#!/usr/bin/perl
# .po as a wiki page type
# Licensed under GPL v2 or greater
# Copyright (C) 2008-2009 intrigeri <intrigeri@boum.org>
# inspired by the GPL'd po4a-translate,
# which is Copyright 2002, 2003, 2004 by Martin Quinson (mquinson#debian.org)
package IkiWiki::Plugin::po;

use warnings;
use strict;
use IkiWiki 3.00;
use Encode;
use Locale::Po4a::Common qw(nowrapi18n !/.*/);
use Locale::Po4a::Chooser;
use Locale::Po4a::Po;
use File::Basename;
use File::Copy;
use File::Spec;
use File::Temp;
use Memoize;
use UNIVERSAL;

my %translations;
my @origneedsbuild;
my %origsubs;

memoize("istranslatable");
memoize("_istranslation");
memoize("percenttranslated");

sub import {
	hook(type => "getsetup", id => "po", call => \&getsetup);
	hook(type => "checkconfig", id => "po", call => \&checkconfig);
	hook(type => "needsbuild", id => "po", call => \&needsbuild);
	hook(type => "scan", id => "po", call => \&scan, last => 1);
	hook(type => "filter", id => "po", call => \&filter);
	hook(type => "htmlize", id => "po", call => \&htmlize);
	hook(type => "pagetemplate", id => "po", call => \&pagetemplate, last => 1);
	hook(type => "rename", id => "po", call => \&renamepages, first => 1);
	hook(type => "delete", id => "po", call => \&mydelete);
	hook(type => "change", id => "po", call => \&change);
	hook(type => "checkcontent", id => "po", call => \&checkcontent);
	hook(type => "canremove", id => "po", call => \&canremove);
	hook(type => "canrename", id => "po", call => \&canrename);
	hook(type => "editcontent", id => "po", call => \&editcontent);
	hook(type => "formbuilder_setup", id => "po", call => \&formbuilder_setup, last => 1);
	hook(type => "formbuilder", id => "po", call => \&formbuilder);

	$origsubs{'bestlink'}=\&IkiWiki::bestlink;
	inject(name => "IkiWiki::bestlink", call => \&mybestlink);
	$origsubs{'beautify_urlpath'}=\&IkiWiki::beautify_urlpath;
	inject(name => "IkiWiki::beautify_urlpath", call => \&mybeautify_urlpath);
	$origsubs{'targetpage'}=\&IkiWiki::targetpage;
	inject(name => "IkiWiki::targetpage", call => \&mytargetpage);
	$origsubs{'urlto'}=\&IkiWiki::urlto;
	inject(name => "IkiWiki::urlto", call => \&myurlto);
	$origsubs{'cgiurl'}=\&IkiWiki::cgiurl;
	inject(name => "IkiWiki::cgiurl", call => \&mycgiurl);
}


# ,----
# | Table of contents
# `----

# 1. Hooks
# 2. Injected functions
# 3. Blackboxes for private data
# 4. Helper functions
# 5. PageSpecs


# ,----
# | Hooks
# `----

sub getsetup () {
	return
		plugin => {
			safe => 0,
			rebuild => 1,
		},
		po_master_language => {
			type => "string",
			example => {
				'code' => 'en',
				'name' => 'English'
			},
			description => "master language (non-PO files)",
			safe => 1,
			rebuild => 1,
		},
		po_slave_languages => {
			type => "string",
			example => {
				'fr' => 'Français',
				'es' => 'Castellano',
				'de' => 'Deutsch'
			},
			description => "slave languages (PO files)",
			safe => 1,
			rebuild => 1,
		},
		po_translatable_pages => {
			type => "pagespec",
			example => "* and !*/Discussion",
			description => "PageSpec controlling which pages are translatable",
			link => "ikiwiki/PageSpec",
			safe => 1,
			rebuild => 1,
		},
		po_link_to => {
			type => "string",
			example => "current",
			description => "internal linking behavior (default/current/negotiated)",
			safe => 1,
			rebuild => 1,
		},
}

sub checkconfig () {
	foreach my $field (qw{po_master_language}) {
		if (! exists $config{$field} || ! defined $config{$field}) {
			error(sprintf(gettext("Must specify %s when using the %s plugin"),
				      $field, 'po'));
		}
	}

	map {
		islanguagecode($_)
			or error(sprintf(gettext("%s is not a valid language code"), $_));
	} ($config{po_master_language}{code}, keys %{$config{po_slave_languages}});

	if (! exists $config{po_translatable_pages} ||
	    ! defined $config{po_translatable_pages}) {
		$config{po_translatable_pages}="";
	}
	if (! exists $config{po_link_to} ||
	    ! defined $config{po_link_to}) {
		$config{po_link_to}='default';
	}
	elsif ($config{po_link_to} !~ /^(default|current|negotiated)$/) {
		warn(sprintf(gettext('%s is not a valid value for po_link_to, falling back to po_link_to=default'),
			     $config{po_link_to}));
		$config{po_link_to}='default';
	}
	elsif ($config{po_link_to} eq "negotiated" && ! $config{usedirs}) {
		warn(gettext('po_link_to=negotiated requires usedirs to be enabled, falling back to po_link_to=default'));
		$config{po_link_to}='default';
	}

	push @{$config{wiki_file_prune_regexps}}, qr/\.pot$/;

