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/**
 * 
 */
package stream;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.Set;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import stream.data.DataFactory;
import stream.util.WildcardPattern;

/**
 * 
 * The Keys class represents a set of key strings, which may
 * include wildcard patterns using the wildcard ? and
 * *. This allows for quickly specifying a list of keys from a data
 * item.
 * 
 * 
 * @author Christian Bockermann 
 * 
 */
public final class Keys implements Serializable {

	/** The unique class ID */
	private static final long serialVersionUID = 1301122628686584473L;

	static Logger log = LoggerFactory.getLogger(Keys.class);


	final String[] keyValues;

	/**
	 * This constructor will split the argument string by occurences of the
	 * ' character and create a Keys instance of the
	 * resulting substrings.
	 * 
	 * @param kString
	 */
	public Keys(String kString) {
		this(kString.split(","));
	}

	/**
	 * This constructor creates an instance of Keys with the given
	 * list of key names. Each key name may contain wildcards.
	 * 
	 * @param ks
	 */
	protected Keys(String... ks) {
		final ArrayList keyValues = new ArrayList();

		for (String k : ks) {
			if (k.trim().isEmpty()) {
				continue;
			} else {
				keyValues.add(k.trim());
			}
		}

		this.keyValues = keyValues.toArray(new String[keyValues.size()]);
	}

	public Keys(Collection ks) {
		final ArrayList keyValues = new ArrayList();

		for (String k : ks) {
			if (k.trim().isEmpty()) {
				continue;
			} else {
				keyValues.add(k.trim());
			}
		}

		this.keyValues = keyValues.toArray(new String[keyValues.size()]);
	}

	public Set select(Data item) {
		if (item == null) {
			return new HashSet();
		}
		return select(item.keySet());
	}

	public Set select(Collection names) {
		return select(names, keyValues);
	}

	public final String toString() {
		StringBuffer s = new StringBuffer();

		for (int i = 0; i < keyValues.length; i++) {
			if (keyValues[i] != null && !keyValues[i].trim().isEmpty()) {
				if (s.length() > 0) {
					s.append(",");
				}
				s.append(keyValues[i].trim());
			}
		}

		return s.toString();
	}

	public Data refine(Data item) {
		Data out = DataFactory.create();
		for (String key : this.select(item.keySet())) {
			out.put(key, item.get(key));
		}
		return out;
	}

	public static String joinValues(Data item, String[] keys, String glue) {
		StringBuffer s = new StringBuffer();

		for (String key : select(item, keys)) {
			Serializable value = item.get(key);
			if (value != null) {
				if (s.length() > 0) {
					s.append(glue);
				}

				s.append(value.toString());
			}
		}

		return s.toString();
	}

	public static Set select(Data item, String filter) {
		if (filter == null || item == null)
			return new LinkedHashSet();

		return select(item, filter.split(","));
	}

	public static Set select(Data item, String[] keys) {
		Set selected = new LinkedHashSet();
		if (item == null)
			return selected;

		return select(item.keySet(), keys);
	}

	public static Set select(Collection ks, String[] keys) {
		Set selected = new LinkedHashSet();
		if (ks == null)
			return selected;

		if (keys == null) {
			selected.addAll(ks);
			return selected;
		}

		for (String key : ks) {
			if (isSelected(key, keys))
				selected.add(key);
		}

		return selected;
	}

	public static boolean isSelected(String value, String[] keys) {

		if (keys == null || keys.length == 0)
			return false;

		boolean included = false;

		for (String k : keys) {
			if (k.startsWith("!")) {
				k = k.substring(1);
				if (included && WildcardPattern.matches(k, value)) {
					included = false;
					log.debug(
							"Removing '{}' from selection due to pattern '!{}'",
							value, k);
				}
			} else {

				if (!included && WildcardPattern.matches(k, value)) {
					included = true;
					log.debug("Adding '{}' to selection due to pattern '{}'",
							value, k);
				}
			}
		}

		return included;
	}


	/**
	 * Get the strings which were used to build this object.
	 * @return the keys
	 */
	public String[] getKeyValues() {
		return keyValues;
	}
}