/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

#include <assert.h>
#include <string.h>
#include "syscfg/syscfg.h"
#if !MYNEWT_VAL(OS_SYSVIEW_TRACE_EVENTQ)
#define OS_TRACE_DISABLE_FILE_API
#endif
#include "os/mynewt.h"

static struct os_eventq os_eventq_main;

void
os_eventq_init(struct os_eventq *evq)
{
    memset(evq, 0, sizeof(*evq));
    STAILQ_INIT(&evq->evq_list);
}

int
os_eventq_inited(const struct os_eventq *evq)
{
    return evq->evq_list.stqh_last != NULL;
}

void
os_eventq_put(struct os_eventq *evq, struct os_event *ev)
{
    int resched;
    os_sr_t sr;

    assert(evq != NULL && os_eventq_inited(evq));

    os_trace_api_u32x2(OS_TRACE_ID_EVENTQ_PUT, (uintptr_t)evq, (uintptr_t)ev);

    OS_ENTER_CRITICAL(sr);

    /* Do not queue if already queued */
    if (OS_EVENT_QUEUED(ev)) {
        OS_EXIT_CRITICAL(sr);
        os_trace_api_ret(OS_TRACE_ID_EVENTQ_PUT);
        return;
    }

    /* Queue the event */
    ev->ev_queued = 1;
    STAILQ_INSERT_TAIL(&evq->evq_list, ev, ev_next);

    resched = 0;
    if (evq->evq_task) {
        /* If task waiting on event, wake it up.
         * Check if task is sleeping, because another event
         * queue may have woken this task up beforehand.
         */
        if (evq->evq_task->t_state == OS_TASK_SLEEP) {
            os_sched_wakeup(evq->evq_task);
            resched = 1;
        }
        /* Either way, NULL out the task, because the task will
         * be awake upon exit of this function.
         */
        evq->evq_task = NULL;
    }

    OS_EXIT_CRITICAL(sr);

    if (resched) {
        os_sched(NULL);
    }

    os_trace_api_ret(OS_TRACE_ID_EVENTQ_PUT);
}

struct os_event *
os_eventq_get_no_wait(struct os_eventq *evq)
{
    struct os_event *ev;

    os_trace_api_u32(OS_TRACE_ID_EVENTQ_GET_NO_WAIT, (uintptr_t)evq);

    ev = STAILQ_FIRST(&evq->evq_list);
    if (ev) {
        STAILQ_REMOVE(&evq->evq_list, ev, os_event, ev_next);
        ev->ev_queued = 0;
    }

    os_trace_api_ret_u32(OS_TRACE_ID_EVENTQ_GET_NO_WAIT, (uintptr_t)ev);

    return ev;
}

struct os_event *
os_eventq_get(struct os_eventq *evq)
{
    struct os_event *ev;
    os_sr_t sr;
    struct os_task *t;

    os_trace_api_u32(OS_TRACE_ID_EVENTQ_GET, (uintptr_t)evq);

    t = os_sched_get_current_task();
    if (evq->evq_owner != t) {
        if (evq->evq_owner == NULL) {
            evq->evq_owner = t;
        } else {
            /*
             * A task is trying to read from event queue which is handled
             * by another.
             */
            assert(0);
        }
    }
    OS_ENTER_CRITICAL(sr);
pull_one:
    ev = STAILQ_FIRST(&evq->evq_list);
    if (ev) {
        STAILQ_REMOVE(&evq->evq_list, ev, os_event, ev_next);
        ev->ev_queued = 0;
        t->t_flags &= ~OS_TASK_FLAG_EVQ_WAIT;
    } else {
        evq->evq_task = t;
        os_sched_sleep(evq->evq_task, OS_TIMEOUT_NEVER);
        t->t_flags |= OS_TASK_FLAG_EVQ_WAIT;
        OS_EXIT_CRITICAL(sr);

        os_sched(NULL);

        OS_ENTER_CRITICAL(sr);
        evq->evq_task = NULL;
        goto pull_one;
    }
    OS_EXIT_CRITICAL(sr);

    os_trace_api_ret_u32(OS_TRACE_ID_EVENTQ_GET, (uintptr_t)ev);

#if MYNEWT_VAL(OS_EVENTQ_DEBUG)
    evq->evq_prev = ev;
#endif

    return (ev);
}

#if MYNEWT_VAL(OS_EVENTQ_MONITOR)
static struct os_eventq_mon *
os_eventq_mon_find(struct os_eventq *evq, struct os_event *ev)
{
    int i;

    if (!evq->evq_mon) {
        return NULL;
    }
    for (i = 0; i < evq->evq_mon_elems; i++) {
        if (evq->evq_mon[i].em_ev == NULL) {
            evq->evq_mon[i].em_ev = ev;
            evq->evq_mon[i].em_cb = ev->ev_cb;
        }
        if (evq->evq_mon[i].em_ev == ev) {
            return &evq->evq_mon[i];
        }
    }
    return NULL;
}
#endif

void
os_eventq_run(struct os_eventq *evq)
{
    struct os_event *ev;
#if MYNEWT_VAL(OS_EVENTQ_MONITOR)
    struct os_eventq_mon *mon;
    uint32_t ticks;
#endif

    ev = os_eventq_get(evq);
    assert(ev->ev_cb != NULL);
#if MYNEWT_VAL(OS_EVENTQ_MONITOR)
    ticks = os_cputime_get32();
#endif
    ev->ev_cb(ev);
#if MYNEWT_VAL(OS_EVENTQ_MONITOR)
    mon = os_eventq_mon_find(evq, ev);
    if (mon) {
        /*
         * If we're monitoring this eventq, and there was space to store
         * this data, record the time spent on the event callback.
         */
        ticks = os_cputime_get32() - ticks;

        mon->em_cnt++;
        mon->em_cum += ticks;
        if (mon->em_min == 0) {
            mon->em_min = ticks;
        }
        if (ticks > mon->em_max) {
            mon->em_max = ticks;
        }
    }
#endif
}

static struct os_event *
os_eventq_poll_0timo(struct os_eventq **evq, int nevqs)
{
    struct os_event *ev;
    os_sr_t sr;
    int i;

    os_trace_api_u32x2(OS_TRACE_ID_EVENTQ_POLL_0TIMO, (uintptr_t)evq[0],
                   (uint32_t)nevqs);

    ev = NULL;

