--How many frames ahead of the "action" to start savestates
preFrames = 45

--Game-specific RAM addresses
RAM = {
	words = {
	    hour = 0x7e09e0,
		min = 0x7e09de,
		sec = 0x7e09dc,
		mil = 0x7e09da,
		missiles = 0x7e09c8,
		superMissiles = 0x7e09cc,
		powerBombs = 0x7e09d0,
		energyTanks = 0x7e09c4,
		reserveTanks = 0x7e09d4,
		items = 0x7e09a4,
		weapons = 0x7e09a8,
		health = 0x7e09c2,
		reserve = 0x7e09d6
	},
	bytes = {
		itemScene = 0x7e0009,
		doorScene = 0x7e05f5,
		elevatorScene = 0x7e0e18,
		transition = 0x7e0925,
		inGame = 0x7e0054 --128 if in game
	}
}

--Game-specific information that needs to be monitored
gameInfo = {
	time = {
		hour = 0,
		min = 0,
		sec = 0,
		mil = 0
	},
	pct = 0,
	scene = {
		item = 0,
		door = 0,
		elevator = 0,
		transition = 0,
		transitionStarted = false,
	},
	health = 0,
	reserve = 0
}

--Locations to output text
output = {
	time = {
		x = 0,
		y = 190
	},
	gameInfo = {
		x = 0,
		y = 200
	}	
}

--Tells the script when to do nothing regarding savestates
function DoNothing()
	UpdateGameInfo()
	
	if not GameActive() or memory.readbyte(RAM.bytes.inGame) ~= 128 then
		return true
	end
	return false
end

--Sets game information at the beginning of an attempt
function SetGameInfo()
	--set in-game time
    gameInfo.hour = memory.readword(RAM.words.hour)
    gameInfo.min = memory.readword(RAM.words.min)
    gameInfo.sec = memory.readword(RAM.words.sec)
    gameInfo.mil = math.floor(memory.readword(RAM.words.mil) * 100 / 60)

	gameInfo.scene.item = memory.readbyte(RAM.bytes.itemScene)
	gameInfo.scene.door = memory.readbyte(RAM.bytes.doorScene)
	gameInfo.scene.elevator = memory.readbyte(RAM.bytes.elevatorScene)
	gameInfo.scene.transition = memory.readbyte(RAM.bytes.transition)
	
	gameInfo.health = memory.readword(RAM.words.health)
	gameInfo.reserve = memory.readword(RAM.words.reserve)

	--set percentage
	local missiles = math.floor(memory.readbyte(RAM.words.missiles) / 5)
    local superMissiles = math.floor(memory.readbyte(RAM.words.superMissiles) / 5)
    local powerBombs = math.floor(memory.readbyte(RAM.words.powerBombs) / 5)
    local energyTanks = math.floor((memory.readword(RAM.words.energyTanks) - 99) / 100)
    local reserveTanks = math.floor(memory.readword(RAM.words.reserveTanks) / 100)

    local items = memory.readword(RAM.words.items)
    local variaSuit = items % 2
    local springBall = math.floor((items % 4) / 2)
    local morphBall = math.floor((items % 8) / 4)
    local screwAttack = math.floor((items % 16) / 8)
    local gravitySuit = math.floor((items % 64) / 32)
    local hiJumpBoots = math.floor((items % 512) / 256)
    local spaceJump = math.floor((items % 1024) / 512)
    local bomb = math.floor((items % 8192) / 4096)
    local speedBooster = math.floor((items % 16384) / 8192)
    local grappleBeam = math.floor((items % 32768) / 16384)
    local xRayScope = math.floor(items / 32768)

    local weapons = memory.readword(RAM.words.weapons)
    local waveBeam = weapons % 2
    local iceBeam = math.floor((weapons % 4) / 2)
    local spazerBeam = math.floor((weapons % 8) / 4)
    local plasmaBeam = math.floor((weapons % 16) / 8)
    local chargeBeam = math.floor((weapons % 8192) / 4096)

    gameInfo.pct = missiles + superMissiles + powerBombs + energyTanks + reserveTanks + variaSuit + springBall + morphBall + screwAttack + gravitySuit + hiJumpBoots + spaceJump + bomb + speedBooster + grappleBeam + xRayScope + waveBeam + iceBeam + spazerBeam + plasmaBeam + chargeBeam
end

function CalculateRtaTime()
    frames = snes9x.framecount()
	hours = math.floor(frames / 216000)
	minutes = math.floor((frames - hours * 216000) / 3600)
	seconds = math.floor((frames - hours * 216000 - minutes * 3600) / 60)
	milliseconds = math.floor((frames - hours * 216000 - minutes * 3600 - seconds * 60) * 100 / 60)
end

--Outputs relevant game information
function OutputGameInfo()
	CalculateRtaTime()
    gui.text(output.gameInfo.x, output.gameInfo.y, "Pct: " .. gameInfo.pct .. "%")
    gui.text(output.gameInfo.x, output.gameInfo.y + 10, "In-Game Time: " .. gameInfo.hour .. ":" .. string.format("%02d",gameInfo.min) .. ":" .. string.format("%02d",gameInfo.sec) .. "." .. string.format("%02d",gameInfo.mil) .. "    RTA Time: " .. hours .. ":" .. string.format("%02d",minutes) .. ":" .. string.format("%02d",seconds) .. "." .. string.format("%02d",milliseconds))
end

function InScene()
	if gameInfo.scene.transition == 10 then
		gameInfo.scene.transitionStarted = true	
	end
	
	if ((gameInfo.scene.item + gameInfo.scene.elevator > 0) or (gameInfo.scene.door > 0 and gameInfo.scene.transition >= 10 and gameInfo.scene.transitionStarted)) then
		if (gameInfo.scene.item + gameInfo.scene.door + gameInfo.scene.elevator ~= 111) then
			return true
		end
	end
	
	gameInfo.scene.transitionStarted = false
	return false
end

function GameActive()
	if (gameInfo.health > 0 or gameInfo.reserve > 0) and (not InScene()) then
		return true
	end
	return false
end

