local ci = component.invoke
function bi(A, method, ...)
 local result = table.pack(pcall(ci, A, method, ...))
 if not result[1] then
  return nil, result[2]
 else
  return table.unpack(result, 2, result.n)
 end
end

-- backwards compatibility, may remove later
local E = component.list("eeprom")()
computer.getBootAddress = function()
 return bi(E, "getData")
end
computer.setBootAddress = function(A)
 return bi(E, "setData", A)
end

local tryLoadFrom = 0

do
 local S = component.list("S")()
 local G = component.list("G")()
 if G and S then
  bi(G, "bind", S)
 end
end
do
 local gA,sA = component.list("gpu")(),component.list("screen")()
 if gA and sA then
 local gP,cy = component.proxy(gA),1
 gP.bind(sA)
 local sx, sy = gP.getResolution()
 local function wl(s)
  gP.set(1,cy,s)
  cy=cy+1
 end
 function tryLoadFrom(A)
  if component.type(A) == "filesystem" then
   local H, R = bi(A, "open", "/init.lua")
   if not H then
    return nil, R
   end
   local buffer = ""
   repeat
    local data, R = bi(A, "read", H, math.huge)
    if not data and R then
     return nil, R
    end
    buffer = buffer .. (data or "")
   until not data
   bi(A, "close", H)
   return load(buffer, "=init")
  elseif component.type(A) == "tape_drive" then
   bi(A,"seek",-math.huge)
   local boottype = bi(A,"read",1)
   if boottype == "!" then
    local rl = tonumber(bi(A,"read",8))
    local buffer = bi(A,"read",rl)
    return load(buffer, "=init")
   end
  elseif component.type(A) == "modem" then
   bi(A,"open",9671)
   bi(A,"broadcast",9671,computer.A())
   s=""
   local bt = computer.uptime()
   while bt+10 > computer.uptime() do
    computer.beep()
    local ev={computer.pullSignal(0.5)}
    if ev[1] == "modem_message" and ev[4] == 9671 then
     bt=computer.uptime()
     if ev[6] == "." then break end
     s=s..ev[6]
    end
   end
   if s ~= "" then
    return load(s,"=init")
   end
  elseif component.type(A) == "internet" then
   local I = component.proxy(A)
   local S = ""
   wl("Paste an address to boot from - or wait for the default.")
   local T = 5
   local U = "https://lain.shadowkat.net/~izaya/ocdoc/PsychOS-build/fsdev/PsychOS-fsdev-latest/severything.lua"
   while computer.uptime() < T do
    t,_,c,C = computer.pullSignal(0.5)
    if t == "clipboard" then
     U = c
    end
   end
   local R=I.request(U)
   if not R then return false end
   repeat
    computer.pullSignal(0.5)
   until R.finishConnect()
   local code, msg = R.response()
   if code ~= 200 then
    return false, code, msg
   end
   repeat
    computer.pullSignal(0.5)
    ns = R.read(2048)
    S=S..(ns or "")
    computer.beep()
   until not ns
   return load(S,"=init")
  end
 end
 
 local bd = {}
 for k,v in ipairs({"filesystem","tape_drive","modem","internet"}) do
  for A in component.list(v) do
   bd[#bd+1] = A
  end
 end

 local cba = computer.getBootAddress()
 local S = (" "):rep(3)
 local function rdraw()
  gP.fill(1,1,sx,sy," ")
  cy=1
  wl("SKS Enhanced BIOS v2")
  wl("Memory: "..tostring(computer.totalMemory()/1024).."K")
  wl(" ")
  for k,v in ipairs(bd) do
  if v == cba then S = " ".."*".." " else S = (" "):rep(3) end
  local e,l = pcall(component.invoke,v,"getLabel")
  if not e then l = "" end
  wl(S..tostring(k).." "..v.." "..component.type(v).." "..(l or ""))
  end
 end
 rdraw()
 local T = 5
 local bhc = false
 while computer.uptime() < T do
  t,_,c,C = computer.pullSignal(0.5)
  if t == "key_down" and c > 48 and c < 58 then
  cba = bd[c-48]
  bhc = true
  rdraw()
  elseif t == "key_down" and c == 32 then
  T = T + 10
  elseif t == "key_down" and c == 13 and C == 28 then
  T = 0
  end
 end
 if bhc then
  computer.setBootAddress(cba)
 end
 end
end

local init, R
if computer.getBootAddress() then
 init, R = tryLoadFrom(computer.getBootAddress())
end
if not init then
 computer.setBootAddress()
 for k,A in ipairs(bd) do
  init, R = tryLoadFrom(A)
  if init then
   computer.setBootAddress(A)
   break
  end
 end
end
if not init then
 error("no bootable medium found" .. (R and (": " .. tostring(R)) or ""), 0)
end
computer.beep(1000, 0.2)
init()