# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.
#
# This Source Code Form is "Incompatible With Secondary Licenses", as
# defined by the Mozilla Public License, v. 2.0.


package Bugzilla::Template;

use 5.14.0;
use strict;
use warnings;

use Bugzilla::Constants;
use Bugzilla::WebService::Constants;
use Bugzilla::Hook;
use Bugzilla::Install::Requirements;
use Bugzilla::Install::Util qw(install_string template_include_path
  include_languages);
use Bugzilla::Classification;
use Bugzilla::Keyword;
use Bugzilla::Util;
use Bugzilla::Error;
use Bugzilla::Search;
use Bugzilla::Token;

use Cwd qw(abs_path);
use MIME::Base64;
use Date::Format ();
use Digest::MD5 qw(md5_hex);
use File::Basename qw(basename dirname);
use File::Find;
use File::Path qw(rmtree mkpath);
use File::Spec;
use IO::Dir;
use List::MoreUtils qw(firstidx);
use Scalar::Util qw(blessed);

use base qw(Template);

use constant FORMAT_TRIPLE => '%19s|%-28s|%-28s';
use constant FORMAT_3_SIZE => [19, 28, 28];
use constant FORMAT_DOUBLE => '%19s %-55s';
use constant FORMAT_2_SIZE => [19, 55];

# Pseudo-constant.
sub SAFE_URL_REGEXP {
  my $safe_protocols = join('|', SAFE_PROTOCOLS);
  return qr/($safe_protocols):[^:\s<>\"][^\s<>\"]+[\w\/]/i;
}

# Convert the constants in the Bugzilla::Constants and Bugzilla::WebService::Constants
# modules into a hash we can pass to the template object for reflection into its "constants"
# namespace (which is like its "variables" namespace, but for constants). To do so, we
# traverse the arrays of exported and exportable symbols and ignoring the rest
# (which, if Constants.pm exports only constants, as it should, will be nothing else).
sub _load_constants {
  my %constants;
  foreach
    my $constant (@Bugzilla::Constants::EXPORT, @Bugzilla::Constants::EXPORT_OK)
  {
    if (ref Bugzilla::Constants->$constant) {
      $constants{$constant} = Bugzilla::Constants->$constant;
    }
    else {
      my @list = (Bugzilla::Constants->$constant);
      $constants{$constant} = (scalar(@list) == 1) ? $list[0] : \@list;
    }
  }

  foreach my $constant (
    @Bugzilla::WebService::Constants::EXPORT,
    @Bugzilla::WebService::Constants::EXPORT_OK
    )
  {
    if (ref Bugzilla::WebService::Constants->$constant) {
      $constants{$constant} = Bugzilla::WebService::Constants->$constant;
    }
    else {
      my @list = (Bugzilla::WebService::Constants->$constant);
      $constants{$constant} = (scalar(@list) == 1) ? $list[0] : \@list;
    }
  }
  return \%constants;
}

# Returns the path to the templates based on the Accept-Language
# settings of the user and of the available languages
# If no Accept-Language is present it uses the defined default
# Templates may also be found in the extensions/ tree
sub _include_path {
  my $lang  = shift || '';
  my $cache = Bugzilla->request_cache;
  $cache->{"template_include_path_$lang"}
    ||= template_include_path({language => $lang});
  return $cache->{"template_include_path_$lang"};
}

sub get_format {
  my $self = shift;
  my ($template, $format, $ctype) = @_;

  $ctype  //= 'html';
  $format //= '';

  # ctype and format can have letters and a hyphen only.
  if ($ctype =~ /[^a-zA-Z\-]/ || $format =~ /[^a-zA-Z\-]/) {
    ThrowUserError('format_not_found',
      {'format' => $format, 'ctype' => $ctype, 'invalid' => 1});
  }
  trick_taint($ctype);
  trick_taint($format);

  $template .= ($format ? "-$format" : "");
  $template .= ".$ctype.tmpl";

  # Now check that the template actually exists. We only want to check
  # if the template exists; any other errors (eg parse errors) will
  # end up being detected later.
  eval { $self->context->template($template); };

  # This parsing may seem fragile, but it's OK:
  # http://lists.template-toolkit.org/pipermail/templates/2003-March/004370.html
  # Even if it is wrong, any sort of error is going to cause a failure
  # eventually, so the only issue would be an incorrect error message
  if ($@ && $@->info =~ /: not found$/) {
    ThrowUserError('format_not_found', {'format' => $format, 'ctype' => $ctype});
  }

  # Else, just return the info
  return {
    'template'  => $template,
    'format'    => $format,
    'extension' => $ctype,
    'ctype'     => Bugzilla::Constants::contenttypes->{$ctype}
  };
}

# This routine quoteUrls contains inspirations from the HTML::FromText CPAN
# module by Gareth Rees <garethr@cre.canon.co.uk>.  It has been heavily hacked,
# all that is really recognizable from the original is bits of the regular
# expressions.
# This has been rewritten to be faster, mainly by substituting 'as we go'.
# If you want to modify this routine, read the comments carefully

sub quoteUrls {
  my ($text, $bug, $comment, $user) = @_;
  return $text unless $text;
  $user ||= Bugzilla->user;

  # We use /g for speed, but uris can have other things inside them
  # (http://foo/bug#3 for example). Filtering that out filters valid
  # bug refs out, so we have to do replacements.
  # mailto can't contain space or #, so we don't have to bother for that
  # Do this by replacing matches with \x{FDD2}$count\x{FDD3}
  # \x{FDDx} is used because it's unlikely to occur in the text
  # and are reserved unicode characters. We disable warnings for now
  # until we require Perl 5.13.9 or newer.
  no warnings 'utf8';

  # If the comment is already wrapped, we should ignore newlines when
  # looking for matching regexps. Else we should take them into account.
  my $s = ($comment && $comment->already_wrapped) ? qr/\s/ : qr/\h/;

