/** 
 * XML Security Library (http://www.aleksey.com/xmlsec).
 *
 * XSLT Transform (http://www.w3.org/TR/xmldsig-core/#sec-XSLT)
 *
 * This is free software; see Copyright file in the source
 * distribution for preciese wording.
 * 
 * Copyright (C) 2002-2003 Aleksey Sanin <aleksey@aleksey.com>
 */
#include "globals.h"

#ifndef XMLSEC_NO_XSLT

#include <stdlib.h>
#include <string.h>
 
#include <libxml/tree.h>
#include <libxslt/xslt.h>
#include <libxslt/xsltInternals.h>
#include <libxslt/transform.h>
#include <libxslt/xsltutils.h>

#include <xmlsec/xmlsec.h>
#include <xmlsec/xmltree.h>
#include <xmlsec/keys.h>
#include <xmlsec/transforms.h>
#include <xmlsec/keys.h>
#include <xmlsec/parser.h>
#include <xmlsec/errors.h>

/**************************************************************************
 *
 * Internal xslt ctx
 *
 *****************************************************************************/
typedef struct _xmlSecXsltCtx			xmlSecXsltCtx, *xmlSecXsltCtxPtr;
struct _xmlSecXsltCtx {
    xsltStylesheetPtr	xslt;
    xmlParserCtxtPtr 	parserCtx;
};	    

/****************************************************************************
 *
 * XSLT transform
 *
 * xmlSecXsltCtx is located after xmlSecTransform
 * 
 ***************************************************************************/
#define xmlSecXsltSize	\
    (sizeof(xmlSecTransform) + sizeof(xmlSecXsltCtx))	
#define xmlSecXsltGetCtx(transform) \
    ((xmlSecXsltCtxPtr)(((xmlSecByte*)(transform)) + sizeof(xmlSecTransform)))

static int		xmlSecXsltInitialize			(xmlSecTransformPtr transform);
static void		xmlSecXsltFinalize			(xmlSecTransformPtr transform);
static int 		xmlSecXsltReadNode			(xmlSecTransformPtr transform,
								 xmlNodePtr node,
								 xmlSecTransformCtxPtr transformCtx);
static int 		xmlSecXsltPushBin			(xmlSecTransformPtr transform, 
								 const xmlSecByte* data,
								 xmlSecSize dataSize,
								 int final,
							         xmlSecTransformCtxPtr transformCtx);
static int  		xmlSecXsltExecute			(xmlSecTransformPtr transform, 
								 int last,
								 xmlSecTransformCtxPtr transformCtx);
static int		xmlSecXslProcess			(xmlSecBufferPtr in,
								 xmlSecBufferPtr out,
								 xsltStylesheetPtr stylesheet);
static xmlSecTransformKlass xmlSecXsltKlass = {
    /* klass/object sizes */
    sizeof(xmlSecTransformKlass),		/* xmlSecSize klassSize */
    xmlSecXsltSize,				/* xmlSecSize objSize */

    xmlSecNameXslt,				/* const xmlChar* name; */
    xmlSecHrefXslt, 				/* const xmlChar* href; */
    xmlSecTransformUsageDSigTransform,		/* xmlSecAlgorithmUsage usage; */

    xmlSecXsltInitialize,			/* xmlSecTransformInitializeMethod initialize; */
    xmlSecXsltFinalize,				/* xmlSecTransformFinalizeMethod finalize; */
    xmlSecXsltReadNode,				/* xmlSecTransformNodeReadMethod readNode; */
    NULL,					/* xmlSecTransformNodeWriteMethod writeNode; */
    NULL,					/* xmlSecTransformSetKeyReqMethod setKeyReq; */
    NULL,					/* xmlSecTransformSetKeyMethod setKey; */
    NULL,					/* xmlSecTransformValidateMethod validate; */
    xmlSecTransformDefaultGetDataType,		/* xmlSecTransformGetDataTypeMethod getDataType; */
    xmlSecXsltPushBin,				/* xmlSecTransformPushBinMethod pushBin; */
    xmlSecTransformDefaultPopBin,		/* xmlSecTransformPopBinMethod popBin; */
    NULL,					/* xmlSecTransformPushXmlMethod pushXml; */
    NULL,					/* xmlSecTransformPopXmlMethod popXml; */
    xmlSecXsltExecute,				/* xmlSecTransformExecuteMethod execute; */
    
    NULL,					/* void* reserved0; */
    NULL,					/* void* reserved1; */
};

