# Selima Website Content Management System
# AddGet.pm: The subroutines to manipulate the arguments in an URL.

#  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: 2003-03-30

package Selima::AddGet;
use 5.008;
use strict;
use warnings;
use base qw(Exporter);
use vars qw(@EXPORT @EXPORT_OK);
BEGIN {
@EXPORT = qw(DUP_OK DUP_NO add_get_arg rem_get_arg);
@EXPORT_OK = @EXPORT;
# Prototype declaration
sub add_get_arg($$$;$);
sub rem_get_arg($@);
}

use URI::Escape qw(uri_escape);

# Constant symbols
use constant DUP_OK => 1;
use constant DUP_NO => 0;

# add_get_arg: Add a get argument to the end of an url
sub add_get_arg($$$;$) {
    local ($_, %_);
    my ($url, $name, $value, $if_dup, $script);
    ($url, $name, $value, $if_dup) = @_;
    $if_dup = DUP_NO if !defined $if_dup;
    
    # Escape the name and value first
    $name = uri_escape($name);
    $value = uri_escape($value);
    
    # No current arguments are appended yet
    return "$url?$name=$value" if $url !~ /\?/;
    
    # It is OK to have duplicated same arguments
    return "$url&$name=$value" if $if_dup == DUP_OK;
    
    # Have arguments already.  We need to check if there is already
    #   a duplicated one and replace it if exists.
    # Split the arguments
    $url =~ /^(.*?)\?(.*)$/;
    ($script, $_) = ($1, $2);
    @_ = split /&/, $_;
    # Remove the matched ones
    @_ = grep !/^$name=/, @_;
    # Add our argument
    push @_, "$name=$value";
    return "$script?" . join("&", @_);
}

# rem_get_arg: Remove a get argument from the end of an url
sub rem_get_arg($@) {
    local ($_, %_);
    my ($url, @names, $script, $name);
    ($url, @names) = @_;
    
    # No current arguments are appended yet
    return $url if $url !~ /\?/;
    
    # Escape the names
    for ($_ = 0; $_ < @names; $_++) {
        # Encode the name first
        $names[$_] = uri_escape($names[$_]);
    }
    
    # Have arguments already.  We need to check if there is already
    #   a duplicated one and remove it if exists.
    # Split the arguments
    $url =~ /^(.*?)\?(.*)$/;
    ($script, $_) = ($1, $2);
    @_ = split /&/, $_;
    # Check one by one
    foreach $name (@names) {
        @_ = grep !/^$name=/, @_;
    }
    # No arguments left
    return $script if scalar(@_) == 0;
    return "$script?" . join("&", @_);
}

return 1;