  # However, note that adding the title (for buglinks) can affect things
  # In particular, attachment matches go before bug titles, so that titles
  # with 'attachment 1' don't double match.
  # Dupe checks go afterwards, because that uses ^ and \Z, which won't occur
  # if it was substituted as a bug title (since that always involve leading
  # and trailing text)

  # Because of entities, it's easier (and quicker) to do this before escaping

  my @things;
  my $count = 0;
  my $tmp;

  my @hook_regexes;
  Bugzilla::Hook::process(
    'bug_format_comment',
    {
      text    => \$text,
      bug     => $bug,
      regexes => \@hook_regexes,
      comment => $comment,
      user    => $user
    }
  );

  foreach my $re (@hook_regexes) {
    my ($match, $replace) = @$re{qw(match replace)};
    if (ref($replace) eq 'CODE') {
      $text =~ s/$match/($things[$count++] = $replace->({matches => [
                                                               $1, $2, $3, $4,
                                                               $5, $6, $7, $8, 
                                                               $9, $10]}))
                               && ("\x{FDD2}" . ($count-1) . "\x{FDD3}")/egx;
    }
    else {
      $text =~ s/$match/($things[$count++] = $replace) 
                              && ("\x{FDD2}" . ($count-1) . "\x{FDD3}")/egx;
    }
  }

  # Provide tooltips for full bug links (Bug 74355)
  my $urlbase_re = '('
    . join('|',
    map {qr/$_/}
    grep($_, Bugzilla->params->{'urlbase'}, Bugzilla->params->{'sslbase'}))
    . ')';
  $text =~ s~\b(${urlbase_re}\Qshow_bug.cgi?id=\E([0-9]+)(\#c([0-9]+))?)\b
              ~($things[$count++] = get_bug_link($3, $1, { comment_num => $5, user => $user })) &&
               ("\x{FDD2}" . ($count-1) . "\x{FDD3}")
              ~egox;

  # non-mailto protocols
  my $safe_protocols = SAFE_URL_REGEXP();
  $text =~ s~\b($safe_protocols)
              ~($tmp = html_quote($1)) &&
               ($things[$count++] = "<a href=\"$tmp\">$tmp</a>") &&
               ("\x{FDD2}" . ($count-1) . "\x{FDD3}")
              ~egox;

  # We have to quote now, otherwise the html itself is escaped
  # THIS MEANS THAT A LITERAL ", <, >, ' MUST BE ESCAPED FOR A MATCH

  $text = html_quote($text);

  # Color quoted text
  $text =~ s~^(&gt;.+)$~<span class="quote">$1</span >~mg;
  $text =~ s~</span >\n<span class="quote">~\n~g;

  # mailto:
  # Use |<nothing> so that $1 is defined regardless
  # &#64; is the encoded '@' character.
  $text =~ s~\b(mailto:|)?([\w\.\-\+\=]+&\#64;[\w\-]+(?:\.[\w\-]+)+)\b
              ~<a href=\"mailto:$2\">$1$2</a>~igx;

  # attachment links
  $text =~ s~\b(attachment$s*\#?$s*([0-9]+)(?:$s+\[details\])?)
              ~($things[$count++] = get_attachment_link($2, $1, $user)) &&
               ("\x{FDD2}" . ($count-1) . "\x{FDD3}")
              ~egmxi;

  # Current bug ID this comment belongs to
  my $current_bugurl = $bug ? ("show_bug.cgi?id=" . $bug->id) : "";

  # This handles bug a, comment b type stuff. Because we're using /g
  # we have to do this in one pattern, and so this is semi-messy.
  # Also, we can't use $bug_re?$comment_re? because that will match the
  # empty string
  my $bug_word     = template_var('terms')->{bug};
  my $bug_re       = qr/\Q$bug_word\E$s*\#?$s*([0-9]+)/i;
  my $comment_word = template_var('terms')->{comment};
  my $comment_re   = qr/(?:\Q$comment_word\E|comment)$s*\#?$s*([0-9]+)/i;
  $text =~ s~\b($bug_re(?:$s*,?$s*$comment_re)?|$comment_re)
              ~ # We have several choices. $1 here is the link, and $2-4 are set
                # depending on which part matched
               (defined($2) ? get_bug_link($2, $1, { comment_num => $3, user => $user }) :
                              "<a href=\"$current_bugurl#c$4\">$1</a>")
              ~egx;

  # Handle a list of bug ids: bugs 1, #2, 3, 4
  # Currently, the only delimiter supported is comma.
  # Concluding "and" and "or" are not supported.
  my $bugs_word = template_var('terms')->{bugs};

  my $bugs_re = qr/\Q$bugs_word\E$s*\#?$s*
                     [0-9]+(?:$s*,$s*\#?$s*[0-9]+)+/ix;

  $text =~ s{($bugs_re)}{
        my $match = $1;
        $match =~ s/((?:#$s*)?([0-9]+))/get_bug_link($2, $1);/eg;
        $match;
    }eg;

  my $comments_word = template_var('terms')->{comments};

  my $comments_re = qr/(?:comments|\Q$comments_word\E)$s*\#?$s*
                         [0-9]+(?:$s*,$s*\#?$s*[0-9]+)+/ix;

  $text =~ s{($comments_re)}{
        my $match = $1;
        $match =~ s|((?:#$s*)?([0-9]+))|<a href="$current_bugurl#c$2">$1</a>|g;
        $match;
    }eg;

  # Old duplicate markers. These don't use $bug_word because they are old
  # and were never customizable.
  $text =~ s~(?<=^\*\*\*\ This\ bug\ has\ been\ marked\ as\ a\ duplicate\ of\ )
               ([0-9]+)
               (?=\ \*\*\*\Z)
              ~get_bug_link($1, $1, { user => $user })
              ~egmx;

