local comp,disks,autocomplete,ev,ent,data,path,exit,dirty,ls,eb,sb,bp=components,{},false,nil,true,"","",false,true,{},false
local c,gpu=comp:getFirst("computer"),comp:getFirst("gpu")
if gpu then sb=gpu:newBuffer(48,32) end
--c.nvram.data="1/ac/boot.lua"
local function resetScreens()
    sb=gpu:newBuffer(64,48)
    for typ, obj in comp:list() do
        if typ=="screen" then gpu:assignBuffer(sb,obj) end
    end
end
resetScreens()

local function displayError(err)
    if not gpu then return end
    gpu:freeAllBuffers()
    resetScreens()
    sb:pasteText(0,0,"FILL_SPILL",err)
end

local function bootloader()
for typ, obj in comp:list() do
    if typ~="massStorage" then goto skip end
    disks[tostring(obj.diskId)]=obj
    ::skip::
end

local function display(text)
    print(text)
    if not sb then print("NO_SB") return end
    sb:pasteText(0,0,"FILL_SPILL",text)
end

local function boot()
    local pos = path:find("/", 1, true)
    if not pos then displayError("EINVAL") sleep(5) return end
    local id,p = path:sub(1,pos-1),path:sub(pos)
    if not disks[id] then displayError("ENODEV") sleep(5) return end
    local init,err=load(disks[id]:open(p):read(-1),"@init","t",_G)
    if err then displayError(err) sleep(5) return end
    local ret = {xpcall(init, debug.traceback)}
    if not ret[1] then
        displayError("EFI PROGRAM ERROR: "..err)
        sleep(5)
        return false
    else
        if ret[2]=="ENTER_BIOS" then
            c.nvram.ENTER_BIOS=true
            return true
        end
        return table.unpack(ret, 2)
    end
end

if c.nvram then
    path=c.nvram.data or ""
    eb=c.nvram.ENTER_BIOS
    c.nvram.ENTER_BIOS=false
end

local function drainev()
    repeat
        ev={c:getMachineEvent()}
        if ev[1]=="charTyped" then ent=false end
    until not ev[1]
end

if path=="" or eb then drainev() ent=false else
    display("Press key to enter boot menu...")
    sleep(3)
    drainev()
    if ent then return boot() end
end

local function proc(key)
    if key=="\n" then exit=true
    elseif key=="\b" then path=path:sub(1,#path-1) dirty=true
    elseif key=="\t" then print("autocomplete")
    else path=path..key dirty=true end
end

local function get()
    data=""
    local pos = path:find("/", 1, true)
    local trailingslash=false
    if path:sub(#path)=="/" then trailingslash=true end
    if not pos then
        for id in pairs(disks) do
            if id:sub(1,#path)==path then
                data=data..id.."\n"
            end
        end
    else
        if not trailingslash then
            local n=""
            for i=#path, 0, -1 do
                if path:sub(i,i)~="/" then
                    n=path:sub(i,i)..n
                else break end
            end
            local ok,ret=pcall(function()
                return disks[path:sub(1,pos-1)]:list(path:sub(pos,#path-#n))
            end)
            if ok then
                ls = ret
            end
            for _,p in ipairs(ls) do
                if p:sub(1,#n) == n then
                    data=data..p.."\n"
                end
            end
        else
            local ok,ret=pcall(function()
                return disks[path:sub(1,pos-1)]:list(path:sub(pos))
            end)

            if ok then
                ls=ret
                for _,p in ipairs(ls) do
                    data=data..p.."\n"
                end
            end
        end
    end
end

if not ent then
    while true do
        get()
        if dirty then
            for i=0,31 do sb:clearRow(i) end
            display("Select boot file...\n"..path.."\n\n"..data)
            dirty=false
        end
        ev={c:getMachineEvent()}
        if ev[1]=="charTyped" then proc(ev[2]) end
        if exit then return boot() end
    end
end
end
local ret={xpcall(bootloader,debug.traceback)}
if not ret[1] then
    displayError(ret[2])
    error(ret[2])
else
    return table.unpack(ret, 2)
end