/*
 * dict.c: dictionary of reusable strings, just used to avoid allocation
 *         and freeing operations.
 *
 * Copyright (C) 2003 Daniel Veillard.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
 * MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE AUTHORS AND
 * CONTRIBUTORS ACCEPT NO RESPONSIBILITY IN ANY CONCEIVABLE MANNER.
 *
 * Author: daniel@veillard.com
 */

#define IN_LIBXML
#include "XmlEnglibxml.h"

#include <string.h>
#include "Libxml2_globals.h"

#define MAX_HASH_LEN 4
// TODO: Optimize: "Magic number" -- make it configurable global parameter
//       1 entry is 16 bytes
#define MIN_DICT_SIZE 128
#define MAX_DICT_HASH 8 * 2048

/* #define ALLOW_REMOVAL */
/* #define DEBUG_GROW */

/*
 * xmlDictAddString:
 * @dict: the dictionnary
 * @name: the name of the userdata
 * @len: the length of the name, if -1 it is recomputed
 *
 * Add the string to the array[s]
 *
 * Returns the pointer of the local string, or NULL in case of error.
 *
 * OOM: possible --> NULL is returned, OOM flag is set
 */
static const xmlChar*
xmlDictAddString(xmlDictPtr dict, const xmlChar *name, int namelen) {
    xmlDictStringsPtr pool;
    const xmlChar *ret;
    int size = 0; /* + sizeof(_xmlDictStrings) == 1024 */

    pool = dict->strings;
    while (pool != NULL) {
        if (pool->end - pool->free > namelen)
            goto found_pool;
        if (pool->size > size) size = pool->size;
            pool = pool->next;
    }
    /*
     * Not found, need to allocate
     */
    if (pool == NULL) {
        if (size == 0) 
            size = 1000;
        else 
            size *= 4; /* exponential growth */

        if (size < 4 * namelen)
            size = 4 * namelen; /* just in case ! */

        pool = (xmlDictStringsPtr) xmlMalloc(sizeof(xmlDictStrings) + size);
        if (pool == NULL)
            return(NULL);
        pool->size = size;
        pool->nbStrings = 0;
        pool->free = &pool->array[0];
        pool->end = &pool->array[size];
        pool->next = dict->strings;
        dict->strings = pool;
    }
found_pool:
    ret = pool->free;
    memcpy(pool->free, name, namelen);
    pool->free += namelen;
    *(pool->free++) = 0;
    return(ret);
}

/*
 * xmlDictAddQString:
 * @dict: the dictionnary
 * @prefix: the prefix of the userdata
 * @name: the name of the userdata
 * @len: the length of the name, if -1 it is recomputed
 *
 * Add the QName to the array[s]
 *
 * Returns the pointer of the local string, or NULL in case of error.
 */
static const xmlChar *
xmlDictAddQString(xmlDictPtr dict, const xmlChar *prefix,
                 const xmlChar *name, int namelen)
{
    xmlDictStringsPtr pool;
    const xmlChar *ret;
    int size = 0; /* + sizeof(_xmlDictStrings) == 1024 */
    int plen;

    if (prefix == NULL) return(xmlDictAddString(dict, name, namelen));
    plen = xmlStrlen(prefix);

    pool = dict->strings;
    while (pool != NULL) {
    if (pool->end - pool->free > namelen)
        goto found_pool;
    if (pool->size > size) size = pool->size;
    pool = pool->next;
    }
    /*
     * Not found, need to allocate
     */
    if (pool == NULL) {
        if (size == 0) size = 1000;
    else size *= 4; /* exponential growth */
        if (size < 4 * namelen)
        size = 4 * namelen; /* just in case ! */
    pool = (xmlDictStringsPtr) xmlMalloc(sizeof(xmlDictStrings) + size);
    if (pool == NULL)
        return(NULL);
    pool->size = size;
    pool->nbStrings = 0;
    pool->free = &pool->array[0];
    pool->end = &pool->array[size];
    pool->next = dict->strings;
    dict->strings = pool;
    }
found_pool:
    ret = pool->free;
    memcpy(pool->free, prefix, plen);
    pool->free += plen;
    *(pool->free++) = ':';
    namelen -= plen + 1;
    memcpy(pool->free, name, namelen);
    pool->free += namelen;
    *(pool->free++) = 0;
    return(ret);
}

