<?php

//=============================================================================
//
// Description:
// 	Various functions for manipulating XML
//
// Functions:
//	array2xml( )
//	generateXsdSig( )
//	libxml_display_error( )
//	libxml_display_errors( )
//	schemaValidate( )
//	schemaValidateSource( )
//	validXsdSig( )
//
//=============================================================================

function array2xml($array, $defaultElement = 'element', $format = false)
{
	//===========================================================================
	// Function: array2eventData
	// Author: Bob Jackman
	// Date: 2008-10-21
	// Description:	Create an XML representation of an array's elements
	//
	// Params:
	//	$array {array} Required:			Array of elements to convert to XML
	//	$defaultElement {string} Optional: Tag name to use for non-associative
	//								array elements. Defaults to 'element'
	//	$format {bool} Optional: 		Whether or not to format the XML
	//								output with tabs and newline
	//								characters
	//
	// Returns: {string}	Resultant XML
	//===========================================================================

	// ====================  Determine Indent Level
	if ($format !== false)
	{
		$stack = debug_backtrace();
		$tabs = 0;
		foreach ($stack as $level) // -- loop through each stack level
		{
			if (isset($level['function']) && $level['function'] == 'array2xml') // -- call to this function
			{
				$tabs++;
			}
		}
	}
	else
	{
		$tabs = 0;
	}

	// ====================  Generate XML
	$xml = '';
	if (is_array($array))
	{
		foreach ($array as $tagName => $value) // -- loop through each array element
		{
			if (is_numeric($tagName)) // -- non-associative key
			{
				$tagName = $defaultElement;
			}

			if (!empty($value)) // -- value exists
			{
				$xml .= str_repeat("\t", $tabs).'<'.$tagName.'>'.($format !== false ? "\n" : '');
				if (is_array($value)) // -- child nodes
				{
					$xml .= array2xml($value, $defaultElement, $format);
				}
				else // -- value node
				{
					$xml .= str_repeat("\t", ($format !== false ? ($tabs + 1) : 0)).$value.($format !== false ? "\n" : '');
				}
				$xml .= str_repeat("\t", ($format !== false ? ($tabs + 1) : 0)).'</'.$tagName.'>'.($format !== false ? "\n" : '');
			}
			else // -- no value
			{
				$xml .= str_repeat("\t", ($format !== false ? ($tabs + 1) : 0)).'<'.$tagName.' />'.($format !== false ? "\n" : '');
			}
		}
	}

	if ($depth <= 1) // -- add a root element
	{
		$xml = '<root>'.($format !== false ? "\n" : '').$xml.($format !== false ? "\n" : '').'</root>';
	}

	// ====================  Return
	return $xml;
}

function schemaValidate($xml, $xsd)
{
	//===========================================================================
	// Function: schemaValidate
	// Author: Bob Jackman
	// Date: 2008-10-21
	// Description:	Validate an XML document against an XSD
	//
	// Params:
	//	$xml {string} Required:	Path to XML file
	//	$xsd {string} Required: 	Path to XSD file
	//
	// Returns: {bool}	TRUE = valid
	//				FALSE = invalid
	//===========================================================================

	if (file_exists($xml)) // -- XML file found
	{
		if (file_exists($xsd)) // -- XSD file found
		{
			// ====================  Config LIBXML
			libxml_use_internal_errors(true);

			// ====================  Load XML Document
			$xmlDoc = new DOMDocument();
			$xmlDoc->load($xml);

			// ====================  Validate XML
			if (!$xmlDoc->schemaValidate($xsd)) // -- invalid
			{
				return false;
			}
			else // -- valid
			{
				return true;
			}
		}
		else // -- XSD file not found
		{
			throw new Exception('XSD File not found. Cannot validate.');
		}
	}
	else // -- XML file not found
	{
		throw new Exception('XML File not found. Cannot validate.');
	}
}

function schemaValidateSource($xml, $xsd)
{
	//===========================================================================
	// Function: schemaValidateSource
	// Author: Bob Jackman
	// Date: 2008-10-21
	// Description:	Validate an XML string against an XSD
	//
	// Params:
	//	$xml {string} Required:	XML string
	//	$xsd {string} Required: 	Path to XSD file
	//
	// Returns: {bool}	TRUE = valid
	//				FALSE = invalid
	//===========================================================================

	if (file_exists($xsd)) // -- XSD file found
	{
		// ====================  Config LIBXML
		libxml_use_internal_errors(true);

		// ====================  Parse XML
		$xmlDoc = new DOMDocument();
		$xmlDoc->loadXML($xml);

