/*
 * IO definitions for query_txt and mquery_txt. This type
 * are identical, but for parsing mquery_txt used parser for text
 * and also morphology is used.
 * Internal structure:
 * query tree, then string with original value.
 * Query tree with plain view. It's means that in array of nodes
 * right child is always next and left position = item+item->left
 * Teodor Sigaev <teodor@stack.net>
 */
#include "postgres.h"

#include <float.h>

#include "access/gist.h"
#include "access/itup.h"
#include "access/rtree.h"
#include "utils/elog.h"
#include "utils/palloc.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "storage/bufpage.h"

#include "txtidx.h"
#include "crc32.h"
#include "query.h"
#include "morph.h"
#include "rewrite.h"

#include "deflex.h"
#include "parser.h"

PG_FUNCTION_INFO_V1(mqtxt_in);
Datum   mqtxt_in(PG_FUNCTION_ARGS);
PG_FUNCTION_INFO_V1(qtxt_in);
Datum   qtxt_in(PG_FUNCTION_ARGS);
PG_FUNCTION_INFO_V1(qtxt_out);
Datum   qtxt_out(PG_FUNCTION_ARGS);

PG_FUNCTION_INFO_V1(execqtxt);
Datum   execqtxt(PG_FUNCTION_ARGS);
PG_FUNCTION_INFO_V1(rexecqtxt);
Datum   rexecqtxt(PG_FUNCTION_ARGS);

PG_FUNCTION_INFO_V1(querytree);
Datum   querytree(PG_FUNCTION_ARGS);

#define END     	0
#define ERR     	1
#define VAL     	2
#define OPR     	3
#define OPEN    	4
#define CLOSE   	5
#define VALTRUE		6	/* for stop words */
#define VALFALSE	7

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

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

	/* state for value's parser */
	TI_IN_STATE	valstate;	
} QPRS_STATE;

/*
 * get token from query string
 */
static int4 
gettoken_query( QPRS_STATE* state, int4* val, int4* lenval, char** strval ) {
	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 ( *(state->buf) != ' ' ) {
					state->valstate.prsbuf = state->buf;
					state->state = WAITOPERATOR;
					if ( gettoken_txtidx( &(state->valstate) ) ) {
						*strval = state->valstate.word;
						*lenval = state->valstate.curpos - state->valstate.word;
						state->buf = state->valstate.prsbuf;
						return VAL;
					} else 
						elog(ERROR, "No operand");
				}
				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) {
	NODE    *tmp = (NODE*)palloc(sizeof(NODE));
	tmp->type=type;
	tmp->val =val;
	if ( distance>0xffff ) 
		elog(ERROR,"Value is too big");
	if ( lenval > 0xffff )
		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) {
	if ( lenval>0xffff )
		elog(ERROR, "Word is too long");

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

	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;
}

/*
 * This function is used for mquery_txt parsing
 */
static void
pushval_morph(QPRS_STATE *state, int typeval, char* strval, int lenval) {
	int4 type, lenlemm;
	int4 count = 0;
	char *lemm;

	start_parse_str( strval, lenval );
	while( (type=tsearch_yylex()) != 0 ) {
		if ( tokenlen>0xffff ) {
			end_parse();
			elog(ERROR, "Word is too long");
		}
		lenlemm = tokenlen;
		lemm = lemmatize( token, &lenlemm, type );
		if ( lemm ) {
			pushval_asis(state,VAL,lemm,lenlemm);
			if ( lemm != token ) pfree(lemm);
		} else {
			pushval_asis(state,VALTRUE,0,0);
		}
		if ( count )
			pushquery(state, OPR, (int4)'&', 0,0);
		count++;	
	}
	end_parse();
}

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

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

typedef struct {
        WordEntry *arrb;
        WordEntry *arre;
	char 	*values;
	char	*operand;
} CHKVAL;

