/*
 * Copyright 2011 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.codehaus.groovy.eclipse.dsl.inferencing.suggestions.ui;

import java.util.HashMap;
import java.util.Map;

import org.codehaus.groovy.eclipse.dsl.inferencing.suggestions.ValueStatus;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Shell;

/**
 * 
 * @author Nieraj Singh
 * @created 2011-05-13
 */
public abstract class AbstractControlManager implements IDialogueControlManager {

    private IControlSelectionListener listener;

    /**
     * Controls to be managed for enabling and disabling based on events
     * generated by external mechanisms.
     */
    private Map<Control, IDialogueControlDescriptor> controls;

    private Shell shell;

    /**
     * By default, control values are assumed to be valid, unless this method is
     * overridden by subclasses and the subclasses
     * explicitly return a non-null ValueStatus with an invalid state.
     * 
     * @param control
     * @param descriptor
     * @return non-null ValueStatus with an invalid state if the control value
     *         is invalid. Null values will be interpreted as valid status.
     */
    protected ValueStatus isControlValueValid(Control control) {
        return null;
    }

    protected void notifyControlChange(Object value, Control control) {
        if (listener != null && handleInvalidCheck(control)) {
            IDialogueControlDescriptor descriptor = controls.get(control);
            ControlSelectionEvent event = new ControlSelectionEvent(value, descriptor);
            listener.handleSelection(event);
        }
    }

    /**
     * Returns false if and only if the control exists for the given descriptor
     * and indicates that the value in the widget
     * is invalid. If the control does not indicate that the value is invalid,
     * it will
     * be assumed valid
     * 
     * @param descriptor
     * @return
     */
    protected boolean handleInvalidCheck(Control control) {

        if (control != null) {
            ValueStatus status = isControlValueValid(control);
            if (status != null && status.isError()) {
                IDialogueControlDescriptor descriptor = controls.get(control);
                ControlSelectionEvent event = new ControlSelectionEvent(descriptor, status.getMessage());
                listener.handleInvalidSelection(event);
                return false;
            }
        }
        return true;
    }

    public Composite createControlArea(Composite parent) {

        controls = new HashMap<Control, IDialogueControlDescriptor>();
        Map<Control, IDialogueControlDescriptor> createdControls = createManagedControls(parent);
        if (createdControls != null) {
            controls.putAll(createdControls);
        }
        shell = parent.getShell();
        return parent;
    }

    /**
     * Shell where controls are shown.
     * 
     * @return
     */
    protected Shell getShell() {
        return shell;
    }

    public void setEnabled(boolean enable) {
        if (controls != null) {
            for (Control control : controls.keySet()) {
                if (!control.isDisposed()) {
                    control.setEnabled(enable);
                }
            }
        }
    }

    public void addSelectionListener(IControlSelectionListener listener) {
        this.listener = listener;
    }

    /**
     * Widgets added to this map are managed in terms of disabling, and enabling
     * based on events generated outside of the
     * control manager.
     * 
     * @param parent
     * @return
     */
    abstract protected Map<Control, IDialogueControlDescriptor> createManagedControls(Composite parent);

}