package com.nilhcem.fakesmtp.gui.tab;
   
   import ch.qos.logback.classic.spi.ILoggingEvent;
   import ch.qos.logback.core.spi.AppenderAttachable;
   import com.nilhcem.fakesmtp.core.Configuration;
   import com.nilhcem.fakesmtp.gui.info.ClearAllButton;
   import com.nilhcem.fakesmtp.log.SMTPLogsAppender;
   import com.nilhcem.fakesmtp.log.SMTPLogsObservable;
   import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import javax.swing.JScrollPane;
  import javax.swing.JTextArea;
  import java.text.SimpleDateFormat;
  import java.util.Date;
  import java.util.Observable;
  import java.util.Observer;
  
  /**
   * Scrolled text area where will be displayed the SMTP logs.
   *
   * @author Nilhcem
   * @since 1.0
   */
  public final class LogsPane implements Observer {
  
  	private final JScrollPane logsPane = new JScrollPane();
  	private final SimpleDateFormat dateFormat = new SimpleDateFormat("hh:mm:ss a");
  	private final JTextArea logsArea = new JTextArea();
  
  	/**
  	 * Creates the text area, sets it as non-editable and sets an observer to intercept logs.
  	 */
  	public LogsPane() {
  		logsArea.setEditable(false);
  		logsPane.getViewport().add(logsArea, null);
  		addObserverToSmtpLogAppender();
  	}
  
  	/**
  	 * Returns the JScrollPane object.
  	 *
  	 * @return the JScrollPane object.
  	 */
  	public JScrollPane get() {
  		return logsPane;
  	}
  
  	/**
  	 * Adds this object to the SMTP logs appender observable, to intercept logs.
  	 * <p>
  	 * The goal is to be informed when the log appender will received some debug SMTP logs.<br>
  	 * When a log is written, the appender will notify this class which will display it in the text area.
  	 * </p>
  	 */
  	private void addObserverToSmtpLogAppender() {
  		Logger smtpLogger = LoggerFactory.getLogger(org.subethamail.smtp.server.Session.class);
  		String appenderName = Configuration.INSTANCE.get("logback.appender.name");
  
  		@SuppressWarnings("unchecked")
  		SMTPLogsAppender<ILoggingEvent> appender = (SMTPLogsAppender<ILoggingEvent>)
  			((AppenderAttachable<ILoggingEvent>) smtpLogger).getAppender(appenderName);
  		if (appender == null) {
  			LoggerFactory.getLogger(LogsPane.class).error("Can't find logger: {}", appenderName);
  		} else {
  			appender.getObservable().addObserver(this);
  		}
  	}
  
  	/**
  	 * Updates the content of the text area.
  	 * <p>
  	 * This method will be called by an observable element.
       * </p>
  	 * <ul>
  	 *   <li>If the observable is a {@link SMTPLogsObservable} object, the text area will display the received log.</li>
  	 *   <li>If the observable is a {@link ClearAllButton} object, the text area will be cleared.</li>
  	 * </ul>
  	 *
  	 * @param o the observable element which will notify this class.
  	 * @param log optional parameter (a {@code String} object, when the observable is a {@code SMTPLogsObservable} object, which will contain the log).
  	 */
  	@Override
  	public void update(Observable o, Object log) {
  		if (o instanceof SMTPLogsObservable) {
  			// Update and scroll pane to the bottom
  			logsArea.append(String.format("%s - %s%n", dateFormat.format(new Date()), log));
  			logsArea.setCaretPosition(logsArea.getText().length());
  		} else if (o instanceof ClearAllButton) {
  			// Remove text
  			logsArea.setText("");
  		}
  	}
  }