/*
 * GeoTools - The Open Source Java GIS Toolkit http://geotools.org
 * (C) 2004-2011, Open Source Geospatial Foundation (OSGeo)
 * 
 * This library is free software; you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License as published by the Free
 * Software Foundation; version 2.1 of the License.
 *
 * This library is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
 */

package org.geotools.filter.expression;

import java.text.SimpleDateFormat;
import java.util.TimeZone;

import org.geotools.factory.CommonFactoryFinder;
import org.junit.Assert;
import org.junit.Test;
import org.opengis.filter.FilterFactory2;

/**
 * Test that {@link FormatDateTimezoneFunction} correctly formats days in various time zones.
 * 
 * @author Ben Caradoc-Davies (CSIRO Earth Science and Resource Engineering)
 */
public class FormatDateTimezoneFunctionTest {

    /**
     * The time whose formatting is under test.
     */
    private static final String TIME = "1948-01-01T00:00:00Z";

    /**
     * {@link SimpleDateFormat} pattern for formatting; we will get just the day in ISO 8601 form.
     */
    private static final String PATTERN = "yyyy-MM-dd";

    /**
     * Expected ISO 8601 formatted day in UTC (zero offset) or time zones with positive offset (east of meridian).
     */
    private static final String DAY = "1948-01-01";

    /**
     * Expected ISO 8601 formatted day in time zones with negative offset (west of meridian).
     */
    private static final String PREVIOUS_DAY = "1947-12-31";

    private static final FilterFactory2 ff = CommonFactoryFinder.getFilterFactory2();

    /**
     * Return {@link #DAY} formatted according to {@link #PATTERN} in a time zone.
     * 
     * @param timezone in one of the formats supported by {@link TimeZone}
     * @return the formatted day
     */
    private String formatTimezone(String timezone) {
        return (String) ff.function(FormatDateTimezoneFunction.NAME.getFunctionName(),
                ff.literal(PATTERN), ff.literal(TIME), ff.literal(timezone)).evaluate(null);
    }

    /**
     * Test formatting in UTC time zone.
     */
    @Test
    public void utc() {
        Assert.assertEquals(DAY, formatTimezone("UTC"));
    }

    /**
     * Test formatting in Canada/Mountain time zone.
     */
    @Test
    public void canadaMountain() {
        Assert.assertEquals(PREVIOUS_DAY, formatTimezone("Canada/Mountain"));
    }

    /**
     * Test formatting in Australia/Perth time zone.
     */
    @Test
    public void australiaPerth() {
        Assert.assertEquals(DAY, formatTimezone("Australia/Perth"));
    }

    /**
     * Test for helpful exception detail if wrong number of parameters.
     */
    @Test
    public void wrongNumberOfParameters() {
        try {
            ff.function(FormatDateTimezoneFunction.NAME.getFunctionName(), ff.literal(PATTERN),
                    ff.literal(TIME)).evaluate(null);
            Assert.fail("Unexpected success");
        } catch (RuntimeException e) {
            Assert.assertEquals(FormatDateTimezoneFunction.NAME.getFunctionName()
                    + ": wrong number of parameters (2 not 3)", e.getMessage());
        }
    }

    /**
     * Test for helpful exception detail if date is invalid.
     */
    @Test
    public void invalidDate() {
        try {
            ff.function(FormatDateTimezoneFunction.NAME.getFunctionName(), ff.literal(PATTERN),
                    ff.literal("not a valid time"), ff.literal("UTC")).evaluate(null);
            Assert.fail("Unexpected success");
        } catch (RuntimeException e) {
            Assert.assertEquals(FormatDateTimezoneFunction.NAME.getFunctionName()
                    + ": could not parse date: not a valid time", e.getMessage());
        }
    }

    /**
     * Test that a null pattern causes null to be returned.
     */
    @Test
    public void nullPattern() {
        Assert.assertNull(ff.function(FormatDateTimezoneFunction.NAME.getFunctionName(),
                ff.literal(null), ff.literal(TIME), ff.literal("UTC")).evaluate(null));
    }

    /**
     * Test that a null date causes null to be returned.
     */
    @Test
    public void nullDate() {
        Assert.assertNull(ff.function(FormatDateTimezoneFunction.NAME.getFunctionName(),
                ff.literal(PATTERN), ff.literal(null), ff.literal("UTC")).evaluate(null));
    }

    /**
     * Test that a null timezone causes null to be returned.
     */
    @Test
    public void nullTimezone() {
        Assert.assertNull(ff.function(FormatDateTimezoneFunction.NAME.getFunctionName(),
                ff.literal(PATTERN), ff.literal(TIME), ff.literal(null)).evaluate(null));
    }

}