Maze Generator

print("generate maze instantly? y/n")
instants = read()
print("play the maze like a game? y/n")
games = read()

if games == "y" then games = true else games = false end
if instants == "y" then instants = true else instants = false end

w,h = term.getSize()
curx = 1
cury = 1
stack = {}
visited = {}
mazex = (h - 1) / 2
mazey = (w - 1) / 2
showstack = true

--non color conversions
textcolors = {
    [colors.black] = " ",
    [colors.blue] = "X",
    [colors.lime] = "@",
    [colors.red] = "F"
}

canvas = {}
for xx = 1,w do
    canvas[xx] = {}
    for yy = 1,h do
        canvas[xx][yy] = colors.blue
    end
end

--first thing is first draw the maze
term.clear()
function draw()
    if term.isColor() then
      for i = 1,w do
        for j = 1,h do
          term.setCursorPos(i,j)
          term.setBackgroundColor(canvas[i][j])
          write(" ")
        end
      end
      term.setBackgroundColor(colors.black)
    else
      for i = 1,w do
        for j = 1,h do
          term.setCursorPos(i,j)
          write(textcolors[canvas[i][j]])
        end
      end
    end
end
draw()

function movecell(x,y)

  -- removing wall and  x at cells
  canvas[curx * 2][cury * 2] = colors.black
  canvas[x * 2][y * 2] = colors.black
  if x > curx then canvas[(x * 2) - 1][y * 2] = colors.black end
  if y > cury then canvas[x * 2][(y * 2) - 1] = colors.black end
  if x < curx then canvas[(x * 2) + 1][y * 2] = colors.black end
  if y < cury then canvas[x * 2][(y * 2) + 1] = colors.black end
  canvas[curx * 2][cury * 2] = colors.black
  curx = x
  cury = y
  canvas[curx * 2][cury * 2] = colors.lime
  if not instants then draw() end---------------------------------------------------
end

function checkvisited(y,x)
  if x <= 0 or y <= 0 or x > mazex or y > mazey then return true end
  local v
  for _,v in pairs(visited) do
    if v[1] == y and v[2] == x then
      return true
    end
  end
  return false
end

function addvisited(x,y)
  table.insert(visited,{x,y})
end

addvisited(curx,cury)

function addstack(x,y)
  table.insert(stack,{x,y})
end

function popstack()
  local val = stack[#stack]
  table.remove(stack,#stack);

  return val[1],val[2]
end

repeat

--find unvisited cells next to current one
  local posiblecells = {}

  if checkvisited(curx-1,cury) == false then
    table.insert(posiblecells,{curx - 1,cury})
  end
  if checkvisited(curx,cury - 1) == false then
    table.insert(posiblecells,{curx,cury - 1})
  end
  if checkvisited(curx + 1,cury) == false then
    table.insert(posiblecells,{curx + 1,cury})
  end
  if checkvisited(curx,cury + 1) == false then
    table.insert(posiblecells,{curx,cury + 1})
  end

  if #posiblecells > 0 then
    addstack(curx,cury)
    local targetx, targety
    local i = math.random(1,#posiblecells)
    targetx = posiblecells[i][1]
    targety = posiblecells[i][2]

    addvisited(targetx,targety)
    movecell(targetx,targety)
  else
    local targetx, targety
    targetx, targety = popstack()
    movecell(targetx,targety)
  end

  --sleep(0.05)
  os.queueEvent("randomevent")
  os.pullEvent()

until #stack == 0

if games then
    canvas[w-1][h-1] = colors.red
    draw()
    running = true
    px = 2
    py = 2
    while running do
        changed = false
        lpx = px
        lpy = py
        event,p1 = os.pullEvent("key")
        if p1 == 200 then
            if canvas[px][py-1] == colors.black or canvas[px][py-1] == colors.red then
                py = py - 1
                changed = true
            end
        elseif p1 == 208 then
            if canvas[px][py+1] == colors.black or canvas[px][py+1] == colors.red then
                py = py + 1
                changed = true
            end
        elseif p1 == 203 then
            if canvas[px-1][py] == colors.black or canvas[px-1][py] == colors.red then
                px = px - 1
                changed = true
            end
        elseif p1 == 205 then
            if canvas[px+1][py] == colors.black or canvas[px+1][py] == colors.red then
                px = px + 1
                changed = true
            end
        elseif p1 == 16 then
            running = false
        end
        if px == w-1 and py == h - 1 then
            running = false
        end
        if changed then
            canvas[px][py] = colors.lime
            canvas[lpx][lpy] = colors.black
            draw()
        end
    end
else
    draw()
    os.pullEvent()
end