w,h=term.getSize() -- 51  19

function monSign()
    monitor=peripheral.wrap("top")
    monitor.setTextScale(0.5)
    monW,monH=monitor.getSize()  --w 15  h 10
    monitor.clear()
    monitor.setCursorPos(6,4)
    monitor.write("SPACE")
    monitor.setCursorPos(4,6)
    monitor.write("INVADERS!")
end

function initVariables()
    keyPress= 0
    curPos=w/2
    bullet=false
    hPos=h-4
    bulletCurPos=0
    gameTimer=0
    alienW = 5
    alienH = 2
    alienLeftStop=2
    alienRightStop=8
    lives=3
    killed= false
    killCounter=0
    noBombs=true
    bombTimer=0
    win=false
    score=0

    alien1 = true
    alien2 = true
    alien3 = true
    alien4 = true
    alien5 = true
    alien6 = true


    bomb1=false
    bomb2=false
    bomb3=false


    alienCount=6
end

function clear()
      term.clear()
      term.setCursorPos(1,1)
      term.setBackgroundColour(colours.black)
      term.setTextColour(colours.white)
end

function gameController()
    local alienMove=1
    local gameTimer = os.startTimer(0.1)
    repeat

        local event,p1,p2,p3 = os.pullEvent()
        if event=="key" and killed == false then
            keyPress=p1
            keyAction()
        elseif event=="timer" then

            if noBombs==true then
                bombTimer = bombTimer+1
                if bombTimer==30 then
                    noBombs=false
                    bombTimer=0
                end
            end
            bombs()

            if killed==true then
                killCounter=killCounter+1
                    if killCounter==10 then
                        killed=false
                        curPos=w/2
                        killCounter=0
                        drawShip(curPos)
                    end
            end

            term.setTextColour(colours.white)
            term.setCursorPos(1,1)
            --print("p1:        "..p1.."  ")
            term.setCursorPos(1,2)
            --print("gameTimer: "..gameTimer.."  ")
            term.setCursorPos(1,3)
            --print("hPos: "..hPos.."  ")
            if p1== gameTimer then
            gameTimer=os.startTimer(0.1)

                if bullet==true then
                    delBullet()
                    hPos=hPos-1
                    if hPos==alienH or HPos==alienH+1 then
                        --checkBulletCollision
                        if alien1 == true and bulletCurPos >= alienW and bulletCurPos <= alienW+3 then
                            delAlien(alienW,alienH)
                            alien1=false
                            alienCount=alienCount-1
                            score=score+50
                            bullet=false
                        elseif alien2 == true and bulletCurPos >= alienW+8 and bulletCurPos <= alienW+11 then
                            delAlien(alienW+8,alienH)
                            alien2=false
                            alienCount=alienCount-1
                            score=score+50
                            bullet=false
                        elseif alien3 == true and bulletCurPos >= alienW+16 and bulletCurPos <= alienW+19 then
                            delAlien(alienW+16,alienH)
                            alien3=false
                            alienCount=alienCount-1
                            score=score+50
                            bullet=false
                        elseif alien4 == true and bulletCurPos >= alienW+24 and bulletCurPos <= alienW+27 then
                            delAlien(alienW+24,alienH)
                            alien4=false
                            alienCount=alienCount-1
                            score=score+50
                            bullet=false
                        elseif alien5 == true and bulletCurPos >= alienW+32 and bulletCurPos <= alienW+35 then
                            delAlien(alienW+32,alienH)
                            alien5=false
                            alienCount=alienCount-1
                            score=score+50
                            bullet=false
                        elseif alien6 == true and bulletCurPos >= alienW+40 and bulletCurPos <= alienW+43 then
                            delAlien(alienW+40,alienH)
                            alien6=false
                            alienCount=alienCount-1
                            score=score+50
                            bullet=false
                        end


