#!/usr/bin/perl

$USAGE = "
 USAGE:    pedit -s,re,re,opt  FILES
 SYNOPSIS: Substitute strings inline in files.
 OPTIONS:
   -s/re/re/gioe  Command to execute on each line of files.
   -Ffilelist     List of files and s/// cmd in filelist.
   -ffilelist     List of files              in filelist.
   -xcmdfile      Take s/// from cmdfile.
   -i.bak         Extension for old file, default is ~
   -q             quiet mode, don't show diffs.
   -v             Verbose.
   -?             help.
 EXAMPLES:
   o Convert / to comma in file x.c and rename orginal x.c to x.c.bak
     > pedit -s#/#,#g -i.bak x.c
   o Filenames are piped.
     > dir/s/b | pedit -s,mosh,MohsinA,gio
   o Filenames in file list.txt
     > pedit -flist.txt -s/x/y/i
   o Commands and filenames in file xyz.
     > pedit -Fxyz
     > cat  xyz
            s/1992/1993/g
            file1.c
            file2.h
   o Format \"column2 column1\" as a table in filetab.
    > cat cmdfile
     s:(.*)/([\\w_\\d.]+)\$:sprintf(\"\%-20s\%s\",\$2,\$1):e
   o Simple use, correct spellings in all h files:
     > perl -pe s/recieve/receive/gi  -i~ *.h
   o Convert LF to CR LF and Back.
     > perl -pe \"s,\\n,\\r\\n,g\"  -i~ UNIXFILES
     > perl -pe \"s,\\r\\n,\\n,g\"  -i~ DOSFILES

 NOTES:  Will not edit, if backup file exists.
 AUTHOR: GPL(C), http://www.cs.albany.edu/~mosh
";

$verbose = 1;
$INPLACE_EDIT = '~';

while( $_ = $ARGV[0], /^-/ ){
    shift;
    if( m/^--$/ ){
        last;
    }elsif( m/^-[Ff](.+)/ ){
        $filename = $1;
        open( FILELIST, "< $filename" )
            || die "Cannot read $filename\n";
        # -F means first line of file is the s/// command.
        $op1 = <FILELIST> if m/-F/;
        @filelist = <FILELIST>;
        @filelist = grep( s/\n//, @filelist );
        close FILELIST;

        print STDERR "From $filename = @ARGV.\n";
    }elsif( m/^-q/ ){
        $quiet++;
        print STDERR "quiet mode, editing at your own risk.\n"
    }elsif( m/^-(s.+)/i ){
        $op1 = $1;
        print STDERR "subst: $op1.\n"
    }elsif( m/^-v(.*)/ ){
        $verbose = $1 || 1;
        print STDERR "verbose = $verbose.\n"
    }elsif( m/^-x(.+)/ ){
        $cmdfile = $1;
        open( CMDFILE, "<$cmdfile") ||
                die "Cannot read -xcmdfile $cmdfile\n";
        $op1 = <CMDFILE>;
        close( CMDFILE );
        print STDERR "cmd=$op1\n";
    }elsif( m/^-i(.+)/ ){
        print STDERR "INPLACE_EDIT=$^I=$INPLACE_EDIT.\n"
            if $verbose >= 2;
        $INPLACE_EDIT = $^I = $1;
        print STDERR "INPLACE_EDIT=$^I=$INPLACE_EDIT;\n";
    }elsif( m/^-\?/ ){
        print $USAGE; exit;
    }else{
        die "Invalid option: $_, see -? for help.\n";
    }
}

die "Need args, see -? for help\n" unless $op1;

if( @filelist ){
    @ARGV = @filelist;
}elsif( ! @ARGV ){
    @ARGV = <STDIN>;
    chop(@ARGV);
}

print STDERR "subst=$op1 \n ARGV = @ARGV \n" if $verbose;

# Filter the files.

foreach (@ARGV) {
    if( -e "$_~" ){
        warn "Skipping $_  backup file $_~ exists.\n";
    }elsif( ! -f $_ ){
        warn "skipping $_, not a file.\n";
    }else{
        push( @NEWARGV, $_ );
    }
}

die "No files to edit? see -? for help.\n" unless @NEWARGV;

@ARGV = @NEWARGV;

$lineschanged = 0;

while( <> ){
    $line = $_;
    if( eval $op1 ){
        $lineschanged++;
        if( $verbose ){
            print STDERR "Changed: $ARGV:$.:\n-$line+$_"
                unless $quiet;
            # Changed: FILE:LINE:
            # -OLD
            # +NEW
        }
    }
    die $@ if $@;
    print $_;
    if( eof ){
        print STDERR "Edited $lineschanged/$. lines of $ARGV\n";
        $lineschanged=0;
        close(ARGV);
    }
}