#!/bin/sh
# http://mg.pov.lt/blog/sysadmin-diary.html is the closest this thing has to
# documentation.
version=1.0.1
changelog=/root/Changelog
editor=vim

if [ x"$1" = x-h ] || [ x"$1" = x--help ]; then
    echo "Usage: $0 [filename] [-a] [message]"
    echo
    echo "Opens an admin change log file (default: $changelog) in $editor"
    echo "or appends a timestamped message to the end and prints it."
    echo
    echo "Options:"
    echo "  -h, --help   this help message"
    echo "  --version    print version number and exit"
    echo "  -a           append to the last message without adding a timestamped header"
    exit
fi

if [ x"$1" = x--version ]; then
    echo "new-changelog-entry version $version"
    echo "Written by Marius Gedminas <marius@gedmin.as>"
    exit
fi

if test -n "$1" && test -f "$1"; then
    changelog=$1
    shift

    case "$changelog" in
        *[Cc]hangelog*)
            ;;
        *)
            echo "Cowardly refusing to edit $changelog since it doesn't mention Changelog in the filename" 1>&2
            exit 1
            ;;
    esac
fi

swapfile="`dirname $changelog`/.`basename $changelog`.swp"

if [ -f $swapfile ]; then
    echo "Someone is currently editing $changelog ($swapfile exists)" 1>&2
    exit 1
fi

if ! [ -w $changelog ] && [ `id -u` -ne 0 ]; then
    exec sudo "$0" "$changelog" "$@"
fi

header=1
if [ x"$1" = x-a ]; then
    header=0
    shift
fi

msg="$*"

if [ $header -eq 1 ]; then
    if [ -f $changelog ]; then
        # append an empty line if it is not there
        test -n "`tail -n 1 $changelog`" && echo >> $changelog
    fi

    # append a header
    cat >> $changelog <<END
`date +'%Y-%m-%d %H:%M %z'`: ${SUDO_USER:-$USER}
  $msg
END
else
    echo "  $msg" >> $changelog
fi

test -z "$msg" \
  && exec $editor $changelog +$ \
  || tail $changelog