## BattleRunner Java subprocess — capture stdout JSON-lines output.

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

const
  DefaultRunnerJar = "/home/davide/Projects/tank-royale/runner/examples/lib/robocode-tankroyale-runner.jar"
  ScriptDir = currentSourcePath().parentDir() / ".." / ".." / "tools" / "battle_runner"

proc runBattleRunner*(serverUrl: string, botDirs: seq[string], rounds: int,
                      timeout: int = 30000): string =
  ## Starts TestBattleRunner as a subprocess. Returns captured stdout on success.
  ## Raises IOError on non-zero exit or TimeoutError on timeout.
  let jar = getEnv("TR_BATTLE_RUNNER", DefaultRunnerJar)
  let classDir = getEnv("TR_BATTLE_RUNNER_DIR", ScriptDir)

  let args = @[
    "-cp", classDir & ":" & jar,
    "TestBattleRunner",
    "--server-url", serverUrl,
    "--rounds", $rounds,
    "--bot-dirs", botDirs.join(",")
  ]

  let p = startProcess("java", args = args,
    options = {poUsePath, poStdErrToStdOut})
  defer:
    p.close()

  let deadline = epochTime() + timeout.float / 1000.0
  var stdout = ""
  var line: string
  # ponytail: poll instead of blocking readLine; 50ms sleep is fine for battle timescales
  while epochTime() < deadline:
    if p.peekExitCode() != -1:
      # Process finished; drain remaining output without blocking
      while p.outputStream.atEnd == false:
        discard p.outputStream.readLine(line)
        stdout.add(line & "\n")
      break
    sleep(50)

  if epochTime() >= deadline and p.peekExitCode() == -1:
    p.terminate()
    raise newException(TimeoutError,
      "BattleRunner timed out after " & $timeout & "ms")

  let code = p.waitForExit()
  if code != 0:
    raise newException(IOError,
      "BattleRunner exited with code " & $code & "\nOutput:\n" & stdout)

  result = stdout

when isMainModule:
  echo "runner_process.nim — usage:"
  echo "  runBattleRunner(serverUrl, botDirs, rounds, timeout)"
  echo ""
  echo "Env vars:"
  echo "  TR_BATTLE_RUNNER      JAR path (default: " & DefaultRunnerJar & ")"
  echo "  TR_BATTLE_RUNNER_DIR  class dir (default: tools/battle_runner/)"
  echo ""
  echo "Cannot self-test without a running TR server. Start one first."