#!/usr/bin/perl

# Copyright (C) 2007, 2008 Simon Josefsson <simon@josefsson.org>

# Copyright (C) 2007 Luis Mondesi <lemsx1@gmail.com>

# * calls git directly. To use it just: 

#   cd ~/Project/my_git_repo; git2cl > ChangeLog

# * implements strptime()

# * fixes bugs in $comment parsing

#   - copy input before we remove leading spaces

#   - skip "merge branch" statements as they don't

#     have information about files (i.e. we never

#     go into $state 2)

#   - behaves like a pipe/filter if input is given from the CLI

#     else it calls git log by itself

#

# The functions mywrap, last_line_len, wrap_log_entry are derived from

# the cvs2cl tool, see <http://www.red-bean.com/cvs2cl/>:

# Copyright (C) 2001,2002,2003,2004 Martyn J. Pearce <fluffy@cpan.org>

# Copyright (C) 1999 Karl Fogel <kfogel@red-bean.com>

#

# git2cl 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, or (at your option)

# any later version.

#

# git2cl 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 git2cl; see the file COPYING.  If not, write to the Free

# Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA

# 02111-1307, USA.

use strict;

use POSIX qw(strftime);

use Text::Wrap qw(wrap);

use FileHandle;

use constant EMPTY_LOG_MESSAGE => '*** empty log message ***';

# this is a helper hash for stptime.

# Assumes you are calling 'git log ...' with LC_ALL=C

my %month = (

    'Jan'=>0,

    'Feb'=>1,

    'Mar'=>2,

    'Apr'=>3,

    'May'=>4,

    'Jun'=>5,

    'Jul'=>6,

    'Aug'=>7,

    'Sep'=>8,

    'Oct'=>9,

    'Nov'=>10,

    'Dec'=>11,

);

my $fh = new FileHandle;

sub key_ready

{

    my ($rin, $nfd);

    vec($rin, fileno(STDIN), 1) = 1;

    return $nfd = select($rin, undef, undef, 0);

}

sub strptime {

    my $str = shift;

    return undef if not defined $str;

    # we are parsing this format

    # Fri Oct 26 00:42:56 2007 -0400

    # to these fields

    # sec, min, hour, mday, mon, year, wday = -1, yday = -1, isdst = -1

    # Luis Mondesi <lemsx1@gmail.com>

    my @date;

    if ($str =~ /([[:alpha:]]{3})\s+([[:alpha:]]{3})\s+([[:digit:]]{1,2})\s+([[:digit:]]{1,2}):([[:digit:]]{1,2}):([[:digit:]]{1,2})\s+([[:digit:]]{4})/){

        push(@date,$6,$5,$4,$3,$month{$2},($7 - 1900),-1,-1,-1);

    } else {

        die ("Cannot parse date '$str'\n'");

    }

    return @date;

}

sub mywrap {

    my ($indent1, $indent2, @text) = @_;

    # If incoming text looks preformatted, don't get clever

    my $text = Text::Wrap::wrap($indent1, $indent2, @text);

    if ( grep /^\s+/m, @text ) {

	return $text;

    }

    my @lines = split /\n/, $text;

    $indent2 =~ s!^((?: {8})+)!"\t" x (length($1)/8)!e;

    $lines[0] =~ s/^$indent1\s+/$indent1/;

    s/^$indent2\s+/$indent2/

	for @lines[1..$#lines];

    my $newtext = join "\n", @lines;

    $newtext .= "\n"

	if substr($text, -1) eq "\n";

    return $newtext;

}

sub last_line_len {

    my $files_list = shift;

    my @lines = split (/\n/, $files_list);

    my $last_line = pop (@lines);

    return length ($last_line);

}

# A custom wrap function, sensitive to some common constructs used in

# log entries.

sub wrap_log_entry {

    my $text = shift;                  # The text to wrap.

    my $left_pad_str = shift;          # String to pad with on the left.

