local w, h = term.getSize()
a = 0
timer = os.startTimer(0)
--variables
snakecolor = colors.green
nInterval = 0.3
fruitcolor = colors.red
textcolor = colors.yellow
edgecolor = colors.blue
HIGHSCORE = 0
HIGHSCOREP = "NoOne"


--functions
function drawpixel(x, y, color)
    term.setCursorPos(x, y)
    term.setBackgroundColor(color)
    term.write(" ")
    term.setBackgroundColor(colors.black)
end

local function printCentred(y, s)
    local x = math.floor((w - string.len(s)) / 2)
    term.setCursorPos(x, y)
    --term.clearLine()
    term.write(s)
end

local function addwall()
    yes = 0
    while true do
        randomx = math.random(1, w)
        randomy = math.random(2, h)
        for i = 1, #sx do
            if sx[i] == randomx and sy[i] == randomy then
                yes = yes + 1
            end
        end
        for i = 1, #fruitx do
            if fruitx[i] == randomx and fruity[i] == randomy then
                yes = yes + 1
            end
        end
        if yes == 0 then
            break
        end
    end
    wallx[#wallx + 1] = randomx
    wally[#wally + 1] = randomy
end

local function addfruit(p1)
    yes = 0
    while true do
        randomx = math.random(1, w)
        randomy = math.random(2, h)
        for i = 1, #sx do
            if sx[i] == randomx and sy[i] == randomy then
                yes = yes + 1
            end
        end
        if yes == 0 then
            break
        end
    end
    fruitx[p1] = randomx
    fruity[p1] = randomy
end

function drawline(xc, yc, xv, yv, color)
    if xc == xv then
        if yc < yv then
            for i = 1, yv - yc + 1 do
                drawpixel(xc, yc + i - 1, color)
            end
        else
            for i = 1, yc - yv + 1 do
                drawpixel(xc, yc - i + 1, color)
            end
        end
    elseif yc == yv then
        if xc < xv then
            for i = 1, xv - xc + 1 do
                drawpixel(xc + i - 1, yc, color)
            end
        else
            for i = 1, xc - xv + 1 do
                drawpixel(xc - i + 1, yc, color)
            end
        end
    end
end

function edge()
    drawline(1, 1, 1, h, edgecolor)
    drawline(1, 1, w, 1, edgecolor)
    drawline(w, 1, w, h, colors.blue)
    drawline(1, h, w, h, edgecolor)
end

function drawgame()
        term.clear()
        for i = 1, #sx do
            term.setCursorPos(sx[i], sy[i])
            term.setBackgroundColor(snakecolor)
            term.write(" ")
            term.setBackgroundColor(colors.black)
        end
        for i = 1, #fruitx do
            term.setCursorPos(fruitx[i], fruity[i])
            term.setBackgroundColor(fruitcolor)
            term.write(" ")
        end
        for i = 1, #wallx do
            term.setCursorPos(wallx[i], wally[i])
            term.setBackgroundColor(edgecolor)
            term.write(" ")
        end
        term.setBackgroundColor(colors.black)
        if diffeculty >= 2 then
            edge()
        end
        drawline(1,1,w,1,edgecolor)
        term.setBackgroundColor(edgecolor)
        term.setCursorPos(1, 1)
        term.write("score:" .. score*(diffeculty+1))
        term.write(" ".."HIGHSCORE:"..HIGHSCORE.." Holder:\""..HIGHSCOREP.."\"")
        term.setCursorPos(w-string.len("Difficulty:" ..diffeculty), 1)
        term.write("Difficulty:" ..diffeculty)
        term.setBackgroundColor(colors.black)
end

function menu(list,clears,where)
selected = 1
if not clears then term.clear() end
term.setTextColor(textcolor)
  for i=1,#list do
    if selected == i then
      printCentred(h/2 - #list/2 + (i-1), "["..list[i].."]")
    else
      printCentred(h/2 - #list/2 + (i-1), list[i])
    end
  end
if where == 1 then printCentred(1,"press BackSpace (<----) to puase") end
while true do
    local event, o1, o2 = os.pullEvent("key")
    term.clear()
    if clears then drawgame() end
    if where == 1 then printCentred(1,"press BackSpace (<----) to puase") end
    if o1 == keys.up then
        selected = selected + -1
    end
    if o1 == keys.down then
        selected = selected - -1
    end
    if selected > #list then
        selected = 1
    end
    if selected < 1 then
        selected = #list
    end
    if o1 == keys.enter then
        break
    end
    for i=1,#list do
      if selected == i then
        printCentred(h/2 - #list/2 + (i-1), "["..list[i].."]")
      else
        printCentred(h/2 - #list/2 + (i-1), list[i])
    end
  end
end
return selected
end

