#!/bin/sh
#
# $Id$
#
# Edit the (text) comments in one or more JPEG files.
#
# Usage:
#
USAGE='Usage: camcomment [-d] [-l] [-m] [-v] jpeg-files'
#
# First, the current commentary is extracted from all files.  The
# editor is then invoked on a file with all comments.  Each file's
# comments are preceded by a header formatted as follows:
#
#	===== file-name =====
#
# When the editor is exited, the revised comments are expected to be
# separated by headers in the same format.  Any revised comments are
# reinserted in the named files; files no longer mentioned in the
# edited file are not modified.  The script is very sensitive to
# format, so be sure to preserve the header lines as they were
# originally given.
#
# Options:
#
# -d		Debug: report what would be done, but don't do it.
# -l		List: print the headers and comments to stdout, but
#		don't invoke an editor or modify comments.
# -m		Metacam: insert any comment that can be extracted with metacam
# -v		Verbose: report each comment modification as it is done.
#

debug=false
list=false
metacam=false
verbose=false

#
# Argument processing
#
while [ $# -gt 0 ]
do
    case "$1" in
	-d)
	    debug=true
	    verbose=true
	    ;;
	-l)
	    list=true
	    ;;
	-m)
	    metacam=true
	    ;;
	-v)
	    verbose=true
	    ;;
	--)
	    shift
	    break
	    ;;
	-*)	
	    echo "$USAGE" 1>&2
	    exit 2
	    ;;
	*)
	    break
	    ;;
    esac
    shift
done

case "$#" in
    0)
	echo "$USAGE" 1>&2
	exit 2
	;;
esac

#
# Process all file arguments
#
#TMP=/tmp/_ccm$$
TMP=_ccm$$

trap "rm -f $TMP.*; exit 1" 1 2 15
trap "rm -f $TMP.*; exit 0" 13

for file
do
    dir=`dirname $file`
    case "$file" in
	*.jpg|*.jpeg|*.JPG|*.JPEG)
	    ;;
	*)
	    echo "Can't handle file '$file', skipping" 1>&2
	    continue
	    ;;
    esac
    echo "===== $file =====" >> $TMP.a
    if $metacam
    then
	metacam -v "$file" 2>/dev/null \
	  | fgrep '[User Comment]:' \
	  | awk 'BEGIN \
		{
		hex["0"] = 0
		hex["1"] = 1
		hex["2"] = 2
		hex["3"] = 3
		hex["4"] = 4
		hex["5"] = 5
		hex["6"] = 6
		hex["7"] = 7
		hex["8"] = 8
		hex["9"] = 9
		hex["A"] = 10
		hex["B"] = 11
		hex["C"] = 12
		hex["D"] = 13
		hex["E"] = 14
		hex["F"] = 15
		hex["a"] = 10
		hex["b"] = 11
		hex["c"] = 12
		hex["d"] = 13
		hex["e"] = 14
		hex["f"] = 15
		}
		{
		comment = ""
		for (i = 3;  i <= NF;  i++)
		    {
		    if ($i != "00")
			{
			char = \
			  hex[substr($i, 1, 1)] * 16 + hex[substr($i, 2, 1)]
			comment = comment sprintf("%c", char)
			}
		    }
		while (comment != "" \
		  &&  substr(comment, length(comment), 1) == " ")
		    comment = substr(comment, 1, length(comment) - 1)
		if (comment != "")
		    print comment
		}' \
	  >> $TMP.a
    fi
    rdjpgcom "$file" | sed '$d' >> $TMP.a
done

#
# If we had any files, bring up the editor and process the results.
#
if $list
then
    cat $TMP.a
elif [ -s $TMP.a ]
then
    #
    # For reasons I don't understand, some versions of
    # emacs seem to let a SIGINT (signal 2) through to the
    # parent shell while they are exiting.  This is
    # inconvenient to say the least, since it aborts the
    # entire list of pending checkins.  So we will ignore
    # SIGINT while the editor is running.
    #
    trap "" 2
    ${EDITOR:-vi} $TMP.a
    trap "rm -f $TMP.*; exit 1" 2

    #
    # Extract a list of files to be recommented, and do so.
    #
    firstFile=true
    for file in `sed -n 's/ *===== *//gp' $TMP.a`
    do
	case "$file" in
	    */*)
		safeName=`echo "$file" | sed 's;/;\\\\/;g'`
		;;
	    *)
		safeName="$file"
		;;
	esac
	if $verbose
	then
	    echo "Modifying comment in $file"
	fi
	if $debug
	then
	    continue
	fi
	if $firstfile
	then
	    sed -e 1d -e '/^===== /,$d' $TMP.a \
	      | wrjpgcom -replace "$file" > $TMP.b
	    firstfile=false
	else
	    sed -e "1,/^===== $safeName =====/d" -e '/^===== /,$d' $TMP.a \
	      | wrjpgcom -replace "$file" > $TMP.b
	fi
	cp $TMP.b "$file"
    done
fi

rm -f $TMP.*