## TR server lifecycle manager — lazy singleton for integration tests.
## Start with ensureServer(), query with getServerUrl().

import std/[osproc, net, os, strutils, times, streams, exitprocs]

const
  DefaultJar = "/home/davide/Projects/tank-royale/server/build/libs/robocode-tankroyale-server-0.35.5-all.jar"
  ReadySignal = "Starting server on port"
  StartupTimeout = 15.0  # seconds

var
  serverProc: Process = nil
  serverPort: int = 0

proc findFreePort(): int =
  let s = newSocket()
  s.bindAddr(Port(0))
  let (_, port) = s.getLocalAddr()
  result = port.int
  s.close()

proc ensureServer*() =
  if serverProc != nil: return

  let jar = getEnv("TR_SERVER_JAR", DefaultJar)
  if not fileExists(jar):
    raise newException(IOError, "TR server JAR not found: " & jar &
      "\nSet TR_SERVER_JAR env var to override.")

  serverPort = findFreePort()
  serverProc = startProcess("java",
    args = @["-jar", jar, "--port", $serverPort, "--enable-initial-position", "--tps", "-1"],
    options = {poUsePath, poStdErrToStdOut})

  exitprocs.addExitProc(proc() =
    if serverProc != nil:
      serverProc.terminate()
      serverProc.close()
  )

  # Wait for ready signal
  let deadline = epochTime() + StartupTimeout
  var ready = false
  while epochTime() < deadline:
    var line: string
    discard serverProc.outputStream.readLine(line)
    if ReadySignal in line:
      ready = true
      break
  if not ready:
    serverProc.terminate()
    serverProc.close()
    serverProc = nil
    raise newException(TimeoutError, "TR server did not start within " & $StartupTimeout & "s")

proc getServerUrl*(): string =
  if serverPort == 0:
    raise newException(CatchableError, "Server not started — call ensureServer() first")
  "ws://localhost:" & $serverPort

when isMainModule:
  echo "Starting TR server..."
  ensureServer()
  echo "Server ready at: ", getServerUrl()
  echo "Sleeping 2s then exiting (addExitProc will kill server)..."
  os.sleep(2000)
  echo "Done."