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package net.sourceforge.barbecue.env;

/**
 * Factory class for getting hold of the current operating environment.
 *
 * @author <a href="mailto:opensource@ianbourke.com">Ian Bourke</a>
 */
public class EnvironmentFactory {

	private static Environment env;
	private static Environment defaultEnvironment;

	///CLOVER:OFF
	/** Cannot construct directly */
	protected EnvironmentFactory() {
	}
	///CLOVER:ON

	/**
	 * Returns the current operating environment.
	 * @return The current environment
	 */
	public static Environment getEnvironment() {
		if (env == null) {
			determineCurrentEnvironment();
		}
		return env;
	}

	/**
	 * Forces the factory to assume headless mode, regardless of whether
	 * this is actually true or not.
	 */
	public static void setHeadlessMode() {
		env = new HeadlessEnvironment();
	}

    /**
	 * Forces the factory to use the environment that does not access the AWT.
	 */
	public static void setNonAWTMode() {
		env = new NonAWTEnvironment(HeadlessEnvironment.DEFAULT_RESOLUTION);
	}

	/**
	 * Forces the factory to use the environment that does not access the AWT.
	 * @param resolution The desired (or current) screen/output resolution
	 */
	public static void setNonAWTMode(int resolution) {
		env = new NonAWTEnvironment(resolution);
	}

	/**
	 * Sets the factory to use the default (discovered) environment.
	 */
	public static void setDefaultMode() {
		determineCurrentEnvironment();
	}

	/**
	 * Sets the default environment for the factory.
	 * Use this to set your own environment implementation.
	 * @param newEnv The new default environment
	 */
	public static void setDefaultEnvironment(Environment newEnv) {
		env = null;
		defaultEnvironment = newEnv;
	}

	private static void determineCurrentEnvironment() {
		Environment current;
		if (defaultEnvironment != null) {
			current = defaultEnvironment;
		} else {
			current = new DefaultEnvironment();
		}
		try {
			// Try to get the res, this will fail in headless mode
			current.getResolution();
		} catch (UnsupportedOperationException e) {
			current = new HeadlessEnvironment();
		} catch (InternalError e) {
			current = new HeadlessEnvironment();
		}
		env = current;
	}
}