-- Network utilities module for auto-boot-ollama-host
-- Provides port checking, Wake-on-LAN functionality, and socket fallback support

local utils = require("utils")

-- Try to load socket module, fallback to basic implementation for LuaJIT
local socket
local socket_available = true
local ok, err = pcall(function() socket = require("socket") end)
if not ok then
  print("Warning: socket module not available, using fallback implementation")
  print("Error:", err)
  socket_available = false
  -- Create a minimal socket fallback for LuaJIT
  socket = {
    gettime = function() return os.time() end,
    sleep = function(sec) os.execute("sleep " .. tostring(sec)) end,
    tcp = function() return nil end, -- Will cause network functions to fail gracefully
    udp = function() return nil end,
    udp4 = function() return nil end
  }
end

local network = {}

-- Check if socket module is fully functional
function network.is_socket_available()
  return socket_available and socket and socket.tcp and socket.udp
end

-- Check if socket module is available for sleep operations
function network.is_sleep_available()
  return socket_available and socket and socket.sleep
end

-- Get the socket module (either real or fallback)
function network.get_socket()
  return socket
end

-- Check if a TCP port is accepting connections within a timeout (seconds)
function network.port_is_up(host, port, timeout_sec)
  host = tostring(host or "127.0.0.1")
  port = tonumber(port or 0) or 0
  local timeout = tonumber(timeout_sec or 1) or 1
  if port <= 0 then return false end

  -- Fallback to basic check if socket is not available
  if not network.is_socket_available() then
    utils.log("Socket module not available, using basic port check")
    local cmd = string.format("nc -z -w1 %s %d 2>/dev/null", host, port)
    local result = os.execute(cmd)
    return result == 0
  end

  local deadline = socket.gettime() + timeout
  while socket.gettime() < deadline do
    local tcp = socket.tcp()
    if not tcp then return false end
    tcp:settimeout(1)
    local ok = tcp:connect(host, port)
    tcp:close()
    if ok then return true end
    socket.sleep(0.5)
  end
  return false
end

-- Convert MAC address string to bytes
-- "AA:BB:CC:DD:EE:FF" -> 6 bytes
-- local function mac_to_bytes(mac)
--   local bytes = {}
--   for byte in mac:gmatch("(%x%x)") do
--     table.insert(bytes, tonumber(byte, 16))
--   end
--   if #bytes ~= 6 then return nil end
--   return string.char(table.unpack(bytes))
-- end

-- Send Wake-on-LAN magic packet
function network.send_wol(mac_str, bcast_ip, port)
  -- Build magic packet
  local bytes = {}
  for byte in mac_str:gmatch("(%x%x)") do
    table.insert(bytes, tonumber(byte, 16))
  end
  if #bytes ~= 6 then return false, "invalid MAC" end

  local mac = string.char(table.unpack(bytes))
  local packet = string.rep(string.char(0xFF), 6) .. mac:rep(16)

  -- Fallback to external tool if socket is not available
  if not network.is_socket_available() then
    utils.log("Socket module not available, using external wakeonlan tool")
    local cmd = string.format("wakeonlan -i %s -p %d %s", bcast_ip, port, mac_str)
    local result = os.execute(cmd)
    return result == 0, result ~= 0 and "wakeonlan command failed" or nil
  end

  -- Create IPv4 UDP socket (udp4 if available), bind to IPv4 wildcard to lock AF_INET
  local udp = assert((socket.udp4 or socket.udp)())
  udp:settimeout(2)
  assert(udp:setsockname("0.0.0.0", 0))    -- force IPv4 family
  assert(udp:setoption("broadcast", true)) -- allow broadcast

  local ok, err = udp:sendto(packet, bcast_ip, port)
  udp:close()
  return ok ~= nil, err
end

return network