/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.opennlp.corpus_server.caseditor;

import org.codehaus.jettison.json.JSONArray;
import org.codehaus.jettison.json.JSONException;
import org.eclipse.core.runtime.jobs.IJobChangeEvent;
import org.eclipse.core.runtime.jobs.JobChangeAdapter;
import org.eclipse.jface.layout.GridDataFactory;
import org.eclipse.jface.preference.IPreferenceStore;
import org.eclipse.jface.viewers.ILabelProviderListener;
import org.eclipse.jface.viewers.IOpenListener;
import org.eclipse.jface.viewers.ITableLabelProvider;
import org.eclipse.jface.viewers.OpenEvent;
import org.eclipse.jface.viewers.StructuredSelection;
import org.eclipse.jface.viewers.TableViewer;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.KeyEvent;
import org.eclipse.swt.events.KeyListener;
import org.eclipse.swt.events.ModifyEvent;
import org.eclipse.swt.events.ModifyListener;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.events.SelectionListener;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Combo;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Text;
import org.eclipse.ui.IEditorInput;
import org.eclipse.ui.IWorkbenchPage;
import org.eclipse.ui.PartInitException;
import org.eclipse.ui.part.PageBook;
import org.eclipse.ui.part.ViewPart;

public class CorpusExplorerView extends ViewPart {

  private static final String LUCENE_QUERY_DELIMITER = ":::";
  
  private PageBook book;
  
  private Text messageText;
  
  private Composite explorerComposite;
  private Text serverUrl;
  private Combo queryText;
  
  private TableViewer searchResultViewer;
  
  private void doSearch() {
    
    String queryString = queryText.getText();
    
    // Remember query and save last queries to the preference store
    int queryIndex = queryText.indexOf(queryString);
    
    if (queryIndex != -1) {
      queryText.remove(queryIndex);
    }
    
    queryText.add(queryString, 0);
    
    if (queryText.getItemCount() > 10) {
      queryText.remove(queryText.getItemCount() - 1);
    }
    
    queryText.setText(queryString);
    
    // TODO: Serialize history to lastUsedQueries settings ...
    StringBuilder lastUsedQueriesString = new StringBuilder();
    
    for (int i = 0; i < queryText.getItemCount(); i++) {
      lastUsedQueriesString.append(queryText.getItem(i));
      lastUsedQueriesString.append(LUCENE_QUERY_DELIMITER);
    }
    
    IPreferenceStore store = CorpusServerPlugin.getDefault().getPreferenceStore();
    
    store.setValue(CorpusServerPreferenceConstants.LAST_USED_SEARCH_QUERIES,
        lastUsedQueriesString.toString());
    
    // get server url
    String serverPath = serverUrl.getText();
    
    final SearchCorpusServerJob searchJob = new SearchCorpusServerJob();
    
    searchJob.setServerAddress(serverPath);
    searchJob.setQuery(queryString);
    
    searchJob.schedule();
    
    setMessage("Fetching results ...");
    
    searchJob.addJobChangeListener(new JobChangeAdapter(){
      @Override
      public void done(final IJobChangeEvent event) {
        
        Display.getDefault().asyncExec(new Runnable() {

          @Override
          public void run() {
            if (event.getResult().isOK()) {
              
              setMessage(null);
              
              searchResultViewer.setItemCount(0);
              JSONArray searchResult = searchJob.getSearchResult();
              
              for (int i = 0; i < searchResult.length(); i++) {
                try {
                  searchResultViewer.add(searchResult.getString(i));
                } catch (JSONException e) {
                  setMessage("Error, failed to parse results.");
                }
              }
            }
            else {
              setMessage("Fetching search results from server failed!");
            }
          }
        });
      }
    }); 
  }
  
  @Override
  public void createPartControl(Composite parent) {

    explorerComposite = new Composite(parent, SWT.NONE);
    GridLayout explorerLayout = new GridLayout();
    explorerLayout.numColumns = 2;
    explorerComposite.setLayout(explorerLayout);

    // URL field to connect to corpus server and corpus
    Label serverLabel = new Label(explorerComposite, SWT.NONE);
    serverLabel.setText("Server:");

    serverUrl = new Text(explorerComposite, SWT.BORDER);
    GridDataFactory.swtDefaults().align(SWT.FILL, SWT.CENTER).grab(true, false)
        .applyTo(serverUrl);

    final IPreferenceStore store = CorpusServerPlugin.getDefault().getPreferenceStore();
    
    String lastUsedServer = store.getString(CorpusServerPreferenceConstants.LAST_USED_SERVER_ADDRESS);
    
    if (lastUsedServer.isEmpty()) {
      lastUsedServer = "http://localhost:8080/corpus-server/rest/corpora/wikinews";
    }
    
    serverUrl.setText(lastUsedServer);
    
    serverUrl.addModifyListener(new ModifyListener() {
      
      @Override
      public void modifyText(ModifyEvent event) {
        store.setValue(CorpusServerPreferenceConstants.LAST_USED_SERVER_ADDRESS, serverUrl.getText());
      }
    });
    
