<?php
// File name:	rel2abs.inc.php
// Description:	PHP subroutine to convert a relative URL to an absolute URL
// Date:	2002-06-10
// Author:	imacat <imacat@pristine.com.tw>
// Copyright:	Copyright (C) 2002-2007 Pristine Communications

// Refer to RFC 1808

// Set the include path
if (!defined("INCPATH_SET")) {
    require_once dirname(__FILE__) . "/incpath.inc.php";
}
// Referenced subroutines
require_once "monica/parseurl.inc.php";
require_once "monica/requri.inc.php";

// Settings
define("REL2ABS_SKIP_FRAGMENT", true);
define("REL2ABS_NO_HOST", true);
define("REL2ABS_RDIFF_KEEP", true);
define("REL2ABS_RDIFF_STRIP", false);

// rel2abs: Conver a relative URL to an absolute URL
//   Refer to RFC 1808
function rel2abs($rel, $base = null, $skip_fragment = false, $no_host = false, $rdiff = true)
{
    // Keep the original.  We may need to bounce intact later.
    $rel_o = $rel;
    // Make the base absolute first
    if (!is_null($base)) {
        $base = rel2abs($base);
    // Default base to the current URL
    } else {
        $base = REQUEST_FULLURI;
    }
    // Skip the fragment
    if (substr($rel, 0, 1) == "#" && $skip_fragment) {
        return $rel;
    }
    // Return if it is completely empty (RFC 1808, 4, step 2, a)
    if ($rel == "") {
        return $base;
    }
    // Parse the URL first
    $rel_a = parse_url_rfc1808($rel);
    // Fail to parse - bounce intact
    if (is_null($rel_a)) {
        return $rel_o;
    }
    if (    !array_key_exists("net_loc", $rel_a)
            && array_key_exists("path", $rel_a)
            && substr($rel_a["path"], 0, 1) == "/"
            && $rdiff) {
        $rel_a["path"] = ROOT_DIFF . $rel_a["path"];
    }
    $base_a = parse_url_rfc1808($base);
    // Fail to parse - bounce intact
    if (is_null($base_a)) {
        return $rel_o;
    }
    if (!array_key_exists("path", $base_a)) {
        $base_a["path"] = "/";
    }
    if (!array_key_exists("scheme", $base_a)) {
        $base_a["scheme"] = "http";
    }
    // Return if it starts with a scheme (RFC 1808, 4, step 2, b)
    if (array_key_exists("scheme", $rel_a)) {
        return $rel;
    }
    // Inherit the scheme of the base URL (RFC 1808, 4, step 2, c)
    $rel_a["scheme"] = $base_a["scheme"];
    $skip_to_7 = false;
    // The net_loc is not empty (RFC 1808, 4, step 3)
    if (array_key_exists("net_loc", $rel_a)) {
        $skip_to_7 = true;
    // Inherit the net_loc of the base URL (if any)
    } else {
        if (array_key_exists("net_loc", $base_a)) {
            $rel_a["net_loc"] = $base_a["net_loc"];
        }
        // The path is not relative (RFC 1808, 4, step 4)
        if (    array_key_exists("path", $rel_a)
                && substr($rel_a["path"], 0, 1) == "/") {
            $skip_to_7 = true;
        } else {
            // The path is empty (RFC 1808, 4, step 5)
            if (!array_key_exists("path", $rel_a)) {
                $rel_a["path"] = $base_a["path"];
                // The params is not empty (RFC 1808, 4, step 5, a)
                if (array_key_exists("params", $rel_a)) {
                    $skip_to_7 = true;
                } else {
                    if (array_key_exists("params", $base_a)) {
                        $rel_a["params"] = $base_a["params"];
                    }
                    // The query is not empty (RFC 1808, 4, step 5, b)
                    if (array_key_exists("query", $rel_a)) {
                        $skip_to_7 = true;
                    } else {
                        if (array_key_exists("query", $base_a)) {
                            $rel_a["query"] = $base_a["query"];
                        }
                        $skip_to_7 = true;
                    }
                }
            }
        }
    }
    // Resolve the path (RFC 1808, 4, step 6)
    if (!$skip_to_7) {
        $rel_a["path"] = preg_replace("/[^\/]+$/", "", $base_a["path"])
            . $rel_a["path"];
        $rel_a["path"] = stdpath($rel_a["path"]);
    }
    
    // Compose the URL (RFC 1808, 4, step 7)
    $abs = "";
    if (!$no_host) {
        $abs .= $rel_a["scheme"] . ":";
        if (array_key_exists("net_loc", $rel_a)) {
            $abs .= "//" . $rel_a["net_loc"];
        }
    }
    $abs .= $rel_a["path"];
    if (array_key_exists("params", $rel_a)) {
        $abs .= ";" . $rel_a["params"];
    }
    if (array_key_exists("query", $rel_a)) {
        $abs .= "?" . $rel_a["query"];
    }
    if (array_key_exists("fragment", $rel_a)) {
        $abs .= "#" . $rel_a["fragment"];
    }
    