    # These do NOT take left_pad_str into account:

    my $length_remaining = shift;      # Amount left on current line.

    my $max_line_length  = shift;      # Amount left for a blank line.

    my $wrapped_text = '';             # The accumulating wrapped entry.

    my $user_indent = '';              # Inherited user_indent from prev line.

    my $first_time = 1;                # First iteration of the loop?

    my $suppress_line_start_match = 0; # Set to disable line start checks.

    my @lines = split (/\n/, $text);

    while (@lines)   # Don't use `foreach' here, it won't work.

    {

	my $this_line = shift (@lines);

	chomp $this_line;

	if ($this_line =~ /^(\s+)/) {

	    $user_indent = $1;

	}

	else {

	    $user_indent = '';

	}

	# If it matches any of the line-start regexps, print a newline now...

	if ($suppress_line_start_match)

	{

	    $suppress_line_start_match = 0;

	}

	elsif (($this_line =~ /^(\s*)\*\s+[a-zA-Z0-9]/)

	       || ($this_line =~ /^(\s*)\* [a-zA-Z0-9_\.\/\+-]+/)

	       || ($this_line =~ /^(\s*)\([a-zA-Z0-9_\.\/\+-]+(\)|,\s*)/)

	       || ($this_line =~ /^(\s+)(\S+)/)

	       || ($this_line =~ /^(\s*)- +/)

	       || ($this_line =~ /^()\s*$/)

	       || ($this_line =~ /^(\s*)\*\) +/)

	       || ($this_line =~ /^(\s*)[a-zA-Z0-9](\)|\.|\:) +/))

	{

	    $length_remaining = $max_line_length - (length ($user_indent));

	}

	# Now that any user_indent has been preserved, strip off leading

	# whitespace, so up-folding has no ugly side-effects.

	$this_line =~ s/^\s*//;

	# Accumulate the line, and adjust parameters for next line.

	my $this_len = length ($this_line);

	if ($this_len == 0)

	{

	    # Blank lines should cancel any user_indent level.

	    $user_indent = '';

	    $length_remaining = $max_line_length;

	}

	elsif ($this_len >= $length_remaining) # Line too long, try breaking it.

	{

	    # Walk backwards from the end.  At first acceptable spot, break

	    # a new line.

	    my $idx = $length_remaining - 1;

	    if ($idx < 0) { $idx = 0 };

	    while ($idx > 0)

	    {

		if (substr ($this_line, $idx, 1) =~ /\s/)

		{

		    my $line_now = substr ($this_line, 0, $idx);

		    my $next_line = substr ($this_line, $idx);

		    $this_line = $line_now;

		    # Clean whitespace off the end.

		    chomp $this_line;

		    # The current line is ready to be printed.

		    $this_line .= "\n${left_pad_str}";

		    # Make sure the next line is allowed full room.

		    $length_remaining = $max_line_length - (length ($user_indent));

		    # Strip next_line, but then preserve any user_indent.

		    $next_line =~ s/^\s*//;

		    # Sneak a peek at the user_indent of the upcoming line, so

		    # $next_line (which will now precede it) can inherit that

		    # indent level.  Otherwise, use whatever user_indent level

		    # we currently have, which might be none.

		    my $next_next_line = shift (@lines);

		    if ((defined ($next_next_line)) && ($next_next_line =~ /^(\s+)/)) {

			$next_line = $1 . $next_line if (defined ($1));

			# $length_remaining = $max_line_length - (length ($1));

			$next_next_line =~ s/^\s*//;

		    }

		    else {

			$next_line = $user_indent . $next_line;

		    }

		    if (defined ($next_next_line)) {

			unshift (@lines, $next_next_line);

		    }

		    unshift (@lines, $next_line);

		    # Our new next line might, coincidentally, begin with one of

		    # the line-start regexps, so we temporarily turn off

		    # sensitivity to that until we're past the line.

		    $suppress_line_start_match = 1;

		    last;

		}

		else

		{

		    $idx--;

		}

	    }

	    if ($idx == 0)