/*
 * xmlDictComputeKey:
 * Calculate the hash key
 *
 * OOM: never
 */
static unsigned long
xmlDictComputeKey(const xmlChar *name, int namelen) {
    unsigned long value = 0L;

    if (name == NULL) return(0);
    value = *name;
    value <<= 5;
    if (namelen > 10) {
        value += name[namelen - 1];
        namelen = 10;
    }
    switch (namelen) {
        case 10: value += name[9];
        case 9: value += name[8];
        case 8: value += name[7];
        case 7: value += name[6];
        case 6: value += name[5];
        case 5: value += name[4];
        case 4: value += name[3];
        case 3: value += name[2];
        case 2: value += name[1];
        default: break;
    }
    return(value);
}

/*
 * xmlDictComputeQKey:
 * Calculate the hash key
 */
static unsigned long
xmlDictComputeQKey(const xmlChar *prefix, const xmlChar *name, int len)
{
    unsigned long value = 0L;
    int plen;

    if (prefix == NULL)
        return(xmlDictComputeKey(name, len));

    plen = xmlStrlen(prefix);
    if (plen == 0)
    value += 30 * (unsigned long) ':';
    else
    value += 30 * (*prefix);

    if (len > 10) {
        value += name[len - (plen + 1 + 1)];
        len = 10;
    if (plen > 10)
        plen = 10;
    }
    switch (plen) {
        case 10: value += prefix[9];
        case 9: value += prefix[8];
        case 8: value += prefix[7];
        case 7: value += prefix[6];
        case 6: value += prefix[5];
        case 5: value += prefix[4];
        case 4: value += prefix[3];
        case 3: value += prefix[2];
        case 2: value += prefix[1];
        case 1: value += prefix[0];
        default: break;
    }
    len -= plen;
    if (len > 0) {
        value += (unsigned long) ':';
    len--;
    }
    switch (len) {
        case 10: value += name[9];
        case 9: value += name[8];
        case 8: value += name[7];
        case 7: value += name[6];
        case 6: value += name[5];
        case 5: value += name[4];
        case 4: value += name[3];
        case 3: value += name[2];
        case 2: value += name[1];
        case 1: value += name[0];
        default: break;
    }
    return(value);
}

/**
 * xmlDictCreate:
 *
 * Create a new dictionary
 *
 * Returns the newly created dictionnary, or NULL if an error occured.
 *
 * OOM: possible --> NULL is returned; OOM flag is set
 */
xmlDictPtr
xmlDictCreate(void) {
    xmlDictPtr dict;

    dict = (xmlDictPtr)xmlMalloc(sizeof(xmlDict));
    if (dict) {
        dict->ref_counter = 1;

        dict->size = MIN_DICT_SIZE;
        dict->nbElems = 0;
        dict->dict = (xmlDictEntryPtr)xmlMalloc(MIN_DICT_SIZE * sizeof(xmlDictEntry));
        dict->strings = NULL;
        dict->subdict = NULL;
        if (dict->dict) {
            memset(dict->dict, 0, MIN_DICT_SIZE * sizeof(xmlDictEntry));
            return(dict);
        }
        xmlFree(dict); // OOM
    }
    return(NULL); // OOM
}

/**
 * xmlDictCreateSub:
 * @sub: an existing dictionnary
 *
 * Create a new dictionary, inheriting strings from the read-only
 * dictionnary @sub. On lookup, strings are first searched in the
 * new dictionnary, then in @sub, and if not found are created in the
 * new dictionnary.
 *
 * Returns the newly created dictionnary, or NULL if an error occured.
 */
xmlDictPtr
xmlDictCreateSub(xmlDictPtr sub) {
    xmlDictPtr dict = xmlDictCreate();

    if ((dict != NULL) && (sub != NULL)) {
        dict->subdict = sub;
    xmlDictReference(dict->subdict);
    }
    return(dict);
}