                        if alienCount==0 then
                            win=true
                            gameOver()
                        end
                    end
                    if hPos<=1 then
                        bullet=false
                    else
                        drawBullet()
                    end
                end

                if  score <0 then score = 0 end
                term.setCursorPos(w-10,h)
                term.setTextColour(colours.white)
                write("Score: "..score)

                delAlienFormation()
                alienW=alienW+alienMove
                if alien1==false then alienLeftStop = -6 end
                if alien1==false and alien2==false then alienLeftStop = -14 end
                if alien1==false and alien2==false and alien3==false then alienLeftStop = -22 end
                if alien1==false and alien2==false and alien3==false and alien4==false then alienLeftStop = -30 end
                if alien1==false and alien2==false and alien3==false and alien4==false and alien5 ==false then alienLeftStop = -38 end
                if alien6==false then alienRightStop = 16 end
                if alien6==false and alien5==false then alienRightStop = 24 end
                if alien6==false and alien5==false and alien4==false then alienRightStop = 32 end
                if alien6==false and alien5==false and alien4==false and alien3==false then alienRightStop = 40 end
                if alien6==false and alien5==false and alien4==false and alien3==false and alien2 ==false then alienRightStop = 48 end

                if alienW> alienRightStop and alienMove ==1 then alienMove= -1 end -- 8
                if alienW < alienLeftStop and alienMove == -1 then alienMove= 1 end -- 2
                drawAlienFormation()


            end
        end


    until event=="char" and p1==("x")
end

function getKey()
    input=read()
    print(input.." = "..keys.getName(input))
end

function keyAction()
    if keyPress == 30 or keyPress == 203 then
        --left - a or left arrow
        delShip(curPos)
        if curPos>5 then
            curPos=curPos-1
        end
        drawShip(curPos)
    elseif keyPress == 32 or keyPress == 205 then
        --right - d or right arrow
        delShip(curPos)
        if curPos < w-3 then
            curPos=curPos+1
        end
        drawShip(curPos)
    elseif keyPress == 57 then
        -- fire - space bar
        if bullet==false then
            hPos=h-4
            bullet=true
            bulletCurPos = curPos
            drawBullet()
        end
    elseif keyPress == 16 then
        quit()
    end
end

function quit()
    os.shutdown()
end

function drawShip(wPos)
    term.setTextColour(colours.white)
    term.setBackgroundColour(colours.white)
    term.setCursorPos(wPos,h-3)
    print("X")
    term.setCursorPos(wPos-1,h-2)
    print("XXX")
    term.setCursorPos(wPos-2,h-1)
    print("XXXXX")
    term.setBackgroundColour(colours.black)
end

function delShip(wPos)
    term.setTextColour(colours.red)
    term.setBackgroundColour(colours.black)
    term.setCursorPos(wPos,h-3)
    print(" ")
    term.setCursorPos(wPos-1,h-2)
    print("   ")
    term.setCursorPos(wPos-2,h-1)
    print("     ")
    --term.setBackgroundColour(colours.black)
end

function drawBullet()
    if bullet==true then
        term.setCursorPos(bulletCurPos,hPos)
        term.setTextColour(colours.orange)
        term.setBackgroundColour(colours.orange)
        print("I")
        term.setTextColour(colours.white)
        term.setBackgroundColour(colours.black)
    end
end

function delBullet()
    term.setCursorPos(bulletCurPos,hPos)
    term.setTextColour(colours.black)
    term.setBackgroundColour(colours.black)
    print(" ")
    term.setTextColour(colours.white)
    term.setBackgroundColour(colours.black)
end

function drawAlien(aW,aH,num)
    term.setCursorPos(aW,aH)
    term.setTextColour(colours.lime)
    term.setBackgroundColour(colours.lime)
    print(string.rep(num,3))
    term.setCursorPos(aW,aH+1)
    print(string.rep(num,1))
    term.setCursorPos(aW+2,aH+1)
    print(string.rep(num,1))
    term.setTextColour(colours.white)
    term.setBackgroundColour(colours.black)
end

function delAlien(aW,aH)
    term.setCursorPos(aW,aH)
    term.setTextColour(colours.black)
    term.setBackgroundColour(colours.black)
    print("   ")
    term.setCursorPos(aW,aH+1)
    print(" ")
    term.setCursorPos(aW+2,aH+1)
    print(" ")
    term.setTextColour(colours.white)
    term.setBackgroundColour(colours.black)
end