		// ====================  Validate XML
		if (!$xmlDoc->schemaValidate($xsd)) // -- invalid
		{
			return false;
		}
		else // -- valid
		{
			return true;
		}
	}
	else // -- XSD file not found
	{
		throw new Exception('XSD File not found. Cannot validate.');
	}
}

function libxml_display_error($error)
{
	//===========================================================================
	// Function: libxml_display_error
	// Author: Bob Jackman
	// Date: 2008-10-21
	// Description:	display LIBXML error
	//
	// Params:
	//	$error {libXMLError} Required:	Lib XML Error Object
	//
	// Returns: {void}
	//===========================================================================

	// ====================  Determine Error Type
	switch ($error->level)
	{
		case LIBXML_ERR_WARNING:
			$return .= "<b>Warning $error->code</b>: ";
			break;
		case LIBXML_ERR_ERROR:
			$return .= "<b>Error $error->code</b>: ";
			break;
		case LIBXML_ERR_FATAL:
			$return .= "<b>Fatal Error $error->code</b>: ";
			break;
	}

	// ====================  Append Error Message
	$return .= trim($error->message);

	// ====================  Append Error Location
	if ($error->file) // -- file location is specified
	{
		$return .= " in <b>$error->file</b>";
	}
	$return .= " on line <b>$error->line</b>\n";

	// =====================  Output Error
	echo $return;
}

function libxml_display_errors()
{
	//===========================================================================
	// Function: libxml_display_errors
	// Author: Bob Jackman
	// Date: 2008-10-21
	// Description:	display all LIBXML errors
	//
	// Params:
	//	None
	//
	// Returns: {void}
	//===========================================================================

	// ====================  Get Lib XML Errors
	$errors = libxml_get_errors();

	if (sizeof($errors)) // -- errors are waiting
	{
		// ====================  Display Errors
		//print '<b>DOMDocument::schemaValidate() Generated Errors!</b>';
		foreach ($errors as $error) // -- loop through each error
		{
			libxml_display_error($error);
		}

	    // ====================  Clear Errors
	    libxml_clear_errors();
	}
}

function validXsdSig(SimpleXMLElement $xmlDoc)
{
	//===========================================================================
	// Function: validXsdSig
	// Author: Bob Jackman
	// Date: 2008-10-21
	// Description:	Determine if the signature contained in an XML document
	//				is a valid Wats digital signature.
	//
	// Params:
	//	$xmlDoc {SimpleXMLElement} Required:	XML Document for which to
	//									validate the signature.
	//
	// Returns: {Bool}	TRUE = valid signature
	//				FALSE = invalid signature / no signature in XML
	//===========================================================================

	// ====================  Copy XML Object
	$xmlDoc = clone $xmlDoc;

	$valid = false;
	if (isset($xmlDoc->signature)) // -- signature exists
	{
		// ====================  Extract Signature
		$sig = strval($xmlDoc->signature->attributes()->value);
		unset($xmlDoc->signature);

		//echo generateXsdSig($xmlDoc)."<br>";

		// ====================  Validate Signature
		if ($sig == generateXsdSig($xmlDoc)) // -- signature is valid
		{
			$valid = true;
		}
	}

	// ====================  Return Validation
	return $valid;
}

function generateXsdSig(SimpleXMLElement $xmlDoc)
{
	//===========================================================================
	// Function: generateXsdSig
	// Author: Bob Jackman
	// Date: 2008-10-21
	// Description:	Generate and append a valid Wats digital signature to the
	//				supplied XML document.
	//
	// Params:
	//	$xmlDoc {SimpleXMLElement} Required:	XML Document for which to
	//									generate a signature.
	//
	// Returns: {String}	Valid Wats digital signature
	//===========================================================================

	// ====================  Copy XML Object
	$xmlDoc = clone $xmlDoc;

	// ********************
	// ********************
	$seed = 'WesternWats'; // -- Changing this seed will invalidate all previously signed documents!!!
	// ********************
	// ********************

	// ====================  Check for Existing Signature
	$sig = null;
	if (isset($xmlDoc->signature)) // -- signature already exists
	{
		if (validXsdSig($xmlDoc)) // -- existing sig is valid
		{
			$sig = strval($xmlDoc->signature->attributes()->value);
		}
		else // -- existing sig is invalid
		{
			unset($xmlDoc->signature);
		}
	}

	if ($sig === null) // -- need a new or replacement sig
	{
		// ====================  Remove All Whitespace
		$xml = preg_replace('/\s*/', '', $xmlDoc->saveXML());

		// ====================  Generate Signature
		$sig = sha1($seed.$xml);
	}

	// ====================  Return Signature Value
	return $sig;
}

?>