#!/bin/bash
# ─────────────────────────────────────────────
#  SPB Git — Personal Git Platform
# ─────────────────────────────────────────────
#  Author  : Simon-Pierre Boucher
#  Contact : contact@spboucher.ai
#  File    : deploy/backup.sh
#  Purpose : Nightly backup — tar.zst of bare repos + data, keep 14
#  License : MIT © Simon-Pierre Boucher
# ─────────────────────────────────────────────
#
# Cron (crontab -e on m3u96a):
#   15 3 * * * /bin/bash <app>/deploy/backup.sh >> <prefix>/spbgit/logs/backup.log 2>&1
#
set -euo pipefail

if [ "$(uname)" = "Darwin" ]; then PREFIX="$HOME/srv"; else PREFIX="/srv"; fi
GIT_ROOT="${SPBGIT_GIT_ROOT:-$PREFIX/git}"
DATA_DIR="${SPBGIT_DATA_DIR:-$PREFIX/spbgit/data}"
BACKUP_DIR="${SPBGIT_BACKUP_DIR:-$PREFIX/spbgit/backups}"
KEEP=14

mkdir -p "$BACKUP_DIR"
STAMP="$(date +%Y%m%d-%H%M%S)"

if tar --help 2>/dev/null | grep -q -- --zstd; then
  ARCHIVE="$BACKUP_DIR/spbgit-$STAMP.tar.zst"
  tar --zstd -cf "$ARCHIVE" -C "$(dirname "$GIT_ROOT")" "$(basename "$GIT_ROOT")" -C "$(dirname "$DATA_DIR")" "$(basename "$DATA_DIR")"
else
  ARCHIVE="$BACKUP_DIR/spbgit-$STAMP.tar.gz"
  tar -czf "$ARCHIVE" -C "$(dirname "$GIT_ROOT")" "$(basename "$GIT_ROOT")" -C "$(dirname "$DATA_DIR")" "$(basename "$DATA_DIR")"
fi

# Rotate: keep the newest $KEEP archives.
ls -1t "$BACKUP_DIR"/spbgit-*.tar.* 2>/dev/null | tail -n +$((KEEP + 1)) | while read -r old; do
  rm -f "$old"
done

SIZE="$(du -h "$ARCHIVE" | cut -f1 | tr -d ' ')"
echo "[$(date -u +%Y-%m-%dT%H:%M:%SZ)] backup ok: $ARCHIVE ($SIZE), $(ls -1 "$BACKUP_DIR"/spbgit-*.tar.* | wc -l | tr -d ' ') archives kept"