#!/usr/bin/env bash
set -euo pipefail

# Configuration
SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
LOG_FILE="$SCRIPT_DIR/backups/db-backup-standalone.log"
MONGO_SERVICE="mongo"
COMPOSE_FILE="$SCRIPT_DIR/docker-compose-standalone.yaml"

# Initialize log file (overwrite if exists)
mkdir -p "$(dirname "$LOG_FILE")"
> "$LOG_FILE"

# Function to log messages
log() {
  local timestamp=$(date '+%Y-%m-%d %H:%M:%S')
  echo "[$timestamp] $*" | tee -a "$LOG_FILE"
}

# stop mongo container while we copy its volume
log "Stopping MongoDB container..."
docker compose -f "$COMPOSE_FILE" stop "$MONGO_SERVICE"

# timestamp for filename
TIMESTAMP=$(date +"%Y-%m-%d-%H-%M")

# backup directory and retention (can be overridden via env)
BACKUP_DIR="${BACKUP_DIR:-$SCRIPT_DIR/backups}"
KEEP="${KEEP:-7}"

mkdir -p "$BACKUP_DIR"

BACKUP_FILE="$BACKUP_DIR/mongo-volume-backup-$TIMESTAMP.tar.gz"

log "Creating backup: $BACKUP_FILE"
sudo tar -czvpf "$BACKUP_FILE" mongo-volume

log "Backup created successfully."

# rotate old backups: keep only the newest $KEEP files
if [ "$KEEP" -gt 0 ]; then
  log "Rotating backups, keeping the newest $KEEP files."

  # gather files sorted newest-first
  mapfile -t files < <(ls -1t "$BACKUP_DIR"/mongo-volume-backup-*.tar.gz 2>/dev/null || true)
  if [ "${#files[@]}" -gt "$KEEP" ]; then
    for f in "${files[@]:$KEEP}"; do
      log "Removing old backup: $f"
      rm -f -- "$f"
    done
  fi

  log "Rotation completed."
else
  log "Backup rotation disabled (KEEP=$KEEP)."
fi

log "Starting MongoDB container..."
docker compose -f "$COMPOSE_FILE" start "$MONGO_SERVICE"

log "Database backup process completed successfully."