/*
 * This file is released under the terms of the Artistic License.  Please see
 * the file LICENSE, included in this package, for details.
 *
 * Copyright The DBT-2 Authors
 *
 * Based on TPC-C Standard Specification Revision 5.11 Clause 2.8.2.
 */

#include <catalog/pg_type.h> /* for OIDs */
#include <executor/spi.h>	 /* this should include most necessary APIs */
#include <fmgr.h>
#include <funcapi.h> /* for returning set of rows in order_status */
#include <postgres.h>
#include <sys/types.h>
#include <unistd.h>

#include "dbt2common.h"

/*
 * Stock Level transaction SQL Statement.
 */

#define STOCK_LEVEL_1 statements[0].plan
#define STOCK_LEVEL_2 statements[1].plan

static cached_statement statements[] = {
		{/* STOCK_LEVEL_1 */
		 "SELECT d_next_o_id\n"
		 "FROM district\n"
		 "WHERE d_w_id = $1\n"
		 "AND d_id = $2",
		 2,
		 {INT4OID, INT4OID}},

		{/* STOCK_LEVEL_2 */
		 "WITH\n"
		 "ol AS (\n"
		 "    SELECT DISTINCT ol_i_id\n"
		 "    FROM order_line\n"
		 "    WHERE ol_w_id = $2\n"
		 "      AND ol_d_id = $1\n"
		 "      AND ol_o_id BETWEEN ($4)\n"
		 "                      AND ($5)\n"
		 ")\n"
		 "SELECT count(*)\n"
		 "FROM ol, stock\n"
		 "WHERE s_w_id = $2\n"
		 "  AND s_i_id = ol_i_id\n"
		 "  AND s_quantity < $3",
		 5,
		 {INT4OID, INT4OID, INT4OID, INT4OID, INT4OID}},

		{NULL}};

/* Prototypes to prevent potential gcc warnings. */
Datum stock_level(PG_FUNCTION_ARGS);

PG_FUNCTION_INFO_V1(stock_level);

Datum stock_level(PG_FUNCTION_ARGS) {
	/* Input variables. */
	int32 w_id = PG_GETARG_INT32(0);
	int32 d_id = PG_GETARG_INT32(1);
	int32 threshold = PG_GETARG_INT32(2);

	TupleDesc tupdesc;
	SPITupleTable *tuptable;
	HeapTuple tuple;

	int d_next_o_id = 0;
	int low_stock = 0;
	int ret;
	char *buf;

	Datum args[5];
	char nulls[5] = {' ', ' ', ' ', ' ', ' '};

	elog(DEBUG1, "IN w_id = %d", w_id);
	elog(DEBUG1, "IN d_id = %d", d_id);
	elog(DEBUG1, "IN threshold = %d", threshold);

	SPI_connect();

	plan_queries(statements);

	args[0] = Int32GetDatum(w_id);
	args[1] = Int32GetDatum(d_id);
	ret = SPI_execute_plan(STOCK_LEVEL_1, args, nulls, true, 0);
	if (ret == SPI_OK_SELECT && SPI_processed > 0) {
		tupdesc = SPI_tuptable->tupdesc;
		tuptable = SPI_tuptable;
		tuple = tuptable->vals[0];

		buf = SPI_getvalue(tuple, tupdesc, 1);
		elog(DEBUG1, "d_next_o_id = %s", buf);
		d_next_o_id = atoi(buf);
	} else {
		ereport(ERROR, (errcode(ERRCODE_INTERNAL_ERROR),
						errmsg("STOCK_LEVEL_1 failed")));
	}

	args[0] = Int32GetDatum(w_id);
	args[1] = Int32GetDatum(d_id);
	args[2] = Int32GetDatum(threshold);
	args[3] = Int32GetDatum(d_next_o_id - 20);
	args[4] = Int32GetDatum(d_next_o_id - 1);
	ret = SPI_execute_plan(STOCK_LEVEL_2, args, nulls, true, 0);
	if (ret == SPI_OK_SELECT && SPI_processed > 0) {
		tupdesc = SPI_tuptable->tupdesc;
		tuptable = SPI_tuptable;
		tuple = tuptable->vals[0];

		buf = SPI_getvalue(tuple, tupdesc, 1);
		elog(DEBUG1, "low_stock = %s", buf);
		low_stock = atoi(buf);
	} else {
		ereport(ERROR, (errcode(ERRCODE_INTERNAL_ERROR),
						errmsg("STOCK_LEVEL_2 failed")));
	}

	SPI_finish();
	PG_RETURN_INT32(low_stock);
}