#!/bin/sh
#
# Usage: genpatch newfile
#        genpatch oldfile newfile
#
# Will output a patch ready for dports (unified diff).
# If only newfile is given, oldfile is assumed as newfile.intermediate (1st)
# or newfile.orig (2nd) if such a file exists
# If the realpath doesn't start with /usr/obj/dports, sends output to stdout
# Otherwise, the patch file will be created in the current directory with a
# filename on the file's location relative to worksource.  The patch will be
# generated from wrksrc location.

#
# Copyright (c) 2004-2011 The NetBSD Foundation, Inc.
# Copyright (c) 2011 by Thomas Klausner <wiz@NetBSD.org>
# Copyright (c) 2012 by John Marino <draco@marino.st>
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR
# ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
# TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
# PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR
# BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
#
# Ensure we always use the same timezone to avoid spurious metadata diffs
export TZ=UTC

if [ $# -le 1 ]
then
	if [ -f "$1.intermediate" ]; then
		old="$1.intermediate"
		new="$1"	
	elif [ -f "$1.orig" ]; then 
		old="$1.orig"
		new="$1"
	else
		echo $0: need at least one valid argument >&2
		exit 1;
	fi
else
	if [ $# -eq 2 ]
	then
		old="$1"
		new="$2"
	else
		echo $0: more than two arguments detected >&2
		exit 1;
	fi
fi

PKGDIFF_FMT="-p --unified=3"

# Strip out the date on the +++ line to reduce needless
# differences in regenerated patches
SEDPLUS='/^---/s|\.[0-9]* +0000$| UTC| ; /^+++/s|\([[:blank:]][-0-9:.+]*\)*$||'

if diff -q ${PKGDIFF_FMT} ${old} ${new} > /dev/null
then
	exit 0
fi

if [ -n "${WORKTREE}" ]; then
objpath=${WORKTREE}
else
objpath=$(realpath %%WORKPATH%%)
fi
cnt1=$(echo ${objpath} | wc -c)
objcount=$(expr $cnt1 - 1)
fullpath=$(dirname `realpath ${old}`)
testpath=$(echo ${fullpath} | cut -c "1-${objcount}")

if [ "${testpath}" = "${objpath}" ]; then
    # Inside standard work area.  Assume genpatch executed from wrksrc
    # and generate patch with appropriate name

    fname=patch-$(echo ${new} | sed -e 's|_|__|g' -e 's|/|_|g')
    diff ${PKGDIFF_FMT} ${old} ${new} | sed -e "${SEDPLUS}" > ${fname}
    echo "generated ${fname}"
else
    # Not in standard work area, just send patch to stdout
    diff ${PKGDIFF_FMT} ${old} ${new} | sed -e "${SEDPLUS}"
fi
