/*
 * Copyright 2002-2007 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.web.bind;

import javax.servlet.ServletRequest;

/**
 * Parameter extraction methods, for an approach distinct from data binding,
 * in which parameters of specific types are required.
 *
 * <p>This approach is very useful for simple submissions, where binding
 * request parameters to a command object would be overkill.
 *
 * @author Juergen Hoeller
 * @author Keith Donald
 * @since 2.0
 */
public abstract class ServletRequestUtils {

	private static final IntParser INT_PARSER = new IntParser();

	private static final LongParser LONG_PARSER = new LongParser();

	private static final FloatParser FLOAT_PARSER = new FloatParser();

	private static final DoubleParser DOUBLE_PARSER = new DoubleParser();

	private static final BooleanParser BOOLEAN_PARSER = new BooleanParser();

	private static final StringParser STRING_PARSER = new StringParser();


	/**
	 * Get an Integer parameter, or <code>null</code> if not present.
	 * Throws an exception if it the parameter value isn't a number.
	 * @param request current HTTP request
	 * @param name the name of the parameter
	 * @return the Integer value, or <code>null</code> if not present
	 * @throws ServletRequestBindingException a subclass of ServletException,
	 * so it doesn't need to be caught
	 */
	public static Integer getIntParameter(ServletRequest request, String name)
			throws ServletRequestBindingException {

		if (request.getParameter(name) == null) {
			return null;
		}
		return new Integer(getRequiredIntParameter(request, name));
	}

	/**
	 * Get an int parameter, with a fallback value. Never throws an exception.
	 * Can pass a distinguished value as default to enable checks of whether it was supplied.
	 * @param request current HTTP request
	 * @param name the name of the parameter
	 * @param defaultVal the default value to use as fallback
	 */
	public static int getIntParameter(ServletRequest request, String name, int defaultVal) {
		if (request.getParameter(name) == null) {
			return defaultVal;
		}
		try {
			return getRequiredIntParameter(request, name);
		}
		catch (ServletRequestBindingException ex) {
			return defaultVal;
		}
	}

	/**
	 * Get an array of int parameters, return an empty array if not found.
	 * @param request current HTTP request
	 * @param name the name of the parameter with multiple possible values
	 */
	public static int[] getIntParameters(ServletRequest request, String name) {
		try {
			return getRequiredIntParameters(request, name);
		}
		catch (ServletRequestBindingException ex) {
			return new int[0];
		}
	}

	/**
	 * Get an int parameter, throwing an exception if it isn't found or isn't a number.
	 * @param request current HTTP request
	 * @param name the name of the parameter
	 * @throws ServletRequestBindingException a subclass of ServletException,
	 * so it doesn't need to be caught
	 */
	public static int getRequiredIntParameter(ServletRequest request, String name)
			throws ServletRequestBindingException {

		return INT_PARSER.parseInt(name, request.getParameter(name));
	}

	/**
	 * Get an array of int parameters, throwing an exception if not found or one is not a number..
	 * @param request current HTTP request
	 * @param name the name of the parameter with multiple possible values
	 * @throws ServletRequestBindingException a subclass of ServletException,
	 * so it doesn't need to be caught
	 */
	public static int[] getRequiredIntParameters(ServletRequest request, String name)
			throws ServletRequestBindingException {

		return INT_PARSER.parseInts(name, request.getParameterValues(name));
	}


	/**
	 * Get a Long parameter, or <code>null</code> if not present.
	 * Throws an exception if it the parameter value isn't a number.
	 * @param request current HTTP request
	 * @param name the name of the parameter
	 * @return the Long value, or <code>null</code> if not present
	 * @throws ServletRequestBindingException a subclass of ServletException,
	 * so it doesn't need to be caught
	 */
	public static Long getLongParameter(ServletRequest request, String name)
			throws ServletRequestBindingException {

		if (request.getParameter(name) == null) {
			return null;
		}
		return new Long(getRequiredLongParameter(request, name));
	}

	/**
	 * Get a long parameter, with a fallback value. Never throws an exception.
	 * Can pass a distinguished value as default to enable checks of whether it was supplied.
	 * @param request current HTTP request
	 * @param name the name of the parameter
	 * @param defaultVal the default value to use as fallback
	 */
	public static long getLongParameter(ServletRequest request, String name, long defaultVal) {
		if (request.getParameter(name) == null) {
			return defaultVal;
		}
		try {
			return getRequiredLongParameter(request, name);
		}
		catch (ServletRequestBindingException ex) {
			return defaultVal;
		}
	}

	/**
	 * Get an array of long parameters, return an empty array if not found.
	 * @param request current HTTP request
	 * @param name the name of the parameter with multiple possible values
	 */
	public static long[] getLongParameters(ServletRequest request, String name) {
		try {
			return getRequiredLongParameters(request, name);
		}
		catch (ServletRequestBindingException ex) {
			return new long[0];
		}
	}

