// Copyright 2015 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.

#include <cinttypes>
#include "common/assert.h"
#include "common/logging/log.h"
#include "core/core_timing.h"
#include "core/hle/kernel/handle_table.h"
#include "core/hle/kernel/kernel.h"
#include "core/hle/kernel/thread.h"
#include "core/hle/kernel/timer.h"

namespace Kernel {

/// The event type of the generic timer callback event
static CoreTiming::EventType* timer_callback_event_type = nullptr;
// TODO(yuriks): This can be removed if Timer objects are explicitly pooled in the future, allowing
//               us to simply use a pool index or similar.
static Kernel::HandleTable timer_callback_handle_table;

Timer::Timer() {}
Timer::~Timer() {}

SharedPtr<Timer> Timer::Create(ResetType reset_type, std::string name) {
    SharedPtr<Timer> timer(new Timer);

    timer->reset_type = reset_type;
    timer->signaled = false;
    timer->name = std::move(name);
    timer->initial_delay = 0;
    timer->interval_delay = 0;
    timer->callback_handle = timer_callback_handle_table.Create(timer).Unwrap();

    return timer;
}

bool Timer::ShouldWait(Thread* thread) const {
    return !signaled;
}

void Timer::Acquire(Thread* thread) {
    ASSERT_MSG(!ShouldWait(thread), "object unavailable!");

    if (reset_type == ResetType::OneShot)
        signaled = false;
}

void Timer::Set(s64 initial, s64 interval) {
    // Ensure we get rid of any previous scheduled event
    Cancel();

    initial_delay = initial;
    interval_delay = interval;

    if (initial == 0) {
        // Immediately invoke the callback
        Signal(0);
    } else {
        CoreTiming::ScheduleEvent(CoreTiming::nsToCycles(initial), timer_callback_event_type,
                                  callback_handle);
    }
}

void Timer::Cancel() {
    CoreTiming::UnscheduleEvent(timer_callback_event_type, callback_handle);
}

void Timer::Clear() {
    signaled = false;
}

void Timer::WakeupAllWaitingThreads() {
    WaitObject::WakeupAllWaitingThreads();

    if (reset_type == ResetType::Pulse)
        signaled = false;
}

void Timer::Signal(int cycles_late) {
    LOG_TRACE(Kernel, "Timer {} fired", GetObjectId());

    signaled = true;

    // Resume all waiting threads
    WakeupAllWaitingThreads();

    if (interval_delay != 0) {
        // Reschedule the timer with the interval delay
        CoreTiming::ScheduleEvent(CoreTiming::nsToCycles(interval_delay) - cycles_late,
                                  timer_callback_event_type, callback_handle);
    }
}

/// The timer callback event, called when a timer is fired
static void TimerCallback(u64 timer_handle, int cycles_late) {
    SharedPtr<Timer> timer =
        timer_callback_handle_table.Get<Timer>(static_cast<Handle>(timer_handle));

    if (timer == nullptr) {
        LOG_CRITICAL(Kernel, "Callback fired for invalid timer {:016X}", timer_handle);
        return;
    }

    timer->Signal(cycles_late);
}

void TimersInit() {
    timer_callback_handle_table.Clear();
    timer_callback_event_type = CoreTiming::RegisterEvent("TimerCallback", TimerCallback);
}

void TimersShutdown() {}

} // namespace Kernel
