/*
 * Code borrowed from PyDev
 */
package org.erlide.ui;

import org.eclipse.jface.bindings.TriggerSequence;
import org.eclipse.jface.bindings.keys.KeySequence;
import org.eclipse.jface.bindings.keys.KeyStroke;
import org.eclipse.swt.events.KeyEvent;
import org.eclipse.ui.PlatformUI;
import org.eclipse.ui.keys.IBindingService;
import org.eclipse.ui.texteditor.ITextEditorActionDefinitionIds;

/**
 * Helper for knowing about keybindings and related actions
 *
 * @author Fabio
 */
public class KeyBindingHelper {

    // pre-defined helpers
    /**
     * @return true if the given event matches a content assistant keystroke
     *         (and false otherwise).
     */
    public static boolean matchesContentAssistKeybinding(final KeyEvent event) {
        return matchesKeybinding(event,
                ITextEditorActionDefinitionIds.CONTENT_ASSIST_PROPOSALS);
    }

    /**
     * @return the key sequence that is the best match for a content assist
     *         request.
     */
    public static KeySequence getContentAssistProposalBinding() {
        return getCommandKeyBinding(
                ITextEditorActionDefinitionIds.CONTENT_ASSIST_PROPOSALS);
    }

    /**
     * @return true if the given event matches a quick assistant keystroke (and
     *         false otherwise).
     */
    public static boolean matchesQuickAssistKeybinding(final KeyEvent event) {
        return matchesKeybinding(event, ITextEditorActionDefinitionIds.QUICK_ASSIST);
    }

    /**
     * @return the key sequence that is the best match for a quick assist
     *         request.
     */
    public static KeySequence getQuickAssistProposalBinding() {
        return getCommandKeyBinding(ITextEditorActionDefinitionIds.QUICK_ASSIST);
    }

    // END pre-defined helpers

    /**
     * @param event
     *            the key event to be checked
     * @param commandId
     *            the command to be checked
     * @return true if the given key event can trigger the passed command (and
     *         false otherwise).
     */
    public static boolean matchesKeybinding(final KeyEvent event,
            final String commandId) {
        final IBindingService bindingSvc = (IBindingService) PlatformUI.getWorkbench()
                .getAdapter(IBindingService.class);
        final TriggerSequence[] activeBindingsFor = bindingSvc
                .getActiveBindingsFor(commandId);

        for (final TriggerSequence seq : activeBindingsFor) {
            if (seq instanceof KeySequence) {
                final KeySequence keySequence = (KeySequence) seq;
                final KeyStroke[] keyStrokes = keySequence.getKeyStrokes();

                for (final KeyStroke keyStroke : keyStrokes) {

                    if (keyStroke.getNaturalKey() == event.keyCode
                            && (keyStroke.getModifierKeys() & event.stateMask) != 0) {

                        return true;
                    }
                }
            }
        }

        return false;
    }

    /**
     * @param commandId
     *            the command we want to know about
     * @return the 'best' key sequence that will activate the given command
     */
    public static KeySequence getCommandKeyBinding(final String commandId) {
        final IBindingService bindingSvc = (IBindingService) PlatformUI.getWorkbench()
                .getAdapter(IBindingService.class);
        final TriggerSequence binding = bindingSvc.getBestActiveBindingFor(commandId);
        if (binding instanceof KeySequence) {
            return (KeySequence) binding;
        }

        return null;
    }

}