  # Now remove the encoding hacks in reverse order
  for (my $i = $#things; $i >= 0; $i--) {
    $text =~ s/\x{FDD2}($i)\x{FDD3}/$things[$i]/eg;
  }

  return $text;
}

# Creates a link to an attachment, including its title.
sub get_attachment_link {
  my ($attachid, $link_text, $user) = @_;
  $user ||= Bugzilla->user;

  my $attachment = new Bugzilla::Attachment({id => $attachid, cache => 1});

  if ($attachment) {
    my $title     = "";
    my $className = "";
    if ($user->can_see_bug($attachment->bug_id)
      && (!$attachment->isprivate || $user->is_insider))
    {
      $title = $attachment->description;
    }
    if ($attachment->isobsolete) {
      $className = "bz_obsolete";
    }

    # Prevent code injection in the title.
    $title = html_quote(clean_text($title));

    $link_text =~ s/ \[details\]$//;
    my $linkval = "attachment.cgi?id=$attachid";

    # If the attachment is a patch, try to link to the diff rather
    # than the text, by default.
    my $patchlink = "";
    if ($attachment->ispatch and Bugzilla->feature('patch_viewer')) {
      $patchlink = '&amp;action=diff';
    }

    # Whitespace matters here because these links are in <pre> tags.
    return
        qq|<span class="$className">|
      . qq|<a href="${linkval}${patchlink}" name="attach_${attachid}" title="$title">$link_text</a>|
      . qq| <a href="${linkval}&amp;action=edit" title="$title">[details]</a>|
      . qq|</span>|;
  }
  else {
    return qq{$link_text};
  }
}

# Creates a link to a bug, including its title.
# It takes either two or three parameters:
#  - The bug number
#  - The link text, to place between the <a>..</a>
#  - An optional comment number, for linking to a particular
#    comment in the bug

sub get_bug_link {
  my ($bug, $link_text, $options) = @_;
  $options ||= {};
  $options->{user} ||= Bugzilla->user;

  if (defined $bug && $bug ne '') {
    if (!blessed($bug)) {
      require Bugzilla::Bug;
      $bug = new Bugzilla::Bug({id => $bug, cache => 1});
    }
    return $link_text if $bug->{error};
  }

  my $template = Bugzilla->template_inner;
  my $linkified;
  $template->process('bug/link.html.tmpl',
    {bug => $bug, link_text => $link_text, %$options},
    \$linkified);
  return $linkified;
}

# We use this instead of format because format doesn't deal well with
# multi-byte languages.
sub multiline_sprintf {
  my ($format, $args, $sizes) = @_;
  my @parts;
  my @my_sizes = @$sizes;    # Copy this so we don't modify the input array.
  foreach my $string (@$args) {
    my $size   = shift @my_sizes;
    my @pieces = split("\n", wrap_hard($string, $size));
    push(@parts, \@pieces);
  }

  my $formatted;
  while (1) {

    # Get the first item of each part.
    my @line = map { shift @$_ } @parts;

    # If they're all undef, we're done.
    last if !grep { defined $_ } @line;

    # Make any single undef item into ''
    @line = map { defined $_ ? $_ : '' } @line;

    # And append a formatted line
    $formatted .= sprintf($format, @line);

    # Remove trailing spaces, or they become lots of =20's in
    # quoted-printable emails.
    $formatted =~ s/\s+$//;
    $formatted .= "\n";
  }
  return $formatted;
}

#####################
# Header Generation #
#####################

# Returns the last modification time of a file, as an integer number of
# seconds since the epoch.
sub _mtime { return (stat($_[0]))[9] }

sub mtime_filter {
  my ($file_url, $mtime) = @_;

  # This environment var is set in the .htaccess if we have mod_headers
  # and mod_expires installed, to make sure that JS and CSS with "?"
  # after them will still be cached by clients.
  return $file_url if !$ENV{BZ_CACHE_CONTROL};
  if (!$mtime) {
    my $cgi_path  = bz_locations()->{'cgi_path'};
    my $file_path = "$cgi_path/$file_url";
    $mtime = _mtime($file_path);
  }
  return "$file_url?$mtime";
}

# Set up the skin CSS cascade:
#
#  1. standard/global.css
#  2. YUI CSS
#  3. Standard Bugzilla stylesheet set
#  4. Third-party "skin" stylesheet set, per user prefs
#  5. Inline css passed to global/header.html.tmpl
#  6. Custom Bugzilla stylesheet set

sub css_files {
  my ($style_urls, $yui, $yui_css) = @_;

  # global.css goes on every page.
  my @requested_css = ('skins/standard/global.css', @$style_urls);

  my @yui_required_css;
  foreach my $yui_name (@$yui) {
    next if !$yui_css->{$yui_name};
    push(@yui_required_css, "js/yui/assets/skins/sam/$yui_name.css");
  }
  unshift(@requested_css, @yui_required_css);

  my @css_sets = map { _css_link_set($_) } @requested_css;

  my %by_type = (standard => [], skin => [], custom => []);
  foreach my $set (@css_sets) {
    foreach my $key (keys %$set) {
      push(@{$by_type{$key}}, $set->{$key});
    }
  }

  # build unified
  $by_type{unified_standard_skin}
    = _concatenate_css($by_type{standard}, $by_type{skin});
  $by_type{unified_custom} = _concatenate_css($by_type{custom});

  return \%by_type;
}

sub _css_link_set {
  my ($file_name) = @_;

  my %set = (standard => mtime_filter($file_name));

