package com.digitbit.client;

import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.json.client.JSONArray;
import com.google.gwt.json.client.JSONException;
import com.google.gwt.json.client.JSONObject;
import com.google.gwt.json.client.JSONParser;
import com.google.gwt.user.client.HTTPRequest;
import com.google.gwt.user.client.ResponseTextHandler;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.ui.Button;
import com.google.gwt.user.client.ui.ChangeListener;
import com.google.gwt.user.client.ui.ClickListener;
import com.google.gwt.user.client.ui.FlexTable;
import com.google.gwt.user.client.ui.HasVerticalAlignment;
import com.google.gwt.user.client.ui.HorizontalPanel;
import com.google.gwt.user.client.ui.Image;
import com.google.gwt.user.client.ui.KeyboardListener;
import com.google.gwt.user.client.ui.Label;
import com.google.gwt.user.client.ui.ListBox;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.TextBox;
import com.google.gwt.user.client.ui.Widget;

/*
* Copyright 2007 Chris Fong <fongcn AT gmail.com>
*
* Licensed 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.
*/
public class GoogleAPITester implements EntryPoint {

	private TextBox searchBox;
	private Button goButton;
	private FlexTable resultsTable;
	private Image progressImage;
	private ListBox functionListBox;
	private Label helpLabel;

	/**
	 * This is the entry point method.
	 */
	public void onModuleLoad() {
		
		HorizontalPanel panel = new HorizontalPanel();
		
		functionListBox = new ListBox();
		functionListBox.addItem("search");
		functionListBox.addItem("spelling");
		functionListBox.setVisibleItemCount(1);
		
		searchBox = new TextBox();
		goButton = new Button();
		goButton.setText("Go");
		progressImage = new Image();
		helpLabel = new Label("");
		
		panel.add(functionListBox);
		panel.add(searchBox);
		panel.add(goButton);
		panel.add(progressImage);
		panel.add(helpLabel);
		panel.setSpacing(5);
		panel.setCellVerticalAlignment(progressImage, HasVerticalAlignment.ALIGN_MIDDLE);
		panel.setCellVerticalAlignment(helpLabel, HasVerticalAlignment.ALIGN_MIDDLE);
		resultsTable = new FlexTable();
		
		
		RootPanel.get("slot1").add(panel);
		RootPanel.get("slot2").add(resultsTable);
		addListeners();
		updateHelpLabel();
		showSearchingNotInProgress();
	}

	private void addListeners() {
		searchBox.addKeyboardListener(new KeyboardListener() {
			public void onKeyDown(Widget sender, char keyCode, int modifiers) {
				// Handle enter in the search box
				if (keyCode == 13)
				{
					startSearch();
				}
			}

			public void onKeyPress(Widget sender, char keyCode, int modifiers) {}
			public void onKeyUp(Widget sender, char keyCode, int modifiers) {}
			
		});
		goButton.addClickListener(new ClickListener() {
			public void onClick(Widget sender) {
				startSearch();
			}
		});
		functionListBox.addChangeListener(new ChangeListener() {
			public void onChange(Widget sender) {
				updateHelpLabel();
				
			}
		});
	}
	
	private void updateHelpLabel() {
		int selectedIndex = functionListBox.getSelectedIndex();
		String selectedFunction = functionListBox.getItemText(selectedIndex);
		if (selectedFunction.equals("search"))
		{
			helpLabel.setText("Enter a search query");
		}
		else if (selectedFunction.equals("spelling")) 
		{
			helpLabel.setText("Enter a phrase. (ie. 'speeling')");
		}
	}

	private class JSONResponseTextHandler implements ResponseTextHandler {
		public void onCompletion(String responseText) {
			try {
				showSearchingNotInProgress();
				// Check if we get a bogus response from the server.
				if (responseText.trim().equals("false") || 
						responseText.trim().equals(""))
				{
					clearResultsTable();
					resultsTable.setHTML(0, 0, 
							"We are having problems connecting with google's servers.  Please try again later.");
					return;
				}
				
				String function = getSelectedFunction();
				if (function.equals("spelling"))
				{
					handleSpellingResponse(responseText);
				}
				else if (function.equals("search"))
				{
					handleSearchResponse(responseText);
				} 
				
			} catch (JSONException e) {
				Window.alert("Exception handling JSON Response: " + e.getMessage());
			}
		}

		private void handleSpellingResponse(String responseText) {
			clearResultsTable();
			// This weird string seems to indicate no spelling suggestion
			if (responseText.trim().equals("{\"!xsi:null\":\"true\"}"))
			{
				resultsTable.setHTML(0, 0, "No spelling suggestions found");
			}
			else
			{
				resultsTable.setHTML(0, 0, responseText);
			}
		}

		private void handleSearchResponse(String responseText) throws JSONException {
			JSONObject jsonObject = (JSONObject) JSONParser.parse(responseText);
			JSONArray resultElements = (JSONArray) jsonObject.get("resultElements");
			for (int i = 0; i < resultElements.size(); i++)
			{
				JSONObject resultElement = (JSONObject) resultElements.get(i);
				String link = "<a href="+resultElement.get("URL")+">"+
					resultElement.get("title")+"</a>";
				resultsTable.setHTML(i*3, 0, link);
				resultsTable.setHTML(i*3+1, 0, resultElement.get("snippet").toString());
				resultsTable.setHTML(i*3+2, 0, 
						"<div class='url_text'>"+resultElement.get("URL").toString()+"</div></br>");
			}
		}
	}

	private void startSearch() {
		showSearchingInProgress();
		String function = getSelectedFunction();
		if (!HTTPRequest.asyncGet(
				"http://www.gwtsite.com/demos/googleapi/google-api-server.php?function="
				+function+"&query="+searchBox.getText(),
				new JSONResponseTextHandler())) 
		{
			Window.alert("Error making request to server");
		}
	}

	private String getSelectedFunction() {
		String function = functionListBox.getItemText(
				functionListBox.getSelectedIndex());
		return function;
	}
	
	public void clearResultsTable() {
		for (int i = 0; i < resultsTable.getRowCount(); i++)
		{
			resultsTable.removeCell(i, 0);
		}
	}

	private void showSearchingNotInProgress() {
		progressImage.setUrl("images/blanksearching.gif");
		helpLabel.setVisible(true);
	}

	private void showSearchingInProgress() {
		progressImage.setUrl("images/searching.gif");
		helpLabel.setVisible(false);
	}

	
}