#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <libpq-fe.h>
#include <netinet/in.h>
#include <arpa/inet.h>

/*
 * Program to export Sputnik data from PostgreSQL database into binary file.
 * Exports tuples with calculated id column.
 */

typedef struct {
	u_int32_t timestamp;
	u_int32_t station;
	u_int32_t id, garbage2;
	u_int8_t size, protocol;
	u_int8_t flags;
	u_int8_t strength;
	u_int32_t seqno;
} __attribute__ ((packed)) beacon_log_t;

#define BUTTON 0x02

int main(int argc, char *argv[])
{
	FILE *f = NULL;
	int M, N, i;
	beacon_log_t b;
	PGconn *connection;
	PGresult *result = NULL;
	int idNo, sequenceNo, epochNo, addressNo, strengthNo, tagsNo;
	char *id, *sequence, *epoch, *address, *strength, *tags;
	struct in_addr station;

	b.garbage2 = 0;
	b.size = 0x10;
	b.protocol = 0x17;
	M = 0;

	connection = PQconnectdb("dbname = tomus");
	if (NULL == connection) {
		return EXIT_FAILURE;
	}
	if (CONNECTION_OK != PQstatus(connection)) {
		printf("%s", PQerrorMessage(connection));
		PQfinish(connection);
		connection = NULL;
		return EXIT_FAILURE;
	}
	result = PQexec(connection, "begin");
	PQclear(result);

	result = PQexec(connection, "DECLARE export CURSOR FOR "
	" SELECT sputnik.id AS id, sequence, time, "
	" extract('epoch' from time) AS epoch, address, strength, tags "
	" FROM sputnik.sputnik INNER JOIN sputnik.station ON sputnik.station = station.id "
	" WHERE sputnik.id IS NOT NULL ORDER BY time, sputnik.id, station.id ");
	if (PGRES_COMMAND_OK != PQresultStatus(result)) {
		printf("%s", PQerrorMessage(connection));
		PQclear(result);
		result = PQexec(connection, "end");
		PQclear(result);
		PQfinish(connection);
		connection = NULL;
		return EXIT_FAILURE;
	}

	f = fopen(argv[1], "wb");
	while (1) {
		result = PQexec(connection, "FETCH NEXT IN export");
		if (PGRES_TUPLES_OK != PQresultStatus(result)) {
			fclose(f);
			printf("%s", PQerrorMessage(connection));
			PQclear(result);
			result = PQexec(connection, "end");
			PQclear(result);
			PQfinish(connection);
			connection = NULL;
			return EXIT_FAILURE;
		}
		N =  PQntuples(result);
		if (0 == N) {
			break;
		}
		M += N;
		idNo = PQfnumber(result, "id");
		sequenceNo = PQfnumber(result, "sequence");
		epochNo = PQfnumber(result, "epoch");
		addressNo = PQfnumber(result, "address");
		strengthNo = PQfnumber(result, "strength");
		tagsNo = PQfnumber(result, "tags");

		for (i = 0; i < N; ++i) {
			id = PQgetvalue(result, i, idNo);
			b.id = htonl(strtoul(id, NULL, 10));
			sequence = PQgetvalue(result, i, sequenceNo);
			b.seqno = htonl(strtol(sequence, NULL, 10));
			epoch = PQgetvalue(result, i, epochNo);
			b.timestamp = htonl(strtoul(epoch, NULL, 10));
			address = PQgetvalue(result, i, addressNo);
			inet_aton(address, &station);
			b.station = htonl(station.s_addr);
			b.garbage2 = station.s_addr;
			strength = PQgetvalue(result, i, strengthNo);
			b.strength = strtoul(strength, NULL, 10);
			tags = PQgetvalue(result, i, tagsNo);
			b.flags = (strlen(tags)) ? BUTTON : 0;

			fwrite(&b, 1, sizeof(beacon_log_t), f);
		}
		PQclear(result);
	}
	fclose(f);

	result = PQexec(connection, "CLOSE export");
	PQclear(result);
	result = PQexec(connection, "end");
	PQclear(result);
	PQfinish(connection);
	connection = NULL;
	printf("Exported %i tuples.\n", M);
	return EXIT_SUCCESS;
}