  # We use (?:^|/) to allow Extensions to use the skins system if they want.
  if ($file_name !~ m{(?:^|/)skins/standard/}) {
    return \%set;
  }

  my $skin           = Bugzilla->user->settings->{skin}->{value};
  my $cgi_path       = bz_locations()->{'cgi_path'};
  my $skin_file_name = $file_name;
  $skin_file_name =~ s{(?:^|/)skins/standard/}{skins/contrib/$skin/};
  if (my $mtime = _mtime("$cgi_path/$skin_file_name")) {
    $set{skin} = mtime_filter($skin_file_name, $mtime);
  }

  my $custom_file_name = $file_name;
  $custom_file_name =~ s{(?:^|/)skins/standard/}{skins/custom/};
  if (my $custom_mtime = _mtime("$cgi_path/$custom_file_name")) {
    $set{custom} = mtime_filter($custom_file_name, $custom_mtime);
  }

  return \%set;
}

sub _concatenate_css {
  my @sources = map {@$_} @_;
  return unless @sources;

  my %files = map {
    (my $file = $_) =~ s/(^[^\?]+)\?.+/$1/;
    $_ => $file;
  } @sources;

  my $cgi_path   = bz_locations()->{cgi_path};
  my $skins_path = bz_locations()->{assetsdir};

  # build minified files
  my @minified;
  foreach my $source (@sources) {
    next unless -e "$cgi_path/$files{$source}";
    my $file = $skins_path . '/' . md5_hex($source) . '.css';
    if (!-e $file) {
      my $content = read_text("$cgi_path/$files{$source}");

      # minify
      $content =~ s{/\*.*?\*/}{}sg;      # comments
      $content =~ s{(^\s+|\s+$)}{}mg;    # leading/trailing whitespace
      $content =~ s{\n}{}g;              # single line

      # rewrite urls
      $content =~ s{url\(([^\)]+)\)}{_css_url_rewrite($source, $1)}eig;

      write_text($file, "/* $files{$source} */\n" . $content . "\n");
    }
    push @minified, $file;
  }

  # concat files
  my $file = $skins_path . '/' . md5_hex(join(' ', @sources)) . '.css';
  if (!-e $file) {
    my $content = '';
    foreach my $source (@minified) {
      $content .= read_text($source);
    }
    write_text($file, $content);
  }

  $file =~ s/^\Q$cgi_path\E\///o;
  return mtime_filter($file);
}

sub _css_url_rewrite {
  my ($source, $url) = @_;

  # rewrite relative urls as the unified stylesheet lives in a different
  # directory from the source
  $url =~ s/(^['"]|['"]$)//g;
  if (substr($url, 0, 1) eq '/' || substr($url, 0, 5) eq 'data:') {
    return 'url(' . $url . ')';
  }
  return
      'url(../../'
    . ($ENV{'PROJECT'} ? '../' : '')
    . dirname($source) . '/'
    . $url . ')';
}

sub _concatenate_js {
  return @_ unless CONCATENATE_ASSETS;
  my ($sources) = @_;
  return [] unless $sources;
  $sources = ref($sources) ? $sources : [$sources];

  my %files = map {
    (my $file = $_) =~ s/(^[^\?]+)\?.+/$1/;
    $_ => $file;
  } @$sources;

  my $cgi_path   = bz_locations()->{cgi_path};
  my $skins_path = bz_locations()->{assetsdir};

  # build minified files
  my @minified;
  foreach my $source (@$sources) {
    next unless -e "$cgi_path/$files{$source}";
    my $file = $skins_path . '/' . md5_hex($source) . '.js';
    if (!-e $file) {
      my $content = read_text("$cgi_path/$files{$source}");

      # minimal minification
      $content =~ s#/\*.*?\*/##sg;     # block comments
      $content =~ s#(^ +| +$)##gm;     # leading/trailing spaces
      $content =~ s#^//.+$##gm;        # single line comments
      $content =~ s#\n{2,}#\n#g;       # blank lines
      $content =~ s#(^\s+|\s+$)##g;    # whitespace at the start/end of file

      write_text($file, ";/* $files{$source} */\n" . $content . "\n");
    }
    push @minified, $file;
  }

  # concat files
  my $file = $skins_path . '/' . md5_hex(join(' ', @$sources)) . '.js';
  if (!-e $file) {
    my $content = '';
    foreach my $source (@minified) {
      $content .= read_text($source);
    }
    write_text($file, $content);
  }

  $file =~ s/^\Q$cgi_path\E\///o;
  return [$file];
}

# YUI dependency resolution
sub yui_resolve_deps {
  my ($yui, $yui_deps) = @_;

  my @yui_resolved;
  foreach my $yui_name (@$yui) {
    my $deps = $yui_deps->{$yui_name} || [];
    foreach my $dep (reverse @$deps) {
      push(@yui_resolved, $dep) if !grep { $_ eq $dep } @yui_resolved;
    }
    push(@yui_resolved, $yui_name) if !grep { $_ eq $yui_name } @yui_resolved;
  }
  return \@yui_resolved;
}

###############################################################################
# Templatization Code

# The Template Toolkit throws an error if a loop iterates >1000 times.
# We want to raise that limit.
# NOTE: If you change this number, you MUST RE-RUN checksetup.pl!!!
# If you do not re-run checksetup.pl, the change you make will not apply
$Template::Directive::WHILE_MAX = 1000000;

# Use the Toolkit Template's Stash module to add utility pseudo-methods
# to template variables.
use Template::Stash;

# Allow keys to start with an underscore or a dot.
$Template::Stash::PRIVATE = undef;

# Add "contains***" methods to list variables that search for one or more
# items in a list and return boolean values representing whether or not
# one/all/any item(s) were found.
$Template::Stash::LIST_OPS->{contains} = sub {
  my ($list, $item) = @_;
  if (ref $item && $item->isa('Bugzilla::Object')) {
    return grep($_->id == $item->id, @$list);
  }
  else {
    return grep($_ eq $item, @$list);
  }
};

$Template::Stash::LIST_OPS->{containsany} = sub {
  my ($list, $items) = @_;
  foreach my $item (@$items) {
    if (ref $item && $item->isa('Bugzilla::Object')) {
      return 1 if grep($_->id == $item->id, @$list);
    }
    else {
      return 1 if grep($_ eq $item, @$list);
    }
  }
  return 0;
};