/*
 * compare 2 string values
 */
static int4
ValCompare( CHKVAL *chkval, WordEntry *ptr, ITEM *item ) {
	if ( ptr->len == item->length )
		return strncmp(
			&(chkval->values[ ptr->pos ]),
			&(chkval->operand[item->distance]),
			item->length ); 

	return ( ptr->len > item->length ) ? 1 : -1;	
} 

/*
 * is there value 'val' in array or not ?
 */
static bool
checkcondition_str( void *checkval, ITEM* val ) {
	WordEntry      *StopLow = ((CHKVAL*)checkval)->arrb;
	WordEntry      *StopHigh = ((CHKVAL*)checkval)->arre;
	WordEntry      *StopMiddle;
	int            difference;
 
      	/* Loop invariant: StopLow <= val < StopHigh */
   
	while (StopLow < StopHigh) {
		StopMiddle = StopLow + (StopHigh - StopLow) / 2;
		difference = ValCompare((CHKVAL*)checkval, StopMiddle, val);
		if (difference == 0) 
			return (true);
		else if (difference < 0)
			StopLow = StopMiddle + 1;
		else
			StopHigh = StopMiddle;
	}

	return (false); 
}

/*
 * check for boolean condition
 */
bool
execute( ITEM* curitem, void *checkval, bool calcnot, bool (*chkcond)(void *checkval, ITEM *val )) {
	if (  curitem->type == VAL ) {
		return (*chkcond)( checkval, curitem );
	} else if ( curitem->val == (int4)'!' ) {
		return ( calcnot ) ?
		( ( execute(curitem + 1, checkval, calcnot, chkcond) ) ? false : true )
		: true;
	} else if ( curitem->val == (int4)'&' ) {
		if ( execute(curitem + curitem->left, checkval, calcnot, chkcond) )
			return execute(curitem + 1, checkval, calcnot, chkcond);
		else
			return false;
	} else { /* |-operator */
		if ( execute(curitem + curitem->left, checkval, calcnot, chkcond) )
			return true;
		else
			return execute(curitem + 1, checkval, calcnot, chkcond);
	}
	return false;
}

/*
 * boolean operations 
 */
Datum
rexecqtxt(PG_FUNCTION_ARGS) {
	return DirectFunctionCall2(
		execqtxt,
		PG_GETARG_DATUM(1),
		PG_GETARG_DATUM(0)
	);
}

Datum
execqtxt(PG_FUNCTION_ARGS) {
	txtidx *val = ( txtidx * )DatumGetPointer(PG_DETOAST_DATUM(PG_GETARG_DATUM(0)));
	QUERYTYPE *query = ( QUERYTYPE * )DatumGetPointer(PG_DETOAST_DATUM(PG_GETARG_DATUM(1)));
	CHKVAL  chkval;
	bool result;
	
	if ( ! val->size ) {
		PG_FREE_IF_COPY(val,0);
		PG_FREE_IF_COPY(query,1);
		PG_RETURN_BOOL( false );
	}

	chkval.arrb = ARRPTR(val);
	chkval.arre = chkval.arrb + val->size;
	chkval.values = STRPTR(val);
	chkval.operand = GETOPERAND( query );
	result = execute( 
		GETQUERY(query), 
		&chkval,
		true, 
		checkcondition_str 
	);

	PG_FREE_IF_COPY(val,0);
	PG_FREE_IF_COPY(query,1);
	PG_RETURN_BOOL( result );
}

/*
 * find left operand in polish notation view
 */
static void
findoprnd( ITEM *ptr, int4 *pos ) {
#ifdef BS_DEBUG
	elog(NOTICE, ( ptr[*pos].type == OPR ) ? 
		"%d  %c" : "%d  %d ", *pos, ptr[*pos].val );
#endif
	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 QUERYTYPE *queryin(char *buf, void (*pushval)(QPRS_STATE*,int,char*,int) ) {
	QPRS_STATE state;
	int4 i;
	QUERYTYPE	*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 value parser's state */
	state.valstate.oprisdelim = true;
	state.valstate.len=32;
	state.valstate.word = (char*)palloc( state.valstate.len );

