imageRename

#!/bin/bash
# Rename image files using their exif or last modification timestamp
# necessary packages:   libimage-exiftool-perl

# define global default values
DRYRUN='false'
EXIFUPDATE='false'
IMAGE_PATH="."
PATTERN="%Y-%m-%d---%H-%M-%S"

#######################################
# Generates new filename
# Globals:
#   None
# Arguments:
#   $1 timestamp of file as string
#   $2 previous filename
# Returns:
#   new filename
#######################################
generate_filename() {
  local datetime
  local old_filename
  readonly datetime="${1}"
  readonly old_filename="${2}"

  local extension
  readonly extension="$(echo "${old_filename}" | grep -o '[^.]*$')"

  local counter=0
  local new_filename="${datetime}.${extension}"
  while [[ "${new_filename}" != "${old_filename}" && -f "${new_filename}" ]]; do
    counter=$((counter + 1))
    new_filename="${datetime} (${counter}).${extension}"
  done

  echo "${new_filename}"
  return 0
}

#######################################
# Get exif timestamp from file
# Globals:
#   PATTERN
# Arguments:
#   $1 filename
# Returns:
#   timestamp
#######################################
get_exif_timestamp() {
  local filename
  readonly filename="${1}"

  # get datetime from exif data
  local exif_create_date
  exif_create_date="$(exiftool -t -s -d "${PATTERN}" -CreateDate "${filename}")"
  local timestamp="${exif_create_date#CreateDate[[:space:]]*}"

  echo "${timestamp}"
  return 0
}

#######################################
# Set exif timestamp to last modified
# timestamp of file
# Globals:
#   EXIFUPDATE
#   DRYRUN
# Arguments:
#   $1 filename
# Returns:
#   None
#######################################
set_exif_timestamp_to_last_modified() {
  local filename
  readonly filename="${1}"

  if [[ "${EXIFUPDATE}" == 'true' ]]; then
    local exif_timestamp
    exif_timestamp="$(date -r "${filename}" "+%Y-%m-%d %H:%M:%S")"
    if [[ "${DRYRUN}" == 'false' ]]; then
      exiftool -overwrite_original_in_place \
        -CreateDate="${exif_timestamp}" "${filename}" 2>&1 >/dev/null
    fi
  fi

  return 0
}

########################################
# Get exif timestamp from file. If not
# available, get last modified timestamp
# Globals:
#   PATTERN
#   EXIFUPDATE
#   DRYRUN
# Arguments:
#   $1 filename
# Returns:
#   0: exif timestamp
#   1: last modified timestamp
########################################
get_timestamp() {
  local filename
  readonly filename="${1}"

  # get datetime from exif data
  local timestamp
  timestamp=$(get_exif_timestamp "${filename}")

  # if not available, get last modification time from file
  if [[ -z "${timestamp}" ]]; then
    timestamp="$(date -r "${filename}" "+${PATTERN}")"

    $(set_exif_timestamp_to_last_modified "${filename}")

    echo "${timestamp}"
    return 1 # indicate that timestamp if not exif, but last modified
  fi

  echo "${timestamp}"
  return 0
}

########################################
# Rename a specified file
# Globals:
#   DRYRUN
# Arguments:
#   $1 old filename
#   $2 new filename
# Returns:
#   message
########################################
rename_file() {
  local old_filename
  local new_filename
  readonly old_filename="${1}"
  readonly new_filename="${2}"

  if [[ "${old_filename}" != "${new_filename}" ]]; then
    echo "${old_filename}  -->  ${new_filename}"
    if [[ "${DRYRUN}" == 'false' ]]; then
      mv -- "${old_filename}" "${new_filename}"
    fi
  else
    echo "keep  ${new_filename}"
  fi

  return 0
}

########################################
# Bind all parameters to flags and path
# Globals:
#   DRYRUN
#   EXIFUPDATE
#   IMAGE_PATH
#   PATTERN
# Arguments:
#   $@ all arguments of script
# Returns:
#   None
########################################
bind_arguments() {
  local flag
  while getopts 'dep:' flag; do
    case "${flag}" in
      d) DRYRUN='true' ;;
      e) EXIFUPDATE='true' ;;
      p) PATTERN="${OPTARG}" ;;
    esac
  done
  shift $((OPTIND - 1)) # image path is now in $1

  readonly DRYRUN
  readonly EXIFUPDATE
  readonly PATTERN

  # validate arguments
  if [[ "$#" -ne 1 ]]; then
    echo "Expecting exactly one parameter. Exiting"
    exit 1
  fi

  readonly IMAGE_PATH="${1}"

  return 0
}

########################################
# Write information about DRYRUN mode
# Globals:
#   DRYRUN
# Arguments:
#   None
# Returns:
#   None
########################################
echo_dryrun_info() {
  if [[ "${DRYRUN}" == 'true' ]]; then
    echo ""
    echo "NOTE: This is a DRYRUN only"
    echo "---------------------------"
    echo ""
  fi

  return 0
}

main() {
  # read script arguments
  bind_arguments "$@"

  if [[ ! -d "${IMAGE_PATH}" ]]; then
    echo "Path '${IMAGE_PATH}' does not exist. Existing"
    exit 2
  fi

  echo_dryrun_info

  cd "${IMAGE_PATH}"

  # loop through all files, use \n as separator to support whitespaces in
  # filename; order alphabetically while interpret numbers
  local filename
  local timestamp
  local new_filename
  find . -type f -printf "%f\n" | sort -V  | while read filename; do

    timestamp=$(get_timestamp "${filename}")
    if [[ $? -eq 1 ]]; then
      echo "${filename}: last modification time used"
    fi
    new_filename=$(generate_filename "${timestamp}" "${filename}")

    rename_file "${filename}" "${new_filename}"
  done
}

# call main function and hand over all parameters
main "$@"