/**
 * xmlSecTransformXsltGetKlass:
 *
 * XSLT transform klass (http://www.w3.org/TR/xmldsig-core/#sec-XSLT):
 *
 * The normative specification for XSL Transformations is [XSLT]. 
 * Specification of a namespace-qualified stylesheet element, which MUST be 
 * the sole child of the Transform element, indicates that the specified style 
 * sheet should be used. Whether this instantiates in-line processing of local 
 * XSLT declarations within the resource is determined by the XSLT processing 
 * model; the ordered application of multiple stylesheet may require multiple 
 * Transforms. No special provision is made for the identification of a remote 
 * stylesheet at a given URI because it can be communicated via an  xsl:include 
 * or  xsl:import within the stylesheet child of the Transform.
 *
 * This transform requires an octet stream as input. If the actual input is an 
 * XPath node-set, then the signature application should attempt to convert it 
 * to octets (apply Canonical XML]) as described in the Reference Processing 
 * Model (section 4.3.3.2).]
 *
 * The output of this transform is an octet stream. The processing rules for 
 * the XSL style sheet or transform element are stated in the XSLT specification
 * [XSLT]. We RECOMMEND that XSLT transform authors use an output method of xml 
 * for XML and HTML. As XSLT implementations do not produce consistent 
 * serializations of their output, we further RECOMMEND inserting a transform 
 * after the XSLT transform to canonicalize the output. These steps will help 
 * to ensure interoperability of the resulting signatures among applications 
 * that support the XSLT transform. Note that if the output is actually HTML, 
 * then the result of these steps is logically equivalent [XHTML].
 *
 * Returns: pointer to XSLT transform klass.
 */
xmlSecTransformId 
xmlSecTransformXsltGetKlass(void) {
    return(&xmlSecXsltKlass);
}
    
static int 
xmlSecXsltInitialize(xmlSecTransformPtr transform) {    
    xmlSecXsltCtxPtr ctx;
    
    xmlSecAssert2(xmlSecTransformCheckId(transform, xmlSecTransformXsltId), -1);
    xmlSecAssert2(xmlSecTransformCheckSize(transform, xmlSecXsltSize), -1);

    ctx = xmlSecXsltGetCtx(transform);
    xmlSecAssert2(ctx != NULL, -1);
    
    /* initialize context */
    memset(ctx, 0, sizeof(xmlSecXsltCtx));
    return(0);
}

static void
xmlSecXsltFinalize(xmlSecTransformPtr transform) {
    xmlSecXsltCtxPtr ctx;

    xmlSecAssert(xmlSecTransformCheckId(transform, xmlSecTransformXsltId));
    xmlSecAssert(xmlSecTransformCheckSize(transform, xmlSecXsltSize));

    ctx = xmlSecXsltGetCtx(transform);
    xmlSecAssert(ctx != NULL);
    
    if(ctx->xslt != NULL) {
	xsltFreeStylesheet(ctx->xslt);
    }
    if(ctx->parserCtx != NULL) {
	xmlFreeParserCtxt(ctx->parserCtx);
    }
    memset(ctx, 0, sizeof(xmlSecXsltCtx));
}

static int
xmlSecXsltReadNode(xmlSecTransformPtr transform, xmlNodePtr node, xmlSecTransformCtxPtr transformCtx) {
    xmlSecXsltCtxPtr ctx;
    xmlBufferPtr buffer;
    xmlDocPtr doc;
    xmlNodePtr cur;
    
    xmlSecAssert2(xmlSecTransformCheckId(transform, xmlSecTransformXsltId), -1);
    xmlSecAssert2(xmlSecTransformCheckSize(transform, xmlSecXsltSize), -1);
    xmlSecAssert2(node != NULL, -1);    
    xmlSecAssert2(transformCtx != NULL, -1);    

    ctx = xmlSecXsltGetCtx(transform);
    xmlSecAssert2(ctx != NULL, -1);
    xmlSecAssert2(ctx->xslt == NULL, -1);

    /* read content in the buffer */    
    buffer = xmlBufferCreate();
    if(buffer == NULL) {
	xmlSecError(XMLSEC_ERRORS_HERE,
		    xmlSecErrorsSafeString(xmlSecTransformGetName(transform)),
		    "xmlBufferCreate",
		    XMLSEC_ERRORS_R_XML_FAILED,
		    XMLSEC_ERRORS_NO_MESSAGE);
	return(-1);
    }    
    cur = node->children;
    while(cur != NULL) {
	xmlNodeDump(buffer, cur->doc, cur, 0, 0);
	cur = cur->next;
    }
    