    return $abs;
}

// abs2rel: Conver an absolute URL to a relative URL
function abs2rel($abs, $base = null)
{
    // Keep the original.  We may need to bounce intact later.
    $abs_o = $abs;
    // Make the base absolute first
    if (!is_null($base)) {
        $base = rel2abs($base);
    // Default base to the current URL
    } else {
        $base = REQUEST_FULLURI;
    }
    $abs = rel2abs($abs, $base);
    // Parse the URL first
    $abs_a = parse_url_rfc1808($abs);
    // Fail to parse - bounce intact
    if (is_null($abs_a)) {
        return $abs_o;
    }
    if (!array_key_exists("path", $abs_a)) {
        $abs_a["path"] = "/";
    }
    $base_a = parse_url_rfc1808($base);
    // Fail to parse - bounce intact
    if (is_null($base_a)) {
        return $abs_o;
    }
    // Return if not the same scheme
    if ($abs_a["scheme"] != $base_a["scheme"]) {
        return $abs;
    }
    unset($abs_a["scheme"]);
    // Return if not the same network location (net_loc)
    if (    !((!array_key_exists("net_loc", $abs_a)
            && !array_key_exists("net_loc", $base_a))
            || (array_key_exists("net_loc", $abs_a)
            && array_key_exists("net_loc", $base_a)
            && $abs_a["net_loc"] == $base_a["net_loc"]))) {
        return $abs;
    }
    unset($abs_a["net_loc"]);
    if (!array_key_exists("path", $abs_a)) {
        $abs_a["path"] = "/";
    }
    // Different path -- find the path difference
    if ($abs_a["path"] != $base_a["path"]) {
        // Remove the last segment from the base URL
        $base_path = preg_replace("/[^\/]+$/", "", $base_a["path"]);
        $abs_path = $abs_a["path"];
        // Remove the leading absolute slash
        $base_path = preg_replace("/^\//", "", $base_path);
        $abs_path = preg_replace("/^\//", "", $abs_path);
        // Check each path segment from the left
        while (preg_match("/^([^\/]+\/)(.*)$/", $base_path, $m)) {
            // Not sharing the same path segment
            if (substr($abs_path, 0, strlen($m[1])) != $m[1]) {
                break;
            }
            $base_path = $m[2];
            $abs_path = substr($abs_path, strlen($m[1]));
            // Nothing left, but false is not what we want
            if ($abs_path === false) {
                $abs_path = "";
                break;
            }
        }
        // Turn each remaining segment to ".." and prepend it to the path
        $abs_a["path"] = preg_replace("/[^\/]+/", "..", $base_path) . $abs_path;
        // Remove the trailing slash of the ancestor directories
        if (    $abs_a["path"] == "../"
                || preg_match("/\/\.\.\/$/", $abs_a["path"])) {
            $abs_a["path"] = substr($abs_a["path"], 0, -1);
        }
        // Nothing left means the current directory
        if ($abs_a["path"] == "") {
            $abs_a["path"] = ".";
        }
    
    // Same path
    } else {
        // Different params
        if (    !((!array_key_exists("params", $abs_a)
                && !array_key_exists("params", $base_a))
                || (array_key_exists("params", $abs_a)
                && array_key_exists("params", $base_a)
                && $abs_a["params"] == $base_a["params"]))) {
            // No further checks
            // Keep the last segment of the path
            $abs_a["path"] = preg_replace("/^\/(?:[^\/]+\/)*/", "", $abs_a["path"]);
            if ($abs_a["path"] == "") {
                $abs_a["path"] = ".";
            }
        
        // Same params
        } else {
            // Different query
            if (    !((!array_key_exists("query", $abs_a)
                    && !array_key_exists("query", $base_a))
                    || (array_key_exists("query", $abs_a)
                    && array_key_exists("query", $base_a)
                    && $abs_a["query"] == $base_a["query"]))) {
                // No further checks
                // Keep the last segment of the path
                $abs_a["path"] = preg_replace("/^\/(?:[^\/]+\/)*/", "", $abs_a["path"]);
                if ($abs_a["path"] == "") {
                    $abs_a["path"] = ".";
                }
            
            // Same query
            } else {
                // Everything is the same (fragment not counted)
                // Keep only the fragment if there is a fragment
                if (array_key_exists("fragment", $abs_a)) {
                    unset($abs_a["path"]);
                    unset($abs_a["params"]);
                    unset($abs_a["query"]);
                
                // No fragment
                } else {
                    // Keep the last segment of the path
                    $abs_a["path"] = preg_replace("/^\/(?:[^\/]+\/)*/", "", $abs_a["path"]);
                    if ($abs_a["path"] == "") {
                        $abs_a["path"] = ".";
                    }
                }
            }
        }
    }
    
    // Compose the URL
    $rel = "";
    if (array_key_exists("path", $abs_a)) {
        $rel .= $abs_a["path"];
    }
    if (array_key_exists("params", $abs_a)) {
        $rel .= ";" . $abs_a["params"];
    }
    if (array_key_exists("query", $abs_a)) {
        $rel .= "?" . $abs_a["query"];
    }
    if (array_key_exists("fragment", $abs_a)) {
        $rel .= "#" . $abs_a["fragment"];
    }
    
    return $rel;
}

// stdpath: Standardize a path name
//   Refer to RFC 1808, 4, step 6
function stdpath($path)
{
    // Remove all the "./" (RFC 1808, 4, step 6, a)
    $path = preg_replace("/(?<=\/)\.\//", "", $path);
    $path = preg_replace("/^\.\//", "", $path);
    // Remove the trailing "." (RFC 1808, 4, step 6, b)
    $path = preg_replace("/(?<=\/)\.$/", "", $path);
    // Remove all the "<segment>/../" (RFC 1808, 4, step 6, c)
    while ( preg_match("/^(.*?)([^\/]+)\/\.\.\/(.*)$/", $path, $m)
            && $m[2] != "..") {
        $path = $m[1] . $m[3];
    }
    // Remove the trailing "<segment>/.." (RFC 1808, 4, step 6, d)
    while ( preg_match("/^(.*?)([^\/]+)\/\.\.$/", $path, $m)
            && $m[2] != "..") {
        $path = $m[1];
    }
    return $path;
}

?>