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/*
 * Copyright 2015-2016 Agapsys Tecnologia Ltda-ME.
 *
 * 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 com.agapsys.web.toolkit.utils;

import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class HttpUtils {

    protected HttpUtils() {}

    public static class MissingParameterException extends Exception {

        private MissingParameterException(String message, Object...msgArgs) {
            super(msgArgs.length > 0 ? String.format(message, msgArgs) : message);
        }
    }

    /**
     * @return request origin IP.
     *
     * @param req HTTP request.
     */
    public static String getOriginIp(HttpServletRequest req) {
        return req.getRemoteAddr();
    }

    /**
     * @return origin user-agent.
     *
     * @param req HTTP request.
     */
    public static String getOriginUserAgent(HttpServletRequest req) {
        return req.getHeader("user-agent");
    }

    /**
     * @return request URI.
     *
     * @param req HTTP request.
     */
    public static String getRequestUri(HttpServletRequest req) {
        StringBuffer requestUrl = req.getRequestURL();
        if (req.getQueryString() != null) {
            requestUrl.append("?").append(req.getQueryString());
        }

        return String.format("%s %s %s", req.getMethod(), requestUrl.toString(), req.getProtocol());
    }

    /**
     * @return cookie value. If there is no such cookie, returns null.
     *
     * @param request HTTP request.
     * @param name cookie name.
     */
    public static String getCookieValue(HttpServletRequest request, String name) {
        Cookie[] cookies = request.getCookies();
        if (cookies != null) {
            for (Cookie cookie : cookies) {
                if (name.equals(cookie.getName())) {
                    return cookie.getValue();
                }
            }
        }
        return null;
    }

    /**
     * Adds a cookie.
     *
     * @param resp HTTP response.
     * @param name cookie name.
     * @param value cookie value.
     * @param maxAge an integer specifying the maximum age of the cookie in seconds; if negative, means the cookie is not stored; if zero, deletes the cookie.
     * @param path cookie path (usually {@linkplain HttpServletRequest#getContextPath()}).
     */
    public static void addCookie(HttpServletResponse resp, String name, String value, int maxAge, String path) {
        if (path == null || !path.startsWith("/"))
            throw new IllegalArgumentException("Invalid path: " + path);

        Cookie cookie = new Cookie(name, value);
        cookie.setPath(path);
        cookie.setMaxAge(maxAge);
        resp.addCookie(cookie);
    }

    /**
     * Adds a cookie for request context path.
     *
     * @param req  HTTP request.
     * @param resp HTTP response.
     * @param name cookie name.
     * @param value cookie value.
     * @param maxAge an integer specifying the maximum age of the cookie in seconds; if negative, means the cookie is not stored; if zero, deletes the cookie.
     */
    public static void addCookie(HttpServletRequest req, HttpServletResponse resp, String name, String value, int maxAge) {
        addCookie(resp, name, value, maxAge, req.getContextPath());
    }

    /**
     * Removes a cookie.
     *
     * @param resp HTTP response.
     * @param name name of the cookie to be removed.
     * @param path cookie path ((usually {@linkplain HttpServletRequest#getContextPath()}).
     */
    public static void removeCookie(HttpServletResponse resp, String name, String path) {
        addCookie(resp, name, null, 0, path);
    }

    /**
     * Removes a cookie for request context path.
     *
     * @param req  HTTP request.
     * @param resp HTTP response.
     * @param name name of the cookie to be removed.
     */
    public static void removeCookie(HttpServletRequest req, HttpServletResponse resp, String name) {
        removeCookie(resp, name, req.getContextPath());
    }

    /**
     * @return an optional parameter contained in the request.
     *
     * @param req          HTTP request.
     * @param paramName    parameter name.
     * @param defaultValue default value if given parameter is not contained in the request.
     */
    public static String getOptionalParameter(HttpServletRequest req, String paramName, String defaultValue) {

        String val = req.getParameter(paramName);
        if (val == null || val.trim().isEmpty())
            val = defaultValue;

        if (val != null)
            val = val.trim();

        return val;
    }

    /**
     * Returns a mandatory parameter contained in the request.
     *
     * @param req  HTTP request.
     * @param paramName parameter name.
     * @return parameter value.
     * @throws MissingParameterException if parameter is not contained in given request.
     */
    public static String getMandatoryParameter(HttpServletRequest req, String paramName) throws MissingParameterException {
        return getMandatoryParameter(req, paramName, "Missing parameter: %s", paramName);
    }

    /**
     * Returns a mandatory parameter contained in the request.
     *
     * @param req  HTTP request.
     * @param paramName parameter name.
     * @param errorMessage error message used by thrown exception.
     * @param errMsgArgs optional error message args if error message is a formatted string.
     * @return parameter value.
     * @throws MissingParameterException if parameter is not contained in given request.
     */
    public static String getMandatoryParameter(HttpServletRequest req, String paramName, String errorMessage, Object...errMsgArgs) throws MissingParameterException {
        String val = getOptionalParameter(req, paramName, "");
        if (val.trim().isEmpty())
            throw new MissingParameterException(errorMessage, errMsgArgs);

        return val;
    }

}