#!/usr/bin/perl -w

# Po4a::Text.pm
# 
# extract and translate translatable strings from a text documents
#
# This program 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.
#
# This program 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.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
#
########################################################################

=head1 NAME

Locale::Po4a::Text - Convert text documents from/to PO files

=head1 DESCRIPTION

The po4a (po for anything) project goal is to ease translations (and more
interestingly, the maintenance of translations) using gettext tools on
areas where they were not expected like documentation.

Locale::Po4a::Text is a module to help the translation of text documents into
other [human] languages.

Paragraphs are splitted on empty lines (or lines containing only spaces or
tabulations).

If a paragraph contains a line starting by a space (or tabulation), this
paragraph won't be rewrapped.

=cut

package Locale::Po4a::Text;

use 5.006;
use strict;
use warnings;

require Exporter;
use vars qw(@ISA @EXPORT);
@ISA = qw(Locale::Po4a::TransTractor);
@EXPORT = qw();

use Locale::Po4a::TransTractor;
use Locale::Po4a::Common;

=head1 OPTIONS ACCEPTED BY THIS MODULE

These are this module's particular options:

=over

=item B<nobullet>

Deactivate detection of bullets.

By default, when a bullet is detected, the bullet paragraph is not considered
as a verbatim paragraph (with the no-wrap flag in the PO file), but the module
rewrap this paragraph in the generated PO file and in the translation.

=cut

my $bullets = 1;

=item B<debianchangelog>

Handle the header and footer of
released versions, which only contain non translatable informations.

=cut

my $debianchangelog = 0;

=item B<fortunes>

Handle the fortunes format, which separate fortunes with a line which
consists in '%' or '%%', and use '%%' as the beginning of a comment.

=cut

my $fortunes = 0;

=item B<markdown>

Handle some special markup in Markdown-formatted texts.

=cut

my $markdown = 0;

sub initialize {
    my $self = shift;
    my %options = @_;

    $self->{options}{'nobullets'}='';

    if (defined $options{'nobullets'}) {
        $bullets = 0;
    }

    if (defined $options{'debianchangelog'}) {
        $debianchangelog=1;
    }

    if (defined $options{'fortunes'}) {
        $fortunes=1;
    }

    if (defined $options{'markdown'}) {
        $markdown=1;
    }
}

sub parse {
    my $self = shift;
    my ($line,$ref);
    my $paragraph="";
    my $wrapped_mode = 1;
    my $expect_header = 1;
    my $end_of_paragraph = 0;
    ($line,$ref)=$self->shiftline();
    my $file = $ref;
    $file =~ s/:[0-9]+$//;
    while (defined($line)) {
        $ref =~ m/^(.*):[0-9]+$/;
        if ($1 ne $file) {
            $file = $1;
            do_paragraph($self,$paragraph,$wrapped_mode);
            $paragraph="";
            $wrapped_mode = 1;
            $expect_header = 1;
        }