	# Translated versions of the underlays are added if available.
	foreach my $underlay ("basewiki",
	                      map { m/^\Q$config{underlaydirbase}\E\/*(.*)/ }
	                          reverse @{$config{underlaydirs}}) {
		next if $underlay=~/^locale\//;

		# Underlays containing the po files for slave languages.
		foreach my $ll (keys %{$config{po_slave_languages}}) {
			add_underlay("po/$ll/$underlay")
				if -d "$config{underlaydirbase}/po/$ll/$underlay";
		}
	
		if ($config{po_master_language}{code} ne 'en') {
			# Add underlay containing translated source files
			# for the master language.
			add_underlay("locale/$config{po_master_language}{code}/$underlay");
		}
	}
}

sub needsbuild () {
	my $needsbuild=shift;

	# backup @needsbuild content so that change() can know whether
	# a given master page was rendered because its source file was changed
	@origneedsbuild=(@$needsbuild);

	flushmemoizecache();
	buildtranslationscache();

	# make existing translations depend on the corresponding master page
	foreach my $master (keys %translations) {
		map add_depends($_, $master), values %{otherlanguages($master)};
	}
}

# Massage the recorded state of internal links so that:
# - it matches the actually generated links, rather than the links as written
#   in the pages' source
# - backlinks are consistent in all cases
sub scan (@) {
	my %params=@_;
	my $page=$params{page};
	my $content=$params{content};

	if (istranslation($page)) {
		foreach my $destpage (@{$links{$page}}) {
			if (istranslatable($destpage)) {
				# replace one occurence of $destpage in $links{$page}
				# (we only want to replace the one that was added by
				# IkiWiki::Plugin::link::scan, other occurences may be
				# there for other reasons)
				for (my $i=0; $i<@{$links{$page}}; $i++) {
					if (@{$links{$page}}[$i] eq $destpage) {
						@{$links{$page}}[$i] = $destpage . '.' . lang($page);
						last;
					}
				}
			}
		}
	}
	elsif (! istranslatable($page) && ! istranslation($page)) {
		foreach my $destpage (@{$links{$page}}) {
			if (istranslatable($destpage)) {
				# make sure any destpage's translations has
				# $page in its backlinks
				push @{$links{$page}},
					values %{otherlanguages($destpage)};
			}
		}
	}
}

# We use filter to convert PO to the master page's format,
# since the rest of ikiwiki should not work on PO files.
sub filter (@) {
	my %params = @_;

	my $page = $params{page};
	my $destpage = $params{destpage};
	my $content = $params{content};
	if (istranslation($page) && ! alreadyfiltered($page, $destpage)) {
		$content = po_to_markup($page, $content);
		setalreadyfiltered($page, $destpage);
	}
	return $content;
}

sub htmlize (@) {
	my %params=@_;

	my $page = $params{page};
	my $content = $params{content};

	# ignore PO files this plugin did not create
	return $content unless istranslation($page);

	# force content to be htmlize'd as if it was the same type as the master page
	return IkiWiki::htmlize($page, $page,
		pagetype(srcfile($pagesources{masterpage($page)})),
		$content);
}

sub pagetemplate (@) {
	my %params=@_;
	my $page=$params{page};
	my $destpage=$params{destpage};
	my $template=$params{template};

	my ($masterpage, $lang) = istranslation($page);

	if (istranslation($page) && $template->query(name => "percenttranslated")) {
		$template->param(percenttranslated => percenttranslated($page));
	}
	if ($template->query(name => "istranslation")) {
		$template->param(istranslation => scalar istranslation($page));
	}
	if ($template->query(name => "istranslatable")) {
		$template->param(istranslatable => istranslatable($page));
	}
	if ($template->query(name => "HOMEPAGEURL")) {
		$template->param(homepageurl => homepageurl($page));
	}
	if ($template->query(name => "otherlanguages")) {
		$template->param(otherlanguages => [otherlanguagesloop($page)]);
		map add_depends($page, $_), (values %{otherlanguages($page)});
	}
	if ($config{discussion} && istranslation($page)) {
		my $discussionlink=gettext("discussion");
		if ($page !~ /.*\/\Q$discussionlink\E$/i &&
		   (length $config{cgiurl} ||
		    exists $links{$masterpage."/".$discussionlink})) {
			$template->param('discussionlink' => htmllink(
				$page,
				$destpage,
				$masterpage . '/' . gettext("Discussion"),
				noimageinline => 1,
				forcesubpage => 0,
				linktext => gettext("Discussion"),
		));
		}
	}
	# Remove broken parentlink to ./index.html on home page's translations.
	# It works because this hook has the "last" parameter set, to ensure it
	# runs after parentlinks' own pagetemplate hook.
	if ($template->param('parentlinks')
	    && istranslation($page)
	    && $masterpage eq "index") {
		$template->param('parentlinks' => []);
	}
} # }}}