# Clone the array reference to leave the original one unaltered.
$Template::Stash::LIST_OPS->{clone} = sub {
  my $list = shift;
  return [@$list];
};

# Allow us to sort the list of fields correctly
$Template::Stash::LIST_OPS->{sort_by_field_name} = sub {

  sub field_name {
    if ($_[0] eq 'noop') {

      # Sort --- first
      return '';
    }

    # Otherwise sort by field_desc or description
    return $_[1]{$_[0]} || $_[0];
  }
  my ($list, $field_desc) = @_;
  return [
    sort { lc field_name($a, $field_desc) cmp lc field_name($b, $field_desc) }
      @$list
  ];
};

# Allow us to still get the scalar if we use the list operation ".0" on it,
# as we often do for defaults in query.cgi and other places.
$Template::Stash::SCALAR_OPS->{0} = sub {
  return $_[0];
};

# Add a "truncate" method to the Template Toolkit's "scalar" object
# that truncates a string to a certain length.
$Template::Stash::SCALAR_OPS->{truncate} = sub {
  my ($string, $length, $ellipsis) = @_;
  return $string if !$length || length($string) <= $length;

  $ellipsis ||= '';
  my $strlen = $length - length($ellipsis);
  my $newstr = substr($string, 0, $strlen) . $ellipsis;
  return $newstr;
};

# Create the template object that processes templates and specify
# configuration parameters that apply to all templates.

###############################################################################

sub process {
  my $self = shift;

  # All of this current_langs stuff allows template_inner to correctly
  # determine what-language Template object it should instantiate.
  my $current_langs = Bugzilla->request_cache->{template_current_lang} ||= [];
  unshift(@$current_langs, $self->context->{bz_language});
  my $retval = $self->SUPER::process(@_);
  shift @$current_langs;
  return $retval;
}

# Construct the Template object

# Note that all of the failure cases here can't use templateable errors,
# since we won't have a template to use...

sub create {
  my $class = shift;
  my %opts  = @_;

  # IMPORTANT - If you make any FILTER changes here, make sure to
  # make them in t/004.template.t also, if required.

  my $config = {

    # Colon-separated list of directories containing templates.
    INCLUDE_PATH => $opts{'include_path'} || _include_path($opts{'language'}),

    # Remove white-space before template directives (PRE_CHOMP) and at the
    # beginning and end of templates and template blocks (TRIM) for better
    # looking, more compact content.  Use the plus sign at the beginning
    # of directives to maintain white space (i.e. [%+ DIRECTIVE %]).
    PRE_CHOMP => 1,
    TRIM      => 1,

    # Bugzilla::Template::Plugin::Hook uses the absolute (in mod_perl)
    # or relative (in mod_cgi) paths of hook files to explicitly compile
    # a specific file. Also, these paths may be absolute at any time
    # if a packager has modified bz_locations() to contain absolute
    # paths.
    ABSOLUTE => 1,
    RELATIVE => $ENV{MOD_PERL} ? 0 : 1,

    COMPILE_DIR => bz_locations()->{'template_cache'},

    # Don't check for a template update until 1 hour has passed since the
    # last check.
    STAT_TTL => 60 * 60,

    # Initialize templates (f.e. by loading plugins like Hook).
    PRE_PROCESS => ["global/variables.none.tmpl"],

    ENCODING => Bugzilla->params->{'utf8'} ? 'UTF-8' : undef,

    # Functions for processing text within templates in various ways.
    # IMPORTANT!  When adding a filter here that does not override a
    # built-in filter, please also add a stub filter to t/004template.t.
    FILTERS => {

      # Render text in required style.

      inactive => [
        sub {
          my ($context, $isinactive) = @_;
          return sub {
            return $isinactive ? '<span class="bz_inactive">' . $_[0] . '</span>' : $_[0];
          }
        },
        1
      ],

      closed => [
        sub {
          my ($context, $isclosed) = @_;
          return sub {
            return $isclosed ? '<span class="bz_closed">' . $_[0] . '</span>' : $_[0];
          }
        },
        1
      ],

      obsolete => [
        sub {
          my ($context, $isobsolete) = @_;
          return sub {
            return $isobsolete ? '<span class="bz_obsolete">' . $_[0] . '</span>' : $_[0];
          }
        },
        1
      ],

      # Returns the text with backslashes, single/double quotes,
      # and newlines/carriage returns escaped for use in JS strings.
      js => sub {
        my ($var) = @_;
        $var =~ s/([\\\'\"\/])/\\$1/g;
        $var =~ s/\n/\\n/g;
        $var =~ s/\r/\\r/g;
        $var =~ s/\x{2028}/\\u2028/g;    # unicode line separator
        $var =~ s/\x{2029}/\\u2029/g;    # unicode paragraph separator
        $var =~ s/\@/\\x40/g;            # anti-spam for email addresses
        $var =~ s/</\\x3c/g;
        $var =~ s/>/\\x3e/g;
        return $var;
      },

      # Converts data to base64
      base64 => sub {
        my ($data) = @_;
        return encode_base64($data);
      },

      # Strips out control characters excepting whitespace
      strip_control_chars => sub {
        my ($data) = @_;
        state $use_utf8 = Bugzilla->params->{'utf8'};

        # Only run for utf8 to avoid issues with other multibyte encodings
        # that may be reassigning meaning to ascii characters.
        if ($use_utf8) {
          $data =~ s/(?![\t\r\n])[[:cntrl:]]//g;
        }
        return $data;
      },

