<?php
/*
########################################################################                                        
Copyright 2007, Michael Schrenk                                                                                 
   This software is designed for use with the book,                                                             
   "Webbots, Spiders, and Screen Scarpers", Michael Schrenk, 2007 No Starch Press, San Francisco CA             
                                                                                                                
W3CŽ SOFTWARE NOTICE AND LICENSE                                                                                
                                                                                                                
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   1. The full text of this NOTICE in a location viewable to users of the redistributed                         
      or derivative work.                                                                                       
   2. Any pre-existing intellectual property disclaimers, notices, or terms and conditions.                     
      If none exist, the W3C Software Short Notice should be included (hypertext is preferred,                  
      text is permitted) within the body of any redistributed or derivative code.                               
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OF ANY USE OF THE SOFTWARE OR DOCUMENTATION.                                                                    
                                                                                                                
The name and trademarks of copyright holders may NOT be used in advertising or publicity pertaining to the      
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documentation will at all times remain with copyright holders.                                                  
########################################################################                                        
*/

########################################################################
#                                                                       
# LIB_resolve_addresses                                                 
#                                                                       
# This library provides routines that create fully resolved             
# web addresses                                                         
#                                                                       
#-----------------------------------------------------------------------
# FUNCTIONS                                                             
#                                                                       
#       resolve_address()               						        
#		    This function returns fully resolved URLs for the $link     
#		    which could be an images, css, javascript file, etc.		
#                                                                       
#       get_base_page_address() 										
#		    Search from right to left for first occurrence of "/". 		
#		    Then use everything from the left of that character as the  
#           page base address.											
#                                                                       
#       get_base_domain_address()                                       
#           Note that the base DOMAIN address is different than the base
#           PAGE address. The base page address may indicate a directory
#           structure, while the base domain address is simply the      
#           domain, without any files or directories.					
#                                                                       
#-----------------------------------------------------------------------

/***********************************************************************
resolve_address($link, $page_base)						                
-------------------------------------------------------------			
DESCRIPTION:															
		This function returns fully resolved URLs for the $link         
		which could be an images, css, javascript file, etc.			
RETURNS:																
		A fully resolved URL for the $link						        
***********************************************************************/
function resolve_address($link, $page_base)
	{
    #---------------------------------------------------------- 
    # CONDITION INCOMING LINK ADDRESS
	#
	$link = trim($link);
	$page_base = trim($page_base);
    
	# if there isn't one, put a "/" at the end of the $page_base
	$page_base = trim($page_base);
	if( (strrpos($page_base, "/")+1) != strlen($page_base) )
		$page_base = $page_base."/";
    
	# remove unwanted characters from $link
	$link = str_replace(";", "", $link);			// remove ; characters
	$link = str_replace("\"", "", $link);			// remove " characters
	$link = str_replace("'", "", $link);			// remove ' characters
	$abs_address = $page_base.$link;
    
    $abs_address = str_replace("/./", "/", $abs_address);
    
	$abs_done = 0;
    
    #---------------------------------------------------------- 
    # LOOK FOR REFERENCES TO THE BASE DOMAIN ADDRESS
    #---------------------------------------------------------- 
    # There are essentially four types of addresses to resolve:
    # 1. References to the base domain address
    # 2. References to higher directories
    # 3. References to the base directory
    # 4. Addresses that are alreday fully resolved
	#
	if($abs_done==0)
		{
		# Use domain base address if $link starts with "/"
		if (substr($link, 0, 1) == "/")
			{
			// find the left_most "."
			$pos_left_most_dot = strrpos($page_base, ".");
	
			# Find the left-most "/" in $page_base after the dot 
			for($xx=$pos_left_most_dot; $xx<strlen($page_base); $xx++)
				{
				if( substr($page_base, $xx, 1)=="/")
					break;
				}
            
			$domain_base_address = get_base_domain_address($page_base);
            
			$abs_address = $domain_base_address.$link;
			$abs_done=1;
			}
		}

    #---------------------------------------------------------- 
    # LOOK FOR REFERENCES TO HIGHER DIRECTORIES
	#
	if($abs_done==0)
		{
		if (substr($link, 0, 3) == "../")
			{
			$page_base=trim($page_base);
			$right_most_slash = strrpos($page_base, "/");
	        
			// remove slash if at end of $page base
			if($right_most_slash==strlen($page_base)-1)
				{
				$page_base = substr($page_base, 0, strlen($page_base)-1);
				$right_most_slash = strrpos($page_base, "/");
				}
            
			if ($right_most_slash<8)
				$unadjusted_base_address = $page_base;
	        