# Add the renamed page translations to the list of to-be-renamed pages.
sub renamepages (@) {
	my %params = @_;

	my %torename = %{$params{torename}};
	my $session = $params{session};

	# Save the page(s) the user asked to rename, so that our
	# canrename hook can tell the difference between:
	#  - a translation being renamed as a consequence of its master page
	#    being renamed
	#  - a user trying to directly rename a translation
	# This is why this hook has to be run first, before the list of pages
	# to rename is modified by other plugins.
	my @orig_torename;
	@orig_torename=@{$session->param("po_orig_torename")}
		if defined $session->param("po_orig_torename");
	push @orig_torename, $torename{src};
	$session->param(po_orig_torename => \@orig_torename);
	IkiWiki::cgi_savesession($session);

	return () unless istranslatable($torename{src});

	my @ret;
	my %otherpages=%{otherlanguages($torename{src})};
	while (my ($lang, $otherpage) = each %otherpages) {
		push @ret, {
			src => $otherpage,
			srcfile => $pagesources{$otherpage},
			dest => otherlanguage($torename{dest}, $lang),
			destfile => $torename{dest}.".".$lang.".po",
			required => 0,
		};
	}
	return @ret;
}

sub mydelete (@) {
	my @deleted=@_;

	map { deletetranslations($_) } grep istranslatablefile($_), @deleted;
}

sub change (@) {
	my @rendered=@_;

	# All meta titles are first extracted at scan time, i.e. before we turn
	# PO files back into translated markdown; escaping of double-quotes in
	# PO files breaks the meta plugin's parsing enough to save ugly titles
	# to %pagestate at this time.
	#
	# Then, at render time, every page passes in turn through the Great
	# Rendering Chain (filter->preprocess->linkify->htmlize), and the meta
	# plugin's preprocess hook is this time in a position to correctly
	# extract the titles from slave pages.
	#
	# This is, unfortunately, too late: if the page A, linking to the page
	# B, is rendered before B, it will display the wrongly-extracted meta
	# title as the link text to B.
	#
	# On the one hand, such a corner case only happens on rebuild: on
	# refresh, every rendered page is fixed to contain correct meta titles.
	# On the other hand, it can take some time to get every page fixed.
	# We therefore re-render every rendered page after a rebuild to fix them
	# at once. As this more or less doubles the time needed to rebuild the
	# wiki, we do so only when really needed.

	if (@rendered
	    && exists $config{rebuild} && defined $config{rebuild} && $config{rebuild}
	    && UNIVERSAL::can("IkiWiki::Plugin::meta", "getsetup")
	    && exists $config{meta_overrides_page_title}
	    && defined $config{meta_overrides_page_title}
	    && $config{meta_overrides_page_title}) {
		debug(sprintf(gettext("rebuilding all pages to fix meta titles")));
		resetalreadyfiltered();
		require IkiWiki::Render;
		foreach my $file (@rendered) {
			debug(sprintf(gettext("building %s"), $file));
			IkiWiki::render($file);
		}
	}

	my $updated_po_files=0;

	# Refresh/create POT and PO files as needed.
	# (But avoid doing so if they are in an underlay directory.)
	foreach my $file (grep {istranslatablefile($_)} @rendered) {
		my $masterfile=srcfile($file);
		my $page=pagename($file);
		my $updated_pot_file=0;
		# Only refresh POT file if it does not exist, or if
		# $pagesources{$page} was changed: don't if only the HTML was
		# refreshed, e.g. because of a dependency.
		if ($masterfile eq "$config{srcdir}/$file" &&
		   ((grep { $_ eq $pagesources{$page} } @origneedsbuild)
		    || ! -e potfile($masterfile))) {
			refreshpot($masterfile);
			$updated_pot_file=1;
		}
		my @pofiles;
		foreach my $po (pofiles($masterfile)) {
			next if ! $updated_pot_file && ! -e $po;
			next if grep { $po=~/\Q$_\E/ } @{$config{underlaydirs}};
			push @pofiles, $po;
		}
		if (@pofiles) {
			refreshpofiles($masterfile, @pofiles);
			map { IkiWiki::rcs_add($_) } @pofiles if $config{rcs};
			$updated_po_files=1;
		}
	}