--Tells the script that the attempt should continue
function ContinueAttempt()
	if GameActive() then
		return true
	end
	return false
end

--Use this function to update info that may be checked later (for example, if you gain a life)
function UpdateGameInfo()
	--set in-game time
    gameInfo.hour = memory.readword(RAM.words.hour)
    gameInfo.min = memory.readword(RAM.words.min)
    gameInfo.sec = memory.readword(RAM.words.sec)
    gameInfo.mil = math.floor(memory.readword(RAM.words.mil) * 100 / 60)
	
	gameInfo.scene.item = memory.readbyte(RAM.bytes.itemScene)
	gameInfo.scene.door = memory.readbyte(RAM.bytes.doorScene)
	gameInfo.scene.elevator = memory.readbyte(RAM.bytes.elevatorScene)
	gameInfo.scene.transition = memory.readbyte(RAM.bytes.transition)

	gameInfo.health = memory.readword(RAM.words.health)
	gameInfo.reserve = memory.readword(RAM.words.reserve)
end

--Tells the script that the last segment was okay (i.e. you didn't die)
function SegmentOk()
	if gameInfo.health > 0 or gameInfo.reserve > 0 then
		return true
	end
	return false
end
 
--Handles all the hotkey stuff
function HandleKeys()
	keys = input.get()

	if press('Q') then
		segment.done = true
	end
	
	if press('R') then
		segment.failed = true
	end

	if press('C') then
		segment.failed = true
		segment.bestTime = 999999
        segment.bestInGameTime = 999999
	end
	
	if press('B') then
		segment.done = true
		segment.rollback = true
	end

	last_keys = keys                                              
end

--Nothing below this point should have to change between games (though it might anyway)

segment = {
	prevStart = savestate.create(),
	prevBest = savestate.create(),
	start = savestate.create(),
	best = savestate.create(),
	bestTime = 999999,
	lastTime = 0,
	curTime = 0,
    prevCurTime = 0,
    bestInGameTime = 999999,
    lastInGameTime = 0,
    curInGameTime = 0,
    prevCurInGameTime = 0,
	done = false,
	actionStart = 0,
	failed = false,
	rollback = false
} 
 
firstSegment = true 
segment.curTime = 0

function press(button)
    if keys[button] and not last_keys[button] then
        return true
    end
    return false
end
 
function StartSegment()
	if firstSegment then
		savestate.save(segment.prevStart)
		firstSegment = false
	end
	
	savestate.save(segment.start)
	segment.done = false
	segment.curTime = movie.framecount()
    segment.curInGameTime = gameInfo.hour * 216000 + gameInfo.min * 3600 + gameInfo.sec * 60 + memory.readword(RAM.words.mil)
    if segment.rollback then
        segment.curTime = segment.prevCurTime
        segment.curInGameTime = segment.prevCurInGameTime
    end
    segment.rollback = false
	segment.bestTime = 999999
    segment.bestInGameTime = 999999
	segment.lastTime = 0
    segment.lastInGameTime = 0    
end
 
function OutputTime()
	gui.text(output.time.x,output.time.y,string.format("Last: %d (%d)  Best: %d (%d)", segment.lastTime, segment.lastInGameTime, segment.bestTime, segment.bestInGameTime))          
end
	
while true do
    SetGameInfo()
	StartSegment()
	
	local closerStart = false

	while not segment.done do
		segment.failed = false
		savestate.load(segment.start)         
		
		while not segment.done and not segment.failed and (DoNothing()) do 
			HandleKeys()
			snes9x.frameadvance()
			OutputGameInfo()
			
			--get a save state that's still in the transition, but close to the action for player control
			if movie.framecount() == segment.actionStart - preFrames then
				savestate.save(segment.start)
				closerStart = true
			end
		end

		SetGameInfo()
		
		if not closerStart then
			segment.actionStart = movie.framecount()
		end

		while not segment.done and not segment.failed and ContinueAttempt() do
			snes9x.frameadvance()
			UpdateGameInfo()
			OutputGameInfo()
			OutputTime()
			HandleKeys()
		end
		
		segment.lastTime = (movie.framecount() - segment.curTime)
        segment.lastInGameTime = gameInfo.hour * 216000 + gameInfo.min * 3600 + gameInfo.sec * 60 + memory.readword(RAM.words.mil) - segment.curInGameTime
		
		if ((segment.bestTime > segment.lastTime) or (segment.bestTime == segment.lastTime and segment.bestInGameTime >= segment.lastInGameTime)) and (segment.lastTime > 10) and not segment.failed and not segment.done and SegmentOk() then
			segment.bestTime = segment.lastTime
            segment.bestInGameTime = segment.lastInGameTime
			savestate.save(segment.best)
		end
	end
	
	if not segment.rollback then
        segment.prevCurTime = segment.curTime
        segment.prevCurInGameTime = segment.curInGameTime
		savestate.save(segment.prevBest)
		savestate.load(segment.best)
		savestate.save(segment.prevStart)
		segment.prevStart, segment.start = segment.start, segment.prevStart
	else
		savestate.load(segment.prevBest)
		savestate.save(segment.best)
		savestate.load(segment.prevStart)
		savestate.save(segment.start)
	end
end