package org.csstudio.sds.cursorservice;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;

import org.eclipse.core.runtime.IConfigurationElement;

/**
 * Describes a {@link CursorSelectionRule}. The description includes the list
 * of cursor states that are declared for the rule (i.e., declared in the
 * contribution which contributes the rule).
 * 
 * @author swende, Joerg Rathlev
 */
public final class RuleDescriptor {
	
	/**
	 * The id of the described rule.
	 */
	private String _id;
	
	/**
	 * The description of the rule. 
	 */
	private String _description;
	
	/**
	 * The cursor states declared for this rule.
	 */
	private List<CursorState> _states;
	
	/**
	 * The configuration element that declared this rule.
	 */
	private IConfigurationElement _configurationElement;

	/**
	 * Creates a new rule descriptor.
	 * 
	 * @param id
	 *            the id of the rule.
	 * @param description
	 *            the description of the rule.
	 * @param states
	 *            the {@code CursorState}s of this rule.
	 * @param configurationElement
	 *            the configuration element that declared this rule. May be
	 *            <code>null</code> if this rule was not declared by an
	 *            extension point.
	 */
	RuleDescriptor(final String id, final String description,
			final Collection<CursorState> states,
			final IConfigurationElement configurationElement) {
		assert id != null;
		assert description != null;
		_id = id;
		_description = description;
		_states = new ArrayList<CursorState>(states);
		_configurationElement = configurationElement;
	}
	
	/**
	 * Returns the configuration element that declared this rule.
	 * 
	 * @return the configuration element that declared this rule, or
	 *         <code>null</code> if this rule was not declared by an extension
	 *         point.
	 */
	IConfigurationElement configurationElement() {
		return _configurationElement;
	}
	
	/**
	 * Returns an unmodifiable list of cursor states declared for the rule
	 * described by this descriptor.
	 * 
	 * @return an unmodifiable list of cursor states declared for the rule
	 *         described by this descriptor.
	 */
	public List<CursorState> cursorStates() {
		return Collections.unmodifiableList(_states);
	}
	
	/**
	 * Returns the cursor state with the speicified id, or <code>null</code>
	 * if the state is not defined for this rule.
	 * 
	 * @param id
	 *            the state id.
	 * @return the cursor state, or <code>null</code> if the state does not
	 *         exist.
	 */
	CursorState state(final String id) {
		for (CursorState state : _states) {
			if (state.getId().equals(id)) {
				return state;
			}
		}
		return null;
	}

	/**
	 * Returns the id of the rule described by this descriptor.
	 * 
	 * @return the id of the rule described by this descriptor.
	 */
	public String getId() {
		return _id;
	}

	/**
	 * Returns the description of the rule described by this descriptor.
	 * 
	 * @return the description of the rule described by this descriptor.
	 */
	public String getDescription() {
		return _description;
	}
}