#ifndef UC_IO_MUX_H_
#define UC_IO_MUX_H_

#include "timers.h"
/** @addtogroup IOMux
 *  @{ 
 *  The IOMux is an I/O multiplexer, implementing a main eventloop.
 *  The event loop can be used to register callbacks for activity on
 *  file descriptors such as sockets and pips, and for timers.
 *  
 *  The IOMux is backed either by the select() system call, or the epoll
 *  facility on Linux. Several IOMuxes can run in different threads concurrently,
 *  but note that the IOMux itself is not thread safe so operations in one thread
 *  cannot work on an IOMux running in another thread.
 *
 *  */
#ifdef __cplusplus
extern "C" {
#endif


#define MUX_EV_READ    (1U << 0x00)
#define MUX_EV_WRITE   (1U << 0x01)
//#define MUX_EV_EXCEPT  (1 << 0x02)
#define MUX_EV_MASK (MUX_EV_READ | MUX_EV_WRITE )

/** 
 * mux implementation to use
*/
enum IOMUX_TYPE {
    IOMUX_TYPE_DEFAULT = 0,
    IOMUX_TYPE_SELECT,
    IOMUX_TYPE_EPOLL
};

/** The IOMux used to issue mux operations. This is to be treated as an opaque
 *  handle. Use  iomux_create() or iomux_create_ex() to create an IOMux, register
 *  callbakcs, and call iomux_run() to process the events
 */
struct IOMux;

struct IOMuxFD;

/** Callback function used in struct IOMuxFD
 * @param mux the mux that issued the callback.
 * @param fd the file desciptor structure.
 * @param event A bitmask of the MUX_EV_XX values. Both a read and a write event
 *        might be signalled in the same callback
 */
typedef void (*iomux_cb)(struct IOMux *mux, struct IOMuxFD *fd, unsigned int event);

/** Represents a watched file descriptor */
struct IOMuxFD {
    /** The file descriptor */
    int fd;
    /** The events to watch for, MUX_EV_XX mask */
    unsigned int what;
    /** callback to call on an event */
    iomux_cb callback;
    /** values available to the caller. These will bbe passed
     * back on the callback */
    void *cookie_ptr;
    int cookie_int;
    int cookie_int2;
};

/** Creates a new IOMux. 
 *
 * @param type the underlying implementation to use @see IOMUX_TYPE
 * @return Newly allocated IOMux. NULL if memory allocation fails.
 */
struct IOMux *iomux_create(enum IOMUX_TYPE type);

/** Creates a new IOMux with a user supplied clock
 *
 * The supplied clock is used for the UCTimers associated
 * with the mux.
 */
struct IOMux *iomux_create_ex(enum IOMUX_TYPE type, struct UCoreClock *uclock);

/** Deletes the IOMux and frees its resources.
 * Can not be called from within a callback */
void iomux_delete(struct IOMux *mux);

/** Runs the event loop of the mux
 *
 * @return if the number of file descriptors and timers are 0 or 
 * an error occurs */
int iomux_run(struct IOMux *mux);

/* Adds a file descriptor to the watch set.
 * The file descriptor integer value must reside in only
 * one struct IOMuxFD. Adding e.g. the same file descriptor
 * in 2 different struct IOMuxFD, one for read events and one for
 * write events is not supported.
 *
 * @return 0 on success, an errno value on error
 */
int iomux_register_fd(struct IOMux *mux, struct IOMuxFD *fd);

/** Removes the file descriptor
 *
 * @return 0 on success, an errno value on error
 */
int iomux_unregister_fd(struct IOMux *mux, struct IOMuxFD *fd);

/** Updates the events to watch for in fd->what
 * @return 0 on success, an errno value on error
 */
int iomux_update_events(struct IOMux *mux, struct IOMuxFD *fd);


/**
 * Convenience macro for setting the new event
 */
#define iomux_set_event(mux, fd, what)\
({\
    (fd)->what = (what);\
    iomux_update_events((mux), (fd));\
})

/**
 * Convenience macro for clearing the new event
 */
#define iomux_clear_event(mux, fd, what)\
({\
    (fd)->what &= ~(what);\
    iomux_update_events((mux), (fd));\
})
/**
 * Convenience macro for adding the new event to the existing events
 */
#define iomux_add_event(mux, fd, what)\
({\
    (fd)->what &= (what);\
    iomux_update_events((mux), (fd));\
})

/** @return a UCTimer instance tied to this mux.
 *  Used to schedule timers within this mux.
 */
struct UCTimers *iomux_get_timers(struct IOMux *mux);

#ifdef __cplusplus
}
#endif

/**  @} (addtogroup)*/
#endif