/**
 * xmlDictReference:
 * @dict: the dictionnary
 *
 * Increment the reference counter of a dictionary
 *
 * Returns 0 in case of success and -1 in case of error
 *
 * OOM: never
 */
int
xmlDictReference(xmlDictPtr dict) {
    if (dict == NULL) return -1;
    dict->ref_counter++;
    return(0);
}

/**
 * xmlDictGrow:
 * @dict: the dictionnary
 * @size: the new size of the dictionnary
 *
 * resize the dictionnary
 *
 * Returns 0 in case of success, -1 in case of failure
 *
 * OOM: possible --> returns -1, OOM is set
 */
static int
xmlDictGrow(xmlDictPtr dict, int size) {
    unsigned long key;
    int oldsize, i;
    xmlDictEntryPtr iter, next;
    struct _xmlDictEntry *olddict;
#ifdef DEBUG_GROW
    unsigned long nbElem = 0;
#endif

    if (dict == NULL)
        return(-1);
    if (size < 8)
        return(-1);
    if (size > 8 * 2048)
        return(-1);

    oldsize = dict->size;
    olddict = dict->dict;
    if (olddict == NULL)
        return(-1);

    dict->dict = (xmlDictEntryPtr)xmlMalloc(size * sizeof(xmlDictEntry));
    if (dict->dict == NULL) {
        dict->dict = olddict;
        return(-1);
    }
    memset(dict->dict, 0, size * sizeof(xmlDictEntry));
    dict->size = size;

    /*  If the two loops are merged, there would be situations where
    a new entry needs to allocated and data copied into it from
    the main dict. So instead, we run through the array twice, first
    copying all the elements in the main array (where we can't get
    conflicts) and then the rest, so we only free (and don't allocate)
    */
    for (i = 0; i < oldsize; i++) {
        if (olddict[i].valid == 0)
            continue;
        key = xmlDictComputeKey(olddict[i].name, olddict[i].len) % dict->size;
        memcpy(&(dict->dict[key]), &(olddict[i]), sizeof(xmlDictEntry));
        dict->dict[key].next = NULL;
#ifdef DEBUG_GROW
        nbElem++;
#endif
    }

    for (i = 0; i < oldsize; i++) {
        iter = olddict[i].next;
        while (iter) {
            next = iter->next;
            /*
            * put back the entry in the new dict
            */
            key = xmlDictComputeKey(iter->name, iter->len) % dict->size;
            if (dict->dict[key].valid == 0) {
                memcpy(&(dict->dict[key]), iter, sizeof(xmlDictEntry));
                dict->dict[key].next = NULL;
                dict->dict[key].valid = 1;
                xmlFree(iter);
            } else {
                iter->next = dict->dict[key].next;
                dict->dict[key].next = iter;
            }
#ifdef DEBUG_GROW
            nbElem++;
#endif
            iter = next;
        } // while (iter)
    } // for (i = 0; i < oldsize; i++)

    xmlFree(olddict);

#ifdef DEBUG_GROW
    xmlGenericError(xmlGenericErrorContext,
        "xmlDictGrow : from %d to %d, %d elems\n", oldsize, size, nbElem);
#endif

    return(0);
}

/**
 * xmlDictFree:
 * @dict: the dictionnary
 *
 * Free the hash @dict and its contents. The userdata is
 * deallocated with @f if provided.
 */
void
xmlDictFree(xmlDictPtr dict) {
    int i;
    xmlDictEntryPtr iter;
    xmlDictEntryPtr next;
    int inside_dict = 0;
    xmlDictStringsPtr pool, nextp;

    if (dict == NULL)
        return;

