package discovery.computername;

/**
 * @author Mark
 */
public final class OtagoComputerNameResolver implements ComputerNameResolver {

	private final String computerName;
	private String labName;
	private String machineId;

	/**
	 * <p>
	 * Otago University lab machines usually have a COMPUTERNAME environment
	 * variable in the form "labname-machineId", eg SB316-23.</p>
	 *
	 * <p>
	 * If the name parameter is set then use that, otherwise use the envVar
	 * parameter to get the name from an environment variable.</p>
	 *
	 * @param name the computer name to use (or null).
	 * @param envVar the environment variable to use if name is not set.
	 *
	 */
	public OtagoComputerNameResolver(final String name, final String envVar) {
		super();

		if (name == null) {
			computerName = System.getenv(envVar);
		} else {
			computerName = name;
		}

	}

	public void resolve() {
		if (computerName == null) {
			throw new InvalidComputerNameException("The computer name has not been provided via a recognisable method.\nTry setting the COMPUTERNAME environment variable, or passing the name as an argument when starting the application.");
		}

		final String[] nameBits = computerName.split("-");

		if (nameBits.length < 2) {
			throw new InvalidComputerNameException("The computer name '" + computerName + "' is not in the expected format (eg SB316-01)");
		}

		this.labName = nameBits[0];
		this.machineId = nameBits[1];
	}

	public String getComputerName() {
		return this.computerName;
	}

	public String getLabName() {
		return this.labName;
	}

	public String getMachineId() {
		return this.machineId;
	}
}