	if ($updated_po_files) {
		commit_and_refresh(
			gettext("updated PO files"),
			"IkiWiki::Plugin::po::change");
	}
}

sub checkcontent (@) {
	my %params=@_;

	if (istranslation($params{page})) {
		my $res = isvalidpo($params{content});
		if ($res) {
			return undef;
		}
		else {
			return "$res";
		}
	}
	return undef;
}

sub canremove (@) {
	my %params = @_;

	if (istranslation($params{page})) {
		return gettext("Can not remove a translation. If the master page is removed, ".
			       "however, its translations will be removed as well.");
	}
	return undef;
}

sub canrename (@) {
	my %params = @_;
	my $session = $params{session};

	if (istranslation($params{src})) {
		my $masterpage = masterpage($params{src});
		# Tell the difference between:
		#  - a translation being renamed as a consequence of its master page
		#    being renamed, which is allowed
		#  - a user trying to directly rename a translation, which is forbidden
		# by looking for the master page in the list of to-be-renamed pages we
		# saved early in the renaming process.
		my $orig_torename = $session->param("po_orig_torename");
		unless (grep { $_ eq $masterpage } @{$orig_torename}) {
			return gettext("Can not rename a translation. If the master page is renamed, ".
				       "however, its translations will be renamed as well.");
		}
	}
	return undef;
}

# As we're previewing or saving a page, the content may have
# changed, so tell the next filter() invocation it must not be lazy.
sub editcontent () {
	my %params=@_;

	unsetalreadyfiltered($params{page}, $params{page});
	return $params{content};
}

sub formbuilder_setup (@) {
	my %params=@_;
	my $form=$params{form};
	my $q=$params{cgi};

	return unless defined $form->field("do");

	if ($form->field("do") eq "create") {
		# Warn the user: new pages must be written in master language.
		my $template=template("pocreatepage.tmpl");
		$template->param(LANG => $config{po_master_language}{name});
		$form->tmpl_param(message => $template->output);
	}
	elsif ($form->field("do") eq "edit") {
		# Remove the rename/remove buttons on slave pages.
		# This has to be done after the rename/remove plugins have added
		# their buttons, which is why this hook must be run last.
		# The canrename/canremove hooks already ensure this is forbidden
		# at the backend level, so this is only UI sugar.
		if (istranslation($form->field("page"))) {
			map {
				for (my $i = 0; $i < @{$params{buttons}}; $i++) {
					if (@{$params{buttons}}[$i] eq $_) {
						delete  @{$params{buttons}}[$i];
						last;
					}
				}
			} qw(Rename Remove);
		}
	}
}

sub formbuilder (@) {
	my %params=@_;
	my $form=$params{form};
	my $q=$params{cgi};

	return unless defined $form->field("do");

	# Do not allow to create pages of type po: they are automatically created.
	# The main reason to do so is to bypass the "favor the type of linking page
	# on page creation" logic, which is unsuitable when a broken link is clicked
	# on a slave (PO) page.
	# This cannot be done in the formbuilder_setup hook as the list of types is
	# computed later.
	if ($form->field("do") eq "create") {
	        foreach my $field ($form->field) {
			next unless "$field" eq "type";
			if ($field->type eq 'select') {
				# remove po from the list of types
				my @types = grep { $_ ne 'po' } $field->options;
				$field->options(\@types) if @types;
			}
		}
	}
}

# ,----
# | Injected functions
# `----

# Implement po_link_to 'current' and 'negotiated' settings.
sub mybestlink ($$) {
	my $page=shift;
	my $link=shift;

	my $res=$origsubs{'bestlink'}->(masterpage($page), $link);
	if (length $res
	    && ($config{po_link_to} eq "current" || $config{po_link_to} eq "negotiated")
	    && istranslatable($res)
	    && istranslation($page)) {
		return $res . "." . lang($page);
	}
	return $res;
}

sub mybeautify_urlpath ($) {
	my $url=shift;

	my $res=$origsubs{'beautify_urlpath'}->($url);
	if ($config{po_link_to} eq "negotiated") {
		$res =~ s!/\Qindex.$config{po_master_language}{code}.$config{htmlext}\E$!/!;
		$res =~ s!/\Qindex.$config{htmlext}\E$!/!;
		map {
			$res =~ s!/\Qindex.$_.$config{htmlext}\E$!/!;
		} (keys %{$config{po_slave_languages}});
	}
	return $res;
}

sub mytargetpage ($$) {
	my $page=shift;
	my $ext=shift;

	if (istranslation($page) || istranslatable($page)) {
		my ($masterpage, $lang) = (masterpage($page), lang($page));
		if (! $config{usedirs} || $masterpage eq 'index') {
			return $masterpage . "." . $lang . "." . $ext;
		}
		else {
			return $masterpage . "/index." . $lang . "." . $ext;
		}
	}
	return $origsubs{'targetpage'}->($page, $ext);
}

sub myurlto ($$;$) {
	my $to=shift;
	my $from=shift;
	my $absolute=shift;

