/* 
    This file was generated by "mtxrun --script "mtx-wtoc.lua" from the metapost cweb files but 
    now maintained as C file.
*/

# include "mpstrings.h"

/*tex
    Housekeeping: 
*/

void mp_add_string_reference(MP mp, mp_string s) 
{
    (void) mp;
    if (s->refs < MAX_STR_REF) {
        (s->refs)++;
    }
}

void mp_delete_string_reference(MP mp, mp_string s) 
{
    if (s->refs < MAX_STR_REF) { 
        if (s->refs > 1) {
            (s->refs)--; 
        } else {
            mp_flush_string(mp, s); 
        }
    } 
}

/*tex
    Here is a routine that compares two strings in the string pool, and it does not assume that 
    they have the same length. If the first string is lexicographically greater than, less than, 
    or equal to the second, the result is respectively positive, negative, or zero.

    An earlier version of this function used |strncmp|, but that produces wrong results in some 
    cases.
*/

# define STRCMP_RESULT(a) ((a) < 0 ? -1 : ((a) > 0 ? 1 : 0))

static int mp_aux_comp_strings_entry(void *p, const void *pa, const void *pb)
{
    const mp_lstring *a = (const mp_lstring *) pa;
    const mp_lstring *b = (const mp_lstring *) pb;
    unsigned char *s = a->str;
    unsigned char *t = b->str;
    size_t l = a->len <= b->len ? a->len : b->len;
    (void) p;
    while (l-- > 0) {
        if (*s != *t) {
            return STRCMP_RESULT(*s - *t);
        } else {
            s++;
            t++;
        }
    }
    return STRCMP_RESULT((int)(a->len - b->len));
}

void *mp_aux_copy_strings_entry(const void *p)
{
    mp_string ff = mp_memory_allocate(sizeof(mp_lstring));
    if (ff) {
        const mp_lstring *fp = (const mp_lstring *) p;
        ff->str = mp_memory_allocate((size_t) fp->len + 1);
        if (ff->str) {
            memcpy((char *) ff->str, (char *) fp->str, fp->len + 1);
            ff->len = fp->len;
            ff->refs = 0;
            return ff;
        }
    }
    return NULL;
}

static void *delete_strings_entry(void *p)
{
    mp_string ff = (mp_string) p;
    mp_memory_free(ff->str);
    mp_memory_free(ff);
    return NULL;
}

static mp_string new_strings_entry(void)
{
    mp_string ff = mp_memory_allocate(sizeof(mp_lstring));
    ff->str = NULL;
    ff->len = 0;
    ff->refs = 0;
    return ff;
}

char *mp_strdup(const char *s)
{
    if (s) {
        char *w = lmt_memory_strdup(s);
        if (w) {
            return w;
        } else {
            printf("mplib ran out of memory, case 3");
            exit(EXIT_FAILURE);
        }
    }
    return NULL;
}

char *mp_strndup(const char *p, size_t l)
{
    if (p) {
        char *r = mp_memory_allocate(l * sizeof(char) + 1);
        if (r) {
            char *s = memcpy(r, p, l);
            *(s + l) = '\0';
            return s;
        } else {
            printf("mplib ran out of memory, case 4");
            exit(EXIT_FAILURE);
        }
    }
    return NULL;
}

// int mp_strcmp(const char *a, const char *b)
// {
//     return a == NULL ? (b == NULL ? 0 : -1) : (b == NULL ? 1 : strcmp(a, b));
// }

void mp_initialize_strings(MP mp)
{
    mp->strings = avl_create(mp_aux_comp_strings_entry, mp_aux_copy_strings_entry, delete_strings_entry, mp_memory_allocate, mp_memory_free, NULL);
    mp->cur_string = NULL;
    mp->cur_length = 0;
    mp->cur_string_size = 0;
}

void mp_free_strings(MP mp)
{
    if (mp->strings != NULL) {
        avl_destroy(mp->strings);
    } else {
        mp->strings = NULL;
        mp_memory_free(mp->cur_string);
        mp->cur_string = NULL;
        mp->cur_length = 0;
        mp->cur_string_size = 0;
    }
}

/*tex
    Most printing is done from |char *|s, but sometimes not. Here are functions that convert an 
    internal string into a |char *| for use by the printing routines, and vice versa.
*/

// char *mp_str(MP mp, mp_string ss)
// {
//     (void) mp;
//     return (char *) ss->str;
// }

mp_string mp_rtsl(MP mp, const char *s, size_t l)
{
    mp_string nstr;
    mp_string str = new_strings_entry();
    str->str = (unsigned char *) mp_strndup(s, l);
    str->len = l;
    nstr = (mp_string) avl_find(str, mp->strings);
    if (nstr == NULL) {
        avl_ins(str, mp->strings, avl_false);
        nstr = (mp_string) avl_find(str, mp->strings);
    }
    delete_strings_entry(str);
    mp_add_string_reference(mp, nstr);
    return nstr;
}

mp_string mp_rts(MP mp, const char *s)
{
    return mp_rtsl(mp, s, strlen(s));
}


/*tex
    Strings are created by appending character codes to |cur_string|. The |mp_append_char| 
    function, defined here, does not check to see if the buffer overflows; this test is supposed 
    to be made before |mp_append_char| is used.

