local c = component.invoke
local computer = computer or require("computer")

local bi = function(a, m, ...)
  local r = table.pack(pcall(c, a, m, ...))
  return r[1], table.unpack(r, 2, r.n)
end

local e = component.list("eeprom")()
computer.getBootAddress = function() return bi(e, "getData") end
computer.setBootAddress = function(a) return bi(e, "setData", a) end

local tryLoad = function(a)
  local h, r = bi(a, "open", "/init.lua")
  if not h then return nil, "Failed to open /init.lua: " .. tostring(r) end
  local b = ""
  repeat
    local d, r = bi(a, "read", h, math.maxinteger or math.huge)
    if not d and r then return nil, "Failed to read /init.lua: " .. tostring(r) end
    b = b .. (d or "")
  until not d
  bi(a, "close", h)
  local i, l = load(b, "=init")
  return i, l
end

local eraseDrive = function(a)
  local g = component.list("gpu")()
  local w, h = bi(g, "getResolution")
  local bx, by, bw, bh = math.floor((w - 60) / 2), math.floor((h - 4) / 2), 60, 4
  bi(g, "setBackground", 0x0000FF)
  bi(g, "fill", bx, by, bw, bh, " ")
  bi(g, "setForeground", 0xFFFFFF)
  bi(g, "setBackground", 0x0000FF)
  bi(g, "set", bx + 2, by + 1, "Erase drive? (Y/N)")
  while true do
    local e = { computer.pullSignal() }
    if e[1] == "key_down" then
      if e[3] == 21 or e[3] == 49 then
        bi(a, "remove", "/init.lua")
        bi(a, "remove", "/boot.lua")
        computer.beep(800, 0.2)
        computer.beep(800, 0.6)
        computer.beep(800, 0.2)
        computer.shutdown(true)
        break
      elseif e[3] == 49 or e[3] == 21 then
        break
      end
    end
  end
end

local drives = {}
for a in component.list("filesystem") do
  local b = bi(a, "getLabel") or "Unnamed"
  if b ~= "tmpfs" then drives[#drives + 1] = { a, b } end
end

local displayError = function(msg)
  local g = component.list("gpu")()
  local w, h = bi(g, "getResolution")
  local bx, by, bw, bh = math.floor((w - 60) / 2), math.floor((h - 4) / 2), 60, 4
  bi(g, "setBackground", 0x0000FF)
  bi(g, "fill", bx, by, bw, bh, " ")
  bi(g, "setForeground", 0xFF0000)
  bi(g, "setBackground", 0x0000FF)
  local tx = math.floor((bw - #msg) / 2) + bx
  local ty = math.floor((bh - 1) / 2) + by
  bi(g, "set", tx, ty, msg)
  computer.beep(800, 1)
  computer.beep(800, 0.5)
  computer.beep(800, 0.5)
end

local displayMenu = function(selIndex)
  local g = component.list("gpu")()
  local w, h = bi(g, "getResolution")
  local bx, by, bw, bh = math.floor((w - 60) / 2), math.floor((h - #drives - 4) / 2), 60, #drives + 4
  bi(g, "setBackground", 0x0000FF)
  bi(g, "fill", bx, by, bw, bh, " ")
  bi(g, "setForeground", 0xFFFFFF)
  bi(g, "setBackground", 0x0000FF)
  bi(g, "set", bx + 2, by + 1, "Select OS to boot:")
  for i, drive in ipairs(drives) do
    local lineY = by + i + 2
    local textColor = i == selIndex and 0xFF0000 or 0xFFFFFF
    bi(g, "setForeground", textColor)
    bi(g, "set", bx + 2, lineY, drive[2] .. " (" .. drive[1] .. ")")
  end
  computer.beep(800, 0.1)
end

local selIndex = math.ceil(#drives / 2)
displayMenu(selIndex)
while true do
  local e = { computer.pullSignal() }
  if e[1] == "key_down" then
    if e[4] == 200 and selIndex > 1 then
      selIndex = selIndex - 1
      displayMenu(selIndex)
    elseif e[4] == 208 and selIndex < #drives then
      selIndex = selIndex + 1
      displayMenu(selIndex)
    elseif e[4] == 18 then
      eraseDrive(drives[selIndex][1])
    elseif e[4] == 28 then
      local i, r = tryLoad(drives[selIndex][1])
      if i then
        computer.setBootAddress(drives[selIndex][1])
        computer.beep(800, 0.2)
        computer.beep(800, 0.6)
        computer.beep(800, 0.2)
        return i()
      else
        displayError("Unable to boot device!")
        computer.beep(800, 0.1)
        computer.beep(800, 0.1)
        computer.beep(800, 0.1)
      end
    end
  end
end