/*******************************************************************************
 * Copyright (c) 2000, 2005 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/

package org.eclipse.ui.keys;

import java.util.Arrays;
import java.util.Collections;
import java.util.Set;
import java.util.SortedSet;
import java.util.StringTokenizer;
import java.util.TreeSet;

import org.eclipse.ui.internal.util.Util;

/**
 * <p>
 * A <code>KeyStroke</code> is defined as an optional set of modifier keys
 * followed optionally by a natural key. A <code>KeyStroke</code> is said to
 * be complete if it contains a natural key. A natural key is any Unicode
 * character (e.g., "backspace", etc.), any character belonging to a natural
 * language (e.g., "A", "1", "[", etc.), or any special control character
 * specific to computers (e.g., "F10", "PageUp", etc.).
 * </p>
 * <p>
 * All <code>KeyStroke</code> objects have a formal string representation
 * available via the <code>toString()</code> method. There are a number of
 * methods to get instances of <code>KeyStroke</code> objects, including one
 * which can parse this formal string representation.
 * </p>
 * <p>
 * All <code>KeyStroke</code> objects, via the <code>format()</code> method,
 * provide a version of their formal string representation translated by
 * platform and locale, suitable for display to a user.
 * </p>
 * <p>
 * <code>KeyStroke</code> objects are immutable. Clients are not permitted to
 * extend this class.
 * </p>
 * 
 * @deprecated Please use org.eclipse.jface.bindings.keys.KeyStroke
 * @since 3.0
 * @see org.eclipse.ui.keys.ModifierKey
 * @see org.eclipse.ui.keys.NaturalKey
 */
public final class KeyStroke implements Comparable {

    /**
     * The delimiter between multiple keys in a single key strokes -- expressed
     * in the formal key stroke grammar. This is not to be displayed to the
     * user. It is only intended as an internal representation.
     */
    public final static String KEY_DELIMITER = "\u002B"; //$NON-NLS-1$

    /**
     * An internal constant used only in this object's hash code algorithm.
     */
    private final static int HASH_FACTOR = 89;

    /**
     * An internal constant used only in this object's hash code algorithm.
     */
    private final static int HASH_INITIAL = KeyStroke.class.getName()
            .hashCode();

    /**
     * The set of delimiters for <code>Key</code> objects allowed during
     * parsing of the formal string representation.
     */
    public final static String KEY_DELIMITERS = KEY_DELIMITER;

    /**
     * Gets an instance of <code>KeyStroke</code> given a single modifier key
     * and a natural key.
     * 
     * @param modifierKey
     *            a modifier key. Must not be <code>null</code>.
     * @param naturalKey
     *            the natural key. May be <code>null</code>.
     * @return a key stroke. Guaranteed not to be <code>null</code>.
     */
    public static KeyStroke getInstance(ModifierKey modifierKey,
            NaturalKey naturalKey) {
        if (modifierKey == null) {
			throw new NullPointerException();
		}

        return new KeyStroke(
                new TreeSet(Collections.singletonList(modifierKey)), naturalKey);
    }

    /**
     * Gets an instance of <code>KeyStroke</code> given an array of modifier
     * keys and a natural key.
     * 
     * @param modifierKeys
     *            the array of modifier keys. This array may be empty, but it
     *            must not be <code>null</code>. If this array is not empty,
     *            it must not contain <code>null</code> elements.
     * @param naturalKey
     *            the natural key. May be <code>null</code>.
     * @return a key stroke. Guaranteed not to be <code>null</code>.
     */
    public static KeyStroke getInstance(ModifierKey[] modifierKeys,
            NaturalKey naturalKey) {
        Util.assertInstance(modifierKeys, ModifierKey.class);
        return new KeyStroke(new TreeSet(Arrays.asList(modifierKeys)),
                naturalKey);
    }

    /**
     * Gets an instance of <code>KeyStroke</code> given a natural key.
     * 
     * @param naturalKey
     *            the natural key. May be <code>null</code>.
     * @return a key stroke. This key stroke will have no modifier keys.
     *         Guaranteed not to be <code>null</code>.
     */
    public static KeyStroke getInstance(NaturalKey naturalKey) {
        return new KeyStroke(Util.EMPTY_SORTED_SET, naturalKey);
    }

    /**
     * Gets an instance of <code>KeyStroke</code> given a set of modifier
     * keys and a natural key.
     * 
     * @param modifierKeys
     *            the set of modifier keys. This set may be empty, but it must
     *            not be <code>null</code>. If this set is not empty, it
     *            must only contain instances of <code>ModifierKey</code>.
     * @param naturalKey
     *            the natural key. May be <code>null</code>.
     * @return a key stroke. Guaranteed not to be <code>null</code>.
     */
    public static KeyStroke getInstance(SortedSet modifierKeys,
            NaturalKey naturalKey) {
        return new KeyStroke(modifierKeys, naturalKey);
    }

    /**
     * Gets an instance of <code>KeyStroke</code> by parsing a given a formal
     * string representation.
     * 
     * @param string
     *            the formal string representation to parse.
     * @return a key stroke. Guaranteed not to be <code>null</code>.
     * @throws ParseException
     *             if the given formal string representation could not be
     *             parsed to a valid key stroke.
     */
    public static KeyStroke getInstance(String string) throws ParseException {
        if (string == null) {
			throw new NullPointerException();
		}

