package envoy.client.data;

import java.io.Serializable;
import java.util.function.Consumer;

import javax.swing.JComponent;

/**
 * Encapsulates a persistent value that is directly or indirectly mutable by the user.
 *
 * @param <T> the type of this {@link SettingsItem}'s value
 * @author Kai S. K. Engelbart
 * @since Envoy Client v0.3-alpha
 */
public final class SettingsItem<T> implements Serializable {

	private T		value;
	private String	userFriendlyName, description;

	private transient Consumer<T> changeHandler;

	private static final long serialVersionUID = 1L;

	/**
	 * Initializes a {@link SettingsItem}. The default value's class will be mapped to a
	 * {@link JComponent} that can be used to display this {@link SettingsItem} to the user.
	 *
	 * @param value            the default value
	 * @param userFriendlyName the user friendly name (short)
	 * @param description      the description (long)
	 * @since Envoy Client v0.3-alpha
	 */
	public SettingsItem(T value, String userFriendlyName, String description) {
		this.value				= value;
		this.userFriendlyName	= userFriendlyName;
		this.description		= description;
	}

	/**
	 * @return the value
	 * @since Envoy Client v0.3-alpha
	 */
	public T get() {
		return value;
	}

	/**
	 * Changes the value of this {@link SettingsItem}. If a {@code ChangeHandler} if defined, it
	 * will be invoked with this value.
	 *
	 * @param value the value to set
	 * @since Envoy Client v0.3-alpha
	 */
	public void set(T value) {
		if (changeHandler != null && value != this.value)
			changeHandler.accept(value);
		this.value = value;
	}

	/**
	 * @return the userFriendlyName
	 * @since Envoy Client v0.3-alpha
	 */
	public String getUserFriendlyName() { return userFriendlyName; }

	/**
	 * @param userFriendlyName the userFriendlyName to set
	 * @since Envoy Client v0.3-alpha
	 */
	public void setUserFriendlyName(String userFriendlyName) {
		this.userFriendlyName = userFriendlyName;
	}

	/**
	 * @return the description
	 * @since Envoy Client v0.3-alpha
	 */
	public String getDescription() { return description; }

	/**
	 * @param description the description to set
	 * @since Envoy Client v0.3-alpha
	 */
	public void setDescription(String description) { this.description = description; }

	/**
	 * Sets a {@code ChangeHandler} for this {@link SettingsItem}. It will be invoked with the
	 * current value once during the registration and every time when the value changes.
	 *
	 * @param changeHandler the changeHandler to set
	 * @since Envoy Client v0.3-alpha
	 */
	public void setChangeHandler(Consumer<T> changeHandler) {
		this.changeHandler = changeHandler;
		changeHandler.accept(value);
	}
}