function drawAlienFormation()
    if alien1==true then drawAlien(alienW,alienH,1) end
    if alien2==true then drawAlien(alienW+8,alienH,2) end
    if alien3==true then drawAlien(alienW+16,alienH,3) end
    if alien4==true then drawAlien(alienW+24,alienH,4) end
    if alien5==true then drawAlien(alienW+32,alienH,5) end
    if alien6==true then drawAlien(alienW+40,alienH,6) end
end

function delAlienFormation()
    if alien1==true then delAlien(alienW,alienH) end
    if alien2==true then delAlien(alienW+8,alienH) end
    if alien3==true then delAlien(alienW+16,alienH) end
    if alien4==true then delAlien(alienW+24,alienH) end
    if alien5==true then delAlien(alienW+32,alienH) end
    if alien6==true then delAlien(alienW+40,alienH) end
end

function drawBomb(bombW,bombH)
    term.setCursorPos(bombW+1,bombH+2)
    term.setBackgroundColour(colours.yellow)
    term.setTextColour(colours.yellow)
    print("*")
    term.setBackgroundColour(colours.black)
    term.setTextColour(colours.white)
end

function delBomb(bombW,bombH)
    term.setCursorPos(bombW+1,bombH+2)
    term.setBackgroundColour(colours.black)
    term.setTextColour(colours.black)
    print(" ")
    term.setBackgroundColour(colours.black)
    term.setTextColour(colours.white)
end

function createBomb()
    chance = math.random(5)
    if chance==1 then
        return true
    else
        return false
    end
end

function selectAlien()
    selAlien= math.random(6)
    --term.setCursorPos(1,8)
    --term.setTextColour(colours.white)
    --print("aliens left "..alienCount)
    --term.setCursorPos(1,9)
    if selAlien==1 and alien1== true then bombW=alienW
    elseif selAlien==2 and alien2== true then bombW=alienW+8
    elseif selAlien==3 and alien3== true then bombW=alienW+16
    elseif selAlien==4 and alien4== true then bombW=alienW+24
    elseif selAlien==5 and alien5== true then bombW=alienW+32
    elseif selAlien==6 and alien6== true then bombW=alienW+40
    end
end

function bombs()
    if bomb1==false and createBomb() == true and noBombs == false then
        selectAlien()
        drawBomb(bombW,alienH)
        bomb1=true
        bomb1W= bombW
        bomb1H=alienH
    elseif bomb1 ==true then
        delBomb(bomb1W,bomb1H)
        bomb1H = bomb1H+1
        if bomb1H ==14 and bomb1W == curPos then
            bomb1=false
            shipHit()
        elseif bomb1H == 15 and bomb1W >= curPos-2 and bomb1W <= curPos then
            bomb1=false
            shipHit()
        elseif bomb1H == 16 and bomb1W >= curPos-4 and bomb1W <= curPos+1 then
            bomb1=false
            shipHit()
        elseif bomb1H > 16 then
            bomb1=false
            term.setCursorPos(1,10)
    print("   ")
        else
            drawBomb(bomb1W,bomb1H)
        end
    end
    if bomb2==false and createBomb() == true and noBombs == false then
        selectAlien()
        drawBomb(bombW,alienH)
        bomb2=true
        bomb2W= bombW
        bomb2H=alienH
    elseif bomb2 ==true then
        delBomb(bomb2W,bomb2H)
        bomb2H = bomb2H+1
        if bomb2H ==14 and bomb2W == curPos then
            bomb2=false
            shipHit()
        elseif bomb2H == 15 and bomb2W >= curPos-2 and bomb2W <= curPos then
            bomb2=false
            shipHit()
        elseif bomb2H == 16 and bomb2W >= curPos-4 and bomb2W <= curPos+1 then
            bomb2=false
            shipHit()
        elseif bomb2H > 16 then
            bomb2=false
            term.setCursorPos(1,10)
    print("   ")
        else
            drawBomb(bomb2W,bomb2H)
        end
    end
    if bomb3==false and createBomb() == true and noBombs == false then
        selectAlien()
        drawBomb(bombW,alienH)
        bomb3=true
        bomb3W= bombW
        bomb3H=alienH
    elseif bomb3 ==true then
        delBomb(bomb3W,bomb3H)
        bomb3H = bomb3H+1
        if bomb3H ==14 and bomb3W == curPos then
            bomb3=false
            shipHit()
        elseif bomb3H == 15 and bomb3W >= curPos-2 and bomb3W <= curPos then
            bomb2=false
            shipHit()
        elseif bomb3H == 16 and bomb3W >= curPos-4 and bomb3W <= curPos+1 then
            bomb3=false
            shipHit()
        elseif bomb3H > 16 then
            bomb3=false
            term.setCursorPos(1,10)
    print("   ")
        else
            drawBomb(bomb3W,bomb3H)
        end
    end
end