	# workaround hard-coded /index.$config{htmlext} in IkiWiki::urlto()
	if (! length $to
	    && $config{po_link_to} eq "current"
	    && istranslatable('index')) {
		return IkiWiki::beautify_urlpath(IkiWiki::baseurl($from) . "index." . lang($from) . ".$config{htmlext}");
	}
	# avoid using our injected beautify_urlpath if run by cgi_editpage,
	# so that one is redirected to the just-edited page rather than to the
	# negociated translation; to prevent unnecessary fiddling with caller/inject,
	# we only do so when our beautify_urlpath would actually do what we want to
	# avoid, i.e. when po_link_to = negotiated
	if ($config{po_link_to} eq "negotiated") {
		my @caller = caller(1);
		my $run_by_editpage = 0;
		$run_by_editpage = 1 if (exists $caller[3] && defined $caller[3]
					 && $caller[3] eq "IkiWiki::cgi_editpage");
		inject(name => "IkiWiki::beautify_urlpath", call => $origsubs{'beautify_urlpath'})
			if $run_by_editpage;
		my $res = $origsubs{'urlto'}->($to,$from,$absolute);
		inject(name => "IkiWiki::beautify_urlpath", call => \&mybeautify_urlpath)
			if $run_by_editpage;
		return $res;
	}
	else {
		return $origsubs{'urlto'}->($to,$from,$absolute)
	}
}

sub mycgiurl (@) {
	my %params=@_;

	# slave pages have no subpages
	if (istranslation($params{'from'})) {
		$params{'from'} = masterpage($params{'from'});
	}
	return $origsubs{'cgiurl'}->(%params);
}

# ,----
# | Blackboxes for private data
# `----

{
	my %filtered;

	sub alreadyfiltered($$) {
		my $page=shift;
		my $destpage=shift;

		return exists $filtered{$page}{$destpage}
			 && $filtered{$page}{$destpage} eq 1;
	}

	sub setalreadyfiltered($$) {
		my $page=shift;
		my $destpage=shift;

		$filtered{$page}{$destpage}=1;
	}

	sub unsetalreadyfiltered($$) {
		my $page=shift;
		my $destpage=shift;

		if (exists $filtered{$page}{$destpage}) {
			delete $filtered{$page}{$destpage};
		}
	}

	sub resetalreadyfiltered() {
		undef %filtered;
	}
}

# ,----
# | Helper functions
# `----

sub maybe_add_leading_slash ($;$) {
	my $str=shift;
	my $add=shift;
	$add=1 unless defined $add;
	return '/' . $str if $add;
	return $str;
}

sub istranslatablefile ($) {
	my $file=shift;

	return 0 unless defined $file;
	my $type=pagetype($file);
	return 0 if ! defined $type || $type eq 'po';
	return 0 if $file =~ /\.pot$/;
	return 1 if pagespec_match(pagename($file), $config{po_translatable_pages});
	return;
}

sub istranslatable ($) {
	my $page=shift;

	$page=~s#^/##;
	return 1 if istranslatablefile($pagesources{$page});
	return;
}

sub _istranslation ($) {
	my $page=shift;

	$page='' unless defined $page && length $page;
	my $hasleadingslash = ($page=~s#^/##);
	my $file=$pagesources{$page};
	return 0 unless defined $file
			 && defined pagetype($file)
			 && pagetype($file) eq 'po';
	return 0 if $file =~ /\.pot$/;

	my ($masterpage, $lang) = ($page =~ /(.*)[.]([a-z]{2})$/);
	return 0 unless defined $masterpage && defined $lang
			 && length $masterpage && length $lang
			 && defined $pagesources{$masterpage}
			 && defined $config{po_slave_languages}{$lang};

	return (maybe_add_leading_slash($masterpage, $hasleadingslash), $lang)
		if istranslatable($masterpage);
}

sub istranslation ($) {
	my $page=shift;

	if (1 < (my ($masterpage, $lang) = _istranslation($page))) {
		my $hasleadingslash = ($masterpage=~s#^/##);
		$translations{$masterpage}{$lang}=$page unless exists $translations{$masterpage}{$lang};
		return (maybe_add_leading_slash($masterpage, $hasleadingslash), $lang);
	}
	return "";
}

sub masterpage ($) {
	my $page=shift;

	if ( 1 < (my ($masterpage, $lang) = _istranslation($page))) {
		return $masterpage;
	}
	return $page;
}

sub lang ($) {
	my $page=shift;

	if (1 < (my ($masterpage, $lang) = _istranslation($page))) {
		return $lang;
	}
	return $config{po_master_language}{code};
}