    To test if there is room to append |l| more characters to |cur_string|, we shall write 
    |str_room(l)|, which tries to make sure there is enough room in the |cur_string|. At the very 
    start of the metapost run and each time after |make_string| has stored a new string in the 
    avl tree, the |cur_string| variable has to be prepared so that it will be ready to start 
    creating a new string. The initial size is fairly arbitrary, but setting it a little higher 
    than expected helps prevent |reallocs|.
*/

# define EXTRA_STRING 500

void mp_str_room(MP mp, int wsize)
{
    /* we always add one more */
    if ((mp->cur_length + (size_t) wsize + 1) > mp->cur_string_size) {
        size_t nsize = mp->cur_string_size + mp->cur_string_size / 5 + EXTRA_STRING;
        if (nsize < (size_t) wsize) {
            nsize = (size_t) wsize + EXTRA_STRING;
        }
        mp->cur_string = (unsigned char *) mp_memory_reallocate(mp->cur_string, (size_t) nsize * sizeof(unsigned char));
        memset(mp->cur_string + mp->cur_length, 0, nsize-mp->cur_length);
        mp->cur_string_size = nsize;
    }
}

void mp_append_char(MP mp, unsigned char c)
{
    *(mp->cur_string + mp->cur_length) = c;
    mp->cur_length++;
}

void mp_append_str(MP mp, const char *s)
{
    int j = 0;
    while ((unsigned char) s[j]) {
        *(mp->cur_string + mp->cur_length) = s[j++];
        mp->cur_length++;
    }
}

void mp_reset_cur_string(MP mp)
{
    mp_memory_free(mp->cur_string);
    mp->cur_length = 0;
    mp->cur_string_size = 63;
    mp->cur_string = (unsigned char *) mp_memory_allocate(64 * sizeof(unsigned char));
    memset(mp->cur_string, 0, 64);
}

/*tex

    \MP's string expressions are implemented in a brute-force way: Every new string or substring 
    that is needed is simply stored into the string pool. Space is eventually reclaimed using the 
    aid of a simple system system of reference counts.

    The number of references to string number |s| will be |s->refs|. The special value |s->refs =
    MAX_STR_REF=127| is used to denote an unknown positive number of references; such strings will
    never be recycled. If a string is ever referred to more than 126 times, simultaneously, we put 
    it in this category. Here's what we do when a string reference disappears:

*/

void mp_flush_string(MP mp, mp_string s) {
    if (s->refs == 0) {
        mp->strings_in_use--;
        mp->pool_in_use = mp->pool_in_use - (int) s->len;
        avl_del(s, mp->strings, NULL);
    }
}

/*tex
    Some C literals that are used as values cannot be simply added, their reference count has to be
    set such that they can not be flushed.
*/

mp_string mp_intern(MP mp, const char *s)
{
    mp_string r = mp_rts(mp, s);
    r->refs = MAX_STR_REF;
    return r;
}

/*tex

    Once a sequence of characters has been appended to |cur_string|, it officially becomes a string
    when the function |make_string| is called. This function returns a pointer to the new string as 
    its value.

 */

mp_string mp_make_string(MP mp)
{
    mp_lstring tmp = {
        .str = mp->cur_string,
        .len = mp->cur_length,
    };
    mp_string str = (mp_string) avl_find(&tmp, mp->strings);
    if (str == NULL) {
        str = mp_memory_allocate(sizeof(mp_lstring));
        str->str = mp->cur_string;
        str->len = tmp.len;
        avl_ins(str, mp->strings, avl_false);
        str = (mp_string) avl_find(&tmp, mp->strings);
        mp->pool_in_use = mp->pool_in_use + (int) str->len;
        if (mp->pool_in_use > mp->max_pool_used) {
            mp->max_pool_used = mp->pool_in_use;
        }
        mp->strings_in_use++;
        if (mp->strings_in_use > mp->max_strings_used) {
            mp->max_strings_used = mp->strings_in_use;
        }
    }
    mp_add_string_reference(mp, str);
    mp_reset_cur_string(mp);
    return str;
}

int mp_str_vs_str(MP mp, mp_string s, mp_string t)
{
    (void) mp;
    return mp_aux_comp_strings_entry(NULL, (const void *) s, (const void *) t);
}

mp_string mp_cat(MP mp, mp_string a, mp_string b)
{
    mp_string str;
    size_t saved_cur_length = mp->cur_length;
    unsigned char *saved_cur_string = mp->cur_string;
    size_t saved_cur_string_size = mp->cur_string_size;
    size_t needed = a->len + b->len;
    mp->cur_length = 0;
    /* |mp->cur_string = NULL;|  needs malloc, spotted by clang */
    mp->cur_string = (unsigned char *) mp_memory_allocate((size_t) (needed + 1) * sizeof(unsigned char));
    mp->cur_string_size = 0;
    mp_str_room(mp, (int) needed + 1);
    memcpy(mp->cur_string, a->str, a->len);
    memcpy(mp->cur_string + a->len, b->str, b->len);
    mp->cur_length = needed;
    mp->cur_string[needed] = '\0';
    str = mp_make_string(mp);
    mp_memory_free(mp->cur_string); /* created by |mp_make_string| */
    mp->cur_length = saved_cur_length;
    mp->cur_string = saved_cur_string;
    mp->cur_string_size = saved_cur_string_size;
    return str;
}

mp_string mp_chop_string(MP mp, mp_string s, int a, int b)
{
    int l = (int) s->len;
    int reversed;
    if (a <= b) {
        reversed = 0;
    } else {
        int k = a;
        a = b;
        b = k;
        reversed = 1;
    }
    if (a < 0) {
        a = 0;
        if (b < 0) {
            b = 0;
        }
    }
    if (b > l) {
        b = l;
        if (a > l) {
            a = l;
        }
    }
    mp_str_room(mp, (b - a));
    if (reversed) {
        for (int k = b - 1; k >= a; k--) {
            mp_append_char(mp, *(s->str + k));
        }
    } else {
        for (int k = a; k < b; k++) {
            mp_append_char(mp, *(s->str + k));
        }
    }
    return mp_make_string(mp);
}
