/*
 * 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 <cstring>
#include <string>

#include "base/fiber.hh"
#include "base/logging.hh"
#include "base/types.hh"
#include "sim/core.hh"
#include "sim/eventq.hh"
#include "sim/init.hh"
#include "systemc/core/kernel.hh"
#include "systemc/core/python.hh"
#include "systemc/core/scheduler.hh"
#include "systemc/ext/core/sc_main.hh"
#include "systemc/ext/utils/sc_report_handler.hh"

// A weak symbol to detect if sc_main has been defined, and if so where it is.
[[gnu::weak]] int sc_main(int argc, char *argv[]);

namespace sc_core
{

namespace
{

bool scMainCalled = false;

int _argc = 0;
char **_argv = NULL;

class ScMainFiber : public Fiber
{
  public:
    std::string resultStr;
    int resultInt;

    ScMainFiber() : resultInt(1) {}

    void
    main()
    {
        if (::sc_main) {
            try {
                resultInt = ::sc_main(_argc, _argv);
                if (resultInt)
                    resultStr = "sc_main returned non-zero";
                else
                    resultStr = "sc_main finished";
                // Make sure no systemc events/notifications are scheduled
                // after sc_main returns.
            } catch (const sc_report &r) {
                // There was an exception nobody caught.
                resultStr = r.what();
            }
            ::sc_gem5::Kernel::scMainFinished(true);
            ::sc_gem5::scheduler.clear();
        } else {
            // If python tries to call sc_main but no sc_main was defined...
            fatal("sc_main called but not defined.\n");
        }
    }
};

ScMainFiber scMainFiber;

// This wrapper adapts the python version of sc_main to the c++ version.
void
sc_main(pybind11::args args)
{
    panic_if(scMainCalled, "sc_main called more than once.");

    _argc = args.size();
    _argv = new char *[_argc];

    // Initialize all the _argvs to NULL so we can delete [] them
    // unconditionally.
    for (int idx = 0; idx < _argc; idx++)
        _argv[idx] = NULL;

    // Attempt to convert all the arguments to strings. If that fails, clean
    // up after ourselves. Also don't count this as a call to sc_main since
    // we never got to the c++ version of that function.
    try {
        for (int idx = 0; idx < _argc; idx++) {
            std::string arg = args[idx].cast<std::string>();
            _argv[idx] = new char[arg.length() + 1];
            strcpy(_argv[idx], arg.c_str());
        }
    } catch (...) {
        // If that didn't work for some reason (probably a conversion error)
        // blow away _argv and _argc and pass on the exception.
        for (int idx = 0; idx < _argc; idx++)
            delete [] _argv[idx];
        delete [] _argv;
        _argc = 0;
        throw;
    }

    // At this point we're going to call the c++ sc_main, so we can't try
    // again later.
    scMainCalled = true;

    scMainFiber.run();
}

int
sc_main_result_code()
{
    return scMainFiber.resultInt;
}

std::string
sc_main_result_str()
{
    return scMainFiber.resultStr;
}

// Make our sc_main wrapper available in the internal _m5 python module under
// the systemc submodule.

struct InstallScMain : public ::sc_gem5::PythonInitFunc
{
    void
    run(pybind11::module &systemc) override
    {
        systemc.def("sc_main", &sc_main);
        systemc.def("sc_main_result_code", &sc_main_result_code);
        systemc.def("sc_main_result_str", &sc_main_result_str);
    }
} installScMain;

sc_stop_mode _stop_mode = SC_STOP_FINISH_DELTA;