      # HTML collapses newlines in element attributes to a single space,
      # so form elements which may have whitespace (ie comments) need
      # to be encoded using &#013;
      # See bugs 4928, 22983 and 32000 for more details
      html_linebreak => sub {
        my ($var) = @_;
        $var = html_quote($var);
        $var =~ s/\r\n/\&#013;/g;
        $var =~ s/\n\r/\&#013;/g;
        $var =~ s/\r/\&#013;/g;
        $var =~ s/\n/\&#013;/g;
        return $var;
      },

      xml => \&Bugzilla::Util::xml_quote,

      # This filter is similar to url_quote but used a \ instead of a %
      # as prefix. In addition it replaces a ' ' by a '_'.
      css_class_quote => \&Bugzilla::Util::css_class_quote,

      # Removes control characters and trims extra whitespace.
      clean_text => \&Bugzilla::Util::clean_text,

      quoteUrls => [
        sub {
          my ($context, $bug, $comment, $user) = @_;
          return sub {
            my $text = shift;
            return quoteUrls($text, $bug, $comment, $user);
          };
        },
        1
      ],

      bug_link => [
        sub {
          my ($context, $bug, $options) = @_;
          return sub {
            my $text = shift;
            return get_bug_link($bug, $text, $options);
          };
        },
        1
      ],

      bug_list_link => sub {
        my ($buglist, $options) = @_;
        return
          join(", ", map(get_bug_link($_, $_, $options), split(/ *, */, $buglist)));
      },

      # In CSV, quotes are doubled, and any value containing a quote or a
      # comma is enclosed in quotes.
      # If a field starts with either "=", "+", "-" or "@", it is preceded
      # by a space to prevent stupid formula execution from Excel & co.
      csv => sub {
        my ($var) = @_;
        $var = ' ' . $var if $var =~ /^[+=@-]/;

       # backslash is not special to CSV, but it can be used to confuse some browsers...
       # so we do not allow it to happen. We only do this for logged-in users.
        $var =~ s/\\/\x{FF3C}/g if Bugzilla->user->id;
        $var =~ s/\"/\"\"/g;
        if ($var !~ /^-?(\d+\.)?\d*$/) {
          $var = "\"$var\"";
        }
        return $var;
      },

      # Format a filesize in bytes to a human readable value
      unitconvert => sub {
        my ($data) = @_;
        my $retval = "";
        my %units = ('KB' => 1024, 'MB' => 1024 * 1024, 'GB' => 1024 * 1024 * 1024,);

        if ($data < 1024) {
          return "$data bytes";
        }
        else {
          my $u;
          foreach $u ('GB', 'MB', 'KB') {
            if ($data >= $units{$u}) {
              return sprintf("%.2f %s", $data / $units{$u}, $u);
            }
          }
        }
      },

      # Format a time for display (more info in Bugzilla::Util)
      time => [
        sub {
          my ($context, $format, $timezone) = @_;
          return sub {
            my $time = shift;
            return format_time($time, $format, $timezone);
          };
        },
        1
      ],

      html => \&Bugzilla::Util::html_quote,

      html_light => \&Bugzilla::Util::html_light_quote,

      email => \&Bugzilla::Util::email_filter,

      mtime => \&mtime_filter,

      # iCalendar contentline filter
      ics => [
        sub {
          my ($context, @args) = @_;
          return sub {
            my ($var)    = shift;
            my ($par)    = shift @args;
            my ($output) = "";

            $var =~ s/[\r\n]/ /g;
            $var =~ s/([;\\\",])/\\$1/g;

            if ($par) {
              $output = sprintf("%s:%s", $par, $var);
            }
            else {
              $output = $var;
            }

            $output =~ s/(.{75,75})/$1\n /g;

            return $output;
          };
        },
        1
      ],

      # Note that using this filter is even more dangerous than
      # using "none," and you should only use it when you're SURE
      # the output won't be displayed directly to a web browser.
      txt => sub {
        my ($var) = @_;

        # Trivial HTML tag remover
        $var =~ s/<[^>]*>//g;

        # And this basically reverses the html filter.
        $var =~ s/\&#64;/@/g;
        $var =~ s/\&lt;/</g;
        $var =~ s/\&gt;/>/g;
        $var =~ s/\&quot;/\"/g;
        $var =~ s/\&amp;/\&/g;

        # Now remove extra whitespace...
        my $collapse_filter = $Template::Filters::FILTERS->{collapse};
        $var = $collapse_filter->($var);

        # And if we're not in the WebService, wrap the message.
        # (Wrapping the message in the WebService is unnecessary
        # and causes awkward things like \n's appearing in error
        # messages in JSON-RPC.)
        unless (i_am_webservice()) {
          $var = wrap_comment($var, 72);
        }
        $var =~ s/\&nbsp;/ /g;

        return $var;
      },

      # Wrap a displayed comment to the appropriate length
      wrap_comment => [
        sub {
          my ($context, $cols) = @_;
          return sub { wrap_comment($_[0], $cols) }
        },
        1
      ],

      # We force filtering of every variable in key security-critical
      # places; we have a none filter for people to use when they
      # really, really don't want a variable to be changed.
      none => sub { return $_[0]; },
    },

    PLUGIN_BASE => 'Bugzilla::Template::Plugin',

    CONSTANTS => _load_constants(),

    # Default variables for all templates
    VARIABLES => {

      # Function for retrieving global parameters.
      'Param' => sub { return Bugzilla->params->{$_[0]}; },

      # Function to create date strings
      'time2str' => \&Date::Format::time2str,

      # Fixed size column formatting for bugmail.
      'format_columns' => sub {
        my $cols     = shift;
        my $format   = ($cols == 3) ? FORMAT_TRIPLE : FORMAT_DOUBLE;
        my $col_size = ($cols == 3) ? FORMAT_3_SIZE : FORMAT_2_SIZE;
        return multiline_sprintf($format, \@_, $col_size);
      },

      # Generic linear search function
      'lsearch' => sub {
        my ($array, $item) = @_;
        return firstidx { $_ eq $item } @$array;
      },

      # Currently logged in user, if any
      # If an sudo session is in progress, this is the user we're faking
      'user' => sub { return Bugzilla->user; },