    /* decrement the counter, it may be shared by a parser and docs */
    dict->ref_counter--;
    if (dict->ref_counter > 0)
        return;

    if (dict->subdict != NULL) {
        xmlDictFree(dict->subdict);
    }

    if (dict->dict) {
        for(i = 0; ((i < dict->size) && (dict->nbElems > 0)); i++)
        {
            iter = &(dict->dict[i]);
            if (iter->valid == 0)
                continue;
            inside_dict = 1;
            while (iter)
            {
                next = iter->next;
                if (!inside_dict)
                    xmlFree(iter);
                dict->nbElems--;
                inside_dict = 0;
                iter = next;
            }
            inside_dict = 0;
        }
        xmlFree(dict->dict);
    }

    pool = dict->strings;
    while (pool != NULL) {
        nextp = pool->next;
        xmlFree(pool);
        pool = nextp;
    }
    xmlFree(dict);
}

/**
 * xmlDictLookup:
 * @dict: the dictionnary
 * @name: the name of the userdata
 * @len: the length of the name, if -1 it is recomputed
 *
 * Add the @name to the hash @dict if not present.
 *
 * Returns the internal copy of the name or NULL in case of internal error
 *
 * OOM: possible --> returns NULL and OOM flag is set
 */
const xmlChar*
xmlDictLookup(xmlDictPtr dict, const xmlChar *name, int len) {
    unsigned long key, okey, nbi = 0;
    xmlDictEntryPtr entry;
    xmlDictEntryPtr insert;
    const xmlChar *ret;

    if ((dict == NULL) || (name == NULL))
        return(NULL);

    if (len < 0)
        len = xmlStrlen(name);

    /*
     * Check for duplicate and insertion location.
     */
    okey = xmlDictComputeKey(name, len);
    key = okey % dict->size;
    if (dict->dict[key].valid == 0) {
        insert = NULL;
    } else {
        for (insert = &(dict->dict[key]); 
             insert->next != NULL; 
             insert = insert->next)
        {
#ifdef __GNUC__
            if (insert->len == len) {
                if (!memcmp(insert->name, name, len))
                    return(insert->name);
            }
#else
            if ((insert->len == len) && (!xmlStrncmp(insert->name, name, len)))
                return(insert->name);
#endif
            nbi++;
        }
#ifdef __GNUC__
        if (insert->len == len) {
            if (!memcmp(insert->name, name, len))
                return(insert->name);
        }
#else
        if ((insert->len == len) && (!xmlStrncmp(insert->name, name, len)))
            return(insert->name);
#endif
    }

    if (dict->subdict) {
        key = okey % dict->subdict->size;
        if (dict->subdict->dict[key].valid != 0) {
            xmlDictEntryPtr tmp;
    
            for (tmp = &(dict->subdict->dict[key]); tmp->next != NULL; tmp = tmp->next)
            {
#ifdef __GNUC__
                if (tmp->len == len) {
                    if (!memcmp(tmp->name, name, len))
                        return(tmp->name);
                }
#else
                if ((tmp->len == len) && (!xmlStrncmp(tmp->name, name, len)))
                        return(tmp->name);
#endif
                nbi++;
            }
#ifdef __GNUC__
            if (tmp->len == len) {
                if (!memcmp(tmp->name, name, len))
                    return(tmp->name);
            }
#else
            if ((tmp->len == len) && (!xmlStrncmp(tmp->name, name, len)))
                return(tmp->name);
#endif
        } // if (dict->subdict->dict[key].valid != 0)

        key = okey % dict->size;
    } // if (dict->subdict)

    ret = xmlDictAddString(dict, name, len); // may set OOM flag
    if (!ret)
        return(NULL);

    if (insert == NULL) {
        entry = &(dict->dict[key]);
    } else {
        entry = (xmlDictEntryPtr)xmlMalloc(sizeof(xmlDictEntry));
        if (entry == NULL)
             return(NULL); //OOM
    }
    entry->name = ret;
    entry->len = len;
    entry->next = NULL;
    entry->valid = 1;

    if (insert != NULL)
        insert->next = entry;

    dict->nbElems++;

    if ((nbi > MAX_HASH_LEN) && 
        (dict->size <= ((MAX_DICT_HASH / 2) / MAX_HASH_LEN)))
    {
        xmlDictGrow(dict, MAX_HASH_LEN * 2 * dict->size);
        if(OOM_FLAG)
            return NULL;
    }

