/*
 * java-gnome, a UI library for writing GTK and GNOME programs from Java!
 *
 * Copyright © 2007      Vreixo Formoso Lopes
 * Copyright © 2007-2010 Operational Dynamics Consulting, Pty Ltd
 *
 * The code in this file, and the program it is a part of, is made available
 * to you by its authors as open source software: you can redistribute it
 * and/or modify it under the terms of the GNU General Public License version
 * 2 ("GPL") as published by the Free Software Foundation.
 *
 * This program 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 GPL for more details.
 *
 * You should have received a copy of the GPL along with this program. If not,
 * see http://www.gnu.org/licenses/. The authors of this program may be
 * contacted through http://java-gnome.sourceforge.net/.
 */
package org.gnome.glib;

import java.util.HashSet;

import org.gnome.gtk.Button;
import org.gnome.gtk.GraphicalTestCase;
import org.gnome.gtk.TreeSelection;
import org.gnome.gtk.TreeView;
import org.gnome.gtk.VBox;
import org.gnome.gtk.ValidatePacking;
import org.gnome.gtk.ValidateProperties;
import org.gnome.gtk.Widget;
import org.gnome.gtk.Window;

/**
 * Validates memory management by checking many possibly conflicting
 * situations. Note that some situations may exist that are not verified
 * because they cannot be automatically checked from the Java side.
 * 
 * FIXME we need a way to check what is being occurred on C side!!
 * 
 * @author Vreixo Formoso
 * @author Andrew Cowie
 */
public class ValidateMemoryManagement extends GraphicalTestCase
{

    /**
     * Subclass Button to simplify automatic testing
     */
    private static class MyButton extends Button implements Button.Clicked
    {
        /*
         * we need a static field to check object finalization. Of course,
         * this not works if many instances are created with same code!!
         */
        static HashSet<Integer> finalized = new HashSet<Integer>();

        private int code;

        public MyButton(String text, int code) {
            super(text);
            this.code = code;
        }

        public int getCode() {
            return code;
        }

        protected void finalize() {
            finalized.add(new Integer(code));

            /*
             * I prefer having this commented, because it helps ensure that we
             * have a robust design against bad user bad practises. Perhaps
             * another test case can validate that once do a more robust
             * design in that regard.
             */
            super.finalize();
        }

        // ignore
        public void onClicked(Button source) {}

    }

    private static class MyHandler implements Button.Clicked
    {
        /*
         * we need a static field to check object finalization. Of course,
         * this not works if many instances are created with same code!!
         */
        static HashSet<Integer> finalized = new HashSet<Integer>();

        private int code;

        public MyHandler(int code) {
            this.code = code;
        }

        protected void finalize() {
            finalized.add(new Integer(code));
        }

        // ignore
        public void onClicked(Button source) {}

    }

    /**
     * Ensures that Java object is removed in the scenario when it is created
     * but never used and then goes out of scope.
     */
    public final void testObjectNeverUsedIsRemoved() {
        MyButton b;

        b = new MyButton("Live free, die young!! Like me", 1);
        b.getClass(); // supress warning

        cycleMainLoop();

        /* eliminate reference so object can go out of scope */
        b = null;

        cycleMainLoop();
        cycleGarbageCollector();

        /* check if button has been deleted */
        assertTrue("An object created but never used is not deleted",
                MyButton.finalized.contains(new Integer(1)));
    }

    /**
     * Ensure that a Java Proxy is <b>not</b> removed when the GObject it is
     * proxying is still being used on C side
     */
    public final void testObjectNotRemovedWhenStillGtkAlive() {
        MyButton b;
        final VBox x;

        x = new VBox(false, 3);
        b = new MyButton("Old rockers never die!!", 2);

        /* add button to VBox */
        x.add(b);

        cycleMainLoop();

        /* object gets out of scope */
        b = null;

        cycleMainLoop();
        cycleGarbageCollector();

        /* check that button hasn't been deleted */
        assertFalse("Object deleted in Java but still alive in GTK",
                MyButton.finalized.contains(new Integer(2)));
    }

    /**
     * Ensure that a Java Proxy is removed when it goes out of scope on the
     * Java side and when GTK has dropped all of its Refs to the GObject on
     * the C side.
     */
    public final void testRemovingAfterNoLongerReachableInBothSides() {
        MyButton b;
        final VBox x;

        x = new VBox(false, 3);
        b = new MyButton("Ready to rock", 3);

        /* add button to VBox */
        x.add(b);

        cycleMainLoop();

        /* out of scope in Gtk+ */
        x.remove(b);

        cycleMainLoop();

        /* out of scope in Java */
        b = null;

        cycleMainLoop();
        cycleGarbageCollector();

        /* check that button has been deleted */
        assertTrue("Object no more needed is not deleted", MyButton.finalized.contains(new Integer(3)));
    }

    /**
     * We have a strong Java reference from the BindingsJavaClosure use by
     * g_signal_connect() to the Java Signal subclass passed as the handler to
     * Plumbing.connectSignal(). If the handler is the Proxy (self
     * delegation), then we have a cyclic reference. This test creates that
     * situation and tries to see if finalization occurs when the GObject ref
     * count drops to 1 (our ToggleRef)
     */
    public final void testAvoidCyclicReferenceFromSignalHookup() {
        MyButton b;
        final VBox x;

        x = new VBox(false, 3);
        b = new MyButton("I will reference myself", 4);

