local camera = {0, 0}
local screen = {800,600}
local squares = nil
local squaresize = 50
local maxx, maxy = 100, 100
--love.window.setMode( 1024, 768 )
function love.load()
   -- build the map
   squares = {}
   for y = 1, maxy do
      local row = {}
      for x = 1, maxx do
         local sq = {set = false}
         table.insert(row, sq)
      end
      table.insert(squares, row)
   end
   screen[1] = love.graphics.getWidth()
   screen[2] = love.graphics.getHeight()
end

function love.draw()
   -- draw the currently visible portion of the map
   -- this draws every partially visible square and relies
   -- on love drawing code to clip the edges
   local camx, camy = unpack(camera)
   local scrx, scry = unpack(screen)
	 
	 --Prevent camera from going off screen
	 local vleft = math.floor(camx/squaresize)
   local vup = math.floor(camy/squaresize)
	 
	 
	 local horc = math.ceil(scrx/squaresize) + 1
   local verc = math.ceil(scry/squaresize) + 1

	 -- Until the number of vertical squares
	 for y = 1, verc do
		 -- Until the number of horizontal squares
      for x = 1, horc do
         if squares[vup+y] and squares[vup+y][vleft+x] then
            local mode = "line"
            if squares[vup+y][vleft+x].set then
               mode = "fill"
            end
            love.graphics.rectangle(mode, (vleft+x-1)*squaresize - camx,
               (vup+y-1)*squaresize - camy, squaresize, squaresize)
         end
      end
   end
end

local scrollspeed = 200
local edge = 100

function love.update(dt)
   -- scroll the screen if mouse is near edges
   local scrx, scry = unpack(screen)
   local mx, my = love.mouse.getPosition()
   if mx < edge/2 then camera[1] = camera[1] - scrollspeed * dt end
   if mx > scrx - edge/2 then camera[1] = camera[1] + scrollspeed * dt end
   if my < edge/2 then camera[2] = camera[2] - scrollspeed * dt end
   if my > scry - edge/2 then camera[2] = camera[2] + scrollspeed * dt end
   -- limit the camera position from wandering off
   if camera[1] < -edge then camera[1] = -edge end
   if camera[2] < -edge then camera[2] = -edge end
   local xlimit, ylimit = maxx*squaresize + edge - scrx, maxy*squaresize + edge - scry
   if camera[1] > xlimit then camera[1] = xlimit end
   if camera[2] > ylimit then camera[2] = ylimit end
end

function love.mousepressed(x, y, button)
   -- toggle the clicked square on left button click
   if button ~= 'l' then return end
   local wx, wy = x + camera[1], y + camera[2]
   local x, y = math.floor(wx/squaresize)+1, math.floor(wy/squaresize)+1
   if squares[y] and squares[y][x] then
      local value = squares[y][x].set
      squares[y][x].set = not value -- toggle bool flag
   end
end