      # Currenly active language
      'current_language' => sub { return Bugzilla->current_language; },

      # If an sudo session is in progress, this is the user who
      # started the session.
      'sudoer' => sub { return Bugzilla->sudoer; },

      # Allow templates to access the "correct" URLBase value
      'urlbase' => sub { return Bugzilla::Util::correct_urlbase(); },

      # Allow templates to access docs url with users' preferred language
      # We fall back to English if documentation in the preferred
      # language is not available
      'docs_urlbase' => sub {
        my $docs_urlbase;
        my $lang = Bugzilla->current_language;

        # Translations currently available on readthedocs.org
        my @rtd_translations = ('en', 'fr');

        if ($lang ne 'en' && -f "docs/$lang/html/index.html") {
          $docs_urlbase = "docs/$lang/html/";
        }
        elsif (-f "docs/en/html/index.html") {
          $docs_urlbase = "docs/en/html/";
        }
        else {
          if (!grep { $_ eq $lang } @rtd_translations) {
            $lang = "en";
          }

          my $version = BUGZILLA_VERSION;
          $version =~ /^(\d+)\.(\d+)/;
          if ($2 % 2 == 1) {

            # second number is odd; development version
            $version = 'latest';
          }
          else {
            $version = "$1.$2";
          }

          $docs_urlbase = "https://bugzilla.readthedocs.org/$lang/$version/";
        }

        return $docs_urlbase;
      },

      # Check whether the URL is safe.
      'is_safe_url' => sub {
        my $url = shift;
        return 0 unless $url;

        my $safe_url_regexp = SAFE_URL_REGEXP();
        return 1 if $url =~ /^$safe_url_regexp$/;

        # Pointing to a local file with no colon in its name is fine.
        return 1 if $url =~ /^[^\s<>\":]+[\w\/]$/i;

        # If we come here, then we cannot guarantee it's safe.
        return 0;
      },

      # Allow templates to generate a token themselves.
      'issue_hash_token' => \&Bugzilla::Token::issue_hash_token,

      'get_login_request_token' => sub {
        my $cookie = Bugzilla->cgi->cookie('Bugzilla_login_request_cookie');
        return $cookie ? issue_hash_token(['login_request', $cookie]) : '';
      },

      'get_api_token' => sub {
        return '' unless Bugzilla->user->id;
        my $cache = Bugzilla->request_cache;
        return $cache->{api_token} //= issue_api_token();
      },

      # A way for all templates to get at Field data, cached.
      'bug_fields' => sub {
        my $cache = Bugzilla->request_cache;
        $cache->{template_bug_fields} ||= Bugzilla->fields({by_name => 1});
        return $cache->{template_bug_fields};
      },

      # A general purpose cache to store rendered templates for reuse.
      # Make sure to not mix language-specific data.
      'template_cache' => sub {
        my $cache = Bugzilla->request_cache->{template_cache} ||= {};
        $cache->{users} ||= {};
        return $cache;
      },

      'css_files'      => \&css_files,
      yui_resolve_deps => \&yui_resolve_deps,
      concatenate_js   => \&_concatenate_js,

      # All classifications (sorted by sortkey, name)
      'all_classifications' => sub {
        return [map { $_->name } Bugzilla::Classification->get_all()];
      },

      # Whether or not keywords are enabled, in this Bugzilla.
      'use_keywords' => sub { return Bugzilla::Keyword->any_exist; },

      # All the keywords.
      'all_keywords' => sub {
        return [map { $_->name } Bugzilla::Keyword->get_all()];
      },

      'feature_enabled' => sub { return Bugzilla->feature(@_); },

      # field_descs can be somewhat slow to generate, so we generate
      # it only once per-language no matter how many times
      # $template->process() is called.
      'field_descs' => sub { return template_var('field_descs') },

      # Calling bug/field-help.none.tmpl once per label is very
      # expensive, so we generate it once per-language.
      'help_html' => sub { return template_var('help_html') },

      # This way we don't have to load field-descs.none.tmpl in
      # many templates.
      'display_value' => \&Bugzilla::Util::display_value,

      'install_string' => \&Bugzilla::Install::Util::install_string,

      'report_columns' => \&Bugzilla::Search::REPORT_COLUMNS,

      # These don't work as normal constants.
      DB_MODULE        => \&Bugzilla::Constants::DB_MODULE,
      REQUIRED_MODULES => \&Bugzilla::Install::Requirements::REQUIRED_MODULES,
      OPTIONAL_MODULES => sub {
        my @optional = @{OPTIONAL_MODULES()};
        foreach my $item (@optional) {
          my @features;
          foreach my $feat_id (@{$item->{feature}}) {
            push(@features, install_string("feature_$feat_id"));
          }
          $item->{feature} = \@features;
        }
        return \@optional;
      },
      'default_authorizer' => sub { return Bugzilla::Auth->new() },

      'login_not_email' => sub {
        my $params = Bugzilla->params;
        my $cache  = Bugzilla->request_cache;

        return $cache->{login_not_email}
          //= ($params->{emailsuffix}
            || ($params->{user_verify_class} =~ /LDAP/ && $params->{LDAPmailattribute})
            || ($params->{user_verify_class} =~ /RADIUS/
            && $params->{RADIUS_email_suffix})) ? 1 : 0;
      },
    },
  };

  # Use a per-process provider to cache compiled templates in memory across
  # requests.
  my $provider_key = join(':', @{$config->{INCLUDE_PATH}});
  my $shared_providers = Bugzilla->process_cache->{shared_providers} ||= {};
  $shared_providers->{$provider_key} ||= Template::Provider->new($config);
  $config->{LOAD_TEMPLATES} = [$shared_providers->{$provider_key}];

  local $Template::Config::CONTEXT = 'Bugzilla::Template::Context';

