vinbt

#!/bin/bash
#
#   vinbt - interactive command line NBT editor
#
#   Copyright (C) 2012-2013 DMBuce <dmbuce@gmail.com>
#
#   This program is free software; you can redistribute it and/or modify
#   it under the terms of the GNU General Public License as published by
#   the Free Software Foundation; either version 2 of the License, or
#   (at your option) any later version.
#
#   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, write to the Free Software Foundation, Inc.,
#   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
#

PROG="$(basename $0)"
USAGE="Usage: $PROG <file>

	Edit an NBT file using a text editor.
"

# print message to stdout
msg() {
	local message="$1"
	shift
	printf "$message\n" "$@"
}

# print warning to stderr
warn() {
	local message="$1"
	shift
	printf "$PROG: $message\n" "$@" >&2
}

# print error to stderr and quit
die() {
	warn "$@"
	exit 1
}

# append dir to PATH
pathmunge () { 
    local dir="$1"
    if [[ -d "$dir" ]] && ! echo "$PATH" | egrep -q "(^|:)$dir($|:)"; then
        if [[ "$2" == "before" ]]; then
            PATH="$dir:$PATH"
        else
            PATH="$PATH:$dir"
        fi
    fi
}

# find norbert
which_norbert() {
	local norbert dir PATHORIG
	PATHORIG="$PATH"

	if [[ "$NORBERT" != "" ]]; then
		echo "$NORBERT"
		return 0
	fi

	for dir in "$HOME/bin" "$PWD"; do
		pathmunge "$dir"
	done

	for norbert in norbert norbert.py; do
		if which "$norbert" 2>/dev/null; then
			PATH="$PATHORIG"
			return 0
		fi
	done

	die "no norbert in (%s)" "$PATH"
}

# find a text editor
which_editor() {
	local editor
	if [[ "$DISPLAY" != "" ]]; then
		editor="${VISUAL}"
	fi
	editor="${editor:-$EDITOR}"
	editor="${editor:-vi}"
	echo "$editor"
}

# print usage and quit if --help given
case "$1" in "-h"|"--help"|"")
	msg "%s" "$USAGE"
	exit
esac

if [[ "$#" != 1 ]]; then
	die "Too many arguments\n%s" "$USAGE"
fi

editor="$(which_editor)"
norbert="$(which_norbert)" || exit $?

file="$1"
tmpfile="$(mktemp --tmpdir "vinbt-$(basename "$file").norbert.XXXXXXXXXX")" \
	|| exit $?
trap "rm -f \"$tmpfile\"" EXIT

$norbert -d 0 -p norbert -f "$file" >"$tmpfile" || exit $?
tmpfileorig="$(<"$tmpfile")"

$editor "$tmpfile"

if diff -q "$tmpfile" <(echo "$tmpfileorig") >/dev/null; then
	warn "no changes made"
	warn "%s unchanged" "$file"
else
	warn "changes made"
	warn "writing changes to %s" "$file"
	if ! $norbert -d 0 -i norbert -f "$tmpfile" -o "$file" >/dev/null; then
		warn "error writing changes"
		savefile="$(mktemp "vinbt-$(basename "$file").norbert.XXXXXXXXXX")" \
			|| exit $?
		warn "saving as %s" "$savefile"
		cp "$tmpfile" "$savefile"
	fi
fi