    /* Note that entry may have been freed at this point by xmlDictGrow */

    return(ret);
}

/**
 * xmlDictQLookup:
 * @dict: the dictionnary
 * @prefix: the prefix
 * @name: the name
 *
 * Add the QName @prefix:@name to the hash @dict if not present.
 *
 * Returns the internal copy of the QName or NULL in case of internal error
 */
const xmlChar *
xmlDictQLookup(xmlDictPtr dict, const xmlChar *prefix, const xmlChar *name) {
    unsigned long okey, key, nbi = 0;
    xmlDictEntryPtr entry;
    xmlDictEntryPtr insert;
    const xmlChar *ret;
    int len;

    if ((dict == NULL) || (name == NULL))
    return(NULL);

    len = xmlStrlen(name);
    if (prefix != NULL)
        len += 1 + xmlStrlen(prefix);

    /*
     * Check for duplicate and insertion location.
     */
    okey = xmlDictComputeQKey(prefix, name, len);
    key = okey % dict->size;
    if (dict->dict[key].valid == 0) {
    insert = NULL;
    } else {
    for (insert = &(dict->dict[key]); insert->next != NULL;
         insert = insert->next) {
        if ((insert->len == len) &&
            (xmlStrQEqual(prefix, name, insert->name)))
        return(insert->name);
        nbi++;
    }
    if ((insert->len == len) &&
        (xmlStrQEqual(prefix, name, insert->name)))
        return(insert->name);
    }

    if (dict->subdict) {
    key = okey % dict->subdict->size;
    if (dict->subdict->dict[key].valid != 0) {
        xmlDictEntryPtr tmp;
        for (tmp = &(dict->subdict->dict[key]); tmp->next != NULL;
         tmp = tmp->next) {
        if ((tmp->len == len) &&
            (xmlStrQEqual(prefix, name, tmp->name)))
            return(tmp->name);
        nbi++;
        }
        if ((tmp->len == len) &&
        (xmlStrQEqual(prefix, name, tmp->name)))
        return(tmp->name);
    }
    key = okey % dict->size;
    }

    ret = xmlDictAddQString(dict, prefix, name, len);
    if (ret == NULL)
        return(NULL);
    if (insert == NULL) {
    entry = &(dict->dict[key]);
    } else {
        entry = (xmlDictEntryPtr)xmlMalloc(sizeof(xmlDictEntry));
    if (entry == NULL)
         return(NULL);
    }
    entry->name = ret;
    entry->len = len;
    entry->next = NULL;
    entry->valid = 1;

    if (insert != NULL)
    insert->next = entry;

    dict->nbElems++;

    if ((nbi > MAX_HASH_LEN) &&
        (dict->size <= ((MAX_DICT_HASH / 2) / MAX_HASH_LEN)))
    xmlDictGrow(dict, MAX_HASH_LEN * 2 * dict->size);
    /* Note that entry may have been freed at this point by xmlDictGrow */

    return(ret);
}


/**
 * xmlDictOwns:
 * @dict: the dictionnary
 * @str: the string
 *
 * check if a string is owned by the disctionary
 *
 * Returns 1 if true, 0 if false and -1 in case of error
 * -1 in case of error
 *
 * OOM: impossible
 */
int
xmlDictOwns(xmlDictPtr dict, const xmlChar *str) {
    xmlDictStringsPtr pool;

    if ((dict == NULL) || (str == NULL))
    {
        return(-1);
    }
    pool = dict->strings;
    while (pool != NULL) {
        if ((str >= pool->array) && (str <= pool->free))
        {
            return(1);
        }
        pool = pool->next;
    }
    if (dict->subdict)
        return(xmlDictOwns(dict->subdict, str));
    return(0);
}