#! /bin/sh

# Extract configuration items into various configuration headers
# This uses the configitems file, a database consisting of text lines with the
# following single-tab-separated fields:
# 1. Name of the configuration item, e.g. PQXX_HAVE_PTRDIFF_T
# 2. Publication marker: public or internal
# 3. A single environmental factor determining the item, e.g. libpq or compiler

# Usage: splitconfig [srcdir]
# where [srcdir] is the main libpqxx source directory containing the configitems
# file, the include directory etc.  This defaults to the current directory.

#set -e

srcdir="$1"
if test -z "${srcdir}" ; then
	srcdir="."
fi


# Some greps don't accept "-" for standard input as an argument to the -f
# option, so we need to use -F instead.  OTOH some versions of GNU grep break
# when the -F or -f option is combined with -w.  The one released with Fedora
# Core 4 contained a speedup patch that caused it to crash altogether, but in
# June 2006 we ran into several 2.5.1 versions that would stop processing when
# a near-match was found that didn't end in a word boundary (e.g. "foo" while
# looking for "fo").
# Attempt to test the available grep and pick our best option.

# Check output of a candidate "grep" command line searching file $SAMPLETXT
# for any of the whole-word patterns in $SAMPLEPAT.  The output of the grep
# command line is passed as $1; $2 is echoed to standard out if the command
# line works.
working_grep() {
	if test -z "$1" ; then
		if ! which grep >/dev/null ; then
			cat <<EOF >&2
Could not run "grep"--no way to proceed!
EOF
		else
			cat <<EOF >&2

This version of grep seems to be broken: searching for literal whole-word
patterns does not match anything.  This problem is known to have occurred with
a patched version of GNU grep shipped with the original Fedora Core 4 release.

EOF
		fi
	elif test -z "`echo "$1" | grep '\<splat\>'`" ; then
		cat <<EOF >&2

This version of grep seems to be broken: searching for literal whole-word
patterns stops when one of the patterns is found, but does not end in a word
boundary.  This problem is known to have happened with some 2.5.1 versions of
GNU grep.

EOF
	elif test -n "`echo "$1" | grep 'barr'`" ; then
		cat <<EOF >&2

This "grep" command line fails to take word boundaries into account.  This means
that, as an example, when looking for an exact match on the word "foo" it does
not distinguish between "foo" and "food".
Please report this to the libpqxx-general mailing list or create a bug ticket on
the libpqxx website.

EOF
	else
		echo "$2"
	fi
}

SAMPLETXT="`${srcdir}/tools/maketemporary`"

# Perform a "grep -F -w -h", or simulate one, searching for any of the patterns
# listed in "$2" (one per line) in file "$3".  A code for the grep command line
# to be used is passed as $1.
wordgrep () {
	GREPCODE="$1"
	PAT="$2"
	TXT="$3"
	case "$GREPCODE" in
	"grep-F")
		# This is the standard, modern, POSIX-compliant way of doing
		# things.  Unfortunately it breaks on some systems.
		grep -F -w -h "$PAT" "$TXT"
		;;
	"grep-f")
		echo "$PAT" | grep -w -h -f - "$TXT"
		;;
	fgrep)
		fgrep -w -h "$PAT" "$TXT"
		;;
	symw)
		for p in $PAT ; do
			grep "\<$p\>" "$TXT"
		done
		;;
	*)
		echo "Unknown grep alternative: '$GREPCODE'" >&2
		rm -f -- "$SAMPLETXT"
		exit 1
		;;
	esac
}

echo -n "Checking for usable grep -F or equivalent... "
SAMPLEPAT="foo
bar
splat"

cat >"$SAMPLETXT" <<EOF
foo
barr
splat
EOF

GREPCODE=''
for g in "grep-F" "grep-f" "fgrep" "symw" ; do
	if test -z "$GREPCODE" ; then
		GREPOUT=`wordgrep "$g" "$SAMPLEPAT" "$SAMPLETXT"`
		GREPCODE="`working_grep "$GREPOUT" "$g"`"
	fi
done
rm -f -- "$SAMPLETXT"
if test -z "$GREPCODE" ; then
	echo "No capable grep found" >&2
	exit 1
fi
echo "$GREPCODE"

CFDB="${srcdir}/configitems"
ORGHDR="include/pqxx/config.h"
LC_ALL=C
PUBLICATIONS=`cut -f 2 "$CFDB" | sort -u`
FACTORS=`cut -f 3 "$CFDB" | sort -u`

for publication in $PUBLICATIONS ; do
	for factor in $FACTORS ; do
		CFGFILE="include/pqxx/config-${publication}-${factor}.h"
		echo -n "Generating $CFGFILE: "
		ITEMS="`grep -w "${publication}" "$CFDB" | grep -w "${factor}" | cut -f 1 | grep -v '^$'`"
		if test -z "$ITEMS" ; then
			echo "no items--skipping"
		else
			wordgrep "$GREPCODE" "$ITEMS" "$ORGHDR" >"$CFGFILE"
			if test -s "$CFGFILE" ; then
				echo "ok"
			else
				rm -f -- "$CFGFILE"
				echo "no items--deleting"
			fi
		fi
	done
done