<?php
// File name:	addget.inc.php
// Description:	PHP subroutines to add a get argument to an url
// Date:	2001-02-13
// Author:	imacat <imacat@pristine.com.tw>
// Copyright:	Copyright (C) 2001-2007 Pristine Communications

// Constant symbols
if (!defined("DUP_OK")) {
    define("DUP_OK", true);
    define("DUP_NO", false);
}

// add_get_arg: Add a get argument to the end of an url
function add_get_arg($cururl, $name, $value, $dup_ok = DUP_NO)
{
    // Encode the name and value first
    $name = urlencode($name);
    $value = urlencode($value);
    
    $pos = strpos($cururl, "?");
    // No current arguments were appended yet
    if ($pos === false) {
        return "$cururl?$name=$value";
    }
    
    // It's OK to have duplicated same arguments
    if ($dup_ok) {
        return "$cururl&$name=$value";
    }
    
    // Have arguments already.  We need to check if there is already
    // a duplicated one and replace it if exists.
    // Split the arguments
    $script = substr($cururl, 0, $pos);
    $argslist = substr($cururl, $pos+1);
    $oldargs = explode("&", $argslist);
    $newargs = array();
    $l = strlen("$name=");
    $found = false;
    foreach ($oldargs as $arg) {
        // Replace existing arguments
        if (substr($arg, 0, $l) == "$name=") {
            // Replace the first one and discard the rest
            if (!$found) {
                $newargs[] = "$name=$value";
                $found = true;
            }
            continue;
        }
        $newargs[] = $arg;
    }
    // Add it if not found at last
    if (!$found) {
        $newargs[] = "$name=$value";
    }
    return "$script?" . implode("&", $newargs);
}

// rem_get_arg: Remove a get argument from the end of an url
function rem_get_arg($cururl, $names)
{
    // If $names is not an array, set to an one-element array
    if (!is_array($names)) {
        $names = array($names);
    }
    // Parse the names
    $lens = array();
    for ($i = 0; $i < count($names); $i++) {
        // Encode the name first
        $names[$i] = urlencode($names[$i]);
        // Save its length
        $lens[$names[$i]] = strlen($names[$i] . "=");
    }
    
    $pos = strpos($cururl, "?");
    // No current arguments are appended yet
    if ($pos === false) {
        return $cururl;
    }
    
    // Have arguments already.  We need to check if there is already
    // a duplicated one and remove it if exists.
    // Split the arguments
    $script = substr($cururl, 0, $pos);
    $argslist = substr($cururl, $pos+1);
    $oldargs = explode("&", $argslist);
    $newargs = array();
    foreach ($oldargs as $arg) {
        // Skip found arguments
        foreach ($names as $name) {
            if (substr($arg, 0, $lens[$name]) == "$name=") {
                continue 2;
            }
        }
        $newargs[] = $arg;
    }
    // No arguments left
    if (count($newargs) == 0) {
        return $script;
    }
    return "$script?" . implode("&", $newargs);
}

?>