#!/bin/sh -ef

cmdcache()
{
	if [ $# -lt 2 ]; then
		echo "cmdcache: not enough arguments" >&2
		pod2usage --exit=2 cmdcache || [ $? = 2 ]
		return 2
	fi

	local cmd="$1"; shift
	local cdir="$HOME/.cmdcache/${cmd##*/}"
	[ -d "$cdir" ] || mkdir -p -m700 "$cdir" || return 1
	[ -n "${RANDOM##*0}" ] || find "$cdir" -type f -mtime +33 -atime +33 -delete

	local file; for file; do :; done
	if [ ! -e "$file" ]; then
		echo "cmdcache: $file: no such file or directory" >&2
		return 1
	fi

	local cache="$*"; cache="$cdir/${cache//[-.\/ ]/_}"
	if [ -f "$cache" ] && ! [ "$file" -nt "$cache" -o "$cache" -nt "$file" ]; then
		cat "$cache"
		return
	fi

	local rc=0
	local mtime0; mtime0="$(stat --format $'%Y\n' "$file")" || return

	"$cmd" "$@" >"$cache" && touch -r "$file" "$cache" || rc=$?
	cat "$cache"
	
	local mtime1; mtime1="$(stat --format $'%Y\n' "$file")" || rc=$?
	if [ $rc = 0 -a "$mtime0" != "$mtime1" ]; then
		echo "cmdcache: $file has changed" >&2
		rc=1
	fi

	[ $rc = 0 ] || rm -f "$cache"
	return $rc
}

if [ -z "$*" -a "${0##*/}" != cmdcache ]; then
	: okay, maybe I am sourced
elif [ "x$*" = x-h -o "x$*" = x--help ]; then
	pod2usage --exit=0 "$0"
else 
	cmdcache "$@"
fi

: <<'__EOF__'

=head1	NAME

cmdcache - simple command cache based on timestamps

=head1	SYNOPSIS

B<cmdcache> I<cmd> [I<args>...] I<FILE>

B<source> B<cmdcache> ''

=head1	AUTHOR

Written by Alexey Tourbin <at@altlinux.org>.

=head1	COPYING

Copyright (c) 2005 Alexey Tourbin, ALT Linux Team.

This 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.

=cut

__EOF__