sub islanguagecode ($) {
	my $code=shift;

	return $code =~ /^[a-z]{2}$/;
}

sub otherlanguage ($$) {
	my $page=shift;
	my $code=shift;

	return masterpage($page) if $code eq $config{po_master_language}{code};
	return masterpage($page) . '.' . $code;
}

sub otherlanguages ($) {
	my $page=shift;

	my %ret;
	return \%ret unless istranslation($page) || istranslatable($page);
	my $curlang=lang($page);
	foreach my $lang
		($config{po_master_language}{code}, keys %{$config{po_slave_languages}}) {
		next if $lang eq $curlang;
		$ret{$lang}=otherlanguage($page, $lang);
	}
	return \%ret;
}

sub potfile ($) {
	my $masterfile=shift;

	(my $name, my $dir, my $suffix) = fileparse($masterfile, qr/\.[^.]*/);
	$dir='' if $dir eq './';
	return File::Spec->catpath('', $dir, $name . ".pot");
}

sub pofile ($$) {
	my $masterfile=shift;
	my $lang=shift;

	(my $name, my $dir, my $suffix) = fileparse($masterfile, qr/\.[^.]*/);
	$dir='' if $dir eq './';
	return File::Spec->catpath('', $dir, $name . "." . $lang . ".po");
}

sub pofiles ($) {
	my $masterfile=shift;

	return map pofile($masterfile, $_), (keys %{$config{po_slave_languages}});
}

sub refreshpot ($) {
	my $masterfile=shift;

	my $potfile=potfile($masterfile);
	my %options = ("markdown" => (pagetype($masterfile) eq 'mdwn') ? 1 : 0);
	my $doc=Locale::Po4a::Chooser::new('text',%options);
	$doc->{TT}{utf_mode} = 1;
	$doc->{TT}{file_in_charset} = 'utf-8';
	$doc->{TT}{file_out_charset} = 'utf-8';
	$doc->read($masterfile);
	# let's cheat a bit to force porefs option to be passed to
	# Locale::Po4a::Po; this is undocument use of internal
	# Locale::Po4a::TransTractor's data, compulsory since this module
	# prevents us from using the porefs option.
	$doc->{TT}{po_out}=Locale::Po4a::Po->new({ 'porefs' => 'none' });
	$doc->{TT}{po_out}->set_charset('utf-8');
	# do the actual work
	$doc->parse;
	IkiWiki::prep_writefile(basename($potfile),dirname($potfile));
	$doc->writepo($potfile);
}

sub refreshpofiles ($@) {
	my $masterfile=shift;
	my @pofiles=@_;

	my $potfile=potfile($masterfile);
	if (! -e $potfile) {
		error("po(refreshpofiles) ".sprintf(gettext("POT file (%s) does not exist"), $potfile));
	}

	foreach my $pofile (@pofiles) {
		IkiWiki::prep_writefile(basename($pofile),dirname($pofile));

		if (! -e $pofile) {
			# If the po file exists in an underlay, copy it
			# from there.
			my ($pobase)=$pofile=~/^\Q$config{srcdir}\E\/?(.*)$/;
			foreach my $dir (@{$config{underlaydirs}}) {
				if (-e "$dir/$pobase") {
					File::Copy::syscopy("$dir/$pobase",$pofile)
						or error("po(refreshpofiles) ".
							 sprintf(gettext("failed to copy underlay PO file to %s"),
								 $pofile));
				}
			}
		}

		if (-e $pofile) {
			system("msgmerge", "--previous", "-q", "-U", "--backup=none", $pofile, $potfile) == 0
				or error("po(refreshpofiles) ".
					 sprintf(gettext("failed to update %s"),
						 $pofile));
		}
		else {
			File::Copy::syscopy($potfile,$pofile)
				or error("po(refreshpofiles) ".
					 sprintf(gettext("failed to copy the POT file to %s"),
						 $pofile));
		}
	}
}

sub buildtranslationscache() {
	# use istranslation's side-effect
	map istranslation($_), (keys %pagesources);
}

sub resettranslationscache() {
	undef %translations;
}

sub flushmemoizecache() {
	Memoize::flush_cache("istranslatable");
	Memoize::flush_cache("_istranslation");
	Memoize::flush_cache("percenttranslated");
}

sub urlto_with_orig_beautiful_urlpath($$) {
	my $to=shift;
	my $from=shift;

	inject(name => "IkiWiki::beautify_urlpath", call => $origsubs{'beautify_urlpath'});
	my $res=urlto($to, $from);
	inject(name => "IkiWiki::beautify_urlpath", call => \&mybeautify_urlpath);

	return $res;
}

sub percenttranslated ($) {
	my $page=shift;