    OS_ENTER_CRITICAL(sr);
    for (i = 0; i < nevqs; i++) {
        ev = STAILQ_FIRST(&evq[i]->evq_list);
        if (ev) {
            STAILQ_REMOVE(&evq[i]->evq_list, ev, os_event, ev_next);
            ev->ev_queued = 0;
            break;
        }
    }
    OS_EXIT_CRITICAL(sr);

    os_trace_api_ret_u32(OS_TRACE_ID_EVENTQ_POLL_0TIMO, (uintptr_t)ev);

    return ev;
}

struct os_event *
os_eventq_poll(struct os_eventq **evq, int nevqs, os_time_t timo)
{
    struct os_event *ev;
    struct os_task *cur_t;
    int i, j;
    os_sr_t sr;

    /* If the timeout is 0, don't involve the scheduler at all.  Grab an event
     * if one is available, else return immediately.
     */
    if (timo == 0) {
        return os_eventq_poll_0timo(evq, nevqs);
    }

    os_trace_api_u32x3(OS_TRACE_ID_EVENTQ_POLL, (uintptr_t)evq[0], (uint32_t)nevqs,
                   (uint32_t)timo);

    ev = NULL;

    OS_ENTER_CRITICAL(sr);
    cur_t = os_sched_get_current_task();

    for (i = 0; i < nevqs; i++) {
        ev = STAILQ_FIRST(&evq[i]->evq_list);
        if (ev) {
            STAILQ_REMOVE(&evq[i]->evq_list, ev, os_event, ev_next);
            ev->ev_queued = 0;
            /* Reset the items that already have an evq task set. */
            for (j = 0; j < i; j++) {
                evq[j]->evq_task = NULL;
            }

            OS_EXIT_CRITICAL(sr);
            goto has_event;
        }
        evq[i]->evq_task = cur_t;
    }

    cur_t->t_flags |= OS_TASK_FLAG_EVQ_WAIT;

    os_sched_sleep(cur_t, timo);
    OS_EXIT_CRITICAL(sr);

    os_sched(NULL);

    OS_ENTER_CRITICAL(sr);
    cur_t->t_flags &= ~OS_TASK_FLAG_EVQ_WAIT;
    for (i = 0; i < nevqs; i++) {
        /* Go through the entire loop to clear the evq_task variable,
         * given this task is no longer sleeping on the event queues.
         * Return the first event found, so only grab the event if
         * we haven't found one.
         */
        if (!ev) {
            ev = STAILQ_FIRST(&evq[i]->evq_list);
            if (ev) {
                STAILQ_REMOVE(&evq[i]->evq_list, ev, os_event, ev_next);
                ev->ev_queued = 0;
            }
        }
        evq[i]->evq_task = NULL;
    }
    OS_EXIT_CRITICAL(sr);

has_event:
    os_trace_api_ret_u32(OS_TRACE_ID_EVENTQ_POLL, (uintptr_t)ev);

    return (ev);
}

void
os_eventq_remove(struct os_eventq *evq, struct os_event *ev)
{
    os_sr_t sr;

    os_trace_api_u32x2(OS_TRACE_ID_EVENTQ_REMOVE, (uintptr_t)evq, (uintptr_t)ev);

    OS_ENTER_CRITICAL(sr);
    if (OS_EVENT_QUEUED(ev)) {
        STAILQ_REMOVE(&evq->evq_list, ev, os_event, ev_next);
    }
    ev->ev_queued = 0;
    OS_EXIT_CRITICAL(sr);

    os_trace_api_ret(OS_TRACE_ID_EVENTQ_REMOVE);
}

struct os_eventq *
os_eventq_dflt_get(void)
{
    return &os_eventq_main;
}

/**
 * [DEPRECATED - packages should manually enqueue start events to the default
 * task instead of calling this function]
 *
 * Reassigns an event queue pointer to the specified value.  This function is
 * used for configuring a package to use a particular event queue.  A package's
 * event queue can generally be reassigned repeatedly.  If the package has a
 * startup event, the event is moved from the current queue (if any) to the
 * specified queue.
 *
 * @param cur_evq               Points to the eventq pointer to reassign.
 *                                  *cur_evq should be NULL if the package's
 *                                  eventq has not been assigned yet.
 * @param new_evq               The eventq that the package should be
 *                                  associated with.
 * @param start_ev              The package's startup event, if any.  If this
 *                                  is non-NULL, the event gets removed from
 *                                  the current queue (if set), and enqueued to
 *                                  the new eventq.
 */
void
os_eventq_designate(struct os_eventq **cur_evq,
                    struct os_eventq *new_evq,
                    struct os_event *start_ev)
{
    struct os_eventq *prev_evq;

    prev_evq = *cur_evq;
    *cur_evq = new_evq;

    if (start_ev != NULL) {
        if (start_ev->ev_queued) {
            assert(prev_evq != NULL);
            os_eventq_remove(prev_evq, start_ev);
        }
        os_eventq_put(new_evq, start_ev);
    }
}