#!/bin/bash
# LMS Second Brain — Backup Script
# Backs up PostgreSQL (from Docker) + S3 files to Backblaze B2
# Place at: /opt/lms-backup/backup.sh on the server
# Cron: 0 3 * * * /opt/lms-backup/backup.sh >> /var/log/lms-backup.log 2>&1

set -euo pipefail

# ── Config ───────────────────────────────────────────────────────────────────
DB_CONTAINER="lms-system-db-1"
DB_USER="lms_user"
DB_NAME="lms_db"

BACKUP_DIR="/tmp/lms-backups"
DATE=$(date +%Y%m%d_%H%M)
DUMP_FILE="${BACKUP_DIR}/db_${DATE}.sql.gz"

# B2 rclone remote name (configured via: rclone config)
B2_REMOTE="b2lms"
B2_BUCKET="lms-backups-second-brain"
B2_DB_PATH="${B2_REMOTE}:${B2_BUCKET}/db"
B2_FILES_PATH="${B2_REMOTE}:${B2_BUCKET}/files"

# Hetzner S3 rclone remote name
S3_REMOTE="hetzner"
S3_BUCKET="lms-uploads"

# Retention: keep last N daily backups
KEEP_DAYS=7

# ── Functions ─────────────────────────────────────────────────────────────────
log() { echo "[$(date '+%Y-%m-%d %H:%M:%S')] $*"; }

# ── Main ──────────────────────────────────────────────────────────────────────
log "=== LMS Backup started ==="
mkdir -p "$BACKUP_DIR"

# 1. PostgreSQL dump
log "Dumping PostgreSQL from container ${DB_CONTAINER}..."
docker exec "$DB_CONTAINER" \
  pg_dump -U "$DB_USER" "$DB_NAME" \
  | gzip > "$DUMP_FILE"
log "Dump created: ${DUMP_FILE} ($(du -sh "$DUMP_FILE" | cut -f1))"

# 2. Upload DB dump to B2
log "Uploading DB dump to Backblaze B2..."
rclone copy "$DUMP_FILE" "$B2_DB_PATH"
log "DB dump uploaded: ${B2_DB_PATH}/$(basename "$DUMP_FILE")"

# 3. Sync S3 files to B2
log "Syncing S3 files to Backblaze B2..."
rclone sync \
  "${S3_REMOTE}:${S3_BUCKET}" \
  "$B2_FILES_PATH" \
  --progress \
  --transfers=8
log "S3 files synced to ${B2_FILES_PATH}"

# 4. Cleanup local temp files
rm -f "$DUMP_FILE"
log "Local temp files cleaned"

# 5. Prune old DB backups on B2 (keep last KEEP_DAYS)
log "Pruning DB backups older than ${KEEP_DAYS} days..."
rclone delete "$B2_DB_PATH" \
  --min-age "${KEEP_DAYS}d" \
  --include "db_*.sql.gz"
log "Pruning done"

log "=== LMS Backup finished successfully ==="