cLinux GRUB menu

--[[
  cLinux001: cLinux 0.0.1 (complete rewrite)
  NAME:        /startup
  CATEGORY:    bootloader
  VERSION:     0.9 (didn't decide a version-system yet.)
  DESCRIPTION: Bootloader, may be called a 'GRUB' clone.

  Made by Piorjade & thecrimulo
]]--

--variables
local bootList = {} --The list with bootable images (.i) is going to be stored here
local selected = 1 --The pre-selected image
local defaultcmd = {} --The default command, which the command is booted with

--functions

local function getList()
    local file = fs.open("/grubcfg", "r")
    local inhalt = file.readAll()
    file.close()
    inhalt = textutils.unserialize(inhalt)
    bootList = inhalt.list
    selected = inhalt.default
    defaultcmd = inhalt.command

    for _, a in ipairs(bootList) do
        local i,j = string.find(a, "../")
        if i then
            table.remove(bootList, _)
        end
    end
end

local function readNoJump() --Reads the user input, but doesn't jump to the next line when finishing
    local str = ""
    local reading = true
    term.setCursorBlink(true)
    sleep(0.2)
    while reading do
        local _, k = os.pullEventRaw()
        local x, y = term.getCursorPos()
        if _ == "key" and k == keys.enter then
            term.setCursorBlink(false)
            reading = false
            return str
        elseif _ == "key" and k == keys.backspace and x > 1 then
            str = string.reverse(str)
            str = string.sub(str, 2)
            str = string.reverse(str)
            local x, y = term.getCursorPos()
            term.setCursorPos(x-1, y)
            term.write(" ")
            term.setCursorPos(x-1, y)
        elseif _ == "char" then
            str = str..tostring(k)
            term.write(tostring(k))
        end
    end
end

local function drawMenu()
    local function clear()
        term.setCursorPos(1,1)
        term.setBackgroundColor(colors.black)
        term.setTextColor(colors.white)
        term.clear()
    end
    clear()


    oldTerm = term.current()
    local w, h = 15, 11
    local wlist = window.create(term.current(), 26-w/2, 10-h/2, w, h)
    local str = "-GRUB-"
    local str2 = "Please select an image."
    local str3 = "Press E to write additional commands."
    local cmd = window.create(term.current(), 26-#str3/2, 19, #str3, 1)
    cmd.setBackgroundColor(colors.gray)
    cmd.clear()
    term.setCursorPos(26-#str/2, 1)
    term.write(str)
    term.setCursorPos(26-#str2/2, 2)
    term.write(str2)
    term.setCursorPos(26-#str3/2, 18)
    term.write(str3)
    local function redrawList()
        wlist.setBackgroundColor(colors.gray)
        wlist.clear()
        wlist.setCursorPos(1,1)
        wlist.setTextColor(colors.white)
        term.redirect(wlist)
        for _, o in ipairs(bootList) do
            local x, y = term.getCursorPos()
            if _ == selected then
                term.setBackgroundColor(colors.lightBlue)
                term.clearLine()
                term.write(o)
                if _ < #bootList then
                    term.setCursorPos(1, y+1)
                end
                term.setBackgroundColor(colors.gray)
            else
                term.write(o)
                if _ < #bootList then
                    term.setCursorPos(1, y+1)
                end
            end
        end
        term.redirect(oldTerm)
    end

    local function redrawCommand()
        term.redirect(cmd)
        term.setCursorPos(1,1)
        term.setBackgroundColor(colors.gray)
        term.setTextColor(colors.lime)
        term.clear()
        if defaultcmd[selected] ~= nil then
            term.write(defaultcmd[selected])
        else
            term.write("NONE")
        end
        term.redirect(oldTerm)
    end

    redrawList()
    redrawCommand()
    local running = true
    term.redirect(wlist)
    while running do
        local _, k = os.pullEventRaw("key")
        if k == keys.up and selected > 1 then
            selected = selected-1
            redrawList()
            redrawCommand()
        elseif k == keys.down and selected < #bootList then
            selected = selected+1
            redrawList()
            redrawCommand()
        elseif k == keys.e then
            term.redirect(cmd)
            term.setCursorPos(1,1)
            term.setBackgroundColor(colors.gray)
            term.setTextColor(colors.lime)
            term.clear()
            local e = readNoJump()
            term.redirect(oldTerm)
            defaultcmd[selected] = e
        elseif k == keys.enter then
            if fs.exists("/boot/"..bootList[selected]) == false then
                clear()
                printError("/boot/"..bootList[selected].." does not exist.")
                running = false
                break
            else
                running = false
                clear()
                local tArgs = {}
                if defaultcmd[selected] ~= nil then
                    repeat
                        local i, j = string.find(defaultcmd[selected], " ")
                        if i then
                            local a = string.sub(defaultcmd[selected], 1, i-1)
                            table.insert(tArgs, a)
                            defaultcmd[selected] = string.sub(defaultcmd[selected], j+1, #defaultcmd[selected])
                        end
                    until i == nil
                    table.insert(tArgs, defaultcmd[selected])
                end

                term.redirect(oldTerm)
                term.setCursorPos(1,1)
                term.clear()
                os.run({}, "/boot/"..bootList[selected], unpack(tArgs))
            end
        end
    end
    term.redirect(oldTerm)
end


if fs.exists("/grubcfg") then
    getList()

    if #bootList <= 11 then
        drawMenu()
    elseif #bootList > 11 then
        printError("/grubcfg: Too many entries.")
    elseif #bootList < 1 then
        printError("/grubcfg: No entries.")
    end
else
    printError("/grubcfg: Not found.")
end