	$page=~s/^\///;
	return gettext("N/A") unless istranslation($page);
	my $file=srcfile($pagesources{$page});
	my $masterfile = srcfile($pagesources{masterpage($page)});
	my %options = (
		"markdown" => (pagetype($masterfile) eq 'mdwn') ? 1 : 0,
	);
	my $doc=Locale::Po4a::Chooser::new('text',%options);
	$doc->process(
		'po_in_name'	=> [ $file ],
		'file_in_name'	=> [ $masterfile ],
		'file_in_charset'  => 'utf-8',
		'file_out_charset' => 'utf-8',
	) or error("po(percenttranslated) ".
		   sprintf(gettext("failed to translate %s"), $page));
	my ($percent,$hit,$queries) = $doc->stats();
	$percent =~ s/\.[0-9]+$//;
	return $percent;
}

sub languagename ($) {
	my $code=shift;

	return $config{po_master_language}{name}
		if $code eq $config{po_master_language}{code};
	return $config{po_slave_languages}{$code}
		if defined $config{po_slave_languages}{$code};
	return;
}

sub otherlanguagesloop ($) {
	my $page=shift;

	my @ret;
	my %otherpages=%{otherlanguages($page)};
	while (my ($lang, $otherpage) = each %otherpages) {
		if (istranslation($page) && masterpage($page) eq $otherpage) {
			push @ret, {
				url => urlto_with_orig_beautiful_urlpath($otherpage, $page),
				code => $lang,
				language => languagename($lang),
				master => 1,
			};
		}
		else {
			push @ret, {
				url => urlto_with_orig_beautiful_urlpath($otherpage, $page),
				code => $lang,
				language => languagename($lang),
				percent => percenttranslated($otherpage),
			}
		}
	}
	return sort {
		return -1 if $a->{code} eq $config{po_master_language}{code};
		return 1 if $b->{code} eq $config{po_master_language}{code};
		return $a->{language} cmp $b->{language};
	} @ret;
}

sub homepageurl (;$) {
	my $page=shift;

	return urlto('', $page);
}

sub deletetranslations ($) {
	my $deletedmasterfile=shift;

	my $deletedmasterpage=pagename($deletedmasterfile);
	my @todelete;
	map {
		my $file = newpagefile($deletedmasterpage.'.'.$_, 'po');
		my $absfile = "$config{srcdir}/$file";
		if (-e $absfile && ! -l $absfile && ! -d $absfile) {
			push @todelete, $file;
		}
	} keys %{$config{po_slave_languages}};

	map {
		if ($config{rcs}) {
			IkiWiki::rcs_remove($_);
		}
		else {
			IkiWiki::prune("$config{srcdir}/$_");
		}
	} @todelete;

	if (@todelete) {
		commit_and_refresh(
			gettext("removed obsolete PO files"),
			"IkiWiki::Plugin::po::deletetranslations");
	}
}

sub commit_and_refresh ($$) {
	my ($msg, $author) = (shift, shift);

	if ($config{rcs}) {
		IkiWiki::disable_commit_hook();
		IkiWiki::rcs_commit_staged($msg, $author, "127.0.0.1");
		IkiWiki::enable_commit_hook();
		IkiWiki::rcs_update();
	}
	# Reinitialize module's private variables.
	resetalreadyfiltered();
	resettranslationscache();
	flushmemoizecache();
	# Trigger a wiki refresh.
	require IkiWiki::Render;
	# without preliminary saveindex/loadindex, refresh()
	# complains about a lot of uninitialized variables
	IkiWiki::saveindex();
	IkiWiki::loadindex();
	IkiWiki::refresh();
	IkiWiki::saveindex();
}

# on success, returns the filtered content.
# on error, if $nonfatal, warn and return undef; else, error out.
sub po_to_markup ($$;$) {
	my ($page, $content) = (shift, shift);
	my $nonfatal = shift;

	$content = '' unless defined $content;
	$content = decode_utf8(encode_utf8($content));
	# CRLF line terminators make poor Locale::Po4a feel bad
	$content=~s/\r\n/\n/g;

	# There are incompatibilities between some File::Temp versions
	# (including 0.18, bundled with Lenny's perl-modules package)
	# and others (e.g. 0.20, previously present in the archive as
	# a standalone package): under certain circumstances, some
	# return a relative filename, whereas others return an absolute one;
	# we here use this module in a way that is at least compatible
	# with 0.18 and 0.20. Beware, hit'n'run refactorers!
	my $infile = new File::Temp(TEMPLATE => "ikiwiki-po-filter-in.XXXXXXXXXX",
				    DIR => File::Spec->tmpdir,
				    UNLINK => 1)->filename;
	my $outfile = new File::Temp(TEMPLATE => "ikiwiki-po-filter-out.XXXXXXXXXX",
				     DIR => File::Spec->tmpdir,
				     UNLINK => 1)->filename;

