/*
 * Copyright 2018 Google, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Authors: Gabe Black
 */

#include "systemc/core/process.hh"

#include "base/logging.hh"
#include "systemc/core/event.hh"
#include "systemc/core/scheduler.hh"
#include "systemc/ext/core/sc_join.hh"
#include "systemc/ext/core/sc_main.hh"
#include "systemc/ext/core/sc_process_handle.hh"
#include "systemc/ext/utils/sc_report_handler.hh"

namespace sc_gem5
{

class UnwindExceptionReset : public ::sc_core::sc_unwind_exception
{
  public:
    UnwindExceptionReset() { _isReset = true; }
};

class UnwindExceptionKill : public ::sc_core::sc_unwind_exception
{
  public:
    UnwindExceptionKill() {}
};

template <typename T>
struct BuiltinExceptionWrapper : public ExceptionWrapperBase
{
  public:
    T t;
    void throw_it() override { throw t; }
};

BuiltinExceptionWrapper<UnwindExceptionReset> resetException;
BuiltinExceptionWrapper<UnwindExceptionKill> killException;


void
Process::forEachKid(const std::function<void(Process *)> &work)
{
    for (auto &kid: get_child_objects()) {
        Process *p_kid = dynamic_cast<Process *>(kid);
        if (p_kid)
            work(p_kid);
    }
}

void
Process::suspend(bool inc_kids)
{
    if (inc_kids)
        forEachKid([](Process *p) { p->suspend(true); });

    if (!_suspended) {
        _suspended = true;
        _suspendedReady = scheduler.suspend(this);

        if (procKind() != ::sc_core::SC_METHOD_PROC_ &&
                scheduler.current() == this) {
            // This isn't in the spec, but Accellera says that a thread that
            // self suspends should be marked ready immediately when it's
            // resumed.
            _suspendedReady = true;
            scheduler.yield();
        }
    }
}

void
Process::resume(bool inc_kids)
{
    if (inc_kids)
        forEachKid([](Process *p) { p->resume(true); });

    if (_suspended) {
        _suspended = false;
        if (_suspendedReady)
            scheduler.resume(this);
        _suspendedReady = false;
    }
}

void
Process::disable(bool inc_kids)
{
    if (inc_kids)
        forEachKid([](Process *p) { p->disable(true); });

    if (!::sc_core::sc_allow_process_control_corners &&
            timeoutEvent.scheduled()) {
        std::string message("attempt to disable a thread with timeout wait: ");
        message += name();
        SC_REPORT_ERROR("Undefined process control interaction",
                message.c_str());
    }

    _disabled = true;
}

void
Process::enable(bool inc_kids)
{

    if (inc_kids)
        forEachKid([](Process *p) { p->enable(true); });

    _disabled = false;
}

void
Process::kill(bool inc_kids)
{
    if (::sc_core::sc_get_status() != ::sc_core::SC_RUNNING) {
        SC_REPORT_ERROR(
                "(E572) a process may not be killed before it is initialized",
                name());
    }

    // Propogate the kill to our children no matter what happens to us.
    if (inc_kids)
        forEachKid([](Process *p) { p->kill(true); });

    // If we're in the middle of unwinding, ignore the kill request.
    if (_isUnwinding)
        return;

    // Update our state.
    terminate();
    _isUnwinding = true;

    // Make sure this process isn't marked ready
    popListNode();

    // Inject the kill exception into this process if it's started.
    if (!_needsStart)
        injectException(killException);
}

void
Process::reset(bool inc_kids)
{
    if (::sc_core::sc_get_status() != ::sc_core::SC_RUNNING) {
        SC_REPORT_ERROR(
                "(E573) a process may not be asynchronously reset while"
                "the simulation is not running", name());
    }

    // Propogate the reset to our children no matter what happens to us.
    if (inc_kids)
        forEachKid([](Process *p) { p->reset(true); });

    // If we're in the middle of unwinding, ignore the reset request.
    if (_isUnwinding)
        return;


    _resetEvent.notify();

    if (_needsStart) {
        scheduler.runNow(this);
    } else {
        _isUnwinding = true;
        injectException(resetException);
    }
}

void
Process::throw_it(ExceptionWrapperBase &exc, bool inc_kids)
{
    if (::sc_core::sc_get_status() != ::sc_core::SC_RUNNING) {
        SC_REPORT_ERROR(
                "(E574) throw_it not allowed unless simulation is running ",
                name());
    }

    if (inc_kids)
        forEachKid([&exc](Process *p) { p->throw_it(exc, true); });

