/*
 * attrvt.c: Implementation of the XSL Transformation 1.0 engine
 *           attribute value template handling part.
 *
 * References:
 *   http://www.w3.org/TR/1999/REC-xslt-19991116
 *
 *   Michael Kay "XSLT Programmer's Reference" pp 637-643
 *   Writing Multiple Output Files
 *
 * See Copyright for the status of this software.
 *
 * daniel@veillard.com
 */

#define IN_LIBXSLT
#include "libxslt.h"

#include <string.h>

#include <libxml/xmlmemory.h>
#include <libxml/tree.h>
#include <libxml/xpath.h>
#include <libxml/xpathInternals.h>
#include "xslt.h"
#include "xsltutils.h"
#include "xsltInternals.h"
#include "templates.h"

#ifdef WITH_XSLT_DEBUG
#define WITH_XSLT_DEBUG_AVT
#endif

#define MAX_AVT_SEG 10

typedef struct _xsltAttrVT xsltAttrVT;
typedef xsltAttrVT *xsltAttrVTPtr;
struct _xsltAttrVT {
    struct _xsltAttrVT *next; /* next xsltAttrVT */
    int nb_seg;     /* Number of segments */
    int max_seg;    /* max capacity before re-alloc needed */
    int strstart;   /* is the start a string */
    /*
     * the namespaces in scope
     */
    xmlNsPtr *nsList;
    int nsNr;
    /*
     * the content is an alternate of string and xmlXPathCompExprPtr
     */
#if __STDC_VERSION__ >= 199901L
    /* Using a C99 flexible array member avoids false positives under UBSan */
    void *segments[];
#else
    void *segments[1];
#endif
};

/**
 * xsltNewAttrVT:
 * @style:  a XSLT process context
 *
 * Build a new xsltAttrVT structure
 *
 * Returns the structure or NULL in case of error
 */
static xsltAttrVTPtr
xsltNewAttrVT(xsltStylesheetPtr style) {
    xsltAttrVTPtr cur;
    size_t size = sizeof(xsltAttrVT) + MAX_AVT_SEG * sizeof(void*);

    cur = (xsltAttrVTPtr) xmlMalloc(size);
    if (cur == NULL) {
    xsltTransformError(NULL, style, NULL,
        "xsltNewAttrVTPtr : malloc failed\n");
    if (style != NULL) style->errors++;
    return(NULL);
    }
    memset(cur, 0, size);

    cur->nb_seg = 0;
    cur->max_seg = MAX_AVT_SEG;
    cur->strstart = 0;
    cur->next = style->attVTs;
    /*
     * Note: this pointer may be changed by a re-alloc within xsltCompileAttr,
     * so that code may change the stylesheet pointer also!
     */
    style->attVTs = (xsltAttrVTPtr) cur;

    return(cur);
}

/**
 * xsltFreeAttrVT:
 * @avt: pointer to an xsltAttrVT structure
 *
 * Free up the memory associated to the attribute value template
 */
static void
xsltFreeAttrVT(xsltAttrVTPtr avt) {
    int i;

    if (avt == NULL) return;

    if (avt->strstart == 1) {
    for (i = 0;i < avt->nb_seg; i += 2)
        if (avt->segments[i] != NULL)
        xmlFree((xmlChar *) avt->segments[i]);
    for (i = 1;i < avt->nb_seg; i += 2)
        xmlXPathFreeCompExpr((xmlXPathCompExprPtr) avt->segments[i]);
    } else {
    for (i = 0;i < avt->nb_seg; i += 2)
        xmlXPathFreeCompExpr((xmlXPathCompExprPtr) avt->segments[i]);
    for (i = 1;i < avt->nb_seg; i += 2)
        if (avt->segments[i] != NULL)
        xmlFree((xmlChar *) avt->segments[i]);
    }
    if (avt->nsList != NULL)
        xmlFree(avt->nsList);
    xmlFree(avt);
}

