#!/bin/sh
set -eu

# Generic database backup triggered through the Docker Engine unix socket.
# Supports PostgreSQL and MySQL/MariaDB containers.

log() {
  printf '%s\n' "$(date -u '+%Y-%m-%dT%H:%M:%SZ') $*"
}

print_usage() {
  cat <<EOF_USAGE >&2
Usage: $0 [--socket=PATH] [--api-version=VERSION] --container=NAME \\
         [--type=postgres|mysql] --backup-prefix=PREFIX [--backup-dir=DIR] \\
         [--mysql-user=USER] [--mysql-password=PASSWORD]

Options:
  --socket=PATH             Docker Engine unix socket path (default: /var/run/docker.sock)
  --api-version=VERSION     Docker API version (default: v1.51)
  --container=NAME          Container name to execute the backup in
  --type=TYPE               Database type: postgres or mysql (auto-detected from container name if omitted)
  --backup-dir=DIR          Directory to store backups (default: /backups)
  --backup-prefix=PREFIX    Backup filename prefix
  --mysql-user=USER         MySQL user (default: root)
  --mysql-password=PASSWORD MySQL password (optional)
  --help                    Show this help message
EOF_USAGE
}

DOCKER_SOCKET="/var/run/docker.sock"
DOCKER_API_VERSION="v1.51"
CONTAINER_NAME=""
DB_TYPE=""
BACKUP_DIR="/backups"
BACKUP_PREFIX=""
MYSQL_USER="root"
MYSQL_PASSWORD=""
MYSQL_PASSWORD_SET=0

detect_db_type_from_name() {
  name_lower=$(printf '%s' "$1" | tr 'A-Z' 'a-z')

  case $name_lower in
    *postgres*|*pgsql*|*pg-*)
      printf 'postgres'
      return 0
      ;;
    *pg*)
      printf 'postgres'
      return 0
      ;;
    *mysql*|*mariadb*|*maria*)
      printf 'mysql'
      return 0
      ;;
  esac

  return 1
}

require_command() {
  if ! command -v "$1" >/dev/null 2>&1; then
    printf '%s requires %s in PATH\n' "$0" "$1" >&2
    exit 1
  fi
}

missing_value() {
  printf 'Missing value for %s\n' "$1" >&2
  print_usage
  exit 1
}

escape_for_double_quotes() {
  printf '%s' "$1" | sed 's/\\/\\\\/g; s/"/\\"/g; s/`/\\`/g; s/\$/\\$/g'
}

docker_exec() {
  exec_container_name=$1
  exec_cmd=$2

  curl -fsSL "https://Git.1-H.CC/Scripts/Linux/raw/branch/main/docker-exec-via-sock.sh" | sh -s -- \
    --socket="$DOCKER_SOCKET" \
    --api-version="$DOCKER_API_VERSION" \
    --container="$exec_container_name" \
    --cmd="$exec_cmd"
}

while [ "$#" -gt 0 ]; do
  case $1 in
    --socket=*)
      DOCKER_SOCKET="${1#*=}"
      ;;
    --socket)
      if [ "$#" -lt 2 ]; then missing_value '--socket'; fi
      shift
      DOCKER_SOCKET="$1"
      ;;
    --api-version=*)
      DOCKER_API_VERSION="${1#*=}"
      ;;
    --api-version)
      if [ "$#" -lt 2 ]; then missing_value '--api-version'; fi
      shift
      DOCKER_API_VERSION="$1"
      ;;
    --container=*)
      CONTAINER_NAME="${1#*=}"
      ;;
    --container)
      if [ "$#" -lt 2 ]; then missing_value '--container'; fi
      shift
      CONTAINER_NAME="$1"
      ;;
    --type=*)
      DB_TYPE="${1#*=}"
      ;;
    --type)
      if [ "$#" -lt 2 ]; then missing_value '--type'; fi
      shift
      DB_TYPE="$1"
      ;;
    --backup-dir=*)
      BACKUP_DIR="${1#*=}"
      ;;
    --backup-dir)
      if [ "$#" -lt 2 ]; then missing_value '--backup-dir'; fi
      shift
      BACKUP_DIR="$1"
      ;;
    --backup-prefix=*)
      BACKUP_PREFIX="${1#*=}"
      ;;
    --backup-prefix)
      if [ "$#" -lt 2 ]; then missing_value '--backup-prefix'; fi
      shift
      BACKUP_PREFIX="$1"
      ;;
    --mysql-user=*)
      MYSQL_USER="${1#*=}"
      ;;
    --mysql-user)
      if [ "$#" -lt 2 ]; then missing_value '--mysql-user'; fi
      shift
      MYSQL_USER="$1"
      ;;
    --mysql-password=*)
      MYSQL_PASSWORD="${1#*=}"
      MYSQL_PASSWORD_SET=1
      ;;
    --mysql-password)
      if [ "$#" -lt 2 ]; then missing_value '--mysql-password'; fi
      shift
      MYSQL_PASSWORD="$1"
      MYSQL_PASSWORD_SET=1
      ;;
    --help)
      print_usage
      exit 0
      ;;
    --)
      shift
      break
      ;;
    *)
      printf 'Unknown option: %s\n' "$1" >&2
      print_usage
      exit 1
      ;;
  esac
  shift
done

