##
##  subst -- Apply sed(1) substitution operations
##  Copyright (c) 2001-2008 Ralf S. Engelschall <rse@engelschall.com>
##
##  This file is part of shtool and 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 file 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
##  USA, or contact Ralf S. Engelschall <rse@engelschall.com>.
##

str_tool="subst"
str_usage="[-v|--verbose] [-t|--trace] [-n|--nop] [-w|--warning] [-q|--quiet] [-s|--stealth] [-i|--interactive] [-b|--backup <ext>] [-e|--exec <cmd>] [-f|--file <cmd-file>] [<file>] [...]"
gen_tmpfile=yes
arg_spec="0+"
opt_spec="v.t.n.w.q.s.i.b:e+f:"
opt_alias="v:verbose,t:trace,n:nop,w:warning,q:quiet,s:stealth,i:interactive,b:backup,e:exec,f:file"
opt_v=no
opt_t=no
opt_n=no
opt_w=no
opt_q=no
opt_s=no
opt_i=no
opt_b=""
opt_e=""
opt_f=""

. ./sh.common

#   remember optional list of file(s)
files="$*"
files_num="$#"

#   parameter consistency check
if [ $# -eq 0 ] && [ ".$opt_b" != . ]; then
    echo "$msgprefix:Error: option -b cannot be applied to stdin" 1>&2
    shtool_exit 1
fi
if [ $# -eq 0 ] && [ ".$opt_s" = .yes ]; then
    echo "$msgprefix:Error: option -s cannot be applied to stdin" 1>&2
    shtool_exit 1
fi

#   build underlying sed(1) command
sedcmd='sed'
if [ ".$opt_e" != . ]; then
    OIFS="$IFS"; IFS="$ASC_NL"; set -- $opt_e; IFS="$OIFS"
    for e
    do
        sedcmd="$sedcmd -e '$e'"
    done
elif [ ".$opt_f" != . ]; then
    if [ ! -f $opt_f ]; then
        echo "$msgprefix:Error: command file \`$opt_f' not found or not a regular file" 1>&2
        shtool_exit 1
    fi
    sedcmd="$sedcmd -f '$opt_f'"
else
    echo "$msgprefix:Error: either -e option(s) or -f option required" 1>&2
    shtool_exit 1
fi

#   determine extension for original file
orig=".orig"
if [ ".$opt_b" != . ]; then
    orig="$opt_b"
fi

#   apply sed(1) operation(s)
if [ ".$files" != . ]; then
    #   apply operation(s) to files
    substdone=no
    for file in $files; do
        test ".$file" = . && continue
        if [ ! -f $file ]; then
            echo "$msgprefix:Warning: file \`$file' not found or not a regular file" 1>&2
            continue
        fi

        #   handle interactive mode
        if [ ".$opt_i" = .yes ]; then
            eval "$sedcmd <$file >$file.new"
            skip=no
            if cmp $file $file.new >/dev/null 2>&1; then
                rm -f $file.new
                skip=yes
            else
                (diff -U1 $file $file.new >$tmpfile) 2>/dev/null
                if [ ".`cat $tmpfile`" = . ]; then
                    (diff -C1 $file $file.new >$tmpfile) 2>/dev/null
                    if [ ".`cat $tmpfile`" = . ]; then
                        echo "$msgprefix:Warning: unable to show difference for file \`$file'" 1>&2
                        cp /dev/null $tmpfile
                    fi
                fi
                rm -f $file.new
                cat $tmpfile
                echo dummy | awk '{ printf("%s", TEXT); }' TEXT=">>> Apply [Y/n]: "
                read input
                if [ ".$input" != .Y ] &&\
                   [ ".$input" != .y ] &&\
                   [ ".$input" != . ]; then
                   skip=yes
                fi
            fi
            if [ ".$skip" = .yes ]; then
                if [ ".$opt_v" = .yes ]; then
                    echo "file \`$file' -- skipped" 1>&2
                fi
                continue
            fi
        fi

        #   apply sed(1) operation(s)
        if [ ".$opt_v" = .yes ]; then
            echo "patching \`$file'" 1>&2
        fi
        if [ ".$opt_t" = .yes ]; then
            echo "\$ cp -p $file $file$orig"
            echo "\$ chmod u+w $file"
            echo "\$ $sedcmd <$file$orig >$file"
        fi
        if [ ".$opt_n" = .no ]; then
            cp -p $file $file$orig
            chmod u+w $file >/dev/null 2>&1 || true
            eval "$sedcmd <$file$orig >$file"
        fi