/**
 * xsltFreeAVTList:
 * @avt: pointer to an list of AVT structures
 *
 * Free up the memory associated to the attribute value templates
 */
void
xsltFreeAVTList(void *avt) {
    xsltAttrVTPtr cur = (xsltAttrVTPtr) avt, next;

    while (cur != NULL) {
        next = cur->next;
    xsltFreeAttrVT(cur);
    cur = next;
    }
}
/**
 * xsltSetAttrVTsegment:
 * @ avt: pointer to an xsltAttrVT structure
 * @ val: the value to be set to the next available segment
 *
 * Within xsltCompileAttr there are several places where a value
 * needs to be added to the 'segments' array within the xsltAttrVT
 * structure, and at each place the allocated size may have to be
 * re-allocated.  This routine takes care of that situation.
 *
 * Returns the avt pointer, which may have been changed by a re-alloc
 */
static xsltAttrVTPtr
xsltSetAttrVTsegment(xsltAttrVTPtr avt, void *val) {
    if (avt->nb_seg >= avt->max_seg) {
        size_t size = sizeof(xsltAttrVT) +
                      (avt->max_seg + MAX_AVT_SEG) * sizeof(void *);
    xsltAttrVTPtr tmp = (xsltAttrVTPtr) xmlRealloc(avt, size);
    if (tmp == NULL) {
            xsltFreeAttrVT(avt);
        return NULL;
    }
        avt = tmp;
    memset(&avt->segments[avt->nb_seg], 0, MAX_AVT_SEG*sizeof(void *));
    avt->max_seg += MAX_AVT_SEG;
    }
    avt->segments[avt->nb_seg++] = val;
    return avt;
}

/**
 * xsltCompileAttr:
 * @style:  a XSLT process context
 * @attr: the attribute coming from the stylesheet.
 *
 * Precompile an attribute in a stylesheet, basically it checks if it is
 * an attribute value template, and if yes, establish some structures needed
 * to process it at transformation time.
 */
void
xsltCompileAttr(xsltStylesheetPtr style, xmlAttrPtr attr) {
    const xmlChar *str;
    const xmlChar *cur;
    xmlChar *ret = NULL;
    xmlChar *expr = NULL;
    xsltAttrVTPtr avt;
    int i = 0, lastavt = 0;

    if ((style == NULL) || (attr == NULL) || (attr->children == NULL))
        return;
    if ((attr->children->type != XML_TEXT_NODE) ||
        (attr->children->next != NULL)) {
        xsltTransformError(NULL, style, attr->parent,
        "Attribute '%s': The content is expected to be a single text "
        "node when compiling an AVT.\n", attr->name);
    style->errors++;
    return;
    }
    str = attr->children->content;
    if ((xmlStrchr(str, '{') == NULL) &&
        (xmlStrchr(str, '}') == NULL)) return;

#ifdef WITH_XSLT_DEBUG_AVT
    xsltGenericDebug(xsltGenericDebugContext,
            "Found AVT %s: %s\n", attr->name, str);
#endif
    if (attr->psvi != NULL) {
#ifdef WITH_XSLT_DEBUG_AVT
    xsltGenericDebug(xsltGenericDebugContext,
            "AVT %s: already compiled\n", attr->name);
#endif
        return;
    }
    /*
    * Create a new AVT object.
    */
    avt = xsltNewAttrVT(style);
    if (avt == NULL)
    return;
    attr->psvi = avt;

    avt->nsList = xmlGetNsList(attr->doc, attr->parent);
    if (avt->nsList != NULL) {
    while (avt->nsList[i] != NULL)
        i++;
    }
    avt->nsNr = i;

    cur = str;
    while (*cur != 0) {
    if (*cur == '{') {
        if (*(cur+1) == '{') {  /* escaped '{' */
            cur++;
        ret = xmlStrncat(ret, str, cur - str);
        cur++;
        str = cur;
        continue;
        }
        if (*(cur+1) == '}') {  /* skip empty AVT */
        ret = xmlStrncat(ret, str, cur - str);
            cur += 2;
        str = cur;
        continue;
        }
        if ((ret != NULL) || (cur - str > 0)) {
        ret = xmlStrncat(ret, str, cur - str);
        str = cur;
        if (avt->nb_seg == 0)
            avt->strstart = 1;
        if ((avt = xsltSetAttrVTsegment(avt, (void *) ret)) == NULL)
            goto error;
        ret = NULL;
        lastavt = 0;
        }