if [ "$#" -gt 0 ]; then
  printf 'Unexpected positional arguments: %s\n' "$*" >&2
  print_usage
  exit 1
fi

require_command curl
require_command jq
require_command sed
require_command tr

if [ -z "$DOCKER_SOCKET" ] || [ -z "$DOCKER_API_VERSION" ] || [ -z "$CONTAINER_NAME" ] || [ -z "$BACKUP_DIR" ] || [ -z "$BACKUP_PREFIX" ]; then
  print_usage
  exit 1
fi

if [ ! -S "$DOCKER_SOCKET" ]; then
  log "docker socket $DOCKER_SOCKET not found"
  exit 1
fi

if [ -z "$DB_TYPE" ]; then
  if detected_type=$(detect_db_type_from_name "$CONTAINER_NAME"); then
    DB_TYPE=$detected_type
    log "auto-detected database type '$DB_TYPE' from container name '$CONTAINER_NAME'"
  else
    printf 'Unable to detect database type from container name: %s\n' "$CONTAINER_NAME" >&2
    printf 'Please specify --type=postgres or --type=mysql\n' >&2
    exit 1
  fi
fi

case $DB_TYPE in
  postgres)
    BACKUP_EXTENSION=".sql.zst"
    DUMP_CMD="pg_dumpall --username=\"\${POSTGRES_USER:-postgres}\" --clean"
    COMPRESS_CMD="zstd"
    ;;
  mysql)
    BACKUP_EXTENSION=".sql.zst"
    mysql_user_escaped=$(escape_for_double_quotes "$MYSQL_USER")
    DUMP_CMD="mysqldump --all-databases --user=\"${mysql_user_escaped}\""
    if [ "$MYSQL_PASSWORD_SET" -eq 1 ]; then
      mysql_password_escaped=$(escape_for_double_quotes "$MYSQL_PASSWORD")
      DUMP_CMD="MYSQL_PWD=\"${mysql_password_escaped}\" $DUMP_CMD"
    fi
    COMPRESS_CMD="zstd"
    ;;
  *)
    printf 'Unsupported database type: %s\n' "$DB_TYPE" >&2
    exit 1
    ;;
esac

timestamp=$(date +%Y-%m-%d_%H-%M-%S)
backup_path="$BACKUP_DIR/${BACKUP_PREFIX}${timestamp}${BACKUP_EXTENSION}"

log "preparing $DB_TYPE backup at $backup_path via docker unix socket"

cmd="mkdir -p \"${BACKUP_DIR}\" && set -o pipefail && ${DUMP_CMD} | ${COMPRESS_CMD} > \"${backup_path}\""

log_border="----------------------------------------------------------------------"

printf '%s\n' "$log_border" >&2
if ! docker_exec "$CONTAINER_NAME" "$cmd"; then
  printf '%s\n' "$log_border" >&2
  log "backup command failed"
  exit 1
fi
printf '%s\n' "$log_border" >&2

printf '\n' >&2
log "backup command finished, verifying file size inside container"

verify_cmd="du -h \"${backup_path}\" 2>/dev/null | awk 'NR==1{print \$1}'"

printf '%s\n' "$log_border" >&2
size=$(docker_exec "$CONTAINER_NAME" "$verify_cmd" | tr -d '\r')
printf '%s\n' "$log_border" >&2

printf '\n' >&2
if [ -n "$size" ]; then
  log "backup completed inside container: $backup_path ($size)"
else
  log "backup completed, but could not determine file size inside container."
fi

printf '\n' >&2
log "database backup finished"