package javax.megaco.message.descriptor;



import java.io.Serializable;





import javax.megaco.MethodInvocationException;

import javax.megaco.message.Descriptor;



/**

 * The class ModemParam shall be used to set the Modem Type in the Modem

 * Descriptor. This also takes the extension string if the modem type is set to

 * extension parameter.

 */

public class ModemParam implements Serializable {



	private ModemType modemType = null;

	private String extModem;



	/**

	 * Constructs a object of class ModemParam with ModemType. This constructor

	 * can take all values of modem type except {@link ModemType.EXT}.

	 * 

	 * @param modemType

	 * @throws IllegalArgumentException

	 *             - If the object of class ModemType is set to NULL or the

	 *             modem type is set to {@link ModemType.EXT}.

	 */

	public ModemParam(ModemType modemType)



	throws IllegalArgumentException {

		if (modemType == null) {

			throw new IllegalArgumentException("ModemType must not be null");

		}



		this.modemType = modemType;

	}



	/**

	 * 

	 * Constructs a object of class ModemParam with extension string. This

	 * implicitly sets the modem type to {@link ModemType.EXT}.

	 * 

	 * @param extModem

	 *            - Sets the string for the extension of the modem type. The

	 *            extension string should be prefixed with "X-" or "X+". The

	 *            extension characters following the prefix should be at most of

	 *            6 characters. The extension string would be set only when the

	 *            modem type specifies {@link ModemType.EXT}.

	 * @throws IllegalArgumentException

	 *             - If the extension string passed to this method is NULL or if

	 *             the extension string is not in proper format. It should be

	 *             prefixed with either "X+" or "X-" followed by at most 6

	 *             characters.

	 */

	public ModemParam(java.lang.String extModem)



	throws IllegalArgumentException {

		modemType = ModemType.EXT;



		if (extModem == null) {

			throw new IllegalArgumentException("ExtModem must not be null");

		}

		// FIXME??

		DescriptorUtils.checkMethodExtensionRules(extModem);

		if (extModem.length() > 8) {

			throw new IllegalArgumentException("ExtModem length must nto exceed 8 characters");

		}

		this.extModem = extModem;



	}



	/**

	 * This method returns the identity of the modem type. The constants for the

	 * modem type are defined in ModemType.

	 * 

	 * @return Returns an integer value that identifies Modem type. It returns

	 *         one of the values defined in, ModemType.

	 */

	public ModemType getModemType() {

		return this.modemType;

	}



	/**

	 * This method returns the extension string of the modem type. The extension

	 * string should be prefixed with "X-" or "X+". The extension characters

	 * following the prefix should be at most of 6 characters. The extension

	 * string would be set only when the modem type specifies

	 * MODEM_TYPE_EXTENSION.

	 * 

	 * @return Gets the string for the extension of the modem type. The

	 *         extension string would be set only when the modem type specifies

	 *         MODEM_TYPE_EXTENSION.

	 * @throws IllegalStateException

	 *             if the method has been called when the modem type denotes

	 *             anything other than MODEM_TYPE_EXT

	 */

	public java.lang.String getExtensionString() throws IllegalStateException {

		if (this.modemType.getModemType() != ModemType.M_EXT) {

			throw new IllegalStateException("ModemType must be: EXT");

		}

		return this.extModem;

	}



}