  Bugzilla::Hook::process('template_before_create', {config => $config});
  my $template = $class->new($config)
    || die("Template creation failed: " . $class->error());
  Bugzilla::Hook::process('template_after_create', {template => $template});

  # Pass on our current language to any template hooks or inner templates
  # called by this Template object.
  $template->context->{bz_language} = $opts{language} || '';

  return $template;
}

# Used as part of the two subroutines below.
our %_templates_to_precompile;

sub precompile_templates {
  my ($output) = @_;

  # Remove the compiled templates.
  my $cache_dir = bz_locations()->{'template_cache'};
  my $datadir   = bz_locations()->{'datadir'};
  if (-e $cache_dir) {
    print install_string('template_removing_dir') . "\n" if $output;

    # This frequently fails if the webserver made the files, because
    # then the webserver owns the directories.
    rmtree($cache_dir);

    # Check that the directory was really removed, and if not, move it
    # into data/deleteme/.
    if (-e $cache_dir) {
      my $deleteme = "$datadir/deleteme";

      print STDERR "\n\n",
        install_string('template_removal_failed',
        {deleteme => $deleteme, template_cache => $cache_dir}),
        "\n\n";
      mkpath($deleteme);
      my $random = generate_random_password();
      rename($cache_dir, "$deleteme/$random") or die "move failed: $!";
    }
  }

  print install_string('template_precompile') if $output;

  # Pre-compile all available languages.
  my $paths = template_include_path({language => Bugzilla->languages});

  foreach my $dir (@$paths) {
    my $template = Bugzilla::Template->create(include_path => [$dir]);

    %_templates_to_precompile = ();

    # Traverse the template hierarchy.
    find({wanted => \&_precompile_push, no_chdir => 1}, $dir);

    # The sort isn't totally necessary, but it makes debugging easier
    # by making the templates always be compiled in the same order.
    foreach my $file (sort keys %_templates_to_precompile) {
      $file =~ s{^\Q$dir\E/}{};

      # Compile the template but throw away the result. This has the side-
      # effect of writing the compiled version to disk.
      $template->context->template($file);
    }

    # Clear out the cached Provider object
    Bugzilla->process_cache->{shared_providers} = undef;
  }

  # Under mod_perl, we look for templates using the absolute path of the
  # template directory, which causes Template Toolkit to look for their
  # *compiled* versions using the full absolute path under the data/template
  # directory. (Like data/template/var/www/html/bugzilla/.) To avoid
  # re-compiling templates under mod_perl, we symlink to the
  # already-compiled templates. This doesn't work on Windows.
  if (!ON_WINDOWS) {

    # We do these separately in case they're in different locations.
    _do_template_symlink(bz_locations()->{'templatedir'});
    _do_template_symlink(bz_locations()->{'extensionsdir'});
  }

  # If anything created a Template object before now, clear it out.
  delete Bugzilla->request_cache->{template};

  print install_string('done') . "\n" if $output;
}

# Helper for precompile_templates
sub _precompile_push {
  my $name = $File::Find::name;
  return if (-d $name);
  return if ($name =~ /\/CVS\//);
  return if ($name !~ /\.tmpl$/);
  $_templates_to_precompile{$name} = 1;
}

# Helper for precompile_templates
sub _do_template_symlink {
  my $dir_to_symlink = shift;

  my $abs_path = abs_path($dir_to_symlink);

  # If $dir_to_symlink is already an absolute path (as might happen
  # with packagers who set $libpath to an absolute path), then we don't
  # need to do this symlink.
  return if ($abs_path eq $dir_to_symlink);

  my $abs_root  = dirname($abs_path);
  my $dir_name  = basename($abs_path);
  my $cache_dir = bz_locations()->{'template_cache'};
  my $container = "$cache_dir$abs_root";
  mkpath($container);
  my $target = "$cache_dir/$dir_name";

  # Check if the directory exists, because if there are no extensions,
  # there won't be an "data/template/extensions" directory to link to.
  if (-d $target) {

    # We use abs2rel so that the symlink will look like
    # "../../../../template" which works, while just
    # "data/template/template/" doesn't work.
    my $relative_target = File::Spec->abs2rel($target, $container);

    my $link_name = "$container/$dir_name";
    symlink($relative_target, $link_name)
      or warn "Could not make $link_name a symlink to $relative_target: $!";
  }
}

1;

__END__

=head1 NAME

Bugzilla::Template - Wrapper around the Template Toolkit C<Template> object

=head1 SYNOPSIS

  my $template = Bugzilla::Template->create;
  my $format = $template->get_format("foo/bar",
                                     scalar($cgi->param('format')),
                                     scalar($cgi->param('ctype')));

=head1 DESCRIPTION

This is basically a wrapper so that the correct arguments get passed into
the C<Template> constructor.

It should not be used directly by scripts or modules - instead, use
C<Bugzilla-E<gt>instance-E<gt>template> to get an already created module.

=head1 SUBROUTINES

=over

=item C<precompile_templates($output)>

Description: Compiles all of Bugzilla's templates in every language.
             Used mostly by F<checksetup.pl>.

Params:      C<$output> - C<true> if you want the function to print
               out information about what it's doing.

Returns:     nothing

=back

=head1 METHODS

=over

=item C<get_format($file, $format, $ctype)>

 Description: Construct a format object from URL parameters.

 Params:      $file   - Name of the template to display.
              $format - When the template exists under several formats
                        (e.g. table or graph), specify the one to choose.
              $ctype  - Content type, see Bugzilla::Constants::contenttypes.

 Returns:     A format object.

=back

=head1 SEE ALSO

L<Bugzilla>, L<Template>

=head1 B<Methods in need of POD>

=over

=item multiline_sprintf

=item create

=item css_files

=item mtime_filter

=item yui_resolve_deps

=item process

=item get_bug_link

=item quoteUrls

=item get_attachment_link

=item SAFE_URL_REGEXP

=back