function shipHit()
    lives=lives-1
    delShip(curPos)
    killed=true
    noBombs=true
    score=score-10
    if score<0 then score =0 end
    if lives==0 then
        gameOver()
    else
        term.setCursorPos(2,h)
        term.setTextColour(colours.white)
        write("Lives: "..lives)
        term.setCursorPos(w-10,h)
        term.setTextColour(colours.white)
        write("Score: "..score)
    end
end

function gameOver()
    clear()
    if win==true then
        term.setCursorPos((w/2)-3, h/2)
        print("YOU WIN")
        win=false
    else
        term.setCursorPos((w/2)-4, h/2)
        print("GAME OVER")
    end
    local scoreStr= tostring(score)
    term.setCursorPos((w/2)-((7+#scoreStr))/2, (h/2)+2)
    print("Score: "..scoreStr)
    sleep(1)
    term.setCursorPos((w/2)-9, (h/2)+5)
    print("Play again (Y or N)")


    while true do
        local event,p1,p2,p3 = os.pullEvent()
        if event=="char" then
            if string.lower(p1)=="y" then
                runGame()
            elseif string.lower(p1)=="n" then
                os.shutdown()
            end
        end
    end

end



function runGame()
    clear()

    initVariables()
    drawShip(curPos)
    drawAlienFormation()

    term.setCursorPos(2,h)
    write("Lives: "..lives)
    term.setCursorPos(w-10,h)
    write("Score: "..score)

    gameController()
end

function line1(h)
    term.setCursorPos(12,h) write("    ")
    term.setCursorPos(18,h) write("    ")
    term.setCursorPos(24,h) write("    ")
    term.setCursorPos(30,h) write("    ")
    term.setCursorPos(36,h) write("    ")
end


function line2(h)
    term.setCursorPos(12,h) write(" ")
    term.setCursorPos(18,h) write(" ")
    term.setCursorPos(21,h) write(" ")
    term.setCursorPos(24,h) write(" ")
    term.setCursorPos(27,h) write(" ")
    term.setCursorPos(30,h) write(" ")
    term.setCursorPos(36,h) write(" ")
end

function line3(h)
    term.setCursorPos(12,h) write("    ")
    term.setCursorPos(18,h) write("    ")
    term.setCursorPos(24,h) write("    ")
    term.setCursorPos(30,h) write(" ")
    term.setCursorPos(36,h) write("   ")
end

function line4(h)
    term.setCursorPos(15,h) write(" ")
    term.setCursorPos(18,h) write(" ")
    term.setCursorPos(24,h) write(" ")
    term.setCursorPos(27,h) write(" ")
    term.setCursorPos(30,h) write(" ")
    term.setCursorPos(36,h) write(" ")
end

function line5(h)
    term.setCursorPos(12,h) write("    ")
    term.setCursorPos(18,h) write(" ")
    term.setCursorPos(24,h) write(" ")
    term.setCursorPos(27,h) write(" ")
    term.setCursorPos(30,h) write("    ")
    term.setCursorPos(36,h) write("    ")
end


function line6(h)
    term.setCursorPos(4,h) write("   ")
    term.setCursorPos(9,h) write(" ")
    term.setCursorPos(12,h) write(" ")
    term.setCursorPos(15,h) write(" ")
    term.setCursorPos(18,h) write(" ")
    term.setCursorPos(21,h) write("    ")
    term.setCursorPos(27,h) write("   ")
    term.setCursorPos(33,h) write("    ")
    term.setCursorPos(39,h) write("   ")
    term.setCursorPos(45,h) write("    ")
end

