#!/usr/bin/env bash
# Pull selected pi0.5 checkpoints off the Brev instance, resumably, params+assets only.
#
#   scripts/fetch_checkpoints.sh --dry-run 7500 15000 22500
#   scripts/fetch_checkpoints.sh 7500 15000 22500
#
# Why a script and not a bare rsync:
#
#  1. Brev's generated ssh_config sets `RequestTTY yes`. rsync over a pty corrupts its own
#     protocol stream ("protocol version mismatch" / garbage). We force -T off.
#  2. `train_state/` is optimizer state -- 30-40 GiB per checkpoint that the robot never reads.
#     Excluded unconditionally. Use --with-train-state only if you intend to RESUME training.
#  3. 12.5 GiB files over a home connection will drop. --partial --append-verify resumes
#     instead of restarting, and re-checksums the bytes already on disk.
#  4. A preflight refuses to start a transfer that cannot fit in local free space, because
#     filling a root filesystem is a much worse afternoon than a clear error message.
set -euo pipefail

HOST="${HOST:-pi-05-pickplace-fft}"
REMOTE_ROOT="${REMOTE_ROOT:-/data/checkpoints/pi05_g1_pickplace/pickplace_full_v1}"
DEST="${DEST:-$HOME/pi05_checkpoints}"
RESERVE_GIB="${RESERVE_GIB:-15}"   # local headroom to leave untouched

DRY=0
WITH_TS=0
STEPS=()
while [ $# -gt 0 ]; do
  case "$1" in
    --dry-run) DRY=1 ;;
    --with-train-state) WITH_TS=1 ;;
    --dest) DEST="$2"; shift ;;
    --host) HOST="$2"; shift ;;
    -h|--help) sed -n '2,20p' "$0"; exit 0 ;;
    -*) echo "unknown flag: $1" >&2; exit 2 ;;
    *) STEPS+=("$1") ;;
  esac
  shift
done

if [ ${#STEPS[@]} -eq 0 ]; then
  echo "usage: $0 [--dry-run] [--with-train-state] [--dest DIR] STEP [STEP ...]" >&2
  echo "       e.g. $0 7500 15000 22500 29999" >&2
  exit 2
fi

RS_HELP=$(rsync --help 2>&1 || true)
MISSING_FLAGS=""
for f in append-verify info partial exclude; do
  case "$RS_HELP" in *"--$f"*) ;; *) MISSING_FLAGS="$MISSING_FLAGS --$f" ;; esac
done
if [ -n "$MISSING_FLAGS" ]; then
  echo "FAIL: this rsync does not support:$MISSING_FLAGS" >&2
  echo "      $(rsync --version 2>&1 | head -1)" >&2
  echo "      Need GNU rsync 3.1+. Debian/Ubuntu: sudo apt install rsync" >&2
  echo "      (stock macOS ships openrsync, which lacks these: brew install rsync)" >&2
  exit 1
fi

SSH_OPTS=(-o RequestTTY=no -o ConnectTimeout=20)
ssh_run() { ssh "${SSH_OPTS[@]}" "$HOST" "$@"; }

echo "host        : $HOST"
echo "remote root : $REMOTE_ROOT"
echo "destination : $DEST"
echo "steps       : ${STEPS[*]}"
echo

if ! ssh_run true 2>/dev/null; then
  echo "Host aliases Brev has configured on this machine:" >&2
  grep -h '^Host ' ~/.brev/ssh_config 2>/dev/null | sed 's/^/  /' >&2 || true
  cat >&2 <<'MSG'
FAIL: cannot reach the instance over ssh.

Brev rotates the instance IP, and ~/.brev/ssh_config is only rewritten when the CLI is logged
in. Refresh it, then re-run:

    brev login
    brev ls          # confirm the instance is RUNNING
    brev refresh     # rewrites ~/.brev/ssh_config with the current IP
MSG
  exit 1
fi

# ---- preflight: what exists remotely, how big, and does it fit locally ----
echo "== remote inventory =="
ssh_run "cd '$REMOTE_ROOT' 2>/dev/null || { echo 'MISSING: $REMOTE_ROOT'; exit 1; }; \
         for s in ${STEPS[*]}; do \
           if [ -d \"\$s\" ]; then \
             printf '%8s  params=%-8s assets=%-7s train_state=%s\n' \"\$s\" \
               \"\$(du -sh \$s/params 2>/dev/null | cut -f1)\" \
               \"\$(du -sh \$s/assets 2>/dev/null | cut -f1)\" \
               \"\$([ -d \$s/train_state ] && du -sh \$s/train_state | cut -f1 || echo none)\"; \
           else echo \"\$s  MISSING\"; fi; \
         done"