    /* parse the buffer */
    doc = xmlSecParseMemory(xmlBufferContent(buffer), 
			     xmlBufferLength(buffer), 1);
    if(doc == NULL) {
	xmlSecError(XMLSEC_ERRORS_HERE,
		    xmlSecErrorsSafeString(xmlSecTransformGetName(transform)),
		    "xmlSecParseMemory",
		    XMLSEC_ERRORS_R_XMLSEC_FAILED,
		    XMLSEC_ERRORS_NO_MESSAGE);
	xmlBufferFree(buffer);
	return(-1);
    }

    /* pre-process stylesheet */    
    ctx->xslt = xsltParseStylesheetDoc(doc);
    if(ctx->xslt == NULL) {
	xmlSecError(XMLSEC_ERRORS_HERE,
		    xmlSecErrorsSafeString(xmlSecTransformGetName(transform)),
		    "xsltParseStylesheetDoc",
		    XMLSEC_ERRORS_R_XSLT_FAILED,
		    XMLSEC_ERRORS_NO_MESSAGE);
	/* after parsing stylesheet doc is assigned
	 * to it and will be freed by xsltFreeStylesheet() */    
	xmlFreeDoc(doc);
	xmlBufferFree(buffer);
	return(-1);
    }
    
    xmlBufferFree(buffer);
    return(0);
}

static int 
xmlSecXsltPushBin(xmlSecTransformPtr transform, const xmlSecByte* data,
				xmlSecSize dataSize, int final, xmlSecTransformCtxPtr transformCtx) {
    xmlSecXsltCtxPtr ctx;
    int ret;
    
    xmlSecAssert2(xmlSecTransformCheckId(transform, xmlSecTransformXsltId), -1);
    xmlSecAssert2(xmlSecTransformCheckSize(transform, xmlSecXsltSize), -1);
    xmlSecAssert2(transformCtx != NULL, -1);

    ctx = xmlSecXsltGetCtx(transform);
    xmlSecAssert2(ctx != NULL, -1);
    xmlSecAssert2(ctx->xslt != NULL, -1);

    /* check/update current transform status */
    if(transform->status == xmlSecTransformStatusNone) {
	xmlSecAssert2(ctx->parserCtx == NULL, -1);
	
	ctx->parserCtx = xmlCreatePushParserCtxt(NULL, NULL, NULL, 0, NULL);
	if(ctx->parserCtx == NULL) {
	    xmlSecError(XMLSEC_ERRORS_HERE,
			xmlSecErrorsSafeString(xmlSecTransformGetName(transform)),
			"xmlCreatePushParserCtxt",
		        XMLSEC_ERRORS_R_XML_FAILED,
			XMLSEC_ERRORS_NO_MESSAGE);
	    return(-1);
	}

        /* required for c14n! */
	ctx->parserCtx->loadsubset = XML_DETECT_IDS | XML_COMPLETE_ATTRS; 
	ctx->parserCtx->replaceEntities = 1;

	transform->status = xmlSecTransformStatusWorking;
    } else if(transform->status == xmlSecTransformStatusFinished) {
	return(0);
    } else if(transform->status != xmlSecTransformStatusWorking) {
	xmlSecError(XMLSEC_ERRORS_HERE, 
		    xmlSecErrorsSafeString(xmlSecTransformGetName(transform)),
		    NULL,
		    XMLSEC_ERRORS_R_INVALID_STATUS,
		    "status=%d", transform->status);
	return(-1);
    }
    xmlSecAssert2(transform->status == xmlSecTransformStatusWorking, -1);
    xmlSecAssert2(ctx->parserCtx != NULL, -1);
    
    /* push data to the input buffer */
    if((data != NULL) && (dataSize > 0)) {
	ret = xmlParseChunk(ctx->parserCtx, (const char*)data, dataSize, 0);
	if(ret != 0) {
	    xmlSecError(XMLSEC_ERRORS_HERE,
			xmlSecErrorsSafeString(xmlSecTransformGetName(transform)),
			"xmlParseChunk",
			XMLSEC_ERRORS_R_XML_FAILED,
			"size=%d", dataSize);
	    return(-1);
	}	
    }    
    
    /* finish parsing, apply xslt transforms and push to next in the chain */
    if(final != 0) {
        xmlDocPtr docIn;
        xmlDocPtr docOut;
        xmlOutputBufferPtr output;

