#!/usr/bin/env bash
# Bounded, non-invasive waiter for the C3 resume gate on a shared host.
# It never stops another process and delegates all launch guards to the main
# CFG launcher after selecting a fresh pair of genuinely idle physical GPUs.

set -euo pipefail

PROJECT_ROOT="/data/myx/RL_post_train"
RESUME_DIR=""
MAX_ATTEMPTS="${CFG_RESUME_MAX_ATTEMPTS:-3}"
POLL_SECONDS="${CFG_RESUME_POLL_SECONDS:-60}"
RUN_PREFIX="recap_cfg_c3_resume"

usage() {
  cat <<'EOF'
Usage: wait_for_cfg_resume_gpu.sh --resume-dir PATH [options]

Options:
  --resume-dir PATH  Existing global_step_20 checkpoint directory.
  --max-attempts N   Retry bound after a shared-GPU race (default: 3).
  --poll-seconds N   Poll interval (default: 60).
  --run-prefix NAME  Prefix for child launcher run IDs.
EOF
}

while (($# > 0)); do
  case "$1" in
    --resume-dir) RESUME_DIR="$2"; shift 2 ;;
    --max-attempts) MAX_ATTEMPTS="$2"; shift 2 ;;
    --poll-seconds) POLL_SECONDS="$2"; shift 2 ;;
    --run-prefix) RUN_PREFIX="$2"; shift 2 ;;
    -h|--help) usage; exit 0 ;;
    *) echo "Unknown argument: $1" >&2; usage >&2; exit 2 ;;
  esac
done

if [[ -z "${RESUME_DIR}" || ! -d "${RESUME_DIR}" ]]; then
  echo "--resume-dir must name an existing checkpoint directory" >&2
  exit 2
fi
if [[ "${RESUME_DIR}" != /data/myx/* ]]; then
  echo "resume-dir must remain under /data/myx: ${RESUME_DIR}" >&2
  exit 2
fi
if [[ ! "${MAX_ATTEMPTS}" =~ ^[1-9][0-9]*$ || ! "${POLL_SECONDS}" =~ ^[1-9][0-9]*$ ]]; then
  echo "max-attempts and poll-seconds must be positive integers" >&2
  exit 2
fi
if [[ ! "${RUN_PREFIX}" =~ ^[A-Za-z0-9_.-]+$ ]]; then
  echo "run-prefix contains unsafe characters: ${RUN_PREFIX}" >&2
  exit 2
fi

LOG_DIR="${PROJECT_ROOT}/logs/recap/cfg"
mkdir -p "${LOG_DIR}"
LOG_FILE="${LOG_DIR}/c3_resume_wait_$(date +%Y%m%d_%H%M%S).log"
exec >>"${LOG_FILE}" 2>&1

echo "CFG_RESUME_WAITER_START resume_dir=${RESUME_DIR} max_attempts=${MAX_ATTEMPTS} poll_seconds=${POLL_SECONDS}"
attempt=0
while ((attempt < MAX_ATTEMPTS)); do
  echo "CFG_RESUME_WAITER_POLL time=$(date --iso-8601=seconds) attempt=${attempt}"
  if ! gpu_rows="$(nvidia-smi --query-gpu=index,memory.used,utilization.gpu --format=csv,noheader,nounits 2>/dev/null)"; then
    echo "CFG_RESUME_WAITER_DRIVER_UNAVAILABLE"
    sleep "${POLL_SECONDS}"
    continue
  fi

  free_gpus=()
  while IFS=',' read -r gpu memory utilization; do
    gpu="$(printf '%s' "${gpu}" | tr -d '[:space:]')"
    memory="$(printf '%s' "${memory}" | tr -d '[:space:]')"
    utilization="$(printf '%s' "${utilization}" | tr -d '[:space:]')"
    [[ "${gpu}" =~ ^[0-9]+$ && "${memory}" =~ ^[0-9]+$ && "${utilization}" =~ ^[0-9]+$ ]] || continue
    compute_pids="$(nvidia-smi -i "${gpu}" --query-compute-apps=pid --format=csv,noheader,nounits 2>/dev/null | awk '$1 ~ /^[0-9]+$/ {print $1}' | tr -d '[:space:]')"
    echo "CFG_RESUME_WAITER_GPU gpu=${gpu} memory_mb=${memory} util_pct=${utilization} compute_pids=${compute_pids:-none}"
    if ((memory <= 1024 && utilization <= 5)) && [[ -z "${compute_pids}" ]]; then
      free_gpus+=("${gpu}")
    fi
  done <<<"${gpu_rows}"

  if ((${#free_gpus[@]} < 2)); then
    echo "CFG_RESUME_WAITER_WAIT free_count=${#free_gpus[@]}"
    sleep "${POLL_SECONDS}"
    continue
  fi
  if pgrep -af "[r]aylet|[g]cs_server|[p]lasma_store" >/dev/null 2>&1; then
    echo "CFG_RESUME_WAITER_RAY_BLOCKED"
    sleep "${POLL_SECONDS}"
    continue
  fi

  gpus="${free_gpus[0]},${free_gpus[1]}"
  run_id="${RUN_PREFIX}_$(date +%Y%m%d_%H%M%S)"
  attempt=$((attempt + 1))
  echo "CFG_RESUME_WAITER_LAUNCH run_id=${run_id} gpus=${gpus} attempt=${attempt}"
  set +e
  "${PROJECT_ROOT}/scripts/run_cfg_task0.sh" \
    --mode c3_resume \
    --gpus "${gpus}" \
    --resume-dir "${RESUME_DIR}" \
    --run-id "${run_id}"
  rc=$?
  set -e
  echo "CFG_RESUME_WAITER_CHILD_DONE run_id=${run_id} exit_code=${rc}"
  if ((rc == 0)); then
    echo "CFG_RESUME_WAITER_DONE run_id=${run_id}"
    exit 0
  fi
  if ((attempt >= MAX_ATTEMPTS)); then
    echo "CFG_RESUME_WAITER_FAILED attempts=${attempt}"
    exit "${rc}"
  fi
  sleep "${POLL_SECONDS}"
done

echo "CFG_RESUME_WAITER_FAILED attempts=${attempt}"
exit 1