#!/bin/bash
set -euo pipefail

BACKUP_DIR="/opt/memento/backups"
WAL_DIR="$BACKUP_DIR/wal"
SNAPSHOT_DIR="$BACKUP_DIR/snapshots"
TIMESTAMP=$(date +%Y%m%d-%H%M%S)
RETENTION_DAYS=7
RETENTION_WEEKS=4
PG_CONTAINER="memento-postgres"
PG_USER="${POSTGRES_USER:-memento}"
PG_DB="${POSTGRES_DB:-memento}"
LOG_FILE="$BACKUP_DIR/backup.log"

mkdir -p "$WAL_DIR" "$SNAPSHOT_DIR"

log() {
  echo "[$(date '+%Y-%m-%d %H:%M:%S')] $1" | tee -a "$LOG_FILE"
}

log "=== Starting backup ==="

SNAPSHOT_FILE="$SNAPSHOT_DIR/memento-$TIMESTAMP.sql.gz"

log "Creating snapshot: $SNAPSHOT_FILE"
docker exec "$PG_CONTAINER" pg_dump -U "$PG_USER" -d "$PG_DB" --format=custom | gzip > "$SNAPSHOT_FILE"

SNAPSHOT_SIZE=$(stat -c%s "$SNAPSHOT_FILE" 2>/dev/null || echo 0)
if [ "$SNAPSHOT_SIZE" -lt 1048576 ]; then
  log "ERROR: Snapshot is only $SNAPSHOT_SIZE bytes (< 1MB). Possible failure!"
  exit 1
fi

log "Snapshot OK: $(( SNAPSHOT_SIZE / 1024 ))KB"

log "Verifying snapshot integrity..."
if gzip -t "$SNAPSHOT_FILE" 2>/dev/null; then
  log "Integrity check: PASSED"
else
  log "ERROR: Snapshot integrity check FAILED!"
  exit 1
fi

log "Cleaning old snapshots (keeping $RETENTION_DAYS days + $RETENTION_WEEKS weekly)..."
cd "$SNAPSHOT_DIR"

find . -name "*.sql.gz" -mtime +$RETENTION_DAYS -delete 2>/dev/null || true

SNAPSHOT_COUNT=$(ls -1 "$SNAPSHOT_DIR"/*.sql.gz 2>/dev/null | wc -l)
log "Cleanup done. $SNAPSHOT_COUNT snapshots remaining"

log "=== Backup complete ==="