#!/bin/sh
##
## SCRIPT NAME: file-identify_aniGIF.sh
##
##+#######
## PURPOSE:
##  For a file-type string (such as 'GIF') passed in the first argument ($1)
##  and a filename passed in the second argument ($2), this script uses
##   1) the 'file' command to determine if the file is the specified file-type
##  and 
##   2) if so, then uses the ImageMagick 'identify' command determine
##      whether the GIF file is an animated-GIF file.
##
##  If the filename IS an animated-GIF, the filename is echoed to stdout.
##  Otherwise, nothing is sent to stdout.
##
##  This shell script is meant to be issued from a shell script
##  'findAniGIFfiles_forCriteria.sh'.
##  That shell script calls this script in a 'find' command.
##
##+#########################################################################
## MAINTENANCE HISTORY:
## Started by: Blaise Montandon 2014may01                                        
## Updated by: Blaise Montandon 2014
##+#########################################################################

## FOR TESTING: (to show statements as they execute)
#  set -x

FILEtype="$1"
INfile="$2"

##+##########################################################
## Use the 'file' and 'identify' commands to determine
## whether 'INfile' is an animated-GIF file.
##+##########################################################
## Example output from the 'file' command on a GIF file:
## $ file file_middle_name.gif
## file_middle_name: GIF image data, version 89a, 444 x 175
##
## So we can look for 'GIF' after the colon character.
##+#########################################################
## Example output from the 'identify' command on a GIF file:
## identify file_middle_name.gif
## file_middle_name.gif GIF 1024x768 1024x768+0+0 8-bit PseudoClass 256c 208kb 
##+##############################################################################
## Example output from the 'identify' command on an animated-GIF file:
## $ identify file_middle_name_ani.gif
## file_middle_name_ani.gif[0] GIF 444x175 444x175+0+0 8-bit PseudoClass 32c 4.28kb 
## file_middle_name_ani.gif[1] GIF 16x18 444x175+49+46 8-bit PseudoClass 32c 4.28kb
## etc. for each 'scene' in the animated-GIF file.
##
## So we can look for '[0]' in the first line of output from 'identify'.
##+##############################################################################

## FOR TESTING: (to show statements as they execute)
#  set -x

GIFfilename=`file "$INfile" | grep ":.*$FILEtype" | cut -d: -f1`

if test "$GIFfilename" = ""
then
   exit
fi

ANIGIFcheck=`identify "$GIFfilename" | head -1 | grep '\[0\]'`

if test "$ANIGIFcheck" = ""
then
   exit
else
   echo "$GIFfilename"
fi