	/* finalize */
	ret = xmlParseChunk(ctx->parserCtx, NULL, 0, 1);
	if((ret != 0) || (ctx->parserCtx->myDoc == NULL)) {
	    xmlSecError(XMLSEC_ERRORS_HERE,
			xmlSecErrorsSafeString(xmlSecTransformGetName(transform)),
			"xmlParseChunk",
			XMLSEC_ERRORS_R_XML_FAILED,
			XMLSEC_ERRORS_NO_MESSAGE);
	    return(-1);
	}	

	/* todo: check that document is well formed? */
	docIn = ctx->parserCtx->myDoc;
	ctx->parserCtx->myDoc = NULL;

	docOut = xsltApplyStylesheet(ctx->xslt, docIn, NULL);
	if(docOut == NULL) {
	    xmlSecError(XMLSEC_ERRORS_HERE,
		        xmlSecErrorsSafeString(xmlSecTransformGetName(transform)),
			"xsltApplyStylesheet",
			XMLSEC_ERRORS_R_XSLT_FAILED,
			XMLSEC_ERRORS_NO_MESSAGE);
	    xmlFreeDoc(docIn);
	    return(-1);
	}
	xmlFreeDoc(docIn);
    
	if(transform->next != NULL) {
	    output = xmlSecTransformCreateOutputBuffer(transform->next, transformCtx);
	    if(output == NULL) {
		xmlSecError(XMLSEC_ERRORS_HERE,
		    	    xmlSecErrorsSafeString(xmlSecTransformGetName(transform)),
			    "xmlSecTransformCreateOutputBuffer",
			    XMLSEC_ERRORS_R_XMLSEC_FAILED,
			    XMLSEC_ERRORS_NO_MESSAGE);
		xmlFreeDoc(docOut);
		return(-1);
	    }
	} else {
	    output = xmlSecBufferCreateOutputBuffer(&(transform->outBuf));
	    if(output == NULL) {
		xmlSecError(XMLSEC_ERRORS_HERE,
			    xmlSecErrorsSafeString(xmlSecTransformGetName(transform)),
			    "xmlSecBufferCreateOutputBuffer",
			    XMLSEC_ERRORS_R_XMLSEC_FAILED,
			    XMLSEC_ERRORS_NO_MESSAGE);
		xmlFreeDoc(docOut);
		return(-1);
	    }
	}	

	ret = xsltSaveResultTo(output, docOut, ctx->xslt);
	if(ret < 0) {
	    xmlSecError(XMLSEC_ERRORS_HERE,
		        xmlSecErrorsSafeString(xmlSecTransformGetName(transform)),
			"xsltSaveResultTo",
			XMLSEC_ERRORS_R_XSLT_FAILED,
			XMLSEC_ERRORS_NO_MESSAGE);
	    xmlOutputBufferClose(output);
	    xmlFreeDoc(docOut);
	    return(-1);
	}
	ret = xmlOutputBufferClose(output);
	if(ret < 0) {
	    xmlSecError(XMLSEC_ERRORS_HERE,
		        xmlSecErrorsSafeString(xmlSecTransformGetName(transform)),
			"xmlOutputBufferClose",
			XMLSEC_ERRORS_R_XML_FAILED,
		        XMLSEC_ERRORS_NO_MESSAGE);
	    xmlFreeDoc(docOut);
	    return(-1);
	}
	xmlFreeDoc(docOut);

	transform->status = xmlSecTransformStatusFinished;
    }

    return(0);
}

static int 
xmlSecXsltExecute(xmlSecTransformPtr transform, int last, xmlSecTransformCtxPtr transformCtx) {
    xmlSecXsltCtxPtr ctx;
    xmlSecBufferPtr in, out;
    xmlSecSize inSize, outSize;
    int ret;

    xmlSecAssert2(xmlSecTransformCheckId(transform, xmlSecTransformXsltId), -1);
    xmlSecAssert2(xmlSecTransformCheckSize(transform, xmlSecXsltSize), -1);
    xmlSecAssert2(transformCtx != NULL, -1);

    ctx = xmlSecXsltGetCtx(transform);
    xmlSecAssert2(ctx != NULL, -1);
    xmlSecAssert2(ctx->xslt != NULL, -1);

    in = &(transform->inBuf);
    out = &(transform->outBuf);
    inSize = xmlSecBufferGetSize(in);
    outSize = xmlSecBufferGetSize(out);    
    
    if(transform->status == xmlSecTransformStatusNone) {
	transform->status = xmlSecTransformStatusWorking;
    } 
    
    if((transform->status == xmlSecTransformStatusWorking) && (last == 0)) {
	/* just do nothing */
	xmlSecAssert2(outSize == 0, -1);

