/*

 * Low-level protocol support for the IPC connection to the engine.

 */

#ifndef IPCBASE_H_

#define IPCBASE_H_

#include <stddef.h>

#include <stdbool.h>

#include <stdint.h>

#define IPCBASE_MAPMSG_BYTES 4097

typedef enum {IPC_NOT_CONNECTED, IPC_LISTENING, IPC_CONNECTED} IpcState;

typedef struct _flib_ipcbase flib_ipcbase;

/**

 * Start an engine connection by listening on a random port. The selected port can

 * be queried with flib_ipcbase_port and has to be passed to the engine.

 *

 * Returns NULL on error. Destroy the created object with flib_ipcbase_destroy.

 *

 * We stop accepting new connections once a connection has been established, so you

 * need to create a new ipcbase in order to start a new connection.

 */

flib_ipcbase *flib_ipcbase_create();

/**

 * Return the listening port

 */

uint16_t flib_ipcbase_port(flib_ipcbase *ipc);

/**

 * Free resources and close sockets. NULL safe.

 */

void flib_ipcbase_destroy(flib_ipcbase *ipc);

/**

 * Determine the current connection state

 */

IpcState flib_ipcbase_state(flib_ipcbase *ipc);

/**

 * Receive a single message (up to 256 bytes) and copy it into the data buffer.

 * Returns the length of the received message, a negative value if no message could

 * be read.

 *

 * The first byte of a message is its content length, which is one less than the returned

 * value.

 *

 * Note: When a connection is closed, you probably want to call this function until

 * no further message is returned, to ensure you see all messages that were sent

 * before the connection closed.

 */

int flib_ipcbase_recv_message(flib_ipcbase *ipc, void *data);

/**

 * Try to receive 4097 bytes. This is the size of the reply the engine sends

 * when successfully queried for map data. The first 4096 bytes are a bit-packed

 * twocolor image of the map (256x128), the last byte is the number of hogs that

 * fit on the map.

 */

int flib_ipcbase_recv_map(flib_ipcbase *ipc, void *data);

/**

 * Blocking send bytes over the socket. No message framing will be added.

 * Returns 0 on success.

 */

int flib_ipcbase_send_raw(flib_ipcbase *ipc, const void *data, size_t len);

/**

 * Write a single message (up to 255 bytes) to the engine. This call blocks until the

 * message is completely written or the connection is closed or an error occurs.

 *

 * Calling this function in a state other than IPC_CONNECTED will fail immediately.

 * Returns 0 on success.

 */

int flib_ipcbase_send_message(flib_ipcbase *ipc, void *data, size_t len);

/**

 * Try to accept a connection. Only has an effect in state IPC_LISTENING.

 */

void flib_ipcbase_accept(flib_ipcbase *ipc);

#endif /* IPCBASE_H_ */