        # TODO: preserve original line ends throughout the code instead
        chomp($line);
        $self->{ref}="$ref";
        if ($debianchangelog and
            $expect_header and
            $line =~ /^(\w[-+0-9a-z.]*)\ \(([^\(\) \t]+)\) # src, version
                       \s+([-+0-9a-z.]+);                 # distribution
                       \s*urgency\s*\=\s*(.*\S)\s*$/ix) { #
            do_paragraph($self,$paragraph,$wrapped_mode);
            $paragraph="";
            $self->pushline("$line\n");
            $expect_header=0;
        } elsif ($debianchangelog and
                 $line =~ m/^ \-\- (.*) <(.*)>  ((\w+\,\s*)?\d{1,2}\s+\w+\s+\d{4}\s+\d{1,2}:\d\d:\d\d\s+[-+]\d{4}(\s+\([^\\\(\)]\))?)$/) {
            # Found trailer
            do_paragraph($self,$paragraph,$wrapped_mode);
            $paragraph="";
            $self->pushline("$line\n");
            $expect_header=1;
        } elsif ($fortunes and
                 $line =~ m/^%%?\s*$/) {
            # Found end of fortune
            do_paragraph($self,$paragraph,$wrapped_mode);
            # FIXME: test if this is still needed when always adding
            #        newline in do_paragraph()
            $self->pushline("\n") unless (   $wrapped_mode == 0
                                          or $paragraph eq "");
            $paragraph="";
            $wrapped_mode = 1;
            $self->pushline("$line\n");
        } elsif ($line =~ /^\s*$/) {
            # Break paragraphs on lines containing only spaces
            do_paragraph($self,$paragraph,$wrapped_mode);
            $paragraph="";
            $wrapped_mode = 1;
            $self->pushline($line."\n");
        } elsif ($line =~ /^-- $/) {
            # Break paragraphs on email signature hint
            do_paragraph($self,$paragraph,$wrapped_mode);
            $paragraph="";
            $wrapped_mode = 1;
            $self->pushline($line."\n");
        } elsif (   $line =~ /^=+$/
                 or $line =~ /^_+$/
                 or $line =~ /^-+$/) {
            $wrapped_mode = 0;
            $paragraph .= $line."\n";
            do_paragraph($self,$paragraph,$wrapped_mode);
            $paragraph="";
            $wrapped_mode = 1;
        } elsif ($markdown and
                 (   $line =~ /^\s*\[\[\!\S+\s*$/     # macro begin
                 or $line =~ /^\s*"""\s*\]\]\s*$/)) { # """ textblock inside macro end
            # Avoid translating Markdown lines containing only markup
            do_paragraph($self,$paragraph,$wrapped_mode);
            $paragraph="";
            $wrapped_mode = 1;
            $self->pushline("$line\n");
        } elsif ($markdown and
                 (   $line =~ /^#/            # headline
                  or $line =~ /^\s*\[\[\!\S[^\]]*\]\]\s*$/)) { # sole macro
            # Preserve some Markdown markup as a single line
            do_paragraph($self,$paragraph,$wrapped_mode);
            $paragraph="$line\n";
            $wrapped_mode = 0;
            $end_of_paragraph = 1;
        } elsif ($markdown and
                 (   $line =~ /^"""/)) { # """ textblock inside macro end
            # Markdown markup needing separation _before_ this line
            do_paragraph($self,$paragraph,$wrapped_mode);
            $paragraph="$line\n";
            $wrapped_mode = 1;
        } else {
            if ($line =~ /^\s/) {
                # A line starting by a space indicates a non-wrap
                # paragraph
                $wrapped_mode = 0;
            }
            if ($markdown and
                     (   $line =~ /\S  $/    # explicit newline
                      or $line =~ /"""$/)) { # """ textblock inside macro begin
                # Markdown markup needing separation _after_ this line
                $end_of_paragraph = 1;
            }
            if ($fortunes) {
                $line =~ s/%%(.*)$//;
            }
# TODO: comments
            $paragraph .= $line."\n";
        }
        # paragraphs starting by a bullet, or numbered
        # or paragraphs with a line containing many consecutive spaces
        # (more than 3)
        # are considered as verbatim paragraphs
        $wrapped_mode = 0 if (   $paragraph =~ m/^(\*|[0-9]+[.)] )/s
                          or $paragraph =~ m/[ \t][ \t][ \t]/s);
        if ($markdown) {
            # Some Markdown markup can (or might) not survive wrapping
            $wrapped_mode = 0 if (
                   $paragraph =~ /^>/ms                  # blockquote
                or $paragraph =~ /^( {8}|\t)/ms          # monospaced
                or $paragraph =~ /^\$(\S+[{}]\S*\s*)+/ms # Xapian macro
                or $paragraph =~ /<(?![a-z]+[:@])/ms     # maybe html (tags but not wiki <URI>)
                or $paragraph =~ /^[^<]+>/ms             # maybe html (tag with vertical space)
                or $paragraph =~ /^\s*\[\[\!\S[^\]]+$/ms # macro begin
            );
        }
        if ($end_of_paragraph) {
            do_paragraph($self,$paragraph,$wrapped_mode);
            $paragraph="";
            $wrapped_mode = 1;
            $end_of_paragraph = 0;
        }
        ($line,$ref)=$self->shiftline();
    }
    if (length $paragraph) {
        do_paragraph($self,$paragraph,$wrapped_mode);
    }
}

sub do_paragraph {
    my ($self, $paragraph, $wrap) = (shift, shift, shift);
    return if ($paragraph eq "");

    if ($bullets) {
        # Detect bullets
        # |        * blah blah
        # |<spaces>  blah
        # |          ^-- aligned
        # <empty line>
        #
        # Other bullets supported:
        # - blah         o blah         + blah
        # 1. blah       1) blah       (1) blah
TEST_BULLET:
        if ($paragraph =~ m/^(\s*)((?:[-*o+]|([0-9]+[.\)])|\([0-9]+\))\s+)([^\n]*\n)(.*)$/s) {
            my $para = $5;
            my $bullet = $2;
            my $indent1 = $1;
            my $indent2 = "$1".(' ' x length $bullet);
            my $text = $4;
            while ($para !~ m/$indent2(?:[-*o+]|([0-9]+[.\)])|\([0-9]+\))\s+/
                   and $para =~ s/^$indent2(\S[^\n]*\n)//s) {
                $text .= $1;
            }
            # TODO: detect if a line starts with the same bullet
            if ($text !~ m/\S[ \t][ \t][ \t]+\S/s) {
                my $bullet_regex = quotemeta($indent1.$bullet);
                $bullet_regex =~ s/[0-9]+/\\d\+/;
                if ($para eq '' or $para =~ m/^$bullet_regex\S/s) {
                    my $trans = $self->translate($text,
                                                 $self->{ref},
                                                 "Bullet: '$indent1$bullet'",
                                                 "wrap" => 1,
                                                 "wrapcol" => - (length $indent2));
                    $trans =~ s/^/$indent1$bullet/s;
                    $trans =~ s/\n(.)/\n$indent2$1/sg;
                    $self->pushline( $trans."\n" );
                    if ($para eq '') {
                        return;
                    } else {
                        # Another bullet
                        $paragraph = $para;
                        goto TEST_BULLET;
                    }
                }
            }
        }
    }
    # TODO: detect indented paragraphs

    my $transfinal = $self->translate($paragraph,
                                      $self->{ref},
                                      "Plain text",
                                      "wrap" => $wrap);

    # TODO: preserve original line ends throughout the code instead
    chomp $transfinal;
    $transfinal .= "\n";

    $self->pushline( $transfinal );
}

1;

=head1 STATUS OF THIS MODULE

Tested successfully on simple text files and NEWS.Debian files.

=head1 AUTHORS

 Nicolas François <nicolas.francois@centraliens.net>

=head1 COPYRIGHT AND LICENSE

 Copyright 2005-2008 by Nicolas FRANÇOIS <nicolas.francois@centraliens.net>.

This program is free software; you may redistribute it and/or modify it
under the terms of GPL (see the COPYING file).