#!/usr/bin/env bash
# ─────────────────────────────────────────────
#  SPB Drive — Personal Cloud Drive
# ─────────────────────────────────────────────
#  Author  : Simon-Pierre Boucher
#  Contact : contact@spboucher.ai
#  File    : deploy/backup.sh
#  Purpose : Nightly backup — sqlite snapshot + hardlink-incremental blobs;
#            retention 14 dailies + 8 weeklies; verify + log
#  License : MIT © Simon-Pierre Boucher
# ─────────────────────────────────────────────
#
# Restore procedure: see README.md § Backups & restore.

set -euo pipefail

DATA_DIR="$HOME/srv/drive"
BACKUP_ROOT="$DATA_DIR/backups"
TODAY="$(date +%Y-%m-%d)"
DEST="$BACKUP_ROOT/$TODAY"
LAST="$(ls -1d "$BACKUP_ROOT"/20* 2>/dev/null | tail -1 || true)"

log() { printf '%s %s\n' "$(date '+%Y-%m-%d %H:%M:%S')" "$*"; }

mkdir -p "$DEST"

# 1 ── SQLite online snapshot (safe under WAL).
log "sqlite backup → $DEST/drive.sqlite"
sqlite3 "$DATA_DIR/db/drive.sqlite" ".backup '$DEST/drive.sqlite'"

# 2 ── Blob store: rsync with hardlinks against the previous backup —
#      unchanged blobs cost zero extra bytes (content-addressed, immutable).
log "files rsync (link-dest: ${LAST:-none})"
if [ -n "$LAST" ] && [ -d "$LAST/files" ] && [ "$LAST" != "$DEST" ]; then
  rsync -a --delete --link-dest="$LAST/files" "$DATA_DIR/files/" "$DEST/files/"
else
  rsync -a --delete "$DATA_DIR/files/" "$DEST/files/"
fi

# 3 ── Auth + keys (chmod 600 preserved).
cp -p "$DATA_DIR/auth.json" "$DATA_DIR/keys.json" "$DEST/" 2>/dev/null || true

# 4 ── Verify: DB integrity + blob count matches.
log "verifying"
sqlite3 "$DEST/drive.sqlite" 'PRAGMA integrity_check;' | grep -q '^ok$' || { log "✗ DB integrity failed"; exit 1; }
SRC_COUNT=$(find "$DATA_DIR/files" -type f | wc -l | tr -d ' ')
DST_COUNT=$(find "$DEST/files" -type f | wc -l | tr -d ' ')
if [ "$SRC_COUNT" != "$DST_COUNT" ]; then
  log "✗ blob count mismatch (src=$SRC_COUNT dst=$DST_COUNT)"; exit 1
fi

# 5 ── Retention: keep 14 dailies; keep Sunday backups 8 weeks.
log "pruning old backups"
for dir in "$BACKUP_ROOT"/20*; do
  [ -d "$dir" ] || continue
  day="$(basename "$dir")"
  age_days=$(( ( $(date +%s) - $(date -j -f %Y-%m-%d "$day" +%s 2>/dev/null || date -d "$day" +%s) ) / 86400 ))
  weekday=$(date -j -f %Y-%m-%d "$day" +%u 2>/dev/null || date -d "$day" +%u)
  if [ "$age_days" -gt 56 ]; then
    rm -rf "$dir"; log "pruned $day (older than 8 weeks)"
  elif [ "$age_days" -gt 14 ] && [ "$weekday" != 7 ]; then
    rm -rf "$dir"; log "pruned $day (daily beyond 14 days)"
  fi
done

log "✓ backup complete: $DEST ($SRC_COUNT blobs, $(du -sh "$DEST" | cut -f1))"