    // Search field to view content of corpus
    Label queryLabel = new Label(explorerComposite, SWT.NONE);
    queryLabel.setText("Query");
    
    queryText = new Combo(explorerComposite, SWT.BORDER);
    
    GridDataFactory.swtDefaults().align(SWT.FILL, SWT.CENTER).grab(true, false)
        .applyTo(queryText);

    
    String lastUsedSearchQueriesString = 
        store.getString(CorpusServerPreferenceConstants.LAST_USED_SEARCH_QUERIES);
    
    // TODO: Set default via preference initializer
    if (lastUsedSearchQueriesString.isEmpty()) {
      lastUsedSearchQueriesString = "*:*";
    }
    
    String lastUsedQueries[] = lastUsedSearchQueriesString.split(LUCENE_QUERY_DELIMITER);
    
    if (lastUsedQueries.length > 0)
      queryText.setText(lastUsedQueries[0]);
    
    for (int i = 0; i < lastUsedQueries.length; i++) {
      queryText.add(lastUsedQueries[i]);
    }
    
    
    queryText.addSelectionListener(new SelectionListener() {
      
      @Override
      public void widgetSelected(SelectionEvent event) {
        doSearch();
      }
      
      @Override
      public void widgetDefaultSelected(SelectionEvent event) {
      }
    });
    
    queryText.addKeyListener(new KeyListener() {
      
      @Override
      public void keyReleased(KeyEvent event) {
        if (event.character ==SWT.CR)
          doSearch();
      }
      
      @Override
      public void keyPressed(KeyEvent event) {
      }
    });
    
    Button queryServer = new Button(explorerComposite, SWT.BORDER);
    queryServer.setText("Query");
    GridDataFactory.swtDefaults().span(2, 1).align(SWT.FILL, SWT.CENTER)
        .grab(true, false).applyTo(queryServer);
    
    queryServer.addSelectionListener(new SelectionListener() {

      @Override
      public void widgetSelected(SelectionEvent event) {
        doSearch();
      }

      @Override
      public void widgetDefaultSelected(SelectionEvent event) {
      }
    });
    
    book = new PageBook(explorerComposite, SWT.NONE);
    
    GridDataFactory.swtDefaults().align(SWT.FILL, SWT.FILL).grab(true, true)
            .span(2, 1).applyTo(book);
    
    messageText = new Text(book, SWT.WRAP | SWT.READ_ONLY);
    messageText.setText("Enter the server address and a query to search a corpus on the Corpus Server.");

    // List with casIds in the corpus ... (might be later replaced with a title)
    // The table should later be virtual, and be able to scroll through very huge
    // lits of CASes ... might be connected to a repository with million of documents
    searchResultViewer = new TableViewer(book);
    GridDataFactory.swtDefaults().align(SWT.FILL, SWT.FILL).grab(true, true)
        .span(2, 1).applyTo(searchResultViewer.getControl());

    searchResultViewer.setLabelProvider(new ITableLabelProvider() {

      @Override
      public void addListener(ILabelProviderListener arg0) {
      }

      @Override
      public void dispose() {
      }

      @Override
      public boolean isLabelProperty(Object arg0, String arg1) {
        return false;
      }

      @Override
      public void removeListener(ILabelProviderListener arg0) {
      }

      @Override
      public Image getColumnImage(Object arg0, int arg1) {
        return null;
      }

      @Override
      public String getColumnText(Object arg0, int arg1) {
        return arg0.toString();
      }});
    
    searchResultViewer.addOpenListener(new IOpenListener() {
      
      @Override
      public void open(OpenEvent event) {
        
        IWorkbenchPage page = CorpusExplorerView.this.getSite().getPage();
        
        StructuredSelection selection = (StructuredSelection) searchResultViewer.getSelection();
        
        if (selection.isEmpty())
          return;
        
        String selectedCAS = (String) selection.getFirstElement();
        
        // Hard code it for now, lets work on retrieval code first ...
        IEditorInput input = new CorpusServerCasEditorInput(serverUrl.getText(), selectedCAS);
        
        try {
          page.openEditor(input, "org.apache.uima.caseditor.editor");
        } catch (PartInitException e) {
          e.printStackTrace();
        }
      }
    });

    book.showPage(messageText);
    
    // TODO: Context menu should have open action
  }

  void setMessage(String message) {
    if (message != null) {
      messageText.setText(message);
      book.showPage(messageText);
    }
    else {
      messageText.setText("");
      book.showPage(searchResultViewer.getControl());
    }
  }
  
  @Override
  public void setFocus() {
    explorerComposite.setFocus();
  }
}