SharedConfiguration.java

package edu.hawaii.ics.yucheng;

import java.io.FileInputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Properties;

/**
 * An enum that defines the types of different queries supported by this program.
 */
enum ConfigurationType {
    createOrDrop, loadCSV, selectOrJoin;
}

/**
 * An object that contains the shared portion of different configuration files. 
 * 
 * @author     Cheng Jade
 * @assignment ICS 421 Assignment 4
 * @date       Mar 22, 2010
 * @bugs       None
 */
public class SharedConfiguration {

    // The catalog node configuration
    public final ConfigurationNode catalog;
    public final Properties properties;
    public ConfigurationType type;

    /**
     * Initialize a new instance of this object.
     */
    public SharedConfiguration(final String path) throws ProgramException {
        // Throw an exception if the specified path is null.
        if (null == path)
            throw new NullPointerException("path");

        // Declare a Properties object and load it with the specified file.
        this.properties = getProperties(path);
        this.catalog = new ConfigurationNode(properties, "catalog");

        if (properties.getProperty("tablename") != null) {
            this.type = ConfigurationType.loadCSV;
        } else if (properties.getProperty("numnodes") != null) {
            this.type = ConfigurationType.createOrDrop;
        } else
            this.type = ConfigurationType.selectOrJoin;
    }

    /**
     * returns a runnable that executes a given list of SQL statements (select
     * or join statements) or load a given list of CSV entries.
     * 
     * @param sqlsOrCSV
     *            The given list of SQL statements or CSV entries.
     *            
     * @return an object that implements Runnable.
     */
    public Runnable getRunnable(final ArrayList<String> sqlsOrCSV) throws ProgramException {
        if (this.type == ConfigurationType.loadCSV) {
            final LoadCSVConfiguration config = new LoadCSVConfiguration(properties, catalog);
            return new LoadCSV(config, sqlsOrCSV);
        }
        if (this.type == ConfigurationType.createOrDrop) {
            final CreateOrDropConfiguration config = new CreateOrDropConfiguration(properties, catalog);
            return new CreateOrDrop(config, sqlsOrCSV);
        }
        final SelectOrJoinConfiguration config = new SelectOrJoinConfiguration(properties, catalog);
        return new SelectOrJoin(config, sqlsOrCSV);
    }

    /**
     * Open a file, check for errors, and return a loaded properties object.
     * 
     * @param path
     *            The path to the properties file.
     * 
     * @return A loaded properties object.
     * 
     * @throws ProgramException
     *             Thrown if there is a problem reading the configuration file.
     */
    private static Properties getProperties(final String path)
            throws ProgramException {
        assert null != path;

        try {
            final FileInputStream file = new FileInputStream(path);
            try {
                final Properties properties = new Properties();
                properties.load(file);
                return properties;
            } finally {
                file.close();
            }
        } catch (final IOException e) {
            throw new ProgramException("Cannot read configuration file.", e);
        }
    }

    /**
     * a test main
     */
    public static void main(String[] args) {
        assert null != args;

        // Print usage information, if wrong number of arguments were used.
        if (args.length != 1) {
            final String name = SharedConfiguration.class.getSimpleName();
            System.err.println("Usage: java " + name + " <path>");
            System.err.println("       <path> path to a configuration file");
            System.exit(1);
            return;
        }
        try {
            // final SharedConfiguration config = new
            // SharedConfiguration(args[0]);
            // System.out.println(config.getConfiguration());
        } catch (final Exception e) {
            System.err.println("faile to parse due to: " + e.getMessage());
            System.exit(1);
        }
    }
}