(20 * rand(20,2)) );
	for i = 1:20
		x = round(world.width * rand(1));
		y = round(world.height * rand(1));
		life = round(20 * rand(1)) - 10;
		% life = 10;
		world.holes = [world.holes,make_hole(x,y,life)];
	end

	steps = 20;
	for i = 1:steps
		old_world = world;
		new_world = world;
		new_world.agent = move_agent( old_world, old_world.agent );
		new_world.holes = update_holes( old_world, old_world.holes );
		world = new_world;
		draw_grid( world );
		input('waiting');
	end
	% draw_grid( world );
	% input('waiting');
	% world.agent.position = [9,10];
	% draw_grid( world );
end

function all = update_holes( world, holes )
	for i = length( holes )
		holes( i ).life -= 1;
		if ( holes( i ).life < 0 )
			holes( i ).x = round(world.width * rand(1));
			holes( i ).y = round(world.height * rand(1));
			holes( i ).life = round(20 * rand(1)) - 10;
			% tiles( i ).life = 10;
		end
	end
	all = holes;
end

function hole = make_hole( x, y, life )
	hole = struct( "x", x, "y", y, "life", life );
end

function value = random_direction()
	global BOT_UP = 1;
	global BOT_DOWN = 2;
	global BOT_LEFT = 3;
	global BOT_RIGHT = 4;
	n = round(4 * rand(1) )
	switch ( n )
		case 1,
			value = BOT_UP;
		case 2,
			value = BOT_DOWN;
		case 3,
			value = BOT_LEFT;
		case 4,
			value = BOT_RIGHT;
		otherwise,
			value = BOT_LEFT;
	end
end

function value = move_agent( world, agent )
	global BOT_UP = 1;
	global BOT_DOWN = 2;
	global BOT_LEFT = 3;
	global BOT_RIGHT = 4;
	switch ( agent.direction )
	case BOT_UP,
		agent.position(2) += 1;
	case BOT_DOWN,
		agent.position(2) -= 1;
	case BOT_LEFT,
		agent.position(1) -= 1;
	case BOT_RIGHT,
		agent.position(1) += 1;
	end
	agent.direction = random_direction();
	if ( agent.position(1) < 1 )
	end
	value = agent;
end

function draw_hole( hole )
	plot(hole.x, hole.y, 'ro' );
end

function draw_grid( world )
	clf;
	xs = [0,0,world.width,world.width,world.width/2];
	ys = [0,world.height,0,world.height,world.height/2];
	hold on;
	plot(xs,ys,'g+');
	for i = 1:length( world.holes )
		hole = world.holes( i );
		if hole.life > 0
			draw_hole( hole );
		end
	end
	% tiles = world.tiles;
	% plot(world.tiles(:,1),world.tiles(:,2),'r+');

	% plot(world.holes(:,1),world.holes(:,2),'ro');

	plot(world.agent.position(1),world.agent.position(2),'px');
	% plot( 0, 0, 'g+' );
	% plot( world.width, 0, 'g+' );
	% plot( 0, world.height, 'g+' );
	% plot( world.width, world.height, 'g+' );
	grid("on");
end