/*
 * For PostgreSQL Database Management System:
 * (formerly known as Postgres, then as Postgres95)
 *
 * Portions Copyright (c) 1996-2010, The PostgreSQL Global Development Group
 *
 * Portions Copyright (c) 1994, The Regents of the University of California
 *
 * Permission to use, copy, modify, and distribute this software and its documentation for any purpose,
 * without fee, and without a written agreement is hereby granted, provided that the above copyright notice
 * and this paragraph and the following two paragraphs appear in all copies.
 *
 * IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR DIRECT,
 * INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS,
 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY
 * OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 * THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA
 * HAS NO OBLIGATIONS TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
 */

#include "postgres.h"

#include "access/attnum.h"
#include "access/htup.h"
#include "access/tupdesc.h"
#include "catalog/pg_type.h"
#include "parser/keywords.h"
#include "fmgr.h"
#include "funcapi.h"
#include "parser/cypher_keywords.h"
#include "parser/cypher_gram.h"
#include "parser/cypher_kwlist_d.h"

/*
 * This list must be sorted by ASCII name, because binary search is used to
 * locate entries.
 */
#define PG_KEYWORD(kwname, value, category) value,

const uint16 CypherKeywordTokens[] = {
#include "parser/cypher_kwlist.h"
};

#undef PG_KEYWORD

#define PG_KEYWORD(kwname, value, category) category,

const uint16 CypherKeywordCategories[] = {
#include "parser/cypher_kwlist.h"
};

#undef PG_KEYWORD

PG_FUNCTION_INFO_V1(get_cypher_keywords);
extern "C" Datum  get_cypher_keywords(PG_FUNCTION_ARGS);
// function to return the list of grammar keywords
Datum get_cypher_keywords(PG_FUNCTION_ARGS)
{
    FuncCallContext *func_ctx;

    if (SRF_IS_FIRSTCALL())
    {
        MemoryContext old_mem_ctx;
        TupleDesc tup_desc;

        func_ctx = SRF_FIRSTCALL_INIT();
        old_mem_ctx = MemoryContextSwitchTo(func_ctx->multi_call_memory_ctx);

        tup_desc = CreateTemplateTupleDesc(3, false);
        TupleDescInitEntry(tup_desc, (AttrNumber)1, "word", TEXTOID, -1, 0);
        TupleDescInitEntry(tup_desc, (AttrNumber)2, "catcode", CHAROID, -1, 0);
        TupleDescInitEntry(tup_desc, (AttrNumber)3, "catdesc", TEXTOID, -1, 0);

        func_ctx->attinmeta = TupleDescGetAttInMetadata(tup_desc);

        MemoryContextSwitchTo(old_mem_ctx);
    }

    func_ctx = SRF_PERCALL_SETUP();

    if (func_ctx->call_cntr < CypherKeyword.num_keywords)
    {
        char *values[3];
        HeapTuple tuple;

        // cast-away-const is ugly but alternatives aren't much better
        values[0] = (char *) GetScanKeyword((int) func_ctx->call_cntr, &CypherKeyword);

        switch (CypherKeywordCategories[func_ctx->call_cntr])
        {
        case UNRESERVED_KEYWORD:
            values[1] = "U";
            values[2] = "unreserved";
            break;
        case COL_NAME_KEYWORD:
            values[1] = "C";
            values[2] = "unreserved (cannot be function or type name)";
            break;
        case TYPE_FUNC_NAME_KEYWORD:
            values[1] = "T";
            values[2] = "reserved (can be function or type name)";
            break;
        case RESERVED_KEYWORD:
            values[1] = "R";
            values[2] = "reserved";
            break;
        default:
            // shouldn't be possible
            values[1] = NULL;
            values[2] = NULL;
            break;
        }

        tuple = BuildTupleFromCStrings(func_ctx->attinmeta, values);

        SRF_RETURN_NEXT(func_ctx, HeapTupleGetDatum(tuple));
    }

    SRF_RETURN_DONE(func_ctx);
}