        #   optionally fix timestamp
        if [ ".$opt_s" = .yes ]; then
            if [ ".$opt_t" = .yes ]; then
                echo "\$ touch -r $file$orig $file"
            fi
            if [ ".$opt_n" = .no ]; then
                touch -r $file$orig $file
            fi
        fi

        #   optionally check whether any content change actually occurred
        if [ ".$opt_q" = .no ]; then
            if cmp $file$orig $file >/dev/null 2>&1; then
                if [ ".$opt_w" = .yes ]; then
                    echo "$msgprefix:Warning: substitution resulted in no content change on file \"$file\"" 1>&2
                fi
            else
                substdone=yes
            fi
        fi

        #   optionally remove preserved original file
        if [ ".$opt_b" = . ]; then
            if [ ".$opt_t" = .yes ]; then
                echo "\$ rm -f $file$orig"
            fi
            if [ ".$opt_n" = .no ]; then
                rm -f $file$orig
            fi
        fi
    done
    if [ ".$opt_q" = .no ] && [ ".$opt_w" = .no ]; then
        if [ ".$substdone" = .no ]; then
            if [ ".$files_num" = .1 ]; then
                echo "$msgprefix:Warning: substitution resulted in no content change on file \"$file\"" 1>&2
            else
                echo "$msgprefix:Warning: substitution resulted in no content change on any file" 1>&2
            fi
        fi
    fi
else
    #   apply operation(s) to stdin/stdout
    if [ ".$opt_v" = .yes ]; then
        echo "patching <stdin>" 1>&2
    fi
    if [ ".$opt_t" = .yes ]; then
        echo "\$ $sedcmd"
    fi
    if [ ".$opt_n" = .no ]; then
        eval "$sedcmd"
    fi
fi

shtool_exit 0

##
##  manual page
##

=pod

=head1 NAME

B<shtool subst> - B<GNU shtool> sed(1) substitution operations

=head1 SYNOPSIS

B<shtool subst>
[B<-v>|B<--verbose>]
[B<-t>|B<--trace>]
[B<-n>|B<--nop>]
[B<-w>|B<--warning>]
[B<-q>|B<--quiet>]
[B<-s>|B<--stealth>]
[B<-i>|B<--interactive>]
[B<-b>|B<--backup> I<ext>]
[B<-e>|B<--exec> I<cmd>]
[B<-f>|B<--file> I<cmd-file>]
[I<file>] [I<file> ...]

=head1 DESCRIPTION

This command applies one or more sed(1) substitution operations to
F<stdin> or any number of files.

=head1 OPTIONS

The following command line options are available.

=over 4

=item B<-v>, B<--verbose>

Display some processing information.

=item B<-t>, B<--trace>

Enable the output of the essential shell commands which are executed.

=item B<-n>, B<--nop>

No operation mode. Actual execution of the essential shell commands
which would be executed is suppressed.

=item B<-w>, B<--warning>

Show warning on substitution operation resulting in no content change
on I<every> file. The default is to show a warning on substitution
operations resulted in no content change on I<all> files.

=item B<-q>, B<--quiet>

Suppress warning on substitution operation resulting in no content change.

=item B<-s>, B<--stealth>

Stealth operation. Preserve timestamp on I<file>.

=item B<-i>, B<--interactive>

Enter interactive mode where the user has to approve each operation.

=item B<-b>, B<--backup> I<ext>

Preserve backup of original file using file name extension I<ext>.
Default is to overwrite the original file.

=item B<-e>, B<--exec> I<cmd>

Specify sed(1) command directly.

=item B<-f>, B<--file> I<cmd-file>

Read sed(1) command from I<file>.

=back

=head1 EXAMPLE

 #   shell script
 shtool subst -i -e 's;(c) \([0-9]*\)-2000;(c) \1-2001;' *.[ch]

 #    RPM spec-file
 %install
     shtool subst -v -n \
         -e 's;^\(prefix=\).*;\1 $RPM_BUILD_ROOT%{_prefix};g' \
         -e 's;^\(sysconfdir=\).*;\1 $RPM_BUILD_ROOT%{_prefix}/etc;g' \
         `find . -name Makefile -print`
     make install

=head1 HISTORY

The B<GNU shtool> B<subst> command was originally written by Ralf S.
Engelschall E<lt>rse@engelschall.comE<gt> in 2001 for B<GNU shtool>.
It was prompted by the need to have a uniform and convenient patching
frontend to sed(1) operations in the B<OpenPKG> package specifications.

=head1 SEE ALSO

shtool(1), sed(1).

=cut