package org.msh.reports;

import java.sql.Connection;


/**
 * This is a singleton class to configure the resource provider 
 * used in the report engine
 * 
 * @author Ricardo Memoria
 *
 */
public final class ReportConfiguration {

	private static ReportConfiguration reportConfiguration;

	private ReportResourceProvider resourceProvider;

	/**
	 * Private constructor to guaranty singleton instance 
	 */
	private ReportConfiguration() {
		super();
	}
	
	/**
	 * Register an implementation of the {@link ReportResourceProvider} interface. This interface
	 * will integrate the report library with the system
	 * @param resourceProvider
	 * @return
	 */
	public void registerResourceProvider(ReportResourceProvider resourceProvider) {
		this.resourceProvider = resourceProvider;
	}

	
	/**
	 * Resolve a name to an object using the {@link NameResolver} interface
	 * @param name
	 * @return
	 */
	public Object resolveName(String name) {
		return checkResourceProvider().resolveName(name);
	}


	/**
	 * Return a database connection
	 * @return
	 */
	public Connection getConnection() {
		return checkResourceProvider().getConnection();
	}

	
	/**
	 * @return
	 */
	private ReportResourceProvider checkResourceProvider() { 
		if (resourceProvider == null)
			throw new RuntimeException("No NameResolver interface provided to " + getClass().getSimpleName());
		return resourceProvider;
	}

	/**
	 * Create the instance of {@link ReportConfiguration}
	 * @return
	 */
	private static synchronized ReportConfiguration createSingletonInstance() {
		if (reportConfiguration == null)
			reportConfiguration = new ReportConfiguration();
		return reportConfiguration;
	}
	
	/**
	 * Return an unique instance of the {@link ReportConfiguration} class
	 * @return
	 */
	public static ReportConfiguration instance() {
		if (reportConfiguration == null)
			createSingletonInstance();
		return reportConfiguration;
	}

}