#! /bin/bash
#

set -e  # abort on errors
shopt -s nullglob  # file globs that don't match expand
		   # to nothing

#
# Check if $EDITOR is set, otherwise set to "vi".
#
: ${EDITOR:=vi}

#
# Check for -f option ()
#
if [ "$1" = -f ]; then
    retry_lock=1
    shift
fi

#
# Detect the name of the file to edit
#
unset FILE

if [ -n "$1" ]; then
    if [ -f "$1" ]; then
	FILE=$1
    else
	if [ -d "$1" ]; then
	    cd $1
	else
	    FILE=$(package_name $1).changelog
	fi
    fi
fi

if [ -z "$FILE" ]; then
    for f in *.changelog; do
	if [ -n "$FILE" ]; then
	    FILE=
	    break
	fi
	FILE=$f
    done
fi

if [ -z "$FILE" ]; then
    for f in *.spec; do
	if [ -n "$FILE" ]; then
	    FILE=
	    break
	fi
	FILE=$f
    done
    if [ -n "$FILE" ]; then
	FILE=$(package_name $FILE).changelog
    fi
fi

if [ -z "$FILE" ]; then
    echo "usage: ${0##*/} [filename[.changelog]|path [file_with_comment]]"
    echo "If no <filename> is given, exactly one *.changelog or"
    echo "*.spec file has to be in the cwd or in <path>."
    echo
    exit 1
fi

#
# Add domain to username (if it's me ;-)
#
user=`whoami`
if [ $user = "uwedr" ]; then
	user="$user@suse.de"
fi

COMMENT_FILE=$2

#
# Create the lockfile and temporary file.
#
lockfile=.${FILE##*/}.lock
if [ "${FILE/\//}" != "$FILE" ]; then
    lockfile=${FILE%/*}/.$lockfile
fi

if [ ! -w "$(dirname "$FILE")" ]; then
    echo "Write access to directory $(dirname "$FILE") required" >&2
    exit 1
fi

if [ -e "$FILE" -a ! -w "$FILE" ]; then
    echo "Write access to file $FILE required" >&2
    exit 1
fi

set -o noclobber
while ! echo $$@$(hostname -f) 2> /dev/null > $lockfile; do
    if [ -z "$retry_lock" ]; then
	echo "$lockfile: Lock by process $(cat $lockfile)" >&2
	echo "Please remove stale lockfiles manually" >&2
	exit 1
    fi
    echo "$lockfile: Waiting for process $(cat $lockfile) to release lock" >&2
    sleep 1
done
set +o noclobber

tmpfile=$(mktemp /tmp/${0##*/}.XXXXXX)
trap "rm -f $lockfile $tmpfile" EXIT

#
# Prepare the working copy and start the editor
#

{   timestamp=$(LC_ALL=POSIX TZ=Europe/Berlin date)
    echo "-------------------------------------------------------------------"
    echo "$timestamp - $user"
    echo
    if [ -z "$COMMENT_FILE" ]; then
	echo "- "
    else
	cat $COMMENT_FILE
    fi
    echo
    if [ -f "$FILE" ]; then
    	cat $FILE
    fi
} >> $tmpfile \
|| exit 1

if [ -z "$COMMENT_FILE" ]; then
    lines=1
    CHKSUM_BEFORE=$(md5sum $tmpfile | awk '{print $1}')
else
    lines=$(wc -l $COMMENT_FILE | awk '{print $1}')
    CHKSUM_BEFORE=has_changed
fi

$EDITOR +$((3+lines)) $tmpfile

if [ "$CHKSUM_BEFORE" = "$(md5sum $tmpfile | awk '{print $1}')" ]; then
    exit 1
fi
cat $tmpfile > $FILE