	/* 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, pushval );
	pfree( state.valstate.word );
	if (!state.num) 
		elog( ERROR,"Empty query");

	/* make finish struct */
	commonlen = COMPUTESIZE(state.num, state.sumlen);
	query = (QUERYTYPE*) 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;
		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 );

#ifdef BS_DEBUG
	cur = pbuf;
	*cur = '\0';
	for( i=0;i<query->size;i++ ) {
		if ( ptr[i].type == OPR ) 
			sprintf(cur, "%c(%d) ", ptr[i].val, ptr[i].left);
		else 
			sprintf(cur, "%d(%s) ", ptr[i].val, GETOPERAND(query) + ptr[i].distance );
		cur = strchr(cur,'\0');	
	}
	elog(NOTICE,"POR: %s", pbuf);
#endif

	return query;
}

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

/*
 * in with morphology
 */
Datum
mqtxt_in(PG_FUNCTION_ARGS) {
	QUERYTYPE *query;
	ITEM*	res;
	int4 len;
#ifdef BS_DEBUG	
	ITEM *ptr;
	int4 i;
	char pbuf[16384],*cur;
#endif
	initmorph();
	query = queryin((char*)PG_GETARG_POINTER(0),pushval_morph);
	res = clean_fakeval( GETQUERY(query), &len );
	if ( ! res ) {
		pfree(query);
		PG_RETURN_NULL();
	}
	memcpy( (void*)GETQUERY(query), (void*)res, len*sizeof(ITEM) );
#ifdef BS_DEBUG
	cur = pbuf;
	*cur = '\0';
	ptr = GETQUERY(query);
	for( i=0;i<len;i++ ) {
		if ( ptr[i].type == OPR ) 
			sprintf(cur, "%c(%d) ", ptr[i].val, ptr[i].left);
		else 
			sprintf(cur, "%d(%s) ", ptr[i].val, GETOPERAND(query) + ptr[i].distance );
		cur = strchr(cur,'\0');	
	}
	elog(NOTICE,"POR: %s", pbuf);
#endif
	pfree(res);
	PG_RETURN_POINTER( query );
}


/*
 * 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 + 2);
		*(in->cur) = '\''; in->cur++;
		while( *op ) {
			if ( *op == '\'' ) {
				*(in->cur) = '\\'; in->cur++;
			}
			*(in->cur) = *op;
			op++; in->cur++;
		}  
		*(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
qtxt_out(PG_FUNCTION_ARGS) {
	QUERYTYPE       *query = (QUERYTYPE*)DatumGetPointer(PG_DETOAST_DATUM(PG_GETARG_DATUM(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 );
}

/*
 * debug function, used only for view query
 * which will be executed in non-leaf pages in index
 */
Datum
querytree(PG_FUNCTION_ARGS) {
	QUERYTYPE       *query = (QUERYTYPE*)DatumGetPointer(PG_DETOAST_DATUM(PG_GETARG_DATUM(0)));
	INFIX   nrm;
	text 	*res;
	ITEM	*q;
	int4	len;


	if ( query->size == 0 )
		elog(ERROR,"Empty");

	q = clean_NOT(GETQUERY(query), &len);

	if ( ! q ) {
		res = (text*) palloc( 1 + VARHDRSZ );
		VARATT_SIZEP(res) = 1 + VARHDRSZ;
		*((char*)VARDATA(res)) = 'T';
	} else {
		nrm.curpol = q;
		nrm.buflen = 32;
		nrm.cur = nrm.buf = (char*)palloc( sizeof(char) * nrm.buflen );
		*(nrm.cur) = '\0';
		nrm.op = GETOPERAND(query);
		infix( &nrm, true );

		res = (text*) palloc( nrm.cur-nrm.buf + VARHDRSZ );
		VARATT_SIZEP(res) = nrm.cur-nrm.buf + VARHDRSZ;
		strncpy( VARDATA(res), nrm.buf, nrm.cur-nrm.buf );
		pfree(q);
	}

	PG_FREE_IF_COPY(query,0);

	PG_RETURN_POINTER( res );
}
