/*
 * Licensed 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.
 *
 * Copyright 2010 Danny Robson <danny@nerdcruft.net>
 */

#include "time.hpp"

#include "debug.hpp"
#include "log.hpp"
#include "platform.hpp"
#include "types/casts.hpp"


using namespace util;

// ----------------------------------------------------------------------------
static const uint64_t SECOND      = 1000000000UL;
static const uint64_t MILLISECOND =    1000000UL;

// ----------------------------------------------------------------------------
#ifdef PLATFORM_WIN32
#include <windows.h>

uint64_t
util::nanoseconds (void) {
    LARGE_INTEGER freq, count;
    QueryPerformanceFrequency (&freq);
    QueryPerformanceCounter   (&count);

    return ((double)count.QuadPart / freq.QuadPart) * SECOND;
}


void
util::sleep (uint64_t ns) {
    Sleep (ns / MILLISECOND);
}

#else
#include <ctime>

uint64_t
util::nanoseconds (void) {
    struct timespec t;
    clock_gettime (CLOCK_MONOTONIC, &t);

    CHECK_GT (t.tv_sec, 0);
    CHECK_GT (t.tv_nsec, 0);

    return static_cast<uint64_t> (t.tv_sec) * SECOND + static_cast<uint64_t> (t.tv_nsec);
}


void
util::sleep (uint64_t ns) {
    struct timespec req, rem;

    req.tv_sec  = sign_cast<time_t> (ns / SECOND);
    req.tv_nsec = sign_cast<long>   (ns % SECOND);

    while (nanosleep (&req, &rem)) {
        req = rem;
    }
}
#endif

// ----------------------------------------------------------------------------
delta_clock::delta_clock ():
    time { util::nanoseconds (), util::nanoseconds () }
{ ; }


float
delta_clock::seconds (void) {
    time.prev = time.curr;
    time.curr = nanoseconds ();

    return (time.curr - time.prev) / static_cast<float> (SECOND);
}

// ----------------------------------------------------------------------------
util::period_query::period_query (float seconds) {
    m_time.start  = nanoseconds ();
    m_time.period = static_cast<uint64_t> (seconds * SECOND);
}


bool
util::period_query::poll (void) {
    uint64_t now  = nanoseconds ();
    uint64_t diff = now - m_time.start;
    if (diff < m_time.period)
        return false;

    m_time.start += diff % m_time.period;
    return true;
}


// ----------------------------------------------------------------------------
util::rate_limiter::rate_limiter (unsigned rate):
    m_last (nanoseconds ()),
    m_target (SECOND / rate)
{ ; }


void
util::rate_limiter::poll (void) {
    uint64_t now = nanoseconds ();
    uint64_t total = now - m_last;

    if (total < m_target)
        sleep (m_target - total);

    m_last = now;
}


// ----------------------------------------------------------------------------
util::polled_duration::polled_duration (std::string name, uint64_t interval):
    m_name     (name),
    m_interval (interval),
    m_next     (nanoseconds () + interval)
{ ; }


void
util::polled_duration::start (void) {
    m_last = nanoseconds ();
}


void
util::polled_duration::stop (void) {
    uint64_t now = nanoseconds ();
    uint64_t dt  = now - m_last;
    m_series.add (dt / MILLISECOND);

    if (m_next < now) {
        LOG_DEBUG ("timing: '%s'. %s", m_name, m_series);
        m_series.reset ();
        m_next = now + m_interval;
    }
}