package com.google.gwt.sample.stockwatcher.client;

import java.util.ArrayList;
import java.util.Date;

import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.event.dom.client.ClickEvent;
import com.google.gwt.event.dom.client.ClickHandler;
import com.google.gwt.event.dom.client.KeyCodes;
import com.google.gwt.event.dom.client.KeyPressEvent;
import com.google.gwt.event.dom.client.KeyPressHandler;
import com.google.gwt.i18n.client.NumberFormat;
import com.google.gwt.user.client.Random;
import com.google.gwt.user.client.Timer;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.ui.Button;
import com.google.gwt.user.client.ui.FlexTable;
import com.google.gwt.user.client.ui.HorizontalPanel;
import com.google.gwt.user.client.ui.Label;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.TextBox;
import com.google.gwt.user.client.ui.VerticalPanel;

/**
 * Entry point classes define <code>onModuleLoad()</code>.
 */
public class StockWatcher implements EntryPoint {
	
	private static final int REFRESH_INTERVAL = 5000; // ms
	
	private VerticalPanel mainPanel = new VerticalPanel();
	private FlexTable stocksFlexTable = new FlexTable();
	private HorizontalPanel addPanel = new HorizontalPanel();
	private TextBox newSymbolTextBox = new TextBox();
	private Button addStockButton = new Button("Add");
	private Label lastUpdatedLabel = new Label();
	private ArrayList<String> stocks = new ArrayList<String>();
	
	private String[] stocksTableColumns = {"Symbol", "Price", "Change", "Remove"};

	/**
	 * This is the entry point method.
	 */
	public void onModuleLoad() {
		// Create table for stock data.
		for (int i = 0; i < stocksTableColumns.length; i++) {
			stocksFlexTable.setText(0, i, stocksTableColumns[i]);
		}
		
		// Assemble Add Stock panel.
		addPanel.add(newSymbolTextBox);
		addPanel.add(addStockButton);
		
		// Assemble Main panel.
		mainPanel.add(stocksFlexTable);
		mainPanel.add(addPanel);
		mainPanel.add(lastUpdatedLabel);
		
		// Associate the Main panel with the HTML host page.
		RootPanel.get("stockList").add(mainPanel);
		
		// Move cursor focus to the input box.
		newSymbolTextBox.setFocus(true);
		
		// Setup timer to refresh list automatically.
		Timer refreshTimer = new Timer() {
			@Override
			public void run() {
				refreshWatchlist();
			}
		};
		refreshTimer.scheduleRepeating(REFRESH_INTERVAL);
		
		// Listen for mouse events on the Add button.
		addStockButton.addClickHandler(new ClickHandler() {
			public void onClick(ClickEvent event) {
				addStock();
			}
		});
		
		// Listen for keyboard events in the input box.
		newSymbolTextBox.addKeyPressHandler(new KeyPressHandler() {
			public void onKeyPress(KeyPressEvent event) {
				if (event.getCharCode() == KeyCodes.KEY_ENTER) {
					addStock();
				}
			}
		});
	}
	
	/**
	 * Add stock to FlexTable. Executed when the user clicks the addStockButton
	 * or presses enter in the newSumbolTextBox.
	 */
	private void addStock() {
		final String symbol = newSymbolTextBox.getText().toUpperCase().trim();
		newSymbolTextBox.setFocus(true);
		
		// Stock code must be between 1 and 10 chars that are numbers/letters/dots
		if (!symbol.matches("^[0-9A-Z\\.]{1,10}$")) {
			Window.alert("'" + symbol + "' is not a valid symbol.");
			newSymbolTextBox.selectAll();
			return;
		}
		
		newSymbolTextBox.setText("");
		
		// Don't add the stock if it's already in the table
		if (stocks.contains(symbol))
			return;
		
		// Add the stock to the table.
		int row = stocksFlexTable.getRowCount();
		stocks.add(symbol);
		stocksFlexTable.setText(row, 0, symbol);
		
		// Add a button to remove this stock from the table.
		Button removeStockButton = new Button("x");
		removeStockButton.addClickHandler(new ClickHandler() {
			public void onClick(ClickEvent event) {
				int removedIndex = stocks.indexOf(symbol);
				stocks.remove(removedIndex);
				stocksFlexTable.removeRow(removedIndex + 1);
			}
		});
		stocksFlexTable.setWidget(row, 3, removeStockButton);
		
		// Get the stock price.
		refreshWatchlist();
	}
	
	/**
	 * Update the price change for each stock.
	 */
	private void refreshWatchlist() {
		final double MAX_PRICE = 100.0;
		final double MAX_PRICE_CHANGE = 0.02;
		
		StockPrice[] prices = new StockPrice[stocks.size()];
		for (int i = 0; i < stocks.size(); i++) {
			double price = Random.nextDouble() * MAX_PRICE;
			double change = price * MAX_PRICE_CHANGE
				* (Random.nextDouble() * 2.0 - 1.0);
			prices[i] = new StockPrice(stocks.get(i), price, change);
		}
		
		updateTable(prices);
	}
	
	/**
	 * Update the price and change fields of all the rows in the stock table.
	 * 
	 * @param prices Stock data for all rows.
	 */
	private void updateTable(StockPrice[] prices) {
		for (int i = 0; i < prices.length; i++) {
			updateTable(prices[i]);
		}
		
		// Display timestamp showing last refresh.
		lastUpdatedLabel.setText("Last update: " + (new Date()).toString());
	}
	
	/**
	 * Update a single row in the stock table.
	 * 
	 * @param price Stock data for a single row.
	 */
	private void updateTable(StockPrice price) {
		// Make sure the stock is still in the stock table.
		if (!stocks.contains(price.getSymbol()))
			return;
		
		int row = stocks.indexOf(price.getSymbol()) + 1;
		
		// Format the data in the price and change fields.
		String priceText = NumberFormat.getFormat("#,##0.00").format(
			price.getPrice());
		NumberFormat changeFormat = NumberFormat.getFormat("+#,##0.00;-#,##0.00");
		String changeText = changeFormat.format(price.getChange());
		String changePercentText = changeFormat.format(price.getChangePercent());
		
		// Populate the price and change fields with new data.
		stocksFlexTable.setText(row, 1, priceText);
		stocksFlexTable.setText(row, 2, changeText + " (" + changePercentText + "%)");
	}
}