/* include some QT and ANSI C library headers. */
#include <QtGui>
#include <QtSql>

#include <cstdlib>

using namespace std;

/* include headers defining the main form. */
#include "mainform.h"

/* declare DB driver and filename. */
static const QString dbDriverStr = "QSQLITE";
static const QString dbFileNameStr = "database.db";

/* GUI string messages. */
static const QString dbConnectErrorStr   = QObject::tr("Database Connection Error");
static const QString dbDriverNotExistStr = QObject::tr("Database driver is not available.");
static const QString dbCannotOpenStr     = QObject::tr("The database cannot open.");

static bool
createDBConnection () {
    /* check the existence of the DB driver. */
    if (!QSqlDatabase::isDriverAvailable (dbDriverStr)) {
        QMessageBox::critical(0, dbConnectErrorStr, dbDriverNotExistStr);
        /* DB connection failed. */
        return false;
    }

    /* connect to the DB with the following driver. */
    QSqlDatabase db = QSqlDatabase::addDatabase(dbDriverStr);

    /* use the following database name. */
    db.setDatabaseName(dbFileNameStr);

    /* if the DB cannot open for any reason print a warning. */
    if (!db.open()) {
        QMessageBox::critical(0, dbConnectErrorStr, dbCannotOpenStr);

        /* DB connection failed. */
        return false;
    }

    /* DB connection successed. */
    return true;
}

/* main function. */
int
main(int argc, char *argv[]) {
    /* create the application. */
    QApplication app(argc, argv);

    /* try to connect to DB. */
    if (!createDBConnection ()) {
        return EXIT_FAILURE;
    }

    /* create the main form of the app. */
    MainForm form;

    /* show the main form. */
    form.show();

    /* run the application. */
    return app.exec();
}