	my $fail = sub ($) {
		my $msg = "po(po_to_markup) - $page : " . shift;
		if ($nonfatal) {
			warn $msg;
			return undef;
		}
		error($msg, sub { unlink $infile, $outfile});
	};

	writefile(basename($infile), File::Spec->tmpdir, $content)
		or return $fail->(sprintf(gettext("failed to write %s"), $infile));

	my $masterfile = srcfile($pagesources{masterpage($page)});
	my %options = (
		"markdown" => (pagetype($masterfile) eq 'mdwn') ? 1 : 0,
	);
	my $doc=Locale::Po4a::Chooser::new('text',%options);
	$doc->process(
		'po_in_name'	=> [ $infile ],
		'file_in_name'	=> [ $masterfile ],
		'file_in_charset'  => 'utf-8',
		'file_out_charset' => 'utf-8',
	) or return $fail->(gettext("failed to translate"));
	$doc->write($outfile)
		or return $fail->(sprintf(gettext("failed to write %s"), $outfile));

	$content = readfile($outfile)
		or return $fail->(sprintf(gettext("failed to read %s"), $outfile));

	# Unlinking should happen automatically, thanks to File::Temp,
	# but it does not work here, probably because of the way writefile()
	# and Locale::Po4a::write() work.
	unlink $infile, $outfile;

	return $content;
}

# returns a SuccessReason or FailReason object
sub isvalidpo ($) {
	my $content = shift;

	# NB: we don't use po_to_markup here, since Po4a parser does
	# not mind invalid PO content
	$content = '' unless defined $content;
	$content = decode_utf8(encode_utf8($content));

	# There are incompatibilities between some File::Temp versions
	# (including 0.18, bundled with Lenny's perl-modules package)
	# and others (e.g. 0.20, previously present in the archive as
	# a standalone package): under certain circumstances, some
	# return a relative filename, whereas others return an absolute one;
	# we here use this module in a way that is at least compatible
	# with 0.18 and 0.20. Beware, hit'n'run refactorers!
	my $infile = new File::Temp(TEMPLATE => "ikiwiki-po-isvalidpo.XXXXXXXXXX",
				    DIR => File::Spec->tmpdir,
				    UNLINK => 1)->filename;

	my $fail = sub ($) {
		my $msg = '[po/isvalidpo] ' . shift;
		unlink $infile;
		return IkiWiki::FailReason->new("$msg");
	};

	writefile(basename($infile), File::Spec->tmpdir, $content)
		or return $fail->(sprintf(gettext("failed to write %s"), $infile));

	my $res = (system("msgfmt", "--check", $infile, "-o", "/dev/null") == 0);

	# Unlinking should happen automatically, thanks to File::Temp,
	# but it does not work here, probably because of the way writefile()
	# and Locale::Po4a::write() work.
	unlink $infile;

	if ($res) {
	    return IkiWiki::SuccessReason->new("valid gettext data");
	}
	return IkiWiki::FailReason->new(gettext("invalid gettext data, go back ".
					"to previous page to continue edit"));
}

# ,----
# | PageSpecs
# `----

package IkiWiki::PageSpec;

sub match_istranslation ($;@) {
	my $page=shift;

	if (IkiWiki::Plugin::po::istranslation($page)) {
		return IkiWiki::SuccessReason->new("is a translation page");
	}
	else {
		return IkiWiki::FailReason->new("is not a translation page");
	}
}

sub match_istranslatable ($;@) {
	my $page=shift;

	if (IkiWiki::Plugin::po::istranslatable($page)) {
		return IkiWiki::SuccessReason->new("is set as translatable in po_translatable_pages");
	}
	else {
		return IkiWiki::FailReason->new("is not set as translatable in po_translatable_pages");
	}
}

sub match_lang ($$;@) {
	my $page=shift;
	my $wanted=shift;

	my $regexp=IkiWiki::glob2re($wanted);
	my $lang=IkiWiki::Plugin::po::lang($page);
	if ($lang !~ /^$regexp$/i) {
		return IkiWiki::FailReason->new("file language is $lang, not $wanted");
	}
	else {
		return IkiWiki::SuccessReason->new("file language is $wanted");
	}
}

sub match_currentlang ($$;@) {
	my $page=shift;
	shift;
	my %params=@_;

	return IkiWiki::FailReason->new("no location provided") unless exists $params{location};

	my $currentlang=IkiWiki::Plugin::po::lang($params{location});
	my $lang=IkiWiki::Plugin::po::lang($page);

	if ($lang eq $currentlang) {
		return IkiWiki::SuccessReason->new("file language is the same as current one, i.e. $currentlang");
	}
	else {
		return IkiWiki::FailReason->new("file language is $lang, whereas current language is $currentlang");
	}
}

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