package envoy.client.data.audio;

import java.io.IOException;
import java.nio.file.*;

import javax.sound.sampled.*;

import envoy.exception.EnvoyException;

/**
 * Records audio and exports it as a byte array.
 *
 * @author Kai S. K. Engelbart
 * @since Envoy Client v0.1-beta
 */
public final class AudioRecorder {

	/**
	 * The default audio format used for recording and play back.
	 *
	 * @since Envoy Client v0.1-beta
	 */
	public static final AudioFormat DEFAULT_AUDIO_FORMAT =
		new AudioFormat(16000, 16, 1, true, false);

	/**
	 * The format in which audio files will be saved.
	 */
	public static final String FILE_FORMAT = "wav";

	private final AudioFormat	format;
	private final DataLine.Info	info;

	private TargetDataLine	line;
	private Path			tempFile;

	/**
	 * Initializes the recorder with the default audio format.
	 *
	 * @since Envoy Client v0.1-beta
	 */
	public AudioRecorder() {
		this(DEFAULT_AUDIO_FORMAT);
	}

	/**
	 * Initializes the recorder with a given audio format.
	 *
	 * @param format the audio format to use
	 * @since Envoy Client v0.1-beta
	 */
	public AudioRecorder(AudioFormat format) {
		this.format	= format;
		info		= new DataLine.Info(TargetDataLine.class, format);
	}

	/**
	 * @return {@code true} if audio recording is supported
	 * @since Envoy Client v0.1-beta
	 */
	public boolean isSupported() { return AudioSystem.isLineSupported(info); }

	/**
	 * @return {@code true} if the recorder is active
	 * @since Envoy Client v0.1-beta
	 */
	public boolean isRecording() { return line != null && line.isActive(); }

	/**
	 * Starts the audio recording.
	 *
	 * @throws EnvoyException if starting the recording failed
	 * @since Envoy Client v0.1-beta
	 */
	public void start() throws EnvoyException {
		try {

			// Open the line
			line = (TargetDataLine) AudioSystem.getLine(info);
			line.open(format);
			line.start();

			// Prepare temp file
			tempFile = Files.createTempFile("recording", FILE_FORMAT);

			// Start the recording
			final var ais = new AudioInputStream(line);
			AudioSystem.write(ais, AudioFileFormat.Type.WAVE, tempFile.toFile());
		} catch (IOException | LineUnavailableException e) {
			throw new EnvoyException("Cannot record voice", e);
		}
	}

	/**
	 * Stops the recording.
	 *
	 * @return the finished recording
	 * @throws EnvoyException if finishing the recording failed
	 * @since Envoy Client v0.1-beta
	 */
	public byte[] finish() throws EnvoyException {
		try {
			line.stop();
			line.close();
			final byte[] data = Files.readAllBytes(tempFile);
			Files.delete(tempFile);
			return data;
		} catch (final IOException e) {
			throw new EnvoyException("Cannot save voice recording", e);
		}
	}

	/**
	 * Cancels the active recording.
	 *
	 * @since Envoy Client v0.1-beta
	 */
	public void cancel() {
		line.stop();
		line.close();
		try {
			Files.deleteIfExists(tempFile);
		} catch (final IOException e) {}
	}
}