/*
 * Copyright (C) 2008 The Android Open Source Project
 *
 * Licensed under the Eclipse Public License, Version 1.0 (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.eclipse.org/org/documents/epl-v10.php
 *
 * 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 com.android.ide.eclipse.editors.menu;

import com.android.ide.eclipse.adt.AdtPlugin;
import com.android.ide.eclipse.adt.sdk.AndroidTargetData;
import com.android.ide.eclipse.common.AndroidConstants;
import com.android.ide.eclipse.common.project.AndroidXPathFactory;
import com.android.ide.eclipse.editors.AndroidEditor;
import com.android.ide.eclipse.editors.descriptors.ElementDescriptor;
import com.android.ide.eclipse.editors.uimodel.UiElementNode;

import org.eclipse.core.resources.IFile;
import org.eclipse.ui.IEditorInput;
import org.eclipse.ui.IEditorPart;
import org.eclipse.ui.PartInitException;
import org.eclipse.ui.part.FileEditorInput;
import org.w3c.dom.Document;
import org.w3c.dom.Node;

import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpressionException;

/**
 * Multi-page form editor for /res/menu XML files. 
 */
public class MenuEditor extends AndroidEditor {

    public static final String ID = AndroidConstants.EDITORS_NAMESPACE + ".menu.MenuEditor"; //$NON-NLS-1$

    /** Root node of the UI element hierarchy */
    private UiElementNode mUiRootNode;

    /**
     * Creates the form editor for resources XML files.
     */
    public MenuEditor() {
        super();
    }

    /**
     * Returns the root node of the UI element hierarchy, which here is
     * the "menu" node.
     */
    @Override
    public UiElementNode getUiRootNode() {
        return mUiRootNode;
    }

    // ---- Base Class Overrides ----

    /**
     * Returns whether the "save as" operation is supported by this editor.
     * <p/>
     * Save-As is a valid operation for the ManifestEditor since it acts on a
     * single source file. 
     *
     * @see IEditorPart
     */
    @Override
    public boolean isSaveAsAllowed() {
        return true;
    }

    /**
     * Create the various form pages.
     */
    @Override
    protected void createFormPages() {
        try {
            addPage(new MenuTreePage(this));
        } catch (PartInitException e) {
            AdtPlugin.log(e, "Error creating nested page"); //$NON-NLS-1$
        }
        
     }

    /* (non-java doc)
     * Change the tab/title name to include the project name.
     */
    @Override
    protected void setInput(IEditorInput input) {
        super.setInput(input);
        if (input instanceof FileEditorInput) {
            FileEditorInput fileInput = (FileEditorInput) input;
            IFile file = fileInput.getFile();
            setPartName(String.format("%1$s", file.getName()));
        }
    }
    
    /**
     * Processes the new XML Model, which XML root node is given.
     * 
     * @param xml_doc The XML document, if available, or null if none exists.
     */
    @Override
    protected void xmlModelChanged(Document xml_doc) {
        // init the ui root on demand
        initUiRootNode(false /*force*/);

        mUiRootNode.setXmlDocument(xml_doc);
        if (xml_doc != null) {
            ElementDescriptor root_desc = mUiRootNode.getDescriptor();
            try {
                XPath xpath = AndroidXPathFactory.newXPath();
                Node node = (Node) xpath.evaluate("/" + root_desc.getXmlName(),  //$NON-NLS-1$
                        xml_doc,
                        XPathConstants.NODE);
                if (node == null && root_desc.isMandatory()) {
                    // Create the root element if it doesn't exist yet (for empty new documents)
                    node = mUiRootNode.createXmlNode();
                }

                // Refresh the manifest UI node and all its descendants 
                mUiRootNode.loadFromXmlNode(node);
                
                // TODO ? startMonitoringMarkers();
            } catch (XPathExpressionException e) {
                AdtPlugin.log(e, "XPath error when trying to find '%s' element in XML.", //$NON-NLS-1$
                        root_desc.getXmlName());
            }
        }
        
        super.xmlModelChanged(xml_doc);
    }
    
    /**
     * Creates the initial UI Root Node, including the known mandatory elements.
     * @param force if true, a new UiRootNode is recreated even if it already exists.
     */
    @Override
    protected void initUiRootNode(boolean force) {
        // The root UI node is always created, even if there's no corresponding XML node.
        if (mUiRootNode == null || force) {
            Document doc = null;
            if (mUiRootNode != null) {
                doc = mUiRootNode.getXmlDocument();
            }
            
            // get the target data from the opened file (and its project)
            AndroidTargetData data = getTargetData();

            ElementDescriptor desc;
            if (data == null) {
                desc = new ElementDescriptor("temp", null /*children*/);
            } else {
                desc = data.getMenuDescriptors().getDescriptor();
            }

            mUiRootNode = desc.createUiNode();
            mUiRootNode.setEditor(this);

            onDescriptorsChanged(doc);
        }
    }

    // ---- Local Methods ----

    /**
     * Reloads the UI manifest node from the XML, and calls the pages to update.
     */
    private void onDescriptorsChanged(Document document) {
        if (document != null) {
            mUiRootNode.loadFromXmlNode(document);
        } else {
            mUiRootNode.reloadFromXmlNode(mUiRootNode.getXmlNode());
        }
    }
}