Add tab for viewing the debug log

This adds a tab where the user can easily see the last X lines of the debug.log file.

Currently it shows the last 100 lines as of the time that SD starts up. Next will be
to have a way to show updated data (such as a refresh button) and allow customizing
the number of lines to show.

src/mainwindow.cpp

@@ -136,6 +136,7 @@ MainWindow::MainWindow(QWidget *parent) :
     qDebug() << "Created RPC";
 
     setupMiningTab();
+    setupDebugLogTab();
 
     restoreSavedStates();
 }
@@ -1984,6 +1985,49 @@ void MainWindow::setupMiningTab() {
         // Mining tab currently only enabled for DragonX
     }
 }
+
+void MainWindow::setupDebugLogTab() {
+    ui->debugLog->setReadOnly(true);
+    ui->debugLog->setPlainText("Some debug stuff");
+
+#ifdef Q_OS_LINUX
+    QFile file(QDir::homePath() + "/.hush/HUSH3/debug.log");
+#elif defined(Q_OS_DARWIN)
+    QFile file(QDir::homePath() + "/Library/Application Support/Hush/HUSH3/debug.log");
+#elif defined(Q_OS_WIN64)
+    QFile file(QDir::homePath() + "/AppData/Roaming/Hush/HUSH3/debug.log");
+#else
+    // Bless Your Heart, You Like Danger!
+    QFile file("~/.hush/HUSH3/debug.log");
+#endif // Q_OS_LINUX
+    if(file.exists()) {
+        DEBUG(": Found debug.log at " << file);
+    } else {
+        DEBUG("No debug.log found!");
+        return;
+    }
+
+    if(file.open(QIODevice::ReadOnly))
+    {
+        qint64 fileSize = file.size();
+        DEBUG("debug.log size=" << fileSize);
+        file.seek(file.size()-1);
+        int count = 0;
+        int lines = 100;
+        while ( (count < lines) && (file.pos() > 0) )
+        {
+            QString ch = file.read(1);
+            file.seek(file.pos()-2);
+            if (ch == "\n")
+                count++;
+        }
+        file.seek(file.pos()+2);
+        QString debugText = file.readAll();
+        ui->debugLog->setPlainText( debugText );
+    }
+
+}
+
 void MainWindow::setupPeersTab() {
     qDebug() << __FUNCTION__;
     // Set up context menu on peers tab
@@ -2134,33 +2178,8 @@ void MainWindow::setupPeersTab() {
         menu.exec(ui->peersTable->viewport()->mapToGlobal(pos));
     });
 
-    /*
     //grep 'BAN THRESHOLD EXCEEDED' ~/.hush/HUSH3/debug.log
     //grep Disconnected ...
-    QFile debuglog = "";
-
-#ifdef Q_OS_LINUX
-    debuglog = "~/.hush/HUSH3/debug.log";
-#elif defined(Q_OS_DARWIN)
-    debuglog = "~/Library/Application Support/Hush/HUSH3/debug.log";
-#elif defined(Q_OS_WIN64)
-    // "C:/Users/<USER>/AppData/Roaming/<APPNAME>",
-    // TODO: get current username
-    debuglog = "C:/Users/<USER>/AppData/Roaming/Hush/HUSH3/debug.log";
-#else
-    // Bless Your Heart, You Like Danger!
-    // There are open bounties to port HUSH softtware to OpenBSD and friends:
-    // git.hush.is/hush/tasks
-    debuglog = "~/.hush/HUSH3/debug.log";
-#endif // Q_OS_LINUX
-
-    if(debuglog.exists()) {
-        qDebug() << __func__ << ": Found debuglog at " << debuglog;
-    } else {
-        qDebug() << __func__ << ": No debug.log found";
-    }
-    */
-
     //ui->recentlyBannedPeers = "Could not open " + debuglog;
 
 }

src/mainwindow.h

@@ -94,6 +94,7 @@ private:
     void setupChatTab();
     void setupMarketTab();
     void setupMiningTab();
+    void setupDebugLogTab();
 
     void slot_change_theme(QString& themeName);
     void slot_change_currency(const QString& currencyName);

src/mainwindow.ui

@@ -1130,6 +1130,24 @@
         </item>
        </layout>
       </widget>
+
+      <widget class="QWidget" name="tab_debug">
+       <attribute name="title">
+        <string>Debug Log</string>
+       </attribute>
+
+      <layout class="QGridLayout" name="gridLayout">
+       <item row="0" column="0" colspan="3">
+        <widget class="QPlainTextEdit" name="debugLog">
+         <property name="plainText">
+          <string/>
+         </property>
+        </widget>
+       </item>
+       </layout>
+
+      </widget>
+
       <widget class="QWidget" name="tab_5">
        <attribute name="title">
         <string>Node info</string>
@@ -1602,6 +1620,7 @@
     </item>
    </layout>
   </widget>
+
   <widget class="QMenuBar" name="menuBar">
    <property name="geometry">
     <rect>