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

# ==============================================================================
# MongoDB Volume Restore Script (Docker Swarm)
# ==============================================================================
#
# PURPOSE:
#   Restores the complete mongo-volume directory from a volume backup tarball.
#   The MongoDB service is scaled down during the restore to ensure consistency.
#
# WHEN TO USE:
#   - For Docker Swarm deployments (not standalone Docker)
#   - To restore from backups created by db-backup--swarm.sh
#   - For disaster recovery scenarios
#   - When you need to restore the complete MongoDB data directory
#
# RESTORE TYPE:
#   - Offline (cold) restore - DB service is scaled to 0 during restore
#   - Volume-level restore - entire mongo-volume directory
#   - Extracts from compressed tarball (.tar.gz)
#
# INPUT:
#   - Requires backup filename as parameter
#   - Looks for file in: ./mongo-backup/
#   - Optional: --pre-backup flag to create safety backup before restore
#
# USAGE:
#   ./db-restore-from-backup--swarm.sh <backup-filename>
#   ./db-restore-from-backup--swarm.sh mongo-volume-backup-2025-11-26-14-30.tar.gz
#   ./db-restore-from-backup--swarm.sh --pre-backup mongo-volume-backup-2025-11-26-14-30.tar.gz
#
# WARNING:
#   This will COMPLETELY REPLACE the mongo-volume directory contents!
#   Use --pre-backup flag to create a safety backup before restore.
#
# NOTE:
#   The MongoDB service will be scaled down to 0 and then back up to 1.
#   Expect downtime during the restore process.
#
# ==============================================================================

# Configuration
MONGO_SERVICE="utility-bills-tracker_mongo"

# Parse command line options
DO_PRE_BACKUP=""

while [[ $# -gt 0 ]]; do
  case $1 in
    --do-pre-backup=*)
      DO_PRE_BACKUP="${1#*=}"
      shift
      ;;
    *)
      TIMESTAMP="$1"
      shift
      ;;
  esac
done

# Usage: ./restore.sh [options] <timestamp>
# Example: ./restore.sh 2025-08-24-14-30
# Options: --do-pre-backup=true/false (skip interactive prompt)

if [ -z "${TIMESTAMP:-}" ]; then
  echo "Usage: $0 [options] <timestamp>"
  echo "Example: $0 2025-08-24-14-30"
  echo ""
  echo "Options:"
  echo "  --do-pre-backup=true    Skip interactive prompt, create pre-restore backup"
  echo "  --do-pre-backup=false   Skip interactive prompt, no pre-restore backup"
  echo ""
  echo "Available backups:"
  ls -1t mongo-backup/mongo-volume-backup-*.tar.gz 2>/dev/null | sed 's/.*mongo-volume-backup-\(.*\)\.tar\.gz/  \1/' || echo "  No backups found"
  exit 1
fi
BACKUP_DIR="${BACKUP_DIR:-mongo-backup}"
BACKUP_FILE="$BACKUP_DIR/mongo-volume-backup-$TIMESTAMP.tar.gz"

# Check if backup file exists
if [ ! -f "$BACKUP_FILE" ]; then
  echo "Error: Backup file '$BACKUP_FILE' not found"
  echo ""
  echo "Available backups:"
  ls -1t "$BACKUP_DIR"/mongo-volume-backup-*.tar.gz 2>/dev/null | sed 's/.*mongo-volume-backup-\(.*\)\.tar\.gz/  \1/' || echo "  No backups found"
  exit 1
fi

echo "Restoring from backup: $BACKUP_FILE"
echo "WARNING: This will replace the current mongo-volume data!"
read -p "Are you sure you want to continue? (y/N): " -n 1 -r
echo
if [[ ! $REPLY =~ ^[Yy]$ ]]; then
  echo "Restore cancelled"
  exit 0
fi

# Scale down mongo service
echo "Scaling down mongo service..."
docker service scale "$MONGO_SERVICE"=0

# Handle pre-restore backup
CREATE_PRE_BACKUP=true
if [ "$DO_PRE_BACKUP" = "false" ]; then
  CREATE_PRE_BACKUP=false
elif [ "$DO_PRE_BACKUP" = "true" ]; then
  CREATE_PRE_BACKUP=true
elif [ -z "$DO_PRE_BACKUP" ]; then
  # Ask user interactively
  read -p "Create pre-restore safety backup? (Y/n): " -n 1 -r
  echo
  if [[ $REPLY =~ ^[Nn]$ ]]; then
    CREATE_PRE_BACKUP=false
  fi
else
  echo "Error: --do-pre-backup must be 'true' or 'false'"
  exit 1
fi

# Create pre-restore backup if requested
if [ "$CREATE_PRE_BACKUP" = true ]; then
  SAFETY_BACKUP="$BACKUP_DIR/mongo-volume-pre-restore-$(date +%Y-%m-%d-%H-%M).tar.gz"
  echo "Creating safety backup: $SAFETY_BACKUP"
  sudo tar -czf "$SAFETY_BACKUP" mongo-volume 2>/dev/null || true
else
  echo "Skipping pre-restore backup"
  SAFETY_BACKUP=""
fi

# Remove current volume
echo "Removing current mongo-volume..."
sudo rm -rf mongo-volume

# Extract backup
echo "Extracting backup..."
sudo tar -xzf "$BACKUP_FILE"

# Set proper permissions
echo "Setting permissions..."
sudo chown -R 999:999 mongo-volume

# Scale mongo service back up
echo "Scaling mongo service back up..."
docker service scale "$MONGO_SERVICE"=1

echo "Restore completed successfully!"
if [ -n "$SAFETY_BACKUP" ]; then
  echo "Safety backup saved as: $SAFETY_BACKUP"
fi