/*
 * Copyright (c) 2001, Dr Martin Porter
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
 * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
 * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
 * Neither the name of the <ORGANIZATION> nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */



#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "header.h"

#define unless(C) if(!(C))

#define CREATE_SIZE 1

extern symbol * create_s(void) {
    symbol * p;
    void * mem = malloc(HEAD + (CREATE_SIZE + 1) * sizeof(symbol));
    if (mem == NULL) return NULL;
    p = (symbol *) (HEAD + (char *) mem);
    CAPACITY(p) = CREATE_SIZE;
    SET_SIZE(p, CREATE_SIZE);
    return p;
}

extern void lose_s(symbol * p) {
    if (p == NULL) return;
    free((char *) p - HEAD);
}

/*
   new_p = X_skip_utf8(p, c, lb, l, n); skips n characters forwards from p + c
   if n +ve, or n characters backwards from p +c - 1 if n -ve. new_p is the new
   position, or 0 on failure.

   -- used to implement hop and next in the utf8 case.
*/

extern int skip_utf8(const symbol * p, int c, int lb, int l, int n) {
    int b;
    if (n >= 0) {
	for (; n > 0; n--) {
	    if (c >= l) return -1;
	    b = p[c++];
	    if (b >= 0xC0) {   /* 1100 0000 */
		while (c < l) {
		    b = p[c];
		    if (b >= 0xC0 || b < 0x80) break;
		    /* break unless b is 10------ */
		    c++;
		}
	    }
	}
    } else {
	for (; n < 0; n++) {
	    if (c <= lb) return -1;
	    b = p[--c];
	    if (b >= 0x80) {   /* 1000 0000 */
		while (c > lb) {
		    b = p[c];
		    if (b >= 0xC0) break; /* 1100 0000 */
		    c--;
		}
	    }
	}
    }
    return c;
}

/* Code for character groupings: utf8 cases */

static int get_utf8(const symbol * p, int c, int l, int * slot) {
    int b0, b1;
    if (c >= l) return 0;
    b0 = p[c++];
    if (b0 < 0xC0 || c == l) {	 /* 1100 0000 */
	* slot = b0; return 1;
    }
    b1 = p[c++];
    if (b0 < 0xE0 || c == l) {	 /* 1110 0000 */
	* slot = (b0 & 0x1F) << 6 | (b1 & 0x3F); return 2;
    }
    * slot = (b0 & 0xF) << 12 | (b1 & 0x3F) << 6 | (*p & 0x3F); return 3;
}

static int get_b_utf8(const symbol * p, int c, int lb, int * slot) {
    int b0, b1;
    if (c <= lb) return 0;
    b0 = p[--c];
    if (b0 < 0x80 || c == lb) {   /* 1000 0000 */
	* slot = b0; return 1;
    }
    b1 = p[--c];
    if (b1 >= 0xC0 || c == lb) {   /* 1100 0000 */
	* slot = (b1 & 0x1F) << 6 | (b0 & 0x3F); return 2;
    }
    * slot = (*p & 0xF) << 12 | (b1 & 0x3F) << 6 | (b0 & 0x3F); return 3;
}

extern int in_grouping_U(struct SN_env * z, unsigned char * s, int min, int max) {
    int ch;
    int w = get_utf8(z->p, z->c, z->l, & ch);
    unless (w) return 0;
    if (ch > max || (ch -= min) < 0 || (s[ch >> 3] & (0X1 << (ch & 0X7))) == 0) return 0;
    z->c += w; return 1;
}

extern int in_grouping_b_U(struct SN_env * z, unsigned char * s, int min, int max) {
    int ch;
    int w = get_b_utf8(z->p, z->c, z->lb, & ch);
    unless (w) return 0;
    if (ch > max || (ch -= min) < 0 || (s[ch >> 3] & (0X1 << (ch & 0X7))) == 0) return 0;
    z->c -= w; return 1;
}

extern int out_grouping_U(struct SN_env * z, unsigned char * s, int min, int max) {
    int ch;
    int w = get_utf8(z->p, z->c, z->l, & ch);
    unless (w) return 0;
    unless (ch > max || (ch -= min) < 0 || (s[ch >> 3] & (0X1 << (ch & 0X7))) == 0) return 0;
    z->c += w; return 1;
}

extern int out_grouping_b_U(struct SN_env * z, unsigned char * s, int min, int max) {
    int ch;
    int w = get_b_utf8(z->p, z->c, z->lb, & ch);
    unless (w) return 0;
    unless (ch > max || (ch -= min) < 0 || (s[ch >> 3] & (0X1 << (ch & 0X7))) == 0) return 0;
    z->c -= w; return 1;
}