        /* connect button to itself. cyclic ref! */
        b.connect(b);

        cycleMainLoop();

        /* add button to VBox */
        x.add(b);

        cycleMainLoop();

        /* out of scope in Gtk+ */
        x.remove(b);

        cycleMainLoop();

        /* out of scope in Java */
        b = null;

        cycleMainLoop();
        cycleGarbageCollector();

        /* check that button has been deleted */
        assertTrue("Reference from the signal handler to an Object where that Object is a" + "\n"
                + "self-delegated signal handler was not cleared! This is, in effect, a cyclic" + "\n"
                + "reference that is not being detected by our memory management mechanism.",
                MyButton.finalized.contains(new Integer(4)));
    }

    /**
     * When user connects a Signal handler, this object must not be deleted so
     * long as the underlying Gtk+ widget still exists. This test checks that
     * effectively this is the behavior, and also verifies that the handler is
     * deleted when no longer needed.
     */
    public final void testSignalHandlerDeletion() {
        MyButton b;
        final VBox x;
        MyHandler h;

        x = new VBox(false, 3);
        b = new MyButton("Button to watch for", 7);

        h = new MyHandler(7);

        /* connect button to handler */
        b.connect(h);

        /* add button to VBox */
        x.add(b);

        /* handler gets out of scope from user point of view */
        h = null;

        cycleMainLoop();
        cycleGarbageCollector();

        /* check that handler has not been deleted */
        assertFalse("Signal handler deleted while still in use.",
                MyHandler.finalized.contains(new Integer(7)));

        cycleMainLoop();

        /* out of scope in Gtk+ */
        x.remove(b);

        cycleMainLoop();

        /* out of scope in Java */
        b = null;

        cycleMainLoop();
        cycleGarbageCollector();

        /* check that handler has been deleted */
        assertTrue("Signal handler not deleted but no longer needed.",
                MyHandler.finalized.contains(new Integer(7)));
    }

    /**
     * Ensures no denaturation occurs, i.e., the Object retrieved from a GTK
     * call is actually the same class (the same fully derived object) as the
     * original object. In fact, it had better be <i>that</i> object.
     */
    /*
     * This test is redundant, because we need not only prevent denaturation,
     * but indeed get the _same_ object, which is tested below. Just keep this
     * here to known better what is the problem if any
     */
    public final void testNoDenaturation() {
        MyButton b;
        Window w;
        Widget c;

        w = new Window();
        b = new MyButton("To be or not to be...", 5);

        /* add button to Window */
        w.add(b);

        cycleMainLoop();

        /* get button from window */
        c = w.getChild();

        cycleMainLoop();

        assertNotNull("Retrieved null from Window.getChild()", c);
        assertTrue("Proxy retrieved for our MyButton subclass is not an instance of Button!",
                c instanceof Button);
        assertTrue("Proxy retrieved is a Button, not a MyButton instance. Denaturation occurred!",
                c instanceof MyButton);

        /* and finally we check object retrieved is the _same_ */
        assertSame("A new Proxy was created when it should have been the already existing one", b, c);
        /* now we delete our refs */
        b = null;
        c = null;

        cycleMainLoop();
        cycleGarbageCollector();

        /* get button again and check */
        c = w.getChild();
        assertTrue("Proxy retrieved after a reference collection cycle is not our" + "\n"
                + "MyButton instance. Denaturation occurred?", c instanceof MyButton);

    }

    /**
     * A new Java object should not be created when developer retrieves a
     * previously referenced Widget from GTK. This is actually tested all over
     * the framework; see {@link ValidatePacking#testGetChildAndParent()} and
     * {@link ValidateProperties#testButtonReliefStyle()}; this test ensures
     * main loop cycling and garbage collection does not interfere.
     */
    public final void testNoMultipleCreation() {
        MyButton b;
        final Window w;
        Widget c;

        w = new Window();
        b = new MyButton("I don't wanna be Dolly", 6);

        /* add button to Window */
        w.add(b);

        cycleMainLoop();

        /* get button from window */
        c = w.getChild();

        assertNotNull("Retrieved a null object", c);
        assertTrue("Not a MyButton instance", c instanceof MyButton);

        /* and finally we check object retrieved is the _same_ */
        assertSame("A different object was created", b, c);

        /* now we delete our refs */
        b = null;
        c = null;

        cycleMainLoop();
        cycleGarbageCollector();

        /* get button again and check */
        c = w.getChild();

        assertNotNull("Retrieved a null object", c);
        assertTrue("Not a MyButton instance", c instanceof MyButton);

        assertEquals("A different object was created", 6, ((MyButton) c).getCode());
    }

    /**
     * Check that objects that are created internally in Gtk+ are correctly
     * managed.
     */
    public final void testCorrectHandlingOfGtkCreatedObjects() {
        TreeView t;
        @SuppressWarnings("unused")
        TreeSelection s;

        t = new TreeView();
        cycleMainLoop();

        /* get the selection, a Gtk+ created object */
        s = t.getSelection();
        cycleMainLoop();

        /* free our ref */
        s = null;
        cycleMainLoop();
        cycleGarbageCollector();

        /*
         * if all was correct, we can retrieve it again.
         */
        s = t.getSelection();
        cycleMainLoop();
    }
}