function line7(h)
    term.setCursorPos(5,h) write(" ")
    term.setCursorPos(9,h) write("  ")
    term.setCursorPos(12,h) write(" ")
    term.setCursorPos(15,h) write(" ")
    term.setCursorPos(18,h) write(" ")
    term.setCursorPos(21,h) write(" ")
    term.setCursorPos(24,h) write(" ")
    term.setCursorPos(27,h) write(" ")
    term.setCursorPos(30,h) write(" ")
    term.setCursorPos(33,h) write(" ")
    term.setCursorPos(39,h) write(" ")
    term.setCursorPos(42,h) write(" ")
    term.setCursorPos(45,h) write(" ")
end

function line8(h)
    term.setCursorPos(5,h) write(" ")
    term.setCursorPos(9,h) write("    ")
    term.setCursorPos(15,h) write(" ")
    term.setCursorPos(18,h) write(" ")
    term.setCursorPos(21,h) write("    ")
    term.setCursorPos(27,h) write(" ")
    term.setCursorPos(30,h) write(" ")
    term.setCursorPos(33,h) write("   ")
    term.setCursorPos(39,h) write("   ")
    term.setCursorPos(45,h) write("    ")
end


function line9(h)
    term.setCursorPos(5,h) write(" ")
    term.setCursorPos(9,h) write(" ")
    term.setCursorPos(11,h) write("  ")
    term.setCursorPos(15,h) write(" ")
    term.setCursorPos(18,h) write(" ")
    term.setCursorPos(21,h) write(" ")
    term.setCursorPos(24,h) write(" ")
    term.setCursorPos(27,h) write(" ")
    term.setCursorPos(30,h) write(" ")
    term.setCursorPos(33,h) write(" ")
    term.setCursorPos(39,h) write(" ")
    term.setCursorPos(42,h) write(" ")
    term.setCursorPos(48,h) write(" ")
end

function line10(h)
    term.setCursorPos(4,h) write("   ")
    term.setCursorPos(9,h) write(" ")
    term.setCursorPos(12,h) write(" ")
    term.setCursorPos(16,h) write("  ")
    term.setCursorPos(21,h) write(" ")
    term.setCursorPos(24,h) write(" ")
    term.setCursorPos(27,h) write("   ")
    term.setCursorPos(33,h) write("    ")
    term.setCursorPos(39,h) write(" ")
    term.setCursorPos(42,h) write(" ")
    term.setCursorPos(45,h) write("    ")
end

function whiteScreen()
    term.setBackgroundColour(colours.white)
    term.clear()
    term.setBackgroundColour(colours.black)
end

function splashScreen()
    whiteScreen()
    sleep(1)

    local scrollH = h+2
    while scrollH > 1 do
        whiteScreen()
        line1(scrollH)
        line2(scrollH+1)
        line3(scrollH+2)
        line4(scrollH+3)
        line5(scrollH+4)
        scrollH=scrollH-1
        sleep(0.1)
    end
    local scrollH = h+2
    while scrollH > 1 do
        whiteScreen()
        line1(2)
        line2(3)
        line3(4)
        line4(5)
        line5(6)
        line6(scrollH+6)
        line7(scrollH+7)
        line8(scrollH+8)
        line9(scrollH+9)
        line10(scrollH+10)
        scrollH=scrollH-1
        sleep(0.1)
    end
    term.setBackgroundColour(colours.white)
    term.setTextColour(colours.black)

    term.setCursorPos((w/2)-6,15)
    print("by Jcdwalel and PumpkinheadAbbey")

    term.setCursorPos((w/2)-15,17)
    print("Left and Right Arrows to move")
    term.setCursorPos((w/2)-6,18)
    print("Space to fire")

    term.setCursorPos((w/2)-10,19)
    write("Press fire when ready")



    while true do
        local event,p1,p2,p3 = os.pullEvent()
        if event=="char" then
            term.setBackgroundColour(colours.black)
            term.clear()
            runGame()
        end
    end
end



monSign()
clear()

term.setCursorPos(w/2-6 ,h/2)
print("Press any key")
while true do
    local event,p1,p2,p3 = os.pullEvent()
    if event=="char" then
        splashScreen()
    end
end