} // anonymous namespace

int
sc_argc()
{
    return _argc;
}

const char *const *
sc_argv()
{
    return _argv;
}

void
sc_start()
{
    Tick now = ::sc_gem5::scheduler.getCurTick();
    sc_start(sc_time::from_value(MaxTick - now), SC_EXIT_ON_STARVATION);
}

void
sc_pause()
{
    if (::sc_gem5::Kernel::status() == SC_RUNNING)
        ::sc_gem5::scheduler.schedulePause();
}

void
sc_start(const sc_time &time, sc_starvation_policy p)
{
    if (time.value() == 0) {
        ::sc_gem5::scheduler.oneCycle();
    } else {
        Tick now = ::sc_gem5::scheduler.getCurTick();
        if (MaxTick - now < time.value()) {
            SC_REPORT_ERROR("(E544) simulation time value overflow, "
                    "simulation aborted", "");
        }
        ::sc_gem5::scheduler.start(now + time.value(), p == SC_RUN_TO_TIME);
    }
}

void
sc_set_stop_mode(sc_stop_mode mode)
{
    if (sc_is_running()) {
        SC_REPORT_ERROR("attempt to set sc_stop mode "
                        "after start will be ignored", "");
        return;
    }
    _stop_mode = mode;
}

sc_stop_mode
sc_get_stop_mode()
{
    return _stop_mode;
}

void
sc_stop()
{
    if (::sc_gem5::Kernel::status() == SC_STOPPED)
        return;

    if (sc_is_running()) {
        bool finish_delta = (_stop_mode == SC_STOP_FINISH_DELTA);
        ::sc_gem5::scheduler.scheduleStop(finish_delta);
    } else {
        ::sc_gem5::Kernel::stop();
    }
}

const sc_time &
sc_time_stamp()
{
    static sc_time tstamp;
    Tick tick = ::sc_gem5::scheduler.getCurTick();
    //XXX We're assuming the systemc time resolution is in ps.
    // If tick is zero, the time scale may not be fixed yet, and
    // SimClock::Int::ps may be zero.
    tstamp = sc_time::from_value(tick ? tick / SimClock::Int::ps : 0);
    return tstamp;
}

sc_dt::uint64
sc_delta_count()
{
    return sc_gem5::scheduler.numCycles();
}

bool
sc_is_running()
{
    return sc_get_status() & (SC_RUNNING | SC_PAUSED);
}

bool
sc_pending_activity_at_current_time()
{
    return ::sc_gem5::scheduler.pendingCurr();
}

bool
sc_pending_activity_at_future_time()
{
    return ::sc_gem5::scheduler.pendingFuture();
}

bool
sc_pending_activity()
{
    return sc_pending_activity_at_current_time() ||
           sc_pending_activity_at_future_time();
}

sc_time
sc_time_to_pending_activity()
{
    return sc_time::from_value(::sc_gem5::scheduler.timeToPending());
}

sc_status
sc_get_status()
{
    return ::sc_gem5::kernel ? ::sc_gem5::kernel->status() : SC_ELABORATION;
}

std::ostream &
operator << (std::ostream &os, sc_status s)
{
    switch (s) {
      case SC_ELABORATION:
        os << "SC_ELABORATION";
        break;
      case SC_BEFORE_END_OF_ELABORATION:
        os << "SC_BEFORE_END_OF_ELABORATION";
        break;
      case SC_END_OF_ELABORATION:
        os << "SC_END_OF_ELABORATION";
        break;
      case SC_START_OF_SIMULATION:
        os << "SC_START_OF_SIMULATION";
        break;
      case SC_RUNNING:
        os << "SC_RUNNING";
        break;
      case SC_PAUSED:
        os << "SC_PAUSED";
        break;
      case SC_STOPPED:
        os << "SC_STOPPED";
        break;
      case SC_END_OF_SIMULATION:
        os << "SC_END_OF_SIMULATION";
        break;

        // Nonstandard
      case SC_END_OF_INITIALIZATION:
        os << "SC_END_OF_INITIALIZATION";
        break;
      case SC_END_OF_UPDATE:
        os << "SC_END_OF_UPDATE";
        break;
      case SC_BEFORE_TIMESTEP:
        os << "SC_BEFORE_TIMESTEP";
        break;

      default:
        if (s & SC_STATUS_ANY) {
            const char *prefix = "(";
            for (sc_status m = (sc_status)0x1;
                    m < SC_STATUS_ANY; m = (sc_status)(m << 1)) {
                if (m & s) {
                    os << prefix;
                    prefix = "|";
                    os << m;
                }
            }
            os << ")";
        } else {
            ccprintf(os, "%#x", s);
        }
    }

    return os;
}

} // namespace sc_core