Morse Teacher ComputerCraft

--Morse code "Teacher" program

morse={"._","_...","_._.","_..",".",".._.","__.","....","..",".___","_._","._..","__","_.","___",".__.","__._","._.","...","_",".._","..._",".__","_.._","_.__","__..",".____","..___","...__","...._",".....","_....","__...","___..","____.","_____"}
letters={"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z","1","2","3","4","5","6","7","8","9","0"}

function hws()
    if fs.exists(".morsestats") and not fs.isDir(".morsestats") then
        r=fs.open(".morsestats","r")
        y=r.readLine()
        if tonumber(y) then
            hs=tonumber(y)
        else
            hs=0
        end
        r.close()
    else
        hs=0
    end
    return hs
end

function clear()
    shell.run("clear")
end

function menu(hs)
    clear()
    tab={"Learn","Test","Exit"," "," ","Highscore: "..hs,"By NNet Inc.(Sylvyrfysh) (C)2013. Full terms of use can be found at nnet.org/programs/tc/morse"}
    for t,y in pairs(tab) do
        print(y)
    end
    while true do
        e={os.pullEvent("mouse_click")}
        if e[4]>3 then

        else
            return tab[e[4]]
        end
    end
end

canRun=true
while canRun do
    notBroken=true
    hs=hws()
    dothing=menu(hs)
    if dothing=="Learn" then
        prnts={}
        for t=1,#morse do
            table.insert(prnts,string.gsub(morse[t],"_","-").." = "..letters[t])
        end
        e,v=term.getSize()
        x=1
        while true do
            clear()
            for t=1,v-1 do
                print(prnts[x])
                x=x+1
            end
            write("Exit")
            p={os.pullEvent()}
            if p[1]=="mouse_scroll" then
                if p[2]==1 then
                    x=19
                else
                    x=1
                end
            elseif p[1]=="mouse_click" and p[4]==v then
                break
            end
        end
    elseif dothing=="Test" then
        clear()
        term.setCursorPos(1,1)
        print("Enter highest letter, or 'all' for all letters: ")
        u=read()
        if u=="all" then
            highest=#morse
        else
            for t,y in pairs(letters) do
                if y==u then
                    highest=t
                    break
                end
                highest=#morse
            end
        end
        clear()
        print("Press '-' for a long tap, or '.' for a short tap.")
        write("Loading.")
        for o=1,5 do
            write(".")
            sleep(1)
        end
        score=0
        while true do
            n=math.random(1,highest)
            clear()
            print(morse[n].." is: Or enter 'exit' to exit.")
            print("Score: "..score)
            term.setCursorPos(1,3)
            g=read()
            if g=="exit" then
                break
            else
                if g==letters[n] then
                    score=score+1
                    if score>hs then
                        if notBroken then
                            print("NEW HIGHSCORE!")
                        end
                        r=fs.open(".morsestats","w")
                        r.write(score)
                        r.close()
                        notBroken=false
                    end
                    print("Great!")
                    sleep(2)

                else
                    print("Oops! That letter was "..letters[n])
                    sleep(2)
                end
            end
        end
    elseif dothing=="Exit" then
        canRun=false
        clear()
        print("Thanks for using Morse by NNet(Sylvyrfysh)!")
    end
end