    // Only inject an exception into threads that have started.
    if (!_needsStart)
        injectException(exc);
}

void
Process::injectException(ExceptionWrapperBase &exc)
{
    excWrapper = &exc;
    scheduler.runNow(this);
};

void
Process::syncResetOn(bool inc_kids)
{
    if (inc_kids)
        forEachKid([](Process *p) { p->syncResetOn(true); });

    _syncReset = true;
}

void
Process::syncResetOff(bool inc_kids)
{
    if (inc_kids)
        forEachKid([](Process *p) { p->syncResetOff(true); });

    _syncReset = false;
}

void
Process::signalReset(bool set, bool sync)
{
    if (set) {
        waitCount(0);
        if (sync) {
            syncResetCount++;
        } else {
            asyncResetCount++;
            cancelTimeout();
            clearDynamic();
            scheduler.runNext(this);
        }
    } else {
        if (sync)
            syncResetCount--;
        else
            asyncResetCount--;
    }
}

void
Process::run()
{
    bool reset;
    do {
        reset = false;
        try {
            func->call();
        } catch(ScHalt) {
            std::cout << "Terminating process " << name() << std::endl;
        } catch(const ::sc_core::sc_unwind_exception &exc) {
            reset = exc.is_reset();
            _isUnwinding = false;
        } catch (...) {
            throw;
        }
    } while (reset);
    needsStart(true);
}

void
Process::addStatic(StaticSensitivity *s)
{
    staticSensitivities.push_back(s);
}

void
Process::setDynamic(DynamicSensitivity *s)
{
    if (dynamicSensitivity) {
        dynamicSensitivity->clear();
        delete dynamicSensitivity;
    }
    dynamicSensitivity = s;
}

void
Process::addReset(ResetSensitivity *s)
{
    resetSensitivities.push_back(s);
}

void
Process::cancelTimeout()
{
    if (timeoutEvent.scheduled())
        scheduler.deschedule(&timeoutEvent);
}

void
Process::setTimeout(::sc_core::sc_time t)
{
    cancelTimeout();
    scheduler.schedule(&timeoutEvent, t);
}

void
Process::timeout()
{
    // A process is considered timed_out only if it was also waiting for an
    // event but got a timeout instead.
    _timedOut = (dynamicSensitivity != nullptr);

    setDynamic(nullptr);
    if (disabled())
        return;

    ready();
}

void
Process::satisfySensitivity(Sensitivity *s)
{
    if (_waitCount) {
        _waitCount--;
        return;
    }

    // If there's a dynamic sensitivity and this wasn't it, ignore.
    if ((dynamicSensitivity || timeoutEvent.scheduled()) &&
            dynamicSensitivity != s) {
        return;
    }

    _timedOut = false;
    // This sensitivity should already be cleared by this point, or the event
    // which triggered it will take care of it.
    delete dynamicSensitivity;
    dynamicSensitivity = nullptr;
    cancelTimeout();
    ready();
}

void
Process::ready()
{
    if (disabled())
        return;
    if (suspended())
        _suspendedReady = true;
    else
        scheduler.ready(this);
}

void
Process::lastReport(::sc_core::sc_report *report)
{
    if (report) {
        _lastReport = std::unique_ptr<::sc_core::sc_report>(
                new ::sc_core::sc_report(*report));
    } else {
        _lastReport = nullptr;
    }
}

::sc_core::sc_report *Process::lastReport() const { return _lastReport.get(); }

Process::Process(const char *name, ProcessFuncWrapper *func, bool internal) :
    ::sc_core::sc_process_b(name), excWrapper(nullptr),
    timeoutEvent([this]() { this->timeout(); }),
    func(func), _internal(internal), _timedOut(false), _dontInitialize(false),
    _needsStart(true), _isUnwinding(false), _terminated(false),
    _suspended(false), _disabled(false), _syncReset(false), syncResetCount(0),
    asyncResetCount(0), _waitCount(0), refCount(0),
    stackSize(::Fiber::DefaultStackSize), dynamicSensitivity(nullptr)
{
    _dynamic =
            (::sc_core::sc_get_status() >
             ::sc_core::SC_BEFORE_END_OF_ELABORATION);
    _newest = this;
}

void
Process::terminate()
{
    _terminated = true;
    _suspendedReady = false;
    _suspended = false;
    _syncReset = false;
    clearDynamic();
    cancelTimeout();
    for (auto s: staticSensitivities) {
        s->clear();
        delete s;
    }
    staticSensitivities.clear();

    _terminatedEvent.notify();

    for (auto jw: joinWaiters)
        jw->signal();
    joinWaiters.clear();
}

Process *Process::_newest;

void
throw_it_wrapper(Process *p, ExceptionWrapperBase &exc, bool inc_kids)
{
    p->throw_it(exc, inc_kids);
}

} // namespace sc_gem5