# Selima Website Content Management System
# LastModf.pm: The web site last-modified time calculator.

#  Copyright (c) 2003-2018 imacat.
#
#  Licensed under the Apache License, Version 2.0 (the "License");
#  you may not use this file except in compliance with the License.
#  You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
#  Unless required by applicable law or agreed to in writing, software
#  distributed under the License is distributed on an "AS IS" BASIS,
#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#  See the License for the specific language governing permissions and
#  limitations under the License.

# Author: imacat <imacat@mail.imacat.idv.tw>
# First written: 2003-03-23

package Selima::LastModf;
use 5.008;
use strict;
use warnings;
use base qw(Exporter);
use vars qw(@EXPORT @EXPORT_OK);
BEGIN {
@EXPORT = qw(not_modified);
@EXPORT_OK = @EXPORT;
# Prototype declaration
sub not_modified(\@\@);
sub find_last_modified(\@\@);
sub check_inc();
sub updmtime_tables(\@);
sub updmtime_file($);
}

use File::Spec::Functions qw(catfile);
use HTTP::Date qw(str2time);

use Selima::CallForm;
use Selima::DataVars qw($DBH :input :l10n :lninfo :lastmod :libdir :requri :siteconf);
use Selima::GetLang;
use Selima::HTTP;
use Selima::Session;

# not_modified: Check if we should send "HTTP/1.1 304 Not Modified"
sub not_modified(\@\@) {
    local ($_, %_);
    my ($tables, $files);
    ($tables, $files) = @_;
    # HTTP/1.1 304 only works for GET or HEAD
    return 0 unless $ENV{"REQUEST_METHOD"} eq "GET"
                    || $ENV{"REQUEST_METHOD"} eq "HEAD";
    # Find the last-modified time
    find_last_modified @$tables, @$files;
    # If-Modified-Since not supplied.  The client had not cached yet.
    return 0 if !exists $ENV{"HTTP_IF_MODIFIED_SINCE"};
    # Malformed If-Modified-Since value
    return 0 if !defined($_ = str2time($ENV{"HTTP_IF_MODIFIED_SINCE"}));
    # We are newer than the cache
    return 0 if $LAST_MODIFIED > $_;
    # Yes, use the cache
    return 1;
}

# find_last_modified: Find the last-modified time
sub find_last_modified(\@\@) {
    local ($_, %_);
    my ($tables, $files);
    ($tables, $files) = @_;
    
    # Checked before
    return if defined $LAST_MODIFIED;
    
    # Remove duplicates
    %_ = map { $_ => 1 } @$tables;
    @$tables = keys %_;
    %_ = map { $_ => 1 } @$files;
    @$files = keys %_;
    
    # Start with EPOCH 1970-01-01 00:00:00
    $LAST_MODIFIED = 0;
    
    # Check myself
    updmtime_file $0;
    # Check mtime from the included modules and gettext MO files
    check_inc;
    # Check the supplied data files
    updmtime_file $_ foreach grep -f $_, @$files;
    # Check the supplied data tables
    updmtime_tables @$tables;
    # Check the saved form and status
    if (defined $GET->param("formid")) {
        $_ = catfile($Selima::Session::DIR, "saveform_" . $GET->param("formid"));
        updmtime_file $_ if -f $_;
    }
    if (defined $GET->param("statid")) {
        $_ = catfile($Selima::Session::DIR, "savestat_" . $GET->param("statid"));
        updmtime_file $_ if -f $_;
    }
    
    return;
}

# check_inc: Check mtime from the included modules and gettext MO files
sub check_inc() {
    local ($_, %_);
    my ($t, $DH);
    
    # Check the included modules
    updmtime_file $_ foreach grep /^\Q$SITE_LIBDIR\E\b/, values %INC;
    $t = COMMON_LIBDIR;
    updmtime_file $_ foreach grep /^$t\b/, values %INC;
    
    # Check the header and footer
    $_ = $DOC_ROOT . "/magicat/include";
    @_ = qw();
    if (@ALL_LINGUAS > 1) {
        push @_, $_ . "/header." . getlang(LN_FILENAME) . ".html";
        push @_, $_ . "/footer." . getlang(LN_FILENAME) . ".html";
    } else {
        push @_, $_ . "/header.html";
        push @_, $_ . "/footer.html";
    }
    foreach (@_) {
        updmtime_file $_ if -e $_;
    }
    
    # Check the gettext mo files
    if (-d $LOCALEDIR) {
        opendir $DH, $LOCALEDIR     or http_500 "$LOCALEDIR: $!";
        @_ = readdir $DH            or http_500 "$LOCALEDIR: $!";
        closedir $DH                or http_500 "$LOCALEDIR: $!";
        foreach (@_) {
            $_ = "$LOCALEDIR/$_/LC_MESSAGES/$PACKAGE.mo";
            updmtime_file $_ if -f $_;
        }
    }
    opendir $DH, COMMON_LOCALEDIR   or http_500 COMMON_LOCALEDIR . ": $!";
    @_ = readdir $DH                or http_500 COMMON_LOCALEDIR . ": $!";
    closedir $DH                    or http_500 COMMON_LOCALEDIR . ": $!";
    foreach (@_) {
        $_ = COMMON_LOCALEDIR . "/$_/LC_MESSAGES/" . COMMON_DOMAIN . ".mo";
        updmtime_file $_ if -f $_;
    }
    
    return;
}

# updmtime_tables: Update the $LAST_MODIFIED with the mtime of tables
sub updmtime_tables(\@) {
    local ($_, %_);
    my ($tables, $sql, $sth);
    $tables = $_[0];
    # Only work when using database
    return if !defined $DBH;
    
    return unless defined($_ = $DBH->lastupd(@$tables));
    $_ = int $_;
    $LAST_MODIFIED = $_ if defined $_ && $LAST_MODIFIED < $_;
    return;
}

# updmtime_file: Update the $LAST_MODIFIED with the mtime of a file
sub updmtime_file($) {
    local ($_, %_);
    $_ = (stat $_[0])[9];
    $LAST_MODIFIED = $_ if $LAST_MODIFIED < $_;
    return;
}

return 1;