#!/usr/bin/env bash
# HEADER
#=======================================================================
#
#  img2date -- Shell script to rename images by their creation date stamp
#
#  SYNOPSIS
#    img2date <imagedir>
#
#  DESCRIPTION
#    Shell script to rename all images in a given directory by their 
#    creation date stamp of the form `YYYY-MM-DD_hh-mm-ss.{jpg,png}`.
#    
#  EXAMPLE
#    $ img2date <imagedir>
#
#  POSITIONAL ARGUMENT
#    <imagedir>     directory where are the image collection
#
#  DEPENDENCIES
#    - exiftool
#    - GNU coreutils
# 
#  INSTALLATION
#     - link file in $PATH (~/bin/)
#
#
#  Copyright (C) 2023 Nicolas Mesnier <nmesnier@free.fr>
#
#  This program is free software: you can redistribute it and/or modify
#  it under the terms of the GNU General Public License version 3 or
#  above as published by the Free Software Foundation.
#
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#
#  You should have received a copy of the GNU General Public License
#  along with this program. If not, see <http://www.gnu.org/licenses/>.
#
#=======================================================================
# END_OF_HEADER
#-----------------------------------------------------------------------
# *** read this header to display help and version
#-----------------------------------------------------------------------
BOH=$(head -200 ${0} | grep -n "^# HEADER" | cut -f1 -d:)
EOH=$(head -200 ${0} | grep -n "^# END_OF_HEADER" | cut -f1 -d:)
function Help(){
  head -$(($EOH-1)) ${0} | tail -$(($EOH-$BOH-1)) \
    | grep -e "^#$" -e "^# " | sed -e "s/^#=*//g"
}
#-----------------------------------------------------------------------
# *** run
#-----------------------------------------------------------------------
DIRECTORY=${1}
for IMG in $(find ${DIRECTORY}/ -regextype sed -regex ".*/*\.\(jpe\?g\|JPE\?G\|png\|PNG\)" | sort);do
    DATE=$(exiftool -T -createdate ${IMG})
    if [ "${DATE}" == "-" ]; then
        DATE=$(exiftool -T -modifydate ${IMG})
    fi
    if [ "${DATE}" != "-" ]; then
        case "$(exiftool -T -filetype ${IMG})" in
        "JPEG" )
            EXT=".jpg";;
        "PNG" )
            EXT=".png";;
        esac
        NAME=${DIRECTORY}/$(echo ${DATE} | tr ":" "-" | tr " " "_" )${EXT}
        mv ${IMG} ${NAME}
    fi
done
#--------------------------------------------------------------------eof