/*
 * txtquery io 
 * Teodor Sigaev <teodor@stack.net>
 */

#include "ltree.h"
#include <ctype.h>
#include "crc32.h"

PG_FUNCTION_INFO_V1(ltxtq_in);
Datum	   ltxtq_in(PG_FUNCTION_ARGS);
PG_FUNCTION_INFO_V1(ltxtq_out);
Datum	   ltxtq_out(PG_FUNCTION_ARGS);


/* parser's states */
#define WAITOPERAND 1
#define INOPERAND 2
#define WAITOPERATOR    3

/*
 * node of query tree, also used
 * for storing polish notation in parser
 */
typedef struct NODE {
	int4	    type;
	int4	    val;
	int2	    distance;
	int2	    length;
	uint16	    flag;
	struct NODE *next;
}       NODE;

typedef struct {
	char       *buf;
	int4	    state;
	int4	    count;
	/* reverse polish notation in list (for temprorary usage) */
	NODE       *str;
	/* number in str */
	int4	    num;

	/* user-friendly operand */
	int4	    lenop;
	int4	    sumlen;
	char       *op;
	char       *curop;
}       QPRS_STATE;

/*
 * get token from query string
 */
static int4
gettoken_query(QPRS_STATE * state, int4 *val, int4 *lenval, char **strval, uint16 *flag)
{
	while (1)
	{
		switch (state->state)
		{
			case WAITOPERAND:
				if (*(state->buf) == '!')
				{
					(state->buf)++;
					*val = (int4) '!';
					return OPR;
				}
				else if (*(state->buf) == '(')
				{
					state->count++;
					(state->buf)++;
					return OPEN;
				}
				else if ( ISALNUM(*(state->buf)) )
				{
					state->state = INOPERAND;
					*strval = state->buf;
					*lenval = 1;
					*flag = 0;
				} else if ( !isspace(*(state->buf)) )
					elog(ERROR,"Operand syntax error");
				break;
			case INOPERAND:
				if ( ISALNUM(*(state->buf)) ) {
					if ( *flag )
						elog(ERROR,"Modificators syntax error");
					(*lenval)++;
				} else if ( *(state->buf) == '%' ) {
					*flag |= LVAR_SUBLEXEM;
				} else if ( *(state->buf) == '@' ) {
					*flag |= LVAR_INCASE;
				} else if ( *(state->buf) == '*' ) {
					*flag |= LVAR_ANYEND;
				} else {
					state->state = WAITOPERATOR;
					return VAL;
				}
				break;
			case WAITOPERATOR:
				if (*(state->buf) == '&' || *(state->buf) == '|')
				{
					state->state = WAITOPERAND;
					*val = (int4) *(state->buf);
					(state->buf)++;
					return OPR;
				}
				else if (*(state->buf) == ')')
				{
					(state->buf)++;
					state->count--;
					return (state->count < 0) ? ERR : CLOSE;
				}
				else if (*(state->buf) == '\0')
					return (state->count) ? ERR : END;
				else if (*(state->buf) != ' ')
					return ERR;
				break;
			default:
				return ERR;
				break;
		}
		(state->buf)++;
	}
	return END;
}

/*
 * push new one in polish notation reverse view
 */
static void
pushquery(QPRS_STATE * state, int4 type, int4 val, int4 distance, int4 lenval, uint16 flag)
{
	NODE       *tmp = (NODE *) palloc(sizeof(NODE));

	tmp->type = type;
	tmp->val = val;
	tmp->flag = flag;
	if (distance > 0xffff)
		elog(ERROR, "Value is too big");
	if (lenval > 0xff)
		elog(ERROR, "Operand is too long");
	tmp->distance = distance;
	tmp->length = lenval;
	tmp->next = state->str;
	state->str = tmp;
	state->num++;
}

/*
 * This function is used for query_txt parsing
 */
static void
pushval_asis(QPRS_STATE * state, int type, char *strval, int lenval, uint16 flag)
{
	if (lenval > 0xffff)
		elog(ERROR, "Word is too long");

	pushquery(state, type, crc32_sz((uint8 *) strval, lenval),
			  state->curop - state->op, lenval, flag);

	while (state->curop - state->op + lenval + 1 >= state->lenop)
	{
		int4	    tmp = state->curop - state->op;

		state->lenop *= 2;
		state->op = (char *) repalloc((void *) state->op, state->lenop);
		state->curop = state->op + tmp;
	}
	memcpy((void *) state->curop, (void *) strval, lenval);
	state->curop += lenval;
	*(state->curop) = '\0';
	state->curop++;
	state->sumlen += lenval + 1;
	return;
}

