#ifndef EVPQ_H

#define EVPQ_H

/*

 * Convenience functions for using libpq (the PostgreSQL client library) with libevent.

 */

#include <event2/event.h>

#include <postgresql/libpq-fe.h>

/*

 * Our PGconn context wrapper.

 */

struct evpq_conn;

/*

 * Callback functions used

 */

struct evpq_callback_info {

    /*

     * This evpq_conn has connected succesfully \o/

     */

    void (*fn_connected)(struct evpq_conn *conn, void *arg);

    /*

     * Got a result.

     */

    void (*fn_result)(struct evpq_conn *conn, PGresult *result, void *arg);

    /*

     * No more results for the query

     */

    void (*fn_done)(struct evpq_conn *conn, void *arg);

    /*

     * The evpq_conn has suffered a complete failure.

     *

     * Most likely, this means that the connection to the server was lost, or not established at all.

     *

     * XXX: add a `what` arg?

     */

    void (*fn_failure)(struct evpq_conn *conn, void *arg);

};

/*

 * evpq_conn states

 */

enum evpq_state {

    EVPQ_INIT,

    EVPQ_CONNECT,

    EVPQ_CONNECTED,

    EVPQ_QUERY,

    EVPQ_FAILURE,

};

/*

 * Create a new evpq connection.

 *

 * This corresponds directly to PQconnectStart, and handles all the libevent setup/polling needed.

 *

 * The connection will initially be in the EVPQ_CONNECT state, and will then either callback via fn_connected

 * (EVPQ_CONNECTED) or fn_failure (EVPQ_FAILURE).

 *

 * cb_info contains the callback functions (and the user argument) to use.

 */

struct evpq_conn *evpq_connect (struct event_base *ev_base, const char *conninfo, const struct evpq_callback_info cb_info, void *cb_arg);

/*

 * Execute a query.

 *

 * This corresponds directly to PQsendQuery. This evpq must be in the EVPQ_CONNECTED state, so you must wait after

 * calling evpq_connect, and you may not run two queries at the same time.

 *

 * The query will result in a series of fn_result (EVPQ_RESULT) calls (if multiple queries in the query string),

 * followed by a fn_done (EVPQ_CONNECTED).

 */

int evpq_query (struct evpq_conn *conn, const char *command);

/*

 * Execute a query with params.

 *

 * See evpq_query and PQsendQueryParams/PQexecParams

 */

int evpq_query_params (struct evpq_conn *conn, const char *command, int nParams, const Oid *paramTypes, const char * const *paramValues, const int *paramLengths, const int *paramFormats, int resultFormat);

/*

 * Connection state ?? la evpq.

 */

enum evpq_state evpq_state (struct evpq_conn *conn);

/*

 * Get the actual PGconn.

 *

 * This can safely be used to access all of the normal PQ functions.

 */

const PGconn *evpq_pgconn (struct evpq_conn *conn);

// convenience wrappers

#define evpq_error_message(conn) PQerrorMessage(evpq_pgconn(conn))

/*

 * Release the evpq_conn, closing all connections and freeing all resources.

 *

 * You must call this yourself in all cases after evpq_connect returns an evpq_conn.

 */

void evpq_release (struct evpq_conn *conn);

#endif /* EVPQ_H */