/*
 * Copyright 2015 Red Hat, Inc. and/or its affiliates.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * 
 *      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.eclipse.webdav.dom;

import java.util.Enumeration;
import java.util.NoSuchElementException;
import org.eclipse.webdav.IContext;
import org.eclipse.webdav.Policy;
import org.eclipse.webdav.internal.kernel.Context;
import org.w3c.dom.Element;
import org.w3c.dom.Node;

/**
 * An element editor for the WebDAV activelock element. See RFC2518
 * section 12.1 for the element's definition.
 * <p>
 * <b>Note:</b> This class/interface is part of an interim API that is still under 
 * development and expected to change significantly before reaching stability. 
 * It is being made available at this early stage to solicit feedback from pioneering 
 * adopters on the understanding that any code that uses this API will almost 
 * certainly be broken (repeatedly) as the API evolves.
 * </p>
 *
 * @see LockDiscovery
 * @see Owner
 */
public class ActiveLock extends ElementEditor {

    // An ordered collection of the element names of the activelock
    // element's children.
    protected static final String[] childNames = new String[] {"lockscope", //$NON-NLS-1$
            "locktype", //$NON-NLS-1$
            "depth", //$NON-NLS-1$
            "owner", //$NON-NLS-1$
            "timeout", //$NON-NLS-1$
            "locktoken"}; //$NON-NLS-1$

    /**
     * Creates a new editor on the given WebDAV activelock element. The
     * element is assumed to be well formed.
     *
     * @param root an activelock element
     * @throws        MalformedElementException if there is reason to
     *                believe that the element is not well formed
     */
    public ActiveLock(Element root) throws MalformedElementException {
        super(root, "activelock"); //$NON-NLS-1$
    }

    /**
     * Adds the given href to this activelock's locktoken. The href must not
     * be <code>null</code>.
     *
     * @param href the href to add
     */
    public void addLockTokenHref(String href) {
        Assert.isNotNull(href);
        Element locktoken = getLastChild(root, "locktoken"); //$NON-NLS-1$
        if (locktoken == null)
            locktoken = setChild(root, "locktoken", childNames, false); //$NON-NLS-1$
        appendChild(locktoken, "href", encodeHref(href)); //$NON-NLS-1$
    }

    /**
     * Returns the depth of this activelock; for example,
     * <code>Context.DEPTH_ZERO</code>.
     *
     * @throws MalformedElementException if there is reason to believe that
     *         this editor's underlying element is not well formed
     * @see    Context
     */
    public String getDepth() throws MalformedElementException {
        String depth = getChildText(root, "depth", false); //$NON-NLS-1$
        ensureNotNull(Policy.bind("ensure.missingDepthElmt"), depth); //$NON-NLS-1$
        ensure(depth.equals(IContext.DEPTH_ZERO) || depth.equals(IContext.DEPTH_ONE) || depth.equals(IContext.DEPTH_INFINITY), Policy.bind("ensure.invalidDepth", depth)); //$NON-NLS-1$
        return depth;
    }

    /**
     * Returns an <code>Enumeration</code> of <code>String</code>s
     * containing this activelock's lock token hrefs.
     *
     * @return an <code>Enumeration</code> of <code>String</code>s
     * @throws MalformedElementException if there is reason to believe that
     *         this editor's underlying element is not well formed
     */
    public Enumeration getLockTokenHrefs() throws MalformedElementException {
        Element locktoken = getLastChild(root, "locktoken"); //$NON-NLS-1$
        Element firstHref = null;
        if (locktoken != null) {
            firstHref = getFirstChild(locktoken, "href"); //$NON-NLS-1$
            ensureNotNull(Policy.bind("ensure.missingHrefElmt"), firstHref); //$NON-NLS-1$
        }
        final Node node = firstHref;
        Enumeration e = new Enumeration() {
            Node currentHref = node;

            public boolean hasMoreElements() {
                return currentHref != null;
            }

            public Object nextElement() {
                if (!hasMoreElements()) {
                    throw new NoSuchElementException();
                }
                String href = getFirstText((Element) currentHref);
                currentHref = getTwin((Element) currentHref, true);
                return decodeHref(href);
            }
        };

        return e;
    }

    /**
     * Returns this activelock's owner, or <code>null</code> if this
     * active lock has no owner.
     *
     * @return this activelock's owner, or <code>null</code>
     * @throws MalformedElementException if there is reason to believe that
     *         this editor's underlying element is not well formed
     */
    public Owner getOwner() throws MalformedElementException {
        Element owner = getLastChild(root, "owner"); //$NON-NLS-1$
        if (owner == null)
            return null;
        return new Owner(owner);
    }

