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

--Game-specific RAM addresses
RAM = {
    bytes = {
        dead = 0x7e0D86, --101 if dead
        inGame = 0x7e0040 --32 if in game
    }
}

--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()
    if not inGame() then
        return true
    end
    return false
end

function inGame()
    local gameVal = memory.readbyte(RAM.bytes.inGame)
    if gameVal == 32 then
        return true
    end
    return false
end

function GameActive()
    if memory.readbyte(RAM.bytes.dead) ~= 101 and inGame() 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

--Tells the script that the last segment was okay (i.e. you didn't die)
function SegmentOk()
    if memory.readbyte(RAM.bytes.dead) ~= 101 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
    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,
    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.rollback = false
    segment.bestTime = 999999
    segment.lastTime = 0
    segment.curTime = movie.framecount()
end

function OutputTime()
    gui.text(output.time.x,output.time.y,string.format("Last: %d  Best: %d", segment.lastTime, segment.bestTime))
end

while true do
    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()

            --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

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

        while not segment.done and not segment.failed and ContinueAttempt() do
            snes9x.frameadvance()
            OutputTime()
            HandleKeys()
        end

        segment.lastTime = (movie.framecount() - segment.curTime)

        if (segment.bestTime > segment.lastTime) and (segment.lastTime > 10) and not segment.failed and not segment.done and SegmentOk() then
            segment.bestTime = segment.lastTime
            savestate.save(segment.best)
        end
    end

    if not segment.rollback then
        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