			$not_done=TRUE;
			while($not_done)
				{
				// bring page base back one level
				list($page_base, $link) = move_address_back_one_level($page_base, $link);
				if(substr($link, 0, 3)!="../")
					$not_done=FALSE;
				}
				if(isset($unadjusted_base_address))		
					$abs_address = $unadjusted_base_address."/".$link;
				else
					$abs_address = $page_base."/".$link;
			$abs_done=1;
			}
		}
        
    #---------------------------------------------------------- 
    # LOOK FOR REFERENCES TO BASE DIRECTORY
	#
	if($abs_done==0)
		{
		if (substr($link, 0, "1") == "/")
			{
			$link = substr($link, 1, strlen($link)-1);	// remove leading "/"
			$abs_address = $page_base.$link;			// combine object with base address
			$abs_done=1;
			}
		}
    
    #---------------------------------------------------------- 
    # LOOK FOR REFERENCES THAT ARE ALREADY ABSOLUTE
	#
    if($abs_done==0)
		{
		if (substr($link, 0, 4) == "http")
			{
			$abs_address = $link;
			$abs_done=1;
			}
		}
    
    #---------------------------------------------------------- 
    # ADD PROTOCOL IDENTIFIER IF NEEDED
	#
	if( (substr($abs_address, 0, 7)!="http://") && (substr($abs_address, 0, 8)!="https://") )
		$abs_address = "http://".$abs_address;
    
	return $abs_address;  
	}

/***********************************************************************
get_base_page_address($url)												
-------------------------------------------------------------			
DESCRIPTION:															
		Search from right to left for first occurrence of "/". 			
 		Then use everything from the left of that character as the page 
		base address.													
																		
		If the position of "/" is less than 7, then that character is 	
		part of an URL that is directly referenced. 					
			(i.e. "http://www.someplace.com".							
		With direct URL references, always make sure that the base page 
		address always ends in a "\".									
INPUTS:																	
		$url															
RETURNS:																
		The base page address for $url									
***********************************************************************/
function get_base_page_address($url)
	{
	$slash_position = strrpos($url, "/");

	if ($slash_position>8)
		$page_base = substr($url, 0, $slash_position+1);  	// "$slash_position+1" to include the "/".
	else
		{
		$page_base = $url;  	// $url is already the page base, without modification.
		if($slash_position!=strlen($url))
			$page_base=$page_base."/";
		}

		
	# If the page base ends with a \\, replace with a \
	$last_two_characters = substr($page_base, strlen($page_base)-2, 2);
	if($last_two_characters=="//")
		$page_base = substr($page_base, 0, strlen($page_base)-1);

	return $page_base;
	}

/***********************************************************************
get_base_domain_address($page_base)										
-------------------------------------------------------------			
DESCRIPTION:															
		Note that the base DOMAIN address is different than the base 	
		PAGE address. The base page address may indicate a directory 	
		structure, while the base domain address is simply the domain, 	
		without any files or directories.								
																		
		The base domain address found by taking everything to the right 
		of the first "/" once past the initial "/"'s found after the  	
		protocol specifier (http:// or https://)						
INPUTS:																	
		$page_base, (from get_base_page_address)						
RETURNS:																
		The base page domain address for URL							
***********************************************************************/
function get_base_domain_address($page_base)
	{
	for ($pointer=8; $pointer<strlen($page_base); $pointer++)
		{
		if (substr($page_base, $pointer, 1)=="/")
			{
			$domain_base=substr($page_base, 0, $pointer);
			break;
			}
		}
	
	$last_two_characters = substr($page_base, strlen($page_base)-2, 2);
	if($last_two_characters=="//")
		$page_base = substr($page_base, 0, strlen($page_base)-1);

	return $domain_base;
	}


/***********************************************************************
move_address_back_one_level($page_base, $object_source)                 
-------------------------------------------------------------			
DESCRIPTION:															
		This function is used by the library and not intended for       
        external use.                                                   
-------------------------------------------------------------			
*/
function move_address_back_one_level($page_base, $object_source)
	{
	// bring page base back one leve
	$right_most_slash = strrpos($page_base, "/");
	$new_page_base = substr($page_base, 0, $right_most_slash);

	// remove "../" from front of object_source
	$object_source = substr($object_source, 3, strlen($object_source)-3);

	$return_array[0]=$new_page_base;
	$return_array[1]=$object_source;
	return $return_array;
	}
?>