#define STACKDEPTH      32
/*
 * make polish notaion of query
 */
static int4
makepol(QPRS_STATE * state)
{
	int4	    val,
				type;
	int4	    lenval;
	char       *strval;
	int4	    stack[STACKDEPTH];
	int4	    lenstack = 0;
	uint16	    flag;

	while ((type = gettoken_query(state, &val, &lenval, &strval,&flag)) != END) {
		switch (type)
		{
			case VAL:
				pushval_asis(state, VAL, strval, lenval,flag);
				while (lenstack && (stack[lenstack - 1] == (int4) '&' ||
									stack[lenstack - 1] == (int4) '!'))
				{
					lenstack--;
					pushquery(state, OPR, stack[lenstack], 0, 0, 0);
				}
				break;
			case OPR:
				if (lenstack && val == (int4) '|')
					pushquery(state, OPR, val, 0, 0, 0);
				else
				{
					if (lenstack == STACKDEPTH)
						elog(ERROR, "Stack too short");
					stack[lenstack] = val;
					lenstack++;
				}
				break;
			case OPEN:
				if (makepol(state) == ERR)
					return ERR;
				if (lenstack && (stack[lenstack - 1] == (int4) '&' ||
								 stack[lenstack - 1] == (int4) '!'))
				{
					lenstack--;
					pushquery(state, OPR, stack[lenstack], 0, 0, 0);
				}
				break;
			case CLOSE:
				while (lenstack)
				{
					lenstack--;
					pushquery(state, OPR, stack[lenstack], 0, 0, 0);
				};
				return END;
				break;
			case ERR:
			default:
				elog(ERROR, "Syntax error");
				return ERR;

		}
	}
	while (lenstack) {
		lenstack--;
		pushquery(state, OPR, stack[lenstack], 0, 0, 0);
	};
	return END;
}

static void
findoprnd(ITEM * ptr, int4 *pos)
{
	if (ptr[*pos].type == VAL || ptr[*pos].type == VALTRUE)
	{
		ptr[*pos].left = 0;
		(*pos)++;
	}
	else if (ptr[*pos].val == (int4) '!')
	{
		ptr[*pos].left = 1;
		(*pos)++;
		findoprnd(ptr, pos);
	}
	else
	{
		ITEM       *curitem = &ptr[*pos];
		int4	    tmp = *pos;

		(*pos)++;
		findoprnd(ptr, pos);
		curitem->left = *pos - tmp;
		findoprnd(ptr, pos);
	}
}


/*
 * input
 */
static ltxtquery *
queryin(char *buf)
{
	QPRS_STATE      state;
	int4	    i;
	ltxtquery  *query;
	int4	    commonlen;
	ITEM       *ptr;
	NODE       *tmp;
	int4	    pos = 0;

#ifdef BS_DEBUG
	char	    pbuf[16384],
			   *cur;
#endif

	/* init state */
	state.buf = buf;
	state.state = WAITOPERAND;
	state.count = 0;
	state.num = 0;
	state.str = NULL;

	/* init list of operand */
	state.sumlen = 0;
	state.lenop = 64;
	state.curop = state.op = (char *) palloc(state.lenop);
	*(state.curop) = '\0';

	/* parse query & make polish notation (postfix, but in reverse order) */
	makepol(&state);
	if (!state.num)
		elog(ERROR, "Empty query");
	/* make finish struct */
	commonlen = COMPUTESIZE(state.num, state.sumlen);
	query = (ltxtquery *) palloc(commonlen);
	query->len = commonlen;
	query->size = state.num;
	ptr = GETQUERY(query);

	/* set item in polish notation */
	for (i = 0; i < state.num; i++)
	{
		ptr[i].type = state.str->type;
		ptr[i].val = state.str->val;
		ptr[i].distance = state.str->distance;
		ptr[i].length = state.str->length;
		ptr[i].flag = state.str->flag;
		tmp = state.str->next;
		pfree(state.str);
		state.str = tmp;
	}

