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package com.github.antelopeframework.mybatis.criterion;

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

import lombok.Getter;

/**
 * A sequence of a logical expressions combined by some
 * associative logical operator
 * 
 * @author yangzhi.yzh
 *
 */
@Getter
public class Junction implements Criterion {
	private static final long serialVersionUID = 1L;
	
	private final Nature nature;
	private final List conditions = new ArrayList();

	protected Junction(Nature nature) {
		this.nature = nature;
	}

	protected Junction(Nature nature, Criterion... criterion) {
		this( nature );
		Collections.addAll( conditions, criterion );
	}

	/**
	 * Adds a criterion to the junction (and/or)
	 *
	 * @param criterion The criterion to add
	 *
	 * @return {@code this}, for method chaining
	 */
	public Junction add(Criterion criterion) {
		conditions.add( criterion );
		return this;
	}
	
	@Override
	public String toSqlString(CriteriaQuery criteriaQuery) {
		if (conditions.size() == 0) {
			return "1=1";
		}

		final StringBuilder buffer = new StringBuilder().append('(');
		final Iterator itr = conditions.iterator();
		while (itr.hasNext()) {
			buffer.append(((Criterion) itr.next()).toSqlString(criteriaQuery));
			if (itr.hasNext()) {
				buffer.append(' ').append(nature.getOperator()).append(' ');
			}
		}

		return buffer.append(')').toString();
	}

	@Override
	public TypedValue[] getTypedValues(CriteriaQuery criteriaQuery) {
		final ArrayList typedValues = new ArrayList();
		for (Criterion condition : conditions) {
			final TypedValue[] subValues = condition.getTypedValues(criteriaQuery);
			Collections.addAll(typedValues, subValues);
		}

		return typedValues.toArray(new TypedValue[typedValues.size()]);
	}

	/**
	 * The type of junction
	 */
	public static enum Nature {
		/**
		 * An AND
		 */
		AND,
		/**
		 * An OR
		 */
		OR;

		/**
		 * The corresponding SQL operator
		 *
		 * @return SQL operator
		 */
		public String getOperator() {
			return name().toLowerCase();
		}
	}

}