#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