	/* set user friendly-operand view */
	memcpy((void *) GETOPERAND(query), (void *) state.op, state.sumlen);
	pfree(state.op);

	/* set left operand's position for every operator */
	pos = 0;
	findoprnd(ptr, &pos);

	return query;
}

/*
 * in without morphology
 */
Datum
ltxtq_in(PG_FUNCTION_ARGS)
{
	PG_RETURN_POINTER(queryin((char *) PG_GETARG_POINTER(0)));
}

/*
 * out function
 */
typedef struct
{
	ITEM       *curpol;
	char       *buf;
	char       *cur;
	char       *op;
	int4	    buflen;
}       INFIX;

#define RESIZEBUF(inf,addsize) \
while( ( inf->cur - inf->buf ) + addsize + 1 >= inf->buflen ) \
{ \
	int4 len = inf->cur - inf->buf; \
	inf->buflen *= 2; \
	inf->buf = (char*) repalloc( (void*)inf->buf, inf->buflen ); \
	inf->cur = inf->buf + len; \
}

/*
 * recursive walk on tree and print it in
 * infix (human-readable) view
 */
static void
infix(INFIX * in, bool first)
{
	if (in->curpol->type == VAL)
	{
		char       *op = in->op + in->curpol->distance;

		RESIZEBUF(in, in->curpol->length * 2 + 5);
		while (*op) {
			*(in->cur) = *op;
			op++;
			in->cur++;
		}
		if ( in->curpol->flag & LVAR_SUBLEXEM ) {
			*(in->cur) = '%';
			in->cur++;
		}
		if ( in->curpol->flag & LVAR_INCASE ) {
			*(in->cur) = '@';
			in->cur++;
		}
		if ( in->curpol->flag & LVAR_ANYEND ) {
			*(in->cur) = '*';
			in->cur++;
		}
		*(in->cur) = '\0';
		in->curpol++;
	}
	else if (in->curpol->val == (int4) '!')
	{
		bool	    isopr = false;

		RESIZEBUF(in, 1);
		*(in->cur) = '!';
		in->cur++;
		*(in->cur) = '\0';
		in->curpol++;
		if (in->curpol->type == OPR)
		{
			isopr = true;
			RESIZEBUF(in, 2);
			sprintf(in->cur, "( ");
			in->cur = strchr(in->cur, '\0');
		}
		infix(in, isopr);
		if (isopr)
		{
			RESIZEBUF(in, 2);
			sprintf(in->cur, " )");
			in->cur = strchr(in->cur, '\0');
		}
	}
	else
	{
		int4	    op = in->curpol->val;
		INFIX	   nrm;

		in->curpol++;
		if (op == (int4) '|' && !first)
		{
			RESIZEBUF(in, 2);
			sprintf(in->cur, "( ");
			in->cur = strchr(in->cur, '\0');
		}

		nrm.curpol = in->curpol;
		nrm.op = in->op;
		nrm.buflen = 16;
		nrm.cur = nrm.buf = (char *) palloc(sizeof(char) * nrm.buflen);

		/* get right operand */
		infix(&nrm, false);

		/* get & print left operand */
		in->curpol = nrm.curpol;
		infix(in, false);

		/* print operator & right operand */
		RESIZEBUF(in, 3 + (nrm.cur - nrm.buf));
		sprintf(in->cur, " %c %s", op, nrm.buf);
		in->cur = strchr(in->cur, '\0');
		pfree(nrm.buf);

		if (op == (int4) '|' && !first)
		{
			RESIZEBUF(in, 2);
			sprintf(in->cur, " )");
			in->cur = strchr(in->cur, '\0');
		}
	}
}

Datum
ltxtq_out(PG_FUNCTION_ARGS)
{
	ltxtquery  *query = PG_GETARG_LTXTQUERY(0);
	INFIX	   nrm;

	if (query->size == 0)
		elog(ERROR, "Empty");
	nrm.curpol = GETQUERY(query);
	nrm.buflen = 32;
	nrm.cur = nrm.buf = (char *) palloc(sizeof(char) * nrm.buflen);
	*(nrm.cur) = '\0';
	nrm.op = GETOPERAND(query);
	infix(&nrm, true);

	PG_FREE_IF_COPY(query, 0);
	PG_RETURN_POINTER(nrm.buf);
}