	/**
	 * Get a long parameter, throwing an exception if it isn't found or isn't a number.
	 * @param request current HTTP request
	 * @param name the name of the parameter
	 * @throws ServletRequestBindingException a subclass of ServletException,
	 * so it doesn't need to be caught
	 */
	public static long getRequiredLongParameter(ServletRequest request, String name)
			throws ServletRequestBindingException {

		return LONG_PARSER.parseLong(name, request.getParameter(name));
	}

	/**
	 * Get an array of long parameters, throwing an exception if not found or one is not a number.
	 * @param request current HTTP request
	 * @param name the name of the parameter with multiple possible values
	 * @throws ServletRequestBindingException a subclass of ServletException,
	 * so it doesn't need to be caught
	 */
	public static long[] getRequiredLongParameters(ServletRequest request, String name)
			throws ServletRequestBindingException {

		return LONG_PARSER.parseLongs(name, request.getParameterValues(name));
	}


	/**
	 * Get a Float parameter, or <code>null</code> if not present.
	 * Throws an exception if it the parameter value isn't a number.
	 * @param request current HTTP request
	 * @param name the name of the parameter
	 * @return the Float value, or <code>null</code> if not present
	 * @throws ServletRequestBindingException a subclass of ServletException,
	 * so it doesn't need to be caught
	 */
	public static Float getFloatParameter(ServletRequest request, String name)
			throws ServletRequestBindingException {

		if (request.getParameter(name) == null) {
			return null;
		}
		return new Float(getRequiredFloatParameter(request, name));
	}

	/**
	 * Get a float parameter, with a fallback value. Never throws an exception.
	 * Can pass a distinguished value as default to enable checks of whether it was supplied.
	 * @param request current HTTP request
	 * @param name the name of the parameter
	 * @param defaultVal the default value to use as fallback
	 */
	public static float getFloatParameter(ServletRequest request, String name, float defaultVal) {
		if (request.getParameter(name) == null) {
			return defaultVal;
		}
		try {
			return getRequiredFloatParameter(request, name);
		}
		catch (ServletRequestBindingException ex) {
			return defaultVal;
		}
	}

	/**
	 * Get an array of float parameters, return an empty array if not found.
	 * @param request current HTTP request
	 * @param name the name of the parameter with multiple possible values
	 */
	public static float[] getFloatParameters(ServletRequest request, String name) {
		try {
			return getRequiredFloatParameters(request, name);
		}
		catch (ServletRequestBindingException ex) {
			return new float[0];
		}
	}

	/**
	 * Get a float parameter, throwing an exception if it isn't found or isn't a number.
	 * @param request current HTTP request
	 * @param name the name of the parameter
	 * @throws ServletRequestBindingException a subclass of ServletException,
	 * so it doesn't need to be caught
	 */
	public static float getRequiredFloatParameter(ServletRequest request, String name)
			throws ServletRequestBindingException {

		return FLOAT_PARSER.parseFloat(name, request.getParameter(name));
	}

	/**
	 * Get an array of float parameters, throwing an exception if not found or one is not a number.
	 * @param request current HTTP request
	 * @param name the name of the parameter with multiple possible values
	 * @throws ServletRequestBindingException a subclass of ServletException,
	 * so it doesn't need to be caught
	 */
	public static float[] getRequiredFloatParameters(ServletRequest request, String name)
			throws ServletRequestBindingException {

		return FLOAT_PARSER.parseFloats(name, request.getParameterValues(name));
	}


	/**
	 * Get a Double parameter, or <code>null</code> if not present.
	 * Throws an exception if it the parameter value isn't a number.
	 * @param request current HTTP request
	 * @param name the name of the parameter
	 * @return the Double value, or <code>null</code> if not present
	 * @throws ServletRequestBindingException a subclass of ServletException,
	 * so it doesn't need to be caught
	 */
	public static Double getDoubleParameter(ServletRequest request, String name)
			throws ServletRequestBindingException {

		if (request.getParameter(name) == null) {
			return null;
		}
		return new Double(getRequiredDoubleParameter(request, name));
	}

	/**
	 * Get a double parameter, with a fallback value. Never throws an exception.
	 * Can pass a distinguished value as default to enable checks of whether it was supplied.
	 * @param request current HTTP request
	 * @param name the name of the parameter
	 * @param defaultVal the default value to use as fallback
	 */
	public static double getDoubleParameter(ServletRequest request, String name, double defaultVal) {
		if (request.getParameter(name) == null) {
			return defaultVal;
		}
		try {
			return getRequiredDoubleParameter(request, name);
		}
		catch (ServletRequestBindingException ex) {
			return defaultVal;
		}
	}

	/**
	 * Get an array of double parameters, return an empty array if not found.
	 * @param request current HTTP request
	 * @param name the name of the parameter with multiple possible values
	 */
	public static double[] getDoubleParameters(ServletRequest request, String name) {
		try {
			return getRequiredDoubleParameters(request, name);
		}
		catch (ServletRequestBindingException ex) {
			return new double[0];
		}
	}

	/**
	 * Get a double parameter, throwing an exception if it isn't found or isn't a number.
	 * @param request current HTTP request
	 * @param name the name of the parameter
	 * @throws ServletRequestBindingException a subclass of ServletException,
	 * so it doesn't need to be caught
	 */
	public static double getRequiredDoubleParameter(ServletRequest request, String name)
			throws ServletRequestBindingException {

		return DOUBLE_PARSER.parseDouble(name, request.getParameter(name));
	}

	/**
	 * Get an array of double parameters, throwing an exception if not found or one is not a number.
	 * @param request current HTTP request
	 * @param name the name of the parameter with multiple possible values
	 * @throws ServletRequestBindingException a subclass of ServletException,