        cur++;
        while ((*cur != 0) && (*cur != '}')) {
        /* Need to check for literal (bug539741) */
        if ((*cur == '\'') || (*cur == '"')) {
            char delim = *(cur++);
            while ((*cur != 0) && (*cur != delim))
            cur++;
            if (*cur != 0)
            cur++;  /* skip the ending delimiter */
        } else
            cur++;
        }
        if (*cur == 0) {
            xsltTransformError(NULL, style, attr->parent,
             "Attribute '%s': The AVT has an unmatched '{'.\n",
             attr->name);
        style->errors++;
        goto error;
        }
        str++;
        expr = xmlStrndup(str, cur - str);
        if (expr == NULL) {
        /*
        * TODO: What needs to be done here?
        */
            XSLT_TODO
        goto error;
        } else {
        xmlXPathCompExprPtr comp;

        comp = xsltXPathCompile(style, expr);
        if (comp == NULL) {
            xsltTransformError(NULL, style, attr->parent,
             "Attribute '%s': Failed to compile the expression "
             "'%s' in the AVT.\n", attr->name, expr);
            style->errors++;
            goto error;
        }
        if (avt->nb_seg == 0)
            avt->strstart = 0;
        if (lastavt == 1) {
            if ((avt = xsltSetAttrVTsegment(avt, NULL)) == NULL)
                goto error;
        }
        if ((avt = xsltSetAttrVTsegment(avt, (void *) comp)) == NULL)
            goto error;
        lastavt = 1;
        xmlFree(expr);
        expr = NULL;
        }
        cur++;
        str = cur;
    } else if (*cur == '}') {
        cur++;
        if (*cur == '}') {  /* escaped '}' */
        ret = xmlStrncat(ret, str, cur - str);
        cur++;
        str = cur;
        continue;
        } else {
            xsltTransformError(NULL, style, attr->parent,
             "Attribute '%s': The AVT has an unmatched '}'.\n",
             attr->name);
        goto error;
        }
    } else
        cur++;
    }
    if ((ret != NULL) || (cur - str > 0)) {
    ret = xmlStrncat(ret, str, cur - str);
    str = cur;
    if (avt->nb_seg == 0)
        avt->strstart = 1;
    if ((avt = xsltSetAttrVTsegment(avt, (void *) ret)) == NULL)
        goto error;
    ret = NULL;
    }

error:
    if (avt == NULL) {
        xsltTransformError(NULL, style, attr->parent,
        "xsltCompileAttr: malloc problem\n");
    } else {
        if (attr->psvi != avt) {  /* may have changed from realloc */
            attr->psvi = avt;
        /*
         * This is a "hack", but I can't see any clean method of
         * doing it.  If a re-alloc has taken place, then the pointer
         * for this AVT may have changed.  style->attVTs was set by
         * xsltNewAttrVT, so it needs to be re-set to the new value!
         */
        style->attVTs = avt;
    }
    }
    if (ret != NULL)
    xmlFree(ret);
    if (expr != NULL)
    xmlFree(expr);
}


/**
 * xsltEvalAVT:
 * @ctxt: the XSLT transformation context
 * @avt: the prevompiled attribute value template info
 * @node: the node hosting the attribute
 *
 * Process the given AVT, and return the new string value.
 *
 * Returns the computed string value or NULL, must be deallocated by the
 *         caller.
 */
xmlChar *
xsltEvalAVT(xsltTransformContextPtr ctxt, void *avt, xmlNodePtr node) {
    xmlChar *ret = NULL, *tmp;
    xmlXPathCompExprPtr comp;
    xsltAttrVTPtr cur = (xsltAttrVTPtr) avt;
    int i;
    int str;

    if ((ctxt == NULL) || (avt == NULL) || (node == NULL))
        return(NULL);
    str = cur->strstart;
    for (i = 0;i < cur->nb_seg;i++) {
        if (str) {
        ret = xmlStrcat(ret, (const xmlChar *) cur->segments[i]);
    } else {
        comp = (xmlXPathCompExprPtr) cur->segments[i];
        tmp = xsltEvalXPathStringNs(ctxt, comp, cur->nsNr, cur->nsList);
        if (tmp != NULL) {
            if (ret != NULL) {
            ret = xmlStrcat(ret, tmp);
            xmlFree(tmp);
        } else {
            ret = tmp;
        }
        }
    }
    str = !str;
    }
    return(ret);
}