function start()
--menu
diffeculty = menu({"easy","normal","HARD","VERY HARD!","IMPOSIBLE!","Leave"},false,1) - 1
--game
nInterval = 0.3
wallx = {}
wally = {}
sx = {6, 5, 4}
sy = {5, 5, 5}
dx = 1
dy = 0
die = false
fb = 0
die = false
if diffeculty > 0 then
    fb = 0.2
end
if diffeculty >= 3 then
    fb = 0.4
end
fruitx = {math.floor(w / 2)}
fruity = {math.floor(h / 2)}
nInterval = nInterval - fb
local timer = os.startTimer(nInterval)
move = 0
if diffeculty ~= 5 then
while true do
    event, o1, o2 = os.pullEvent()
    if event == "timer" and o1 == timer then
        timer = os.startTimer(nInterval)
    end
    if event == "key" then
        if o1 == keys.right and dx == 0 and move == 0 then
            dx = 1
            dy = 0
            move = 1
        end
        if o1 == keys.left and dx == 0 and move == 0 then
            dx = -1
            dy = 0
            move = 1
        end
        if o1 == keys.up and dy == 0 and move == 0 then
            dx = 0
            dy = -1
            move = 1
        end
        if o1 == keys.down and dy == 0 and move == 0 then
            dx = 0
            dy = 1
            move = 1
        end
        if o1 == keys.backspace then
          if menu({"Resume","Difficulty Select"},true) == 2 then
            break
          end
          timer = os.startTimer(nInterval)
        end
        if o1 == keys.space then
            addfruit(#fruitx + 1)
        end
    end
    if event == "timer" then
        move = 0
        table.insert(sx, 1, sx[1] + dx)
        table.insert(sy, 1, sy[1] + dy)
        for i = 1, #sx - 1 do
            if sx[1] == sx[i + 1] and sy[1] == sy[i + 1] then
                die = true
            end
        end
        for i = 1, #wallx do
            if sx[1] == wallx[i] and sy[1] == wally[i] then
                die = true
            end
        end
        for i = 1, #fruitx do
            if fruitx[i] == sx[1] and sy[1] == fruity[i] then
                addfruit(i)
                if diffeculty == 4 then addwall() end
                grow = true
            end
        end
        if #fruitx == 0 then
          addfruit(1)
        end
        if not grow then
            sx[#sx] = nil
            sy[#sy] = nil
        end
        grow = false
        if diffeculty < 2 then
            if sx[1] > w then
                sx[1] = 1
            end
            if sx[1] < 1 then
                sx[1] = w
            end
            if sy[1] > h then
                sy[1] = 2
            end
            if sy[1] < 2 then
                sy[1] = h
            end
        else
            if sx[1] > w - 1 then
                die = true
            end
            if sx[1] < 2 then
                die = true
            end
            if sy[1] > h - 1 then
                die = true
            end
            if sy[1] < 2 then
                die = true
            end
        end
        score = #sx -3
        drawgame()
        if score*(diffeculty+1) > HIGHSCORE then
            HIGHSCOREP = "you"
            HIGHSCORE = score*(diffeculty+1)
        end
        if die then
            score = score*(diffeculty+1)
            term.clear()
            printCentred(math.floor(h / 2) - 1, "you died")
            printCentred(math.floor(h / 2), "score:" .. score)
            if HIGHSCOREP == "you" then
            HIGHSCOREP = "__"
            printCentred(math.floor(h / 2) + 1, "NEW HIGH SCORE!")
            printCentred(math.floor(h / 2) + 2, "EnterName:"..HIGHSCOREP)
            shift = 0
            while true do
                local event, key = os.pullEvent("key")
                if key == keys.leftShift or key == keys.rightShift then
                    shift = 1 - shift
                end
                kes = keys.getName(key)
                if shift == 1 then kes = string.upper(kes) end
                if #kes == 1 and string.sub(HIGHSCOREP,1,1) ~= "_" then
                    HIGHSCOREP = string.sub(HIGHSCOREP,1,1)
                    HIGHSCOREP = HIGHSCOREP..kes
                end
                if #kes == 1 and string.sub(HIGHSCOREP,1,1) == "_" then
                    HIGHSCOREP = kes.."_"
                end
                if key == keys.backspace and string.sub(HIGHSCOREP,2,2) == "_" then
                    HIGHSCOREP = "__"
                end
                if key == keys.backspace and string.sub(HIGHSCOREP,2,2) ~= "_" then
                    HIGHSCOREP = string.sub(HIGHSCOREP,1,1)
                    HIGHSCOREP = HIGHSCOREP.."_"
                end
                if key == keys.enter and string.sub(HIGHSCOREP,2,2) ~= "_" then
                    break
                end
                printCentred(math.floor(h / 2) + 2, "EnterName:"..HIGHSCOREP)
            end
            printCentred(math.floor(h / 2) + 1, "NEW HIGH SCORE!")
            printCentred(math.floor(h / 2) + 2, "press ENTER to play agian")
            else
            printCentred(math.floor(h / 2) + 1, "press ENTER to play agian")
            end
            while true do
                local event, key = os.pullEvent("key")
                if key == keys.enter then
                    break
                end
            end
            break
        end
    end
end
start()
end
term.clear()
term.setCursorPos(1,1)
end
start()