#! /usr/bin/perl

# Copyright (C) 1999-2013 Free Software Foundation, Inc.
#
# This file is part of GNU Emacs.

# GNU Emacs 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 3 of the License, or
# (at your option) any later version.

# GNU Emacs 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 GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.


# Extract entries from ChangeLogs matching specified criteria.
# Optionally format the resulting output to a form suitable for RCS
# logs, like they are used in Emacs, for example.  In this format,
# author lines, leading spaces, and file names are removed.

require 5;
use strict;

# Parse command line options.

use vars qw($author $regexp $exclude $from_date $to_date
            $rcs_log $with_date $version $help $reverse
            @entries);

use Getopt::Long;

my $result;

if (@ARGV == 0) {

    # No arguments cannot possibly mean "show everything"!!
    $result = 0;

} else {

    $result = GetOptions ("author=s" => \$author,
                          "text=s"  => \$regexp,
                          "exclude=s"  => \$exclude,
                          "from-date=s" => \$from_date,
                          "to-date=s" => \$to_date,
                          "rcs-log" => \$rcs_log,
                          "with-date" => \$with_date,
                          "reverse!" => \$reverse,
                          "version" => \$version,
                          "help"    => \$help);

    # If date options are specified, check that they have the format
    # YYYY-MM-DD.

    $result = 0 if $from_date && $from_date !~ /^\d\d\d\d-\d\d-\d\d$/;
    $result = 0 if $to_date && $to_date !~ /^\d\d\d\d-\d\d-\d\d$/;
}

# Print usage information and exit when necessary.

if ($result == 0 || $help) {
    print <<USAGE;

Usage: $0 [options] [CHANGELOG...]

Print entries in ChangeLogs matching various criteria.
Valid options are:

  --author=AUTHOR         Match entries whose author line matches
			  regular expression AUTHOR
  --text=TEXT             Match entries whose text matches regular
			  expression TEXT
  --exclude=TEXT	  Exclude entries matching TEXT
  --from-date=YYYY-MM-DD  Match entries not older than given date
  --to-date=YYYY-MM-DD    Match entries not younger than given date
  --rcs-log		  Format output suitable for RCS log entries
  --with-date		  Print short date line in RCS log
  --reverse               Show entries in reverse (chronological) order
  --version		  Print version info
  --help		  Print this help

If no CHANGELOG is specified scan the files "ChangeLog" and
"ChangeLog.N+" in the current directory.  Old-style dates in ChangeLogs
are not recognized.
USAGE
    exit !$help;
}

# Print version info and exit if `--version' was specified.

if ($version) {
    print "0.3\n";
    exit 0;
}


# Value is non-zero if HEADER matches according to command line
# options specified, i.e. it matches $author, and its date is in
# the range $from_date <= date <= $to_date.

sub header_match_p {
    my $header = shift;

    return 0 unless $header;

    # No match if AUTHOR-regexp specified and doesn't match.
    return 0 if $author && $header !~ /$author/;

    # Check that the date of the entry matches if date options
    # `--from-date' and/or `--to-date' were specified .  Old-style
    # dates in ChangeLogs are not recognized, and never match.
    if ($from_date || $to_date) {
	if ($header =~ /^(\d\d\d\d-\d\d-\d\d)/) {
	    my $date = $1;
	    return 0 if $from_date && $date lt $from_date;
	    return 0 if $to_date && $date gt $to_date;
	} else {
	    # Don't bother recognizing old-style dates.
	    return 0;
	}
    }

    return 1;
}


# Value is non-zero if ENTRY matches the criteria specified on the
# command line, i.e. it matches $regexp, and it doesn't match
# $exclude.

sub entry_match_p {
    my $entry = shift;

    return 0 unless $entry;

    if ($regexp) {
	return 1 if ($entry =~ /$regexp/
		     && (!$exclude || $entry !~ $exclude));
    } else {
	return 1 if !$exclude || $entry !~ $exclude;
    }

    return 0;
}


# Print HEADER and/or ENTRY in a format suitable for what was
# specified on the command line.  If $rcs_log is specified, author
# lines are not printed, and leading spaces and file names are removed
# from ChangeLog entries.

sub print_log {
    my ($header, $entry) = @_;
    my $output = '';

    if ($rcs_log) {
	# Remove leading whitespace from entry.
	$entry =~ s/^\s+//mg;
	# Remove file name parts.
	$entry =~ s/^\*.*\(/(/mg;
	# Remove file name parts, 2.
	$entry =~ s/^\*.*://mg;
        if ($with_date) {
	    $header =~ /(\d\d\d\d-\d\d-\d\d)/;
	    $output = "!changelog-date $1\n";
	}
	$output .= $entry;
    } else {
	$output .= $header . $entry;
    }

    if ($reverse) {
        push @entries, $output;
    } else {
        print $output;
    }
}

# Scan LOG for matching entries, and print them to standard output.

sub parse_changelog {
    my $log = shift;
    my $entry = undef;
    my $header = undef;

    @entries = () if $reverse;

    # Open the ChangeLog.
    open (IN, "< $log") || die "Cannot open $log: $!";

    while (defined(my $line = <IN>)) {
	if ($line =~ /^\S/) {
	    # Line is an author-line.  Print previous entry if
	    # it matches.
	    print_log ($header, $entry)
		if header_match_p ($header) && entry_match_p ($entry);

	    $entry = "";
  	    $header = $line;

	    # Add empty lines below the header.
	    while (defined($line = <IN>) && $line =~ /^\s*$/) {
	        $header = "$header$line";
	    }
        }

        last unless defined $line;

	if ($line =~ /^\s*\*/) {
	    # LINE is the first line of a ChangeLog entry.  Print
	    # previous entry if it matches.
	    print_log ($header, $entry)
		if header_match_p ($header) && entry_match_p ($entry);
	    $entry = $line;
	} else {
	    # Add LINE to the current entry.
	    $entry = "$entry$line";
	}
    }

    # Print last entry if it matches.
    print_log ($header, $entry)
	if header_match_p ($header) && entry_match_p ($entry);

    close IN;

    if ($reverse) {
        for (my $entry = @entries; $entry; $entry--) {
            print $entries[$entry-1];
        }
    }
}


# Main program.  Process ChangeLogs.

# If files were specified on the command line, parse those files in the
# order supplied by the user; otherwise parse default files ChangeLog and
# ChangeLog.NNN according to $reverse.
unless (@ARGV > 0) {
    @ARGV = ("ChangeLog");

    push @ARGV,
      map {"ChangeLog.$_"}
        sort {$b <=> $a}
          map {/\.(\d+)$/; $1}
            do {
                opendir D, '.';
                grep /^ChangeLog\.\d+$/, readdir D;
            };

    @ARGV = reverse @ARGV if $reverse;
}

while (defined (my $log = shift @ARGV)) {
    parse_changelog ($log) if -f $log;
}


# grep-changelog ends here.