/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 *                                                                         *
 *  Copyright (C) 2016 Simon Stürz <simon.stuerz@guh.io>                   *
 *                                                                         *
 *  This file is part of guh.                                              *
 *                                                                         *
 *  Guh is free software: you can redistribute it and/or modify            *
 *  it under the terms of the GNU General Public License as published by   *
 *  the Free Software Foundation, version 2 of the License.                *
 *                                                                         *
 *  Guh is distributed in the hope that it will be useful,                 *
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of         *
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the          *
 *  GNU General Public License for more details.                           *
 *                                                                         *
 *  You should have received a copy of the GNU General Public License      *
 *  along with guh. If not, see <http://www.gnu.org/licenses/>.            *
 *                                                                         *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/*!
    \class guhserver::GuhApplication
    \brief Application class of the guh server.

    \ingroup core
    \inmodule server

    The \l{GuhApplication} is a subclass of the \{http://doc.qt.io/qt-5/qcoreapplication.html}{QCoreApplication}
    and is responsable to catch system signals like SIGQUIT, SIGINT, SIGTERM, SIGHUP, SIGSEGV. This class
    will provide a backtrace on a segmentation fault (SIGSEGV).


    \sa GuhService
*/

#include "guhapplication.h"
#include "loggingcategories.h"
#include "guhcore.h"

#include <execinfo.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/wait.h>
#include <unistd.h>
#include <cxxabi.h>

namespace guhserver {

static bool s_aboutToShutdown = false;
static bool s_multipleShutdownDetected = false;
static int s_shutdownCounter = 0;

static void printBacktrace()
{
    void* trace[20];

    int traceLength = backtrace(trace, sizeof(trace) / sizeof(void*));
    if (traceLength == 0)
        return;

    char** symbolList = backtrace_symbols(trace, traceLength);
    size_t funktionNameSize = 256;
    char* functionName = (char*)malloc(funktionNameSize);
    for (int i = 1; i < traceLength; i++) {
        QString address = QString().sprintf("%p", trace[i]);
        QString fileName = QString(symbolList[i]);
        int fileIndex = fileName.indexOf("(");
        QString lineCommand = QString("addr2line %1 -e %2").arg(address).arg(fileName.left(fileIndex));

        // Read stdout from addr2line
        char buffer[1024];
        FILE *lineFile = popen(lineCommand.toLatin1().data(), "r");
        QString line(fgets(buffer, sizeof(buffer), lineFile));
        pclose(lineFile);

        char *begin_name = 0, *begin_offset = 0, *end_offset = 0;
        // find parentheses and +address offset surrounding the mangled name:
        // ./module(function+0x15c) [0x8048a6d]
        for (char *p = symbolList[i]; *p; ++p) {
            if (*p == '(')
                begin_name = p;
            else if (*p == '+')
                begin_offset = p;
            else if (*p == ')' && begin_offset) {
                end_offset = p;
                break;
            }
        }

        QString functionString;
        if (begin_name && begin_offset && end_offset && begin_name < begin_offset) {
            int status;
            *begin_name++ = '\0';
            *begin_offset++ = '\0';
            *end_offset = '\0';
            char* ret = abi::__cxa_demangle(begin_name, functionName, &funktionNameSize, &status);
            if (status == 0) {
                functionName = ret;
                functionString = QString("    %1").arg(QString().sprintf("%s+%s", functionName, begin_offset));
            } else {
                functionString = QString("    %1").arg(QString().sprintf("%s()+%s", begin_name, begin_offset));
            }
        }

#if (QT_VERSION < QT_VERSION_CHECK(5, 2, 0))
        // qCCritical was introduced int Qt 5.2.0
        qCWarning(dcApplication) << QString("[%1] %2").arg(i).arg(symbolList[i]);
        if (!functionString.isEmpty())
            qCWarning(dcApplication) << functionString;

        qCWarning(dcApplication) << QString("    %1").arg(line.remove("\n"));
#else
        qCCritical(dcApplication) << QString("[%1] %2").arg(i).arg(symbolList[i]);
        if (!functionString.isEmpty())
            qCCritical(dcApplication) << functionString;

        qCCritical(dcApplication) << QString("    %1").arg(line.remove("\n"));
#endif // QT_VERSION

    }

    free(functionName);
    free(symbolList);
}

static void catchUnixSignals(const std::vector<int>& quitSignals, const std::vector<int>& ignoreSignals = std::vector<int>())
{
    auto handler = [](int sig) ->void {
        switch (sig) {
        case SIGQUIT:
            qCDebug(dcApplication) << "Cought SIGQUIT quit signal...";
            break;
        case SIGINT:
            qCDebug(dcApplication) << "Cought SIGINT quit signal...";
            break;
        case SIGTERM:
            qCDebug(dcApplication) << "Cought SIGTERM quit signal...";
            break;
        case SIGHUP:
            qCDebug(dcApplication) << "Cought SIGHUP quit signal...";
            break;
        case SIGSEGV: {
            qCDebug(dcApplication) << "Cought SIGSEGV signal. Segmentation fault!";
            printBacktrace();
            exit(1);
        }
        default:
            break;
        }

        if (s_aboutToShutdown) {
            switch (s_shutdownCounter) {
            case 0:
                qCWarning(dcApplication()) << "Already shutting down. Be nice and give me some time to clean up, please.";
                break;
            case 1:
                qCCritical(dcApplication()) << "I told you, I'm already shutting down. Be nice and give me some time to clean up, PLEASE.";
                break;
            case 2:
                qCCritical(dcApplication()) << "Still shutting down...";
                break;
            case 3:
                qCCritical(dcApplication()) << "Hmpf...";
                break;
            case 4:
                qCCritical(dcApplication()) << "It's getting boring...";
                break;
            case 5:
                qCCritical(dcApplication()) << "S H U T T I N G  DOWN";
                break;
            case 6:
                qCCritical(dcApplication()) << "S H U T T I N G  DOWN";
                break;
            case 7:
                qCCritical(dcApplication()) << "S H U T T I N G  DOWN";
                break;
            default:
                qCCritical(dcApplication()) << "Fuck this shit. I'm out...";
                GuhApplication::quit();
                break;
            }
            s_shutdownCounter++;
            return;
        }

        qCDebug(dcApplication) << "=====================================";
        qCDebug(dcApplication) << "Shutting down guh daemon";
        qCDebug(dcApplication) << "=====================================";

        s_aboutToShutdown = true;
        GuhCore::instance()->destroy();

        if (s_multipleShutdownDetected)
            qCDebug(dcApplication) << "Ok, ok, I'm done! :)";

        GuhApplication::quit();
    };

    // all these signals will be ignored.
    for (int sig : ignoreSignals)
        signal(sig, SIG_IGN);

    for (int sig : quitSignals)
        signal(sig, handler);
}


/*! Constructs a GuhApplication with the given argument count \a argc and argument vector \a argv. */
GuhApplication::GuhApplication(int &argc, char **argv) :
    QCoreApplication(argc, argv)
{
    catchUnixSignals({SIGQUIT, SIGINT, SIGTERM, SIGHUP, SIGSEGV});
}

}