    /**
     * Returns this activelock's timeout, or <code>null</code> if this
     * active lock has no timeout.
     *
     * @return this activelock's timeout, or <code>null</code>
     * @throws MalformedElementException if there is reason to believe that
     *         this editor's underlying element is not well formed
     */
    public String getTimeout() throws MalformedElementException {
        return getChildText(root, "timeout", false); //$NON-NLS-1$
    }

    /**
     * Returns <code>true</code> if this activelock is shared, or
     * <code>false</code> if it is exclusive.
     *
     * @return a boolean indicating whether this activelock is shared or
     *         exclusive
     * @throws MalformedElementException if there is reason to believe that
     *         this editor's underlying element is not well formed
     */
    public boolean isShared() throws MalformedElementException {

        Element lockscope = getFirstChild(root, "lockscope"); //$NON-NLS-1$
        ensureNotNull(Policy.bind("ensure.missingLockscopeElmt "), lockscope); //$NON-NLS-1$

        String[] names = new String[] {"shared", "exclusive"}; //$NON-NLS-1$ //$NON-NLS-2$
        Element sharedOrExclusive = getFirstChild(lockscope, names);
        ensureNotNull(Policy.bind("ensure.missingSharedOrExclusiveElmt"), sharedOrExclusive); //$NON-NLS-1$

        boolean isShared = isDAVElement(sharedOrExclusive, "shared"); //$NON-NLS-1$
        ensure(getNextSibling(sharedOrExclusive, names) == null, Policy.bind("ensure.conflictingSharedOrExclusiveElmt")); //$NON-NLS-1$

        return isShared;
    }

    /**
     * Sets the depth of this activelock to the given depth. The depth must
     * not be null and must be one of:
     * <ul>
     * <li><code>Context.DEPTH_ZERO</code>
     * <li><code>Context.DEPTH_ONE</code>
     * <li><code>Context.DEPTH_INFINITY</code>
     * </ul>
     *
     * @param depth the depth for this activelock
     * @see         Context
     */
    public void setDepth(String depth) {
        Assert.isNotNull(depth);
        Assert.isTrue(depth.equals(IContext.DEPTH_ZERO) || depth.equals(IContext.DEPTH_ONE) || depth.equals(IContext.DEPTH_INFINITY));
        setChild(root, "depth", depth, childNames, false); //$NON-NLS-1$
    }

    /**
     * Sets whether this activelock is shared or exclusive. If isShared is
     * <code>true</code>, the activelock is set as shared, otherwise, the
     * activelock is set as exclusive.
     *
     * @param isShared a boolean indicating whether this activelock will be
     *                 set to be shared or exclusive
     */
    public void setIsShared(boolean isShared) {
        Element lockscope = setChild(root, "lockscope", childNames, true); //$NON-NLS-1$
        if (isShared)
            appendChild(lockscope, "shared"); //$NON-NLS-1$
        else
            appendChild(lockscope, "exclusive"); //$NON-NLS-1$
    }

    /**
     * Creates and sets an owner element on this activelock and returns an
     * editor on it.
     *
     * @return an editor on an owner element
     */
    public Owner setOwner() {
        Element owner = setChild(root, "owner", childNames, false); //$NON-NLS-1$
        Owner result = null;
        try {
            result = new Owner(owner);
        } catch (MalformedElementException e) {
            Assert.isTrue(false, Policy.bind("assert.internalError")); //$NON-NLS-1$
        }
        return result;
    }

    /**
     * Sets the timeout on this activelock to the given timeout. If the
     * timeout is <code>null</code> the current timeout is removed.
     *
     * @param timeout the timeout value for this activelock, or
     *                <code>null</code> for no timeout
     */
    public void setTimeout(String timeout) {
        if (timeout == null) {
            Element child = getLastChild(root, "timeout"); //$NON-NLS-1$
            if (child != null)
                root.removeChild(child);
        } else
            setChild(root, "timeout", timeout, childNames, false); //$NON-NLS-1$
    }
}
