FilterCriteria.java

/**
 * Copyright (c) 2014-2017 by the respective copyright holders.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 */
package org.eclipse.smarthome.core.persistence;

import java.util.Date;

import org.eclipse.smarthome.core.types.State;

/**
 * This class is used to define a filter for queries to a {@link PersistenceService}.
 *
 * <p>
 * It is designed as a Java bean, for which the different properties are constraints on the query result. These
 * properties include the item name, begin and end date and the item state. A compare operator can be defined to compare
 * not only state equality, but also its decimal value (<,>).
 * <p>
 * <p>
 * Additionally, the filter criteria supports ordering and paging of the result, so the caller can ask to only return
 * chunks of the result of a certain size (=pageSize) from a starting index (pageNumber*pageSize).
 * </p>
 * <p>
 * All setter methods return the filter criteria instance, so that the methods can be easily chained in order to define
 * a filter.
 *
 * @author Kai Kreuzer - Initial contribution and API
 */
public class FilterCriteria {

    /** Enumeration with all possible compare options */
    public enum Operator {
        EQ("="), NEQ("!="), GT(">"), LT("<"), GTE(">="), LTE("<=");

        private final String symbol;

        Operator(String symbol) {
            this.symbol = symbol;
        }

        String getSymbol() {
            return symbol;
        }
    }

    /** Enumeration with all ordering options */
    public enum Ordering {
        ASCENDING, DESCENDING
    }

    /** filter result to only contain entries for the given item */
    private String itemName;

    /** filter result to only contain entries that are newer than the given date */
    private Date beginDate;

    /** filter result to only contain entries that are older than the given date */
    private Date endDate;

    /** return the result list from starting index pageNumber*pageSize only */
    private int pageNumber = 0;

    /** return at most this many results */
    private int pageSize = Integer.MAX_VALUE;

    /** use this operator to compare the item state */
    private Operator operator = Operator.EQ;

    /** how to sort the result list by date */
    private Ordering ordering = Ordering.DESCENDING;

    /** filter result to only contain entries that evaluate to true with the given operator and state */
    private State state;

    public String getItemName() {
        return itemName;
    }

    public Date getBeginDate() {
        return beginDate;
    }

    public Date getEndDate() {
        return endDate;
    }

    public int getPageNumber() {
        return pageNumber;
    }

    public int getPageSize() {
        return pageSize;
    }

    public Operator getOperator() {
        return operator;
    }

    public Ordering getOrdering() {
        return ordering;
    }

    public State getState() {
        return state;
    }

    public FilterCriteria setItemName(String itemName) {
        this.itemName = itemName;
        return this;
    }

    public FilterCriteria setBeginDate(Date beginDate) {
        this.beginDate = beginDate;
        return this;
    }

    public FilterCriteria setEndDate(Date endDate) {
        this.endDate = endDate;
        return this;
    }

    public FilterCriteria setPageNumber(int pageNumber) {
        this.pageNumber = pageNumber;
        return this;
    }

    public FilterCriteria setPageSize(int pageSize) {
        this.pageSize = pageSize;
        return this;
    }

    public FilterCriteria setOperator(Operator operator) {
        this.operator = operator;
        return this;
    }

    public FilterCriteria setOrdering(Ordering ordering) {
        this.ordering = ordering;
        return this;
    }

    public FilterCriteria setState(State state) {
        this.state = state;
        return this;
    }

}