#include <stdlib.h>
#include <string.h>
#include <string.h>
#include <assert.h>
#include "ucore/clock.h"
#include "ucore/backtrace.h"
#include "iomux_impl.h"


//dispatchers for the IOMux implementations */

struct IOMux *iomux_create(enum IOMUX_TYPE type)
{
    return iomux_create_ex(type, &uc_timeofday_clock);
}

struct IOMux *iomux_create_ex(enum IOMUX_TYPE type, struct UCoreClock *uclock)
{
    struct IOMux *mux = calloc(1, sizeof *mux);
    int rc = -1;


    switch (type) {
        case IOMUX_TYPE_DEFAULT:
        case IOMUX_TYPE_EPOLL:
            rc = iomux_epoll_init(mux);
            break;
        case IOMUX_TYPE_SELECT:
            rc = iomux_select_init(mux);
            break;
    }

    if (rc != 0) {
        //try fallback to select
        rc = iomux_select_init(mux);
    }

    if (rc == 0) {
        mux->uclock = uclock;
        uc_timers_init_ex(&mux->timers, mux->uclock);
    } else {
        free(mux);
        mux = NULL;
    }

    return mux;
}

void iomux_delete(struct IOMux *mux)
{
    mux->ops.delete_impl(mux);
    memset(mux, 0xfa, sizeof *mux);
    free(mux);
}

//convert the difference between future and now
static inline void future_to_interval(const struct timeval *future, 
                                      const struct timeval *now, 
                                      struct timeval *result)
{
    if (timercmp(future, now, >)) {
        timersub(future, now, result);
    } else {
        result->tv_sec = 0;
        result->tv_usec = 0;
    }
}

static int iomux_run_timers(struct IOMux *mux, struct timeval *timeout)
{
    struct timeval first_timer;

    if (uc_timers_first(&mux->timers, &first_timer) == 0) {
        struct timeval now;
        mux->uclock->now(mux->uclock, &now);
        future_to_interval(&first_timer, &now, timeout);
        /*TRACEF("now %d %d future %d %d interval %d %d\n", now.tv_sec, now.tv_usec,
                                                          first_timer.tv_sec, first_timer.tv_usec,
                                                          timeout->tv_sec, timeout->tv_usec);
        */
      
        assert(timeout->tv_sec >= 0);
        assert(timeout->tv_usec >= 0);

        return 1;
    } 

    return 0;
}

int iomux_run(struct IOMux *mux)
{
    for (;;) {
        int rc;
        struct timeval timeout;
        struct timeval *timeoutp;

        if (iomux_run_timers(mux, &timeout)) {
            timeoutp = &timeout;
        } else {
            timeoutp = NULL;
        }

        rc = mux->ops.run_impl(mux, timeoutp);
        if (rc < 0)
            return rc;

        if (rc == 0 && timeoutp == NULL) //no more fd or timer events, ever
            return 0;
    }

    UC_NOT_REACED();
    return -44;
}

int iomux_timers_run(struct IOMux *mux)
{
    int event_cnt;

    event_cnt = uc_timers_run(&mux->timers);
    assert(event_cnt >= 0);

    return event_cnt;
}

int iomux_register_fd(struct IOMux *mux, struct IOMuxFD *fd)
{
    assert(mux != NULL);
    assert(fd != NULL);
    assert(fd->callback != NULL);
    assert(fd->fd >= 0);
    return mux->ops.register_fd_impl(mux, fd);
}

int iomux_unregister_fd(struct IOMux *mux, struct IOMuxFD *fd)
{
    assert(mux != NULL);
    assert(fd != NULL);
    assert(fd->fd >= 0);
    return mux->ops.unregister_fd_impl(mux, fd);
}

int iomux_update_events(struct IOMux *mux, struct IOMuxFD *fd, unsigned int what)
{
    int rc = 0;
    assert(mux != NULL);
    assert(fd != NULL);
    assert(fd->callback != NULL);
    assert(fd->fd >= 0);
    
    if (fd->what != what) {
        rc = mux->ops.update_events_impl(mux, fd);
    }

    return rc;
}

struct UCoreClock *iomux_get_clock(struct IOMux *mux)
{
    return mux->uclock;
}

struct UCTimers *iomux_get_timers(struct IOMux *mux)
{
    return &mux->timers;
}

struct IOMux *iomux_from_timers(struct UCTimers *timers)
{
    return (struct IOMux*)timers; //timers is the 1. member of IOMux
}