# Bytes we are actually about to move.
if [ "$WITH_TS" -eq 1 ]; then SUBDIRS="params assets train_state"; else SUBDIRS="params assets"; fi
NEED_KB=$(ssh_run "cd '$REMOTE_ROOT'; t=0; for s in ${STEPS[*]}; do for d in $SUBDIRS; do \
            [ -d \"\$s/\$d\" ] && t=\$((t + \$(du -sk \"\$s/\$d\" | cut -f1))); done; done; echo \$t")
NEED_GIB=$(( NEED_KB / 1024 / 1024 ))

mkdir -p "$DEST"
AVAIL_KB=$(df -Pk "$DEST" | tail -1 | awk '{print $4}')
AVAIL_GIB=$(( AVAIL_KB / 1024 / 1024 ))

echo
echo "transfer size : ${NEED_GIB} GiB  (train_state $([ "$WITH_TS" -eq 1 ] && echo INCLUDED || echo excluded))"
echo "local free    : ${AVAIL_GIB} GiB at $DEST"
echo "reserve       : ${RESERVE_GIB} GiB"

if [ $(( NEED_GIB + RESERVE_GIB )) -gt "$AVAIL_GIB" ]; then
  cat >&2 <<MSG

FAIL: will not fit. Need ${NEED_GIB} GiB + ${RESERVE_GIB} GiB reserve, have ${AVAIL_GIB} GiB.

Options, cheapest first:
  * fetch fewer steps -- each params+assets pair is ~12.5 GiB
  * --dest /path/on/a/bigger/volume
  * push to the Hugging Face Hub from the instance instead, and pull one at a time later
  * lower the reserve with RESERVE_GIB=5 (only if you know what is on that volume)
MSG
  exit 1
fi

RSYNC=(rsync -a --info=progress2 --partial --append-verify --human-readable
       -e "ssh ${SSH_OPTS[*]}")
[ "$WITH_TS" -eq 1 ] || RSYNC+=(--exclude 'train_state/')
[ "$DRY" -eq 1 ] && RSYNC+=(--dry-run)

echo
for s in "${STEPS[@]}"; do
  echo "== $s =="
  "${RSYNC[@]}" "$HOST:$REMOTE_ROOT/$s" "$DEST/"
done

[ "$DRY" -eq 1 ] && { echo; echo "dry run -- nothing written."; exit 0; }

# ---- verify: norm_stats present, and remote/local byte counts agree ----
echo
echo "== verify =="
fail=0
for s in "${STEPS[@]}"; do
  if ! find "$DEST/$s/assets" -name norm_stats.json 2>/dev/null | grep -q .; then
    echo "  $s  FAIL: no assets/**/norm_stats.json -- policy would serve garbage"; fail=1; continue
  fi
  r=$(ssh_run "cd '$REMOTE_ROOT/$s'; du -sk $SUBDIRS 2>/dev/null | awk '{t+=\$1} END {print t}'")
  l=$(cd "$DEST/$s" && du -sk $SUBDIRS 2>/dev/null | awk '{t+=$1} END {print t}')
  # du can differ by a few blocks across filesystems; 1% is generous but still catches truncation.
  if [ "$r" -gt 0 ] && [ $(( (r - l) * 100 / r )) -gt 1 ] ; then
    echo "  $s  FAIL: remote ${r}KB vs local ${l}KB -- incomplete, re-run to resume"; fail=1
  else
    echo "  $s  OK ($(du -sh "$DEST/$s" | cut -f1))"
  fi
done

echo
if [ "$fail" -eq 1 ]; then
  echo "Some checkpoints did not verify. Re-run the same command -- rsync resumes."
  exit 1
fi
echo "All requested checkpoints verified in $DEST."
echo "Do NOT terminate the instance until you have confirmed at least one loads locally:"
echo "  uv run python scripts/load_checkpoint_test.py $DEST/${STEPS[0]}"