/* Code for character groupings: non-utf8 cases */

extern int in_grouping(struct SN_env * z, unsigned char * s, int min, int max) {
    int ch;
    if (z->c >= z->l) return 0;
    ch = z->p[z->c];
    if (ch > max || (ch -= min) < 0 || (s[ch >> 3] & (0X1 << (ch & 0X7))) == 0) return 0;
    z->c++; return 1;
}

extern int in_grouping_b(struct SN_env * z, unsigned char * s, int min, int max) {
    int ch;
    if (z->c <= z->lb) return 0;
    ch = z->p[z->c - 1];
    if (ch > max || (ch -= min) < 0 || (s[ch >> 3] & (0X1 << (ch & 0X7))) == 0) return 0;
    z->c--; return 1;
}

extern int out_grouping(struct SN_env * z, unsigned char * s, int min, int max) {
    int ch;
    if (z->c >= z->l) return 0;
    ch = z->p[z->c];
    unless (ch > max || (ch -= min) < 0 || (s[ch >> 3] & (0X1 << (ch & 0X7))) == 0) return 0;
    z->c++; return 1;
}

extern int out_grouping_b(struct SN_env * z, unsigned char * s, int min, int max) {
    int ch;
    if (z->c <= z->lb) return 0;
    ch = z->p[z->c - 1];
    unless (ch > max || (ch -= min) < 0 || (s[ch >> 3] & (0X1 << (ch & 0X7))) == 0) return 0;
    z->c--; return 1;
}

extern int eq_s(struct SN_env * z, int s_size, symbol * s) {
    if (z->l - z->c < s_size || memcmp(z->p + z->c, s, s_size * sizeof(symbol)) != 0) return 0;
    z->c += s_size; return 1;
}

extern int eq_s_b(struct SN_env * z, int s_size, symbol * s) {
    if (z->c - z->lb < s_size || memcmp(z->p + z->c - s_size, s, s_size * sizeof(symbol)) != 0) return 0;
    z->c -= s_size; return 1;
}

extern int eq_v(struct SN_env * z, symbol * p) {
    return eq_s(z, SIZE(p), p);
}

extern int eq_v_b(struct SN_env * z, symbol * p) {
    return eq_s_b(z, SIZE(p), p);
}

extern int find_among(struct SN_env * z, struct among * v, int v_size) {

    int i = 0;
    int j = v_size;

    int c = z->c; int l = z->l;
    symbol * q = z->p + c;

    struct among * w;

    int common_i = 0;
    int common_j = 0;

    int first_key_inspected = 0;

    while(1) {
	int k = i + ((j - i) >> 1);
	int diff = 0;
	int common = common_i < common_j ? common_i : common_j; /* smaller */
	w = v + k;
	{
	    int i; for (i = common; i < w->s_size; i++) {
		if (c + common == l) { diff = -1; break; }
		diff = q[common] - w->s[i];
		if (diff != 0) break;
		common++;
	    }
	}
	if (diff < 0) { j = k; common_j = common; }
		 else { i = k; common_i = common; }
	if (j - i <= 1) {
	    if (i > 0) break; /* v->s has been inspected */
	    if (j == i) break; /* only one item in v */

	    /* - but now we need to go round once more to get
	       v->s inspected. This looks messy, but is actually
	       the optimal approach.  */

	    if (first_key_inspected) break;
	    first_key_inspected = 1;
	}
    }
    while(1) {
	w = v + i;
	if (common_i >= w->s_size) {
	    z->c = c + w->s_size;
	    if (w->function == 0) return w->result;
	    {
		int res = w->function(z);
		z->c = c + w->s_size;
		if (res) return w->result;
	    }
	}
	i = w->substring_i;
	if (i < 0) return 0;
    }
}

/* find_among_b is for backwards processing. Same comments apply */

extern int find_among_b(struct SN_env * z, struct among * v, int v_size) {

    int i = 0;
    int j = v_size;

    int c = z->c; int lb = z->lb;
    symbol * q = z->p + c - 1;

    struct among * w;

    int common_i = 0;
    int common_j = 0;

    int first_key_inspected = 0;

    while(1) {
	int k = i + ((j - i) >> 1);
	int diff = 0;
	int common = common_i < common_j ? common_i : common_j;
	w = v + k;
	{
	    int i; for (i = w->s_size - 1 - common; i >= 0; i--) {
		if (c - common == lb) { diff = -1; break; }
		diff = q[- common] - w->s[i];
		if (diff != 0) break;
		common++;
	    }
	}
	if (diff < 0) { j = k; common_j = common; }
		 else { i = k; common_i = common; }
	if (j - i <= 1) {
	    if (i > 0) break;
	    if (j == i) break;
	    if (first_key_inspected) break;
	    first_key_inspected = 1;
	}
    }
    while(1) {
	w = v + i;
	if (common_i >= w->s_size) {
	    z->c = c - w->s_size;
	    if (w->function == 0) return w->result;
	    {
		int res = w->function(z);
		z->c = c - w->s_size;
		if (res) return w->result;
	    }
	}
	i = w->substring_i;
	if (i < 0) return 0;
    }
}