        SortedSet modifierKeys = new TreeSet();
        NaturalKey naturalKey = null;
        StringTokenizer stringTokenizer = new StringTokenizer(string,
                KEY_DELIMITERS, true);
        int i = 0;

        while (stringTokenizer.hasMoreTokens()) {
            String token = stringTokenizer.nextToken();

            if (i % 2 == 0) {
                if (stringTokenizer.hasMoreTokens()) {
                    token = token.toUpperCase();
                    ModifierKey modifierKey = (ModifierKey) ModifierKey.modifierKeysByName
                            .get(token);

                    if (modifierKey == null || !modifierKeys.add(modifierKey)) {
						throw new ParseException(
                                "Cannot create key stroke with duplicate or non-existent modifier key: " //$NON-NLS-1$
                                        + token);
					}
                } else if (token.length() == 1) {
                    naturalKey = CharacterKey.getInstance(token.charAt(0));
                    break;
                } else {
                    token = token.toUpperCase();
                    naturalKey = (NaturalKey) CharacterKey.characterKeysByName
                            .get(token);

                    if (naturalKey == null) {
						naturalKey = (NaturalKey) SpecialKey.specialKeysByName
                                .get(token);
					}

                    if (naturalKey == null) {
						throw new ParseException(
                                "Cannot create key stroke with invalid natural key: " //$NON-NLS-1$
                                        + token);
					}
                }
            }

            i++;
        }

        try {
            return new KeyStroke(modifierKeys, naturalKey);
        } catch (Throwable t) {
            throw new ParseException("Cannot create key stroke with " //$NON-NLS-1$
                    + modifierKeys + " and " + naturalKey); //$NON-NLS-1$
        }
    }

    /**
     * The cached hash code for this object. Because <code>KeyStroke</code>
     * objects are immutable, their hash codes need only to be computed once.
     * After the first call to <code>hashCode()</code>, the computed value
     * is cached here for all subsequent calls.
     */
    private transient int hashCode;

    /**
     * A flag to determine if the <code>hashCode</code> field has already
     * been computed.
     */
    private transient boolean hashCodeComputed;

    /**
     * The set of modifier keys for this key stroke.
     */
    private SortedSet modifierKeys;

    /**
     * The set of modifier keys for this key stroke in the form of an array.
     * Used internally by <code>int compareTo(Object)</code>.
     */
    private transient ModifierKey[] modifierKeysAsArray;

    /**
     * The natural key for this key stroke.
     */
    private NaturalKey naturalKey;

    /**
     * Constructs an instance of <code>KeyStroke</code> given a set of
     * modifier keys and a natural key.
     * 
     * @param modifierKeys
     *            the set of modifier keys. This set may be empty, but it must
     *            not be <code>null</code>. If this set is not empty, it
     *            must only contain instances of <code>ModifierKey</code>.
     * @param naturalKey
     *            the natural key. May be <code>null</code>.
     */
    private KeyStroke(SortedSet modifierKeys, NaturalKey naturalKey) {
        this.modifierKeys = Util.safeCopy(modifierKeys, ModifierKey.class);
        this.naturalKey = naturalKey;
        this.modifierKeysAsArray = (ModifierKey[]) this.modifierKeys
                .toArray(new ModifierKey[this.modifierKeys.size()]);
    }

    /**
     * @see java.lang.Comparable#compareTo(java.lang.Object)
     */
    public int compareTo(Object object) {
        KeyStroke castedObject = (KeyStroke) object;
        int compareTo = Util.compare(modifierKeysAsArray,
                castedObject.modifierKeysAsArray);

        if (compareTo == 0) {
			compareTo = Util.compare(naturalKey, castedObject.naturalKey);
		}

        return compareTo;
    }

    /**
     * @see java.lang.Object#equals(java.lang.Object)
     */
    public boolean equals(Object object) {
        if (!(object instanceof KeyStroke)) {
			return false;
		}

        KeyStroke castedObject = (KeyStroke) object;
        
        if (!modifierKeys.equals(castedObject.modifierKeys)) {
			return false;
		}
        return Util.equals(naturalKey, castedObject.naturalKey);
    }

    /**
     * Formats this key stroke into the current default look.
     * 
     * @return A string representation for this key stroke using the default
     *         look; never <code>null</code>.
     */
    public String format() {
        return KeyFormatterFactory.getDefault().format(this);
    }

    /**
     * Returns the set of modifier keys for this key stroke.
     * 
     * @return the set of modifier keys. This set may be empty, but is
     *         guaranteed not to be <code>null</code>. If this set is not
     *         empty, it is guaranteed to only contain instances of <code>ModifierKey</code>.
     */
    public Set getModifierKeys() {
        return Collections.unmodifiableSet(modifierKeys);
    }

    /**
     * Returns the natural key for this key stroke.
     * 
     * @return the natural key. May be <code>null</code>.
     */
    public NaturalKey getNaturalKey() {
        return naturalKey;
    }

    /**
     * @see java.lang.Object#hashCode()
     */
    public int hashCode() {
        if (!hashCodeComputed) {
            hashCode = HASH_INITIAL;
            hashCode = hashCode * HASH_FACTOR + modifierKeys.hashCode();
            hashCode = hashCode * HASH_FACTOR + Util.hashCode(naturalKey);
            hashCodeComputed = true;
        }

        return hashCode;
    }

    /**
     * Returns whether or not this key stroke is complete. Key strokes are
     * complete iff they have a natural key which is not <code>null</code>.
     * 
     * @return <code>true</code>, iff the key stroke is complete.
     */
    public boolean isComplete() {
        return naturalKey != null;
    }

    /**
     * Returns the formal string representation for this key stroke.
     * 
     * @return The formal string representation for this key stroke. Guaranteed
     *         not to be <code>null</code>.
     * @see java.lang.Object#toString()
     */
    public String toString() {
        return KeyFormatterFactory.getFormalKeyFormatter().format(this);
    }
}