-- game loop --

function _init()
	cls()
	walls={}
	make_player()
	make_walls()
	-- top-left and lower-right
	-- bounds of player area
	a1,b1=8,8
	a2,b2=112,112
end

function _update60()
	-- keep inside the play area
	move_player()
	p.x=mid(a1,p.x,a2)
	p.y=mid(b1,p.y,b2)
end

function _draw()
	cls()
	draw_map()
	draw_player()

	for w in all(walls) do
		spr(w.wsp,w.wx,w.wy)
	end	
end

-- map --

function draw_map()
	map(0,0,0,0,16,16)
end

-- player --

function make_player()
	p={
	x=40,
	y=40,
	w=8,
	h=8,
	speed=2,
	sprite=1,
	}
end

function move_player()
	--move player with buttons
	--interacts with wall collision
	if (btn(⬅️)) then
		for newx=p.x,p.x-p.speed,-1 
			do
				if not box_hit(newx,p.y,
					p.w,p.h,
					w.wx,w.wy,
					w.ww,w.wh) 
				then
					p.x=newx
			end
		end
	end

		if (btn(➡️)) then
		for newx=p.x,p.x+p.speed 
			do
				if not box_hit(newx,p.y,
						p.w,p.h,
						w.wx,w.wy,
						w.ww,w.wh) 
				then
					p.x=newx
			end
		end
	end

		if (btn(⬆️)) then
		for newy=p.y,p.y-p.speed,-1 
			do
				if not box_hit(p.x,newy,
						p.w,p.h,
						w.wx,w.wy,
						w.ww,w.wh) 
				then
					p.y=newy
			end
		end
	end

		if (btn(⬇️)) then
		for newy=p.y,p.y+p.speed 
			do
				if not box_hit(p.x,newy,
						p.w,p.h,
						w.wx,w.wy,
						w.ww,w.wh) 
				then
					p.y=newy
			end
		end
	end
end

--draw player
function draw_player()
	spr(p.sprite,p.x,p.y)
end

-- walls --

function make_walls()
	for x=0,15 do
		for y=0,15 do
			if mget(x,y)==65 then
				add(walls,{
					wx=x*8,
					wy=y*8,
					ww=8,
					wh=8,
					wsp=66
				})
				mset(x,y,64)
			end
		end
	end
end

--wall collision calculations

function box_hit(x1,y1,
		w1,h1,
		x2,y2,
		w2,h2)

		local hit=false
		local xd=abs((x1+(w1/2))-(x2+w2/2))
		local xs=w1/2+w2/2
		local yd=abs((y1+(h1/2))-(y2+h2/2))
		local ys=h1/2+h2/2	

	if xd < xs and yd < ys then
		hit=true
	end

	return hit

end