/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements.  See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 javax.servlet.http;

import java.io.IOException;
import java.util.Hashtable;
import java.util.ResourceBundle;
import java.util.StringTokenizer;

import javax.servlet.ServletInputStream;

/**
 * @deprecated            As of Java(tm) Servlet API 2.3.
 *                        These methods were only useful
 *                        with the default encoding and have been moved
 *                        to the request interfaces.
 */
@SuppressWarnings("dep-ann") // Spec API does not use @Deprecated
public class HttpUtils {

    private static final String LSTRING_FILE =
        "javax.servlet.http.LocalStrings";
    private static final ResourceBundle lStrings =
        ResourceBundle.getBundle(LSTRING_FILE);


    /**
     * Constructs an empty <code>HttpUtils</code> object.
     *
     */
    public HttpUtils() {
        // NOOP
    }


    /**
     *
     * Parses a query string passed from the client to the
     * server and builds a <code>HashTable</code> object
     * with key-value pairs.
     * The query string should be in the form of a string
     * packaged by the GET or POST method, that is, it
     * should have key-value pairs in the form <i>key=value</i>,
     * with each pair separated from the next by a &amp; character.
     *
     * <p>A key can appear more than once in the query string
     * with different values. However, the key appears only once in
     * the hashtable, with its value being
     * an array of strings containing the multiple values sent
     * by the query string.
     *
     * <p>The keys and values in the hashtable are stored in their
     * decoded form, so
     * any + characters are converted to spaces, and characters
     * sent in hexadecimal notation (like <i>%xx</i>) are
     * converted to ASCII characters.
     *
     * @param s                a string containing the query to be parsed
     *
     * @return                a <code>HashTable</code> object built
     *                         from the parsed key-value pairs
     *
     * @exception IllegalArgumentException        if the query string
     *                                                is invalid
     *
     */
    public static Hashtable<String,String[]> parseQueryString(String s) {

        String valArray[] = null;

        if (s == null) {
            throw new IllegalArgumentException();
        }
        Hashtable<String,String[]> ht = new Hashtable<>();
        StringBuilder sb = new StringBuilder();
        StringTokenizer st = new StringTokenizer(s, "&");
        while (st.hasMoreTokens()) {
            String pair = st.nextToken();
            int pos = pair.indexOf('=');
            if (pos == -1) {
                // XXX
                // should give more detail about the illegal argument
                throw new IllegalArgumentException();
            }
            String key = parseName(pair.substring(0, pos), sb);
            String val = parseName(pair.substring(pos+1, pair.length()), sb);
            if (ht.containsKey(key)) {
                String oldVals[] = ht.get(key);
                valArray = new String[oldVals.length + 1];
                for (int i = 0; i < oldVals.length; i++)
                    valArray[i] = oldVals[i];
                valArray[oldVals.length] = val;
            } else {
                valArray = new String[1];
                valArray[0] = val;
            }
            ht.put(key, valArray);
        }
        return ht;
    }


    /**
     *
     * Parses data from an HTML form that the client sends to
     * the server using the HTTP POST method and the
     * <i>application/x-www-form-urlencoded</i> MIME type.
     *
     * <p>The data sent by the POST method contains key-value
     * pairs. A key can appear more than once in the POST data
     * with different values. However, the key appears only once in
     * the hashtable, with its value being
     * an array of strings containing the multiple values sent
     * by the POST method.
     *
     * <p>The keys and values in the hashtable are stored in their
     * decoded form, so
     * any + characters are converted to spaces, and characters
     * sent in hexadecimal notation (like <i>%xx</i>) are
     * converted to ASCII characters.
     *
     *
     *
     * @param len        an integer specifying the length,
     *                        in characters, of the
     *                        <code>ServletInputStream</code>
     *                        object that is also passed to this
     *                        method
     *
     * @param in        the <code>ServletInputStream</code>
     *                        object that contains the data sent
     *                        from the client
     *
     * @return                a <code>HashTable</code> object built
     *                        from the parsed key-value pairs
     *
     *
     * @exception IllegalArgumentException        if the data
     *                        sent by the POST method is invalid
     *
     */
    public static Hashtable<String,String[]> parsePostData(int len,
                                          ServletInputStream in) {
        // XXX
        // should a length of 0 be an IllegalArgumentException

        // cheap hack to return an empty hash
        if (len <=0)
            return new Hashtable<>();

        if (in == null) {
            throw new IllegalArgumentException();
        }

        // Make sure we read the entire POSTed body.
        byte[] postedBytes = new byte [len];
        try {
            int offset = 0;

            do {
                int inputLen = in.read (postedBytes, offset, len - offset);
                if (inputLen <= 0) {
                    String msg = lStrings.getString("err.io.short_read");
                    throw new IllegalArgumentException (msg);
                }
                offset += inputLen;
            } while ((len - offset) > 0);

        } catch (IOException e) {
            throw new IllegalArgumentException(e.getMessage(), e);
        }

        // XXX we shouldn't assume that the only kind of POST body
        // is FORM data encoded using ASCII or ISO Latin/1 ... or
        // that the body should always be treated as FORM data.
        try {
            String postedBody = new String(postedBytes, 0, len, "8859_1");
            return parseQueryString(postedBody);
        } catch (java.io.UnsupportedEncodingException e) {
            // XXX function should accept an encoding parameter & throw this
            // exception.  Otherwise throw something expected.
            throw new IllegalArgumentException(e.getMessage(), e);
        }
    }


    /*
     * Parse a name in the query string.
     */
    private static String parseName(String s, StringBuilder sb) {
        sb.setLength(0);
        for (int i = 0; i < s.length(); i++) {
            char c = s.charAt(i);
            switch (c) {
            case '+':
                sb.append(' ');
                break;
            case '%':
                try {
                    sb.append((char) Integer.parseInt(s.substring(i+1, i+3),
                                                      16));
                    i += 2;
                } catch (NumberFormatException e) {
                    // XXX
                    // need to be more specific about illegal arg
                    throw new IllegalArgumentException();
                } catch (StringIndexOutOfBoundsException e) {
                    String rest  = s.substring(i);
                    sb.append(rest);
                    if (rest.length()==2)
                        i++;
                }

                break;
            default:
                sb.append(c);
                break;
            }
        }
        return sb.toString();
    }


    /**
     *
     * Reconstructs the URL the client used to make the request,
     * using information in the <code>HttpServletRequest</code> object.
     * The returned URL contains a protocol, server name, port
     * number, and server path, but it does not include query
     * string parameters.
     *
     * <p>Because this method returns a <code>StringBuffer</code>,
     * not a string, you can modify the URL easily, for example,
     * to append query parameters.
     *
     * <p>This method is useful for creating redirect messages
     * and for reporting errors.
     *
     * @param req        a <code>HttpServletRequest</code> object
     *                        containing the client's request
     *
     * @return                a <code>StringBuffer</code> object containing
     *                        the reconstructed URL
     *
     */
    public static StringBuffer getRequestURL (HttpServletRequest req) {
        StringBuffer url = new StringBuffer ();
        String scheme = req.getScheme ();
        int port = req.getServerPort ();
        String urlPath = req.getRequestURI();

        url.append (scheme);                // http, https
        url.append ("://");
        url.append (req.getServerName ());
        if ((scheme.equals ("http") && port != 80) || (scheme.equals ("https") && port != 443)) {
            url.append (':');
            url.append (req.getServerPort ());
        }

        url.append(urlPath);
        return url;
    }
}