	    {

		# We bottomed out because the line is longer than the

		# available space.  But that could be because the space is

		# small, or because the line is longer than even the maximum

		# possible space.  Handle both cases below.

		if ($length_remaining == ($max_line_length - (length ($user_indent))))

		{

		    # The line is simply too long -- there is no hope of ever

		    # breaking it nicely, so just insert it verbatim, with

		    # appropriate padding.

		    $this_line = "\n${left_pad_str}${this_line}";

		}

		else

		{

		    # Can't break it here, but may be able to on the next round...

		    unshift (@lines, $this_line);

		    $length_remaining = $max_line_length - (length ($user_indent));

		    $this_line = "\n${left_pad_str}";

		}

	    }

	}

	else  # $this_len < $length_remaining, so tack on what we can.

	{

	    # Leave a note for the next iteration.

	    $length_remaining = $length_remaining - $this_len;

	    if ($this_line =~ /\.$/)

	    {

		$this_line .= "  ";

		$length_remaining -= 2;

	    }

	    else  # not a sentence end

	    {

		$this_line .= " ";

		$length_remaining -= 1;

	    }

	}

	# Unconditionally indicate that loop has run at least once.

	$first_time = 0;

	$wrapped_text .= "${user_indent}${this_line}";

    }

    # One last bit of padding.

    $wrapped_text .= "\n";

    return $wrapped_text;

}

# main

my @date;

my $author;

my @files;

my $comment;

my $state; # 0-header 1-comment 2-files

my $done = 0;

$state = 0;

# if reading from STDIN, we assume that we are

# getting git log as input

if (key_ready())

{

    #my $dummyfh; # don't care about writing

    #($fh,$dummyfh) = FileHandle::pipe;

    $fh->fdopen(*STDIN, 'r');

}

else

{

    $fh->open("LC_ALL=C git log --pretty --numstat --summary|")

	or die("Cannot execute git log...$!\n");

}

while (my $_l = <$fh>) {

    #print STDERR "debug ($state, " . (@date ? (strftime "%Y-%m-%d", @date) : "") . "): `$_'\n";

    if ($state == 0) {

	if ($_l =~ m,^Author: (.*),) {

	    $author = $1;

	}

	if ($_l =~ m,^Date: (.*),) {

	    @date = strptime($1);

	}

	$state = 1 if ($_l =~ m,^$, and $author and (@date+0>0));

    } elsif ($state == 1) {

        # * modifying our input text is a bad choice

        #   let's make a copy of it first, then we remove spaces 

        # * if we meet a "merge branch" statement, we need to start

        #   over and find a real entry

        # Luis Mondesi <lemsx1@gmail.com>

        my $_s = $_l;

	$_s =~ s/^    //g;

        if ($_s =~ m/^Merge branch/)

        {

            $state=0;

            next;

        }

	$comment = $comment . $_s;

	$state = 2 if ($_l =~ m,^$,);

    } elsif ($state == 2) {

	if ($_l =~ m,^([0-9]+)\t([0-9]+)\t(.*)$,) {

	    push @files, $3;

	}

	$done = 1 if ($_l =~ m,^$,);

    }

    if ($done) {

	print (strftime "%Y-%m-%d  $author\n\n", @date);

	my $files = join (", ", @files);

	$files = mywrap ("\t", "\t", "* $files"), ": ";

	if (index($comment, EMPTY_LOG_MESSAGE) > -1 ) {

	    $comment = "[no log message]\n";

	}

	my $files_last_line_len = 0;

	$files_last_line_len = last_line_len($files) + 1;

	my $msg = wrap_log_entry($comment, "\t", 69-$files_last_line_len, 69);

	$msg =~ s/[ \t]+\n/\n/g;

	print "$files: $msg\n";

	@date = ();

	$author = "";

	@files = ();

	$comment = "";

	$state = 0;

	$done = 0;

    }

}

if (@date + 0)

{

    print (strftime "%Y-%m-%d  $author\n\n", @date);

    my $msg = wrap_log_entry($comment, "\t", 69, 69);

    $msg =~ s/[ \t]+\n/\n/g;

    print "\t* $msg\n";

}