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