/* Increase the size of the buffer pointed to by p to at least n symbols.
 * If insufficient memory, returns NULL and frees the old buffer.
 */
static symbol * increase_size(symbol * p, int n) {
    symbol * q;
    int new_size = n + 20;
    void * mem = realloc((char *) p - HEAD,
			 HEAD + (new_size + 1) * sizeof(symbol));
    if (mem == NULL) {
	lose_s(p);
	return NULL;
    }
    q = (symbol *) (HEAD + (char *)mem);
    CAPACITY(q) = new_size;
    return q;
}

/* to replace symbols between c_bra and c_ket in z->p by the
   s_size symbols at s.
   Returns 0 on success, -1 on error.
   Also, frees z->p (and sets it to NULL) on error.
*/
extern int replace_s(struct SN_env * z, int c_bra, int c_ket, int s_size, const symbol * s, int * adjptr)
{
    int adjustment;
    int len;
    if (z->p == NULL) {
	z->p = create_s();
	if (z->p == NULL) return -1;
    }
    adjustment = s_size - (c_ket - c_bra);
    len = SIZE(z->p);
    if (adjustment != 0) {
	if (adjustment + len > CAPACITY(z->p)) {
	    z->p = increase_size(z->p, adjustment + len);
	    if (z->p == NULL) return -1;
	}
	memmove(z->p + c_ket + adjustment,
		z->p + c_ket,
		(len - c_ket) * sizeof(symbol));
	SET_SIZE(z->p, adjustment + len);
	z->l += adjustment;
	if (z->c >= c_ket)
	    z->c += adjustment;
	else
	    if (z->c > c_bra)
		z->c = c_bra;
    }
    unless (s_size == 0) memmove(z->p + c_bra, s, s_size * sizeof(symbol));
    if (adjptr != NULL)
	*adjptr = adjustment;
    return 0;
}

static int slice_check(struct SN_env * z) {

    if (z->bra < 0 ||
	z->bra > z->ket ||
	z->ket > z->l ||
	z->p == NULL ||
	z->l > SIZE(z->p)) /* this line could be removed */
    {
#if 0
	fprintf(stderr, "faulty slice operation:\n");
	debug(z, -1, 0);
#endif
	return -1;
    }
    return 0;
}

extern int slice_from_s(struct SN_env * z, int s_size, symbol * s) {
    if (slice_check(z)) return -1;
    return replace_s(z, z->bra, z->ket, s_size, s, NULL);
}

extern int slice_from_v(struct SN_env * z, symbol * p) {
    return slice_from_s(z, SIZE(p), p);
}

extern int slice_del(struct SN_env * z) {
    return slice_from_s(z, 0, 0);
}

extern int insert_s(struct SN_env * z, int bra, int ket, int s_size, symbol * s) {
    int adjustment;
    if (replace_s(z, bra, ket, s_size, s, &adjustment))
	return -1;
    if (bra <= z->bra) z->bra += adjustment;
    if (bra <= z->ket) z->ket += adjustment;
    return 0;
}

extern int insert_v(struct SN_env * z, int bra, int ket, symbol * p) {
    int adjustment;
    if (replace_s(z, bra, ket, SIZE(p), p, &adjustment))
	return -1;
    if (bra <= z->bra) z->bra += adjustment;
    if (bra <= z->ket) z->ket += adjustment;
    return 0;
}

extern symbol * slice_to(struct SN_env * z, symbol * p) {
    if (slice_check(z)) {
	lose_s(p);
	return NULL;
    }
    {
	int len = z->ket - z->bra;
	if (CAPACITY(p) < len) {
	    p = increase_size(p, len);
	    if (p == NULL)
		return NULL;
	}
	memmove(p, z->p + z->bra, len * sizeof(symbol));
	SET_SIZE(p, len);
    }
    return p;
}

extern symbol * assign_to(struct SN_env * z, symbol * p) {
    int len = z->l;
    if (CAPACITY(p) < len) {
	p = increase_size(p, len);
	if (p == NULL)
	    return NULL;
    }
    memmove(p, z->p, len * sizeof(symbol));
    SET_SIZE(p, len);
    return p;
}

#if 0
extern void debug(struct SN_env * z, int number, int line_count) {
    int i;
    int limit = SIZE(z->p);
    /*if (number >= 0) printf("%3d (line %4d): '", number, line_count);*/
    if (number >= 0) printf("%3d (line %4d): [%d]'", number, line_count,limit);
    for (i = 0; i <= limit; i++) {
	if (z->lb == i) printf("{");
	if (z->bra == i) printf("[");
	if (z->c == i) printf("|");
	if (z->ket == i) printf("]");
	if (z->l == i) printf("}");
	if (i < limit)
	{   int ch = z->p[i];
	    if (ch == 0) ch = '#';
	    printf("%c", ch);
	}
    }
    printf("'\n");
}
#endif
