#!/usr/bin/env bash
# scripts/migrate-onyx.sh — Phase 2 migration helper.
#
# Usage:
#   ./migrate-onyx.sh <source-dir-on-onyx> <target-dir-on-nullstone>
#
# Example:
#   ./migrate-onyx.sh "$HOME/Downloads/qbt/" \
#                     /home/user/media/_downloads/complete/
#
# What it does:
#   1. rsync <source-dir> → user@nullstone:<target-dir> over LAN.
#   2. Copies onyx's .torrent + .fastresume files to /tmp/qbt-migrate/
#      on nullstone (you mass-add them via qbt webui afterwards).
#   3. Prints a checklist of remaining manual steps.
#
# Pre-reqs:
#   - run from onyx (the SOURCE machine).
#   - ssh user@nullstone reachable on LAN.
#   - nullstone qbt stack already up (Phase 1 complete) — check with
#     `bash killswitch-test.sh` first.

set -euo pipefail

SRC="${1:-}"
DST="${2:-}"
NULLSTONE="${NULLSTONE_SSH:-user@192.168.0.100}"
DRY_RUN="${DRY_RUN:-1}"

usage() {
    cat <<EOF
Usage: $0 <source-dir> <target-dir-on-nullstone>

Env:
  NULLSTONE_SSH   default: user@192.168.0.100
  DRY_RUN         default: 1 (rsync --dry-run). Set DRY_RUN=0 to actually copy.

Example (dry-run):
  $0 "\$HOME/Downloads/qbt/" /home/user/media/_downloads/complete/

Example (real):
  DRY_RUN=0 $0 "\$HOME/Downloads/qbt/" /home/user/media/_downloads/complete/
EOF
    exit 2
}

[ -z "$SRC" ] || [ -z "$DST" ] && usage
[ -d "$SRC" ] || { echo "Source dir not found: $SRC" >&2; exit 1; }

QBT_BACKUP="$HOME/.local/share/qBittorrent/BT_backup"
[ -d "$QBT_BACKUP" ] || { echo "qBittorrent BT_backup dir missing: $QBT_BACKUP" >&2; exit 1; }

RSYNC_FLAGS=(-av --info=progress2 --partial --human-readable)
if [ "$DRY_RUN" = "1" ]; then
    RSYNC_FLAGS+=(--dry-run)
    echo "=== DRY-RUN — no data will be copied. Set DRY_RUN=0 to run for real. ==="
fi

echo "=== Step 1/3: rsync data files to nullstone ==="
rsync "${RSYNC_FLAGS[@]}" "$SRC" "$NULLSTONE:$DST"

echo
echo "=== Step 2/3: ship .torrent + .fastresume to nullstone /tmp/qbt-migrate/ ==="
ssh "$NULLSTONE" "mkdir -p /tmp/qbt-migrate"
if [ "$DRY_RUN" = "1" ]; then
    echo "(dry-run) would scp $QBT_BACKUP/*.torrent $QBT_BACKUP/*.fastresume → $NULLSTONE:/tmp/qbt-migrate/"
else
    scp -q "$QBT_BACKUP"/*.torrent "$QBT_BACKUP"/*.fastresume "$NULLSTONE:/tmp/qbt-migrate/"
fi

echo
echo "=== Step 3/3: remaining manual steps ==="
cat <<EOF

Manual steps on the nullstone qbt webui (https://qbt.s8n.ru):

  1. "Add Torrent" → multi-select all files in /tmp/qbt-migrate/*.torrent
     Save path: $DST
     [ ] UNCHECK "Start torrent" — we want them queued, not auto-resumed.

  2. Select all newly-added torrents → right-click → "Force recheck"
     qbt will hash-match files in $DST → mark each at 100% → start seeding.

  3. Check tracker status per torrent. Private trackers may reject the new
     source IP (Proton exit). See docs/trackers.md for the per-tracker
     mitigation playbook.

  4. On onyx (THIS machine): pause torrents one-by-one as nullstone takes
     over each. Do NOT stop onyx-qbt entirely until every torrent shows
     seeding on nullstone for 24h with zero tracker errors.

Fastresume path-rewrite (optional, only if save_path drift breaks recheck):

  ssh $NULLSTONE 'python3 - <<PYEOF
import os, re, sys
from pathlib import Path
src_prefix = "/home/admin/Downloads/qbt"     # onyx path
dst_prefix = "/downloads/complete"            # nullstone path inside qbt container
for fr in Path("/tmp/qbt-migrate").glob("*.fastresume"):
    data = fr.read_bytes()
    if src_prefix.encode() in data:
        new = data.replace(src_prefix.encode(), dst_prefix.encode())
        fr.write_bytes(new)
        print("rewrote:", fr.name)
PYEOF'

  (Only run if force-recheck fails — qbt 5 usually handles re-pathing via
  the UI's "Save path" field on add.)
EOF