    } else  if((transform->status == xmlSecTransformStatusWorking) && (last != 0)) {
	xmlSecAssert2(outSize == 0, -1);

	ret = xmlSecXslProcess(in, out, ctx->xslt);
	if(ret < 0) {
	    xmlSecError(XMLSEC_ERRORS_HERE, 
			xmlSecErrorsSafeString(xmlSecTransformGetName(transform)),
			"xmlSecXslProcess",
			XMLSEC_ERRORS_R_XMLSEC_FAILED,
			XMLSEC_ERRORS_NO_MESSAGE);
	    return(-1);
	}
	
	ret = xmlSecBufferRemoveHead(in, inSize);
	if(ret < 0) {
	    xmlSecError(XMLSEC_ERRORS_HERE, 
			xmlSecErrorsSafeString(xmlSecTransformGetName(transform)),
			"xmlSecBufferRemoveHead",
			XMLSEC_ERRORS_R_XMLSEC_FAILED,
			"size=%d", inSize);
	    return(-1);
	}
	
	transform->status = xmlSecTransformStatusFinished;
    } else if(transform->status == xmlSecTransformStatusFinished) {
	/* the only way we can get here is if there is no input */
	xmlSecAssert2(inSize == 0, -1);
    } else {
	xmlSecError(XMLSEC_ERRORS_HERE, 
		    xmlSecErrorsSafeString(xmlSecTransformGetName(transform)),
		    NULL,
		    XMLSEC_ERRORS_R_INVALID_STATUS,
		    "status=%d", transform->status);
	return(-1);
    }
    return(0);
}

/* TODO: create PopBin method instead */
static int 
xmlSecXslProcess(xmlSecBufferPtr in, xmlSecBufferPtr out,  xsltStylesheetPtr stylesheet) {
    xmlDocPtr docIn = NULL;
    xmlDocPtr docOut = NULL;
    xmlOutputBufferPtr output = NULL;
    int res = -1;
    int ret;

    xmlSecAssert2(in != NULL, -1);
    xmlSecAssert2(out != NULL, -1);
    xmlSecAssert2(stylesheet != NULL, -1);

    docIn = xmlSecParseMemory(xmlSecBufferGetData(in), xmlSecBufferGetSize(in), 1);
    if(docIn == NULL) {
	xmlSecError(XMLSEC_ERRORS_HERE,
		    NULL,
		    "xmlSecParseMemory",
		    XMLSEC_ERRORS_R_XMLSEC_FAILED,
		    XMLSEC_ERRORS_NO_MESSAGE);
	goto done;	
    }

    docOut = xsltApplyStylesheet(stylesheet, docIn, NULL);
    if(docOut == NULL) {
	xmlSecError(XMLSEC_ERRORS_HERE,
		    NULL,
		    "xsltApplyStylesheet",
		    XMLSEC_ERRORS_R_XSLT_FAILED,
		    XMLSEC_ERRORS_NO_MESSAGE);
	goto done;	
    }

    output = xmlSecBufferCreateOutputBuffer(out);
    if(output == NULL) {
	xmlSecError(XMLSEC_ERRORS_HERE,
		    NULL,
		    "xmlSecBufferCreateOutputBuffer",
		    XMLSEC_ERRORS_R_XMLSEC_FAILED,
		    XMLSEC_ERRORS_NO_MESSAGE);
	goto done;	
    }

    ret = xsltSaveResultTo(output, docOut, stylesheet);
    if(ret < 0) {
	xmlSecError(XMLSEC_ERRORS_HERE,
		    NULL,
		    "xsltSaveResultTo",
		    XMLSEC_ERRORS_R_XSLT_FAILED,
		    XMLSEC_ERRORS_NO_MESSAGE);
	goto done;	
    }

    ret = xmlOutputBufferClose(output);
    output = NULL;
    if(ret < 0) {
	xmlSecError(XMLSEC_ERRORS_HERE,
		    NULL,
		    "xmlOutputBufferClose",
		    XMLSEC_ERRORS_R_XML_FAILED,
		    XMLSEC_ERRORS_NO_MESSAGE);
	return(-1);
    }

    res = 0;

done:   
    if(output != NULL) xmlOutputBufferClose(output);
    if(docIn != NULL) xmlFreeDoc(docIn);
    if(docOut != NULL) xmlFreeDoc(docOut);
    return(res);    
}

#endif /* XMLSEC_NO_XSLT */