//
// ========================================================================
// Copyright (c) 1995-2020 Mort Bay Consulting Pty Ltd and others.
//
// This program and the accompanying materials are made available under
// the terms of the Eclipse Public License 2.0 which is available at
// https://www.eclipse.org/legal/epl-2.0
//
// This Source Code may also be made available under the following
// Secondary Licenses when the conditions for such availability set
// forth in the Eclipse Public License, v. 2.0 are satisfied:
// the Apache License v2.0 which is available at
// https://www.apache.org/licenses/LICENSE-2.0
//
// SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
// ========================================================================
//

package org.eclipse.jetty.util;

import java.net.URI;
import java.net.URISyntaxException;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;

import org.eclipse.jetty.util.Utf8Appendable.NotUtf8Exception;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

URI Utility methods.

This class assists with the decoding and encoding or HTTP URI's.
It differs from the java.net.URL class as it does not provide
communications ability, but it does assist with query string
formatting.

See Also:
UrlEncoded/**
 * URI Utility methods.
 * <p>
 * This class assists with the decoding and encoding or HTTP URI's.
 * It differs from the java.net.URL class as it does not provide
 * communications ability, but it does assist with query string
 * formatting.
 * </p>
 *
 * @see UrlEncoded
 */
public class URIUtil
    implements Cloneable
{
    private static final Logger LOG = LoggerFactory.getLogger(URIUtil.class);
    public static final String SLASH = "/";
    public static final String HTTP = "http";
    public static final String HTTPS = "https";

    // Use UTF-8 as per http://www.w3.org/TR/html40/appendix/notes.html#non-ascii-chars
    public static final Charset __CHARSET = StandardCharsets.UTF_8;

    private URIUtil()
    {
    }

    
Encode a URI path.
This is the same encoding offered by URLEncoder, except that
the '/' character is not encoded.
Params:
path – The path the encode
Returns:
The encoded path/**
     * Encode a URI path.
     * This is the same encoding offered by URLEncoder, except that
     * the '/' character is not encoded.
     *
     * @param path The path the encode
     * @return The encoded path
     */
    public static String encodePath(String path)
    {
        if (path == null || path.length() == 0)
            return path;

        StringBuilder buf = encodePath(null, path, 0);
        return buf == null ? path : buf.toString();
    }

    
Encode a URI path.
Params:
path – The path the encode
buf – StringBuilder to encode path into (or null)
Returns:
The StringBuilder or null if no substitutions required./**
     * Encode a URI path.
     *
     * @param path The path the encode
     * @param buf StringBuilder to encode path into (or null)
     * @return The StringBuilder or null if no substitutions required.
     */
    public static StringBuilder encodePath(StringBuilder buf, String path)
    {
        return encodePath(buf, path, 0);
    }

    
Encode a URI path.
Params:
path – The path the encode
buf – StringBuilder to encode path into (or null)
Returns:
The StringBuilder or null if no substitutions required./**
     * Encode a URI path.
     *
     * @param path The path the encode
     * @param buf StringBuilder to encode path into (or null)
     * @return The StringBuilder or null if no substitutions required.
     */
    private static StringBuilder encodePath(StringBuilder buf, String path, int offset)
    {
        byte[] bytes = null;
        if (buf == null)
        {
            loop:
            for (int i = offset; i < path.length(); i++)
            {
                char c = path.charAt(i);
                switch (c)
                {
                    case '%':
                    case '?':
                    case ';':
                    case '#':
                    case '"':
                    case '\'':
                    case '<':
                    case '>':
                    case ' ':
                    case '[':
                    case '\\':
                    case ']':
                    case '^':
                    case '`':
                    case '{':
                    case '|':
                    case '}':
                        buf = new StringBuilder(path.length() * 2);
                        break loop;
                    default:
                        if (c > 127)
                        {
                            bytes = path.getBytes(URIUtil.__CHARSET);
                            buf = new StringBuilder(path.length() * 2);
                            break loop;
                        }
                }
            }
            if (buf == null)
                return null;
        }

        int i;

        loop:
        for (i = offset; i < path.length(); i++)
        {
            char c = path.charAt(i);
            switch (c)
            {
                case '%':
                    buf.append("%25");
                    continue;
                case '?':
                    buf.append("%3F");
                    continue;
                case ';':
                    buf.append("%3B");
                    continue;
                case '#':
                    buf.append("%23");
                    continue;
                case '"':
                    buf.append("%22");
                    continue;
                case '\'':
                    buf.append("%27");
                    continue;
                case '<':
                    buf.append("%3C");
                    continue;
                case '>':
                    buf.append("%3E");
                    continue;
                case ' ':
                    buf.append("%20");
                    continue;
                case '[':
                    buf.append("%5B");
                    continue;
                case '\\':
                    buf.append("%5C");
                    continue;
                case ']':
                    buf.append("%5D");
                    continue;
                case '^':
                    buf.append("%5E");
                    continue;
                case '`':
                    buf.append("%60");
                    continue;
                case '{':
                    buf.append("%7B");
                    continue;
                case '|':
                    buf.append("%7C");
                    continue;
                case '}':
                    buf.append("%7D");
                    continue;

                default:
                    if (c > 127)
                    {
                        bytes = path.getBytes(URIUtil.__CHARSET);
                        break loop;
                    }
                    buf.append(c);
            }
        }

        if (bytes != null)
        {
            for (; i < bytes.length; i++)
            {
                byte c = bytes[i];
                switch (c)
                {
                    case '%':
                        buf.append("%25");
                        continue;
                    case '?':
                        buf.append("%3F");
                        continue;
                    case ';':
                        buf.append("%3B");
                        continue;
                    case '#':
                        buf.append("%23");
                        continue;
                    case '"':
                        buf.append("%22");
                        continue;
                    case '\'':
                        buf.append("%27");
                        continue;
                    case '<':
                        buf.append("%3C");
                        continue;
                    case '>':
                        buf.append("%3E");
                        continue;
                    case ' ':
                        buf.append("%20");
                        continue;
                    case '[':
                        buf.append("%5B");
                        continue;
                    case '\\':
                        buf.append("%5C");
                        continue;
                    case ']':
                        buf.append("%5D");
                        continue;
                    case '^':
                        buf.append("%5E");
                        continue;
                    case '`':
                        buf.append("%60");
                        continue;
                    case '{':
                        buf.append("%7B");
                        continue;
                    case '|':
                        buf.append("%7C");
                        continue;
                    case '}':
                        buf.append("%7D");
                        continue;
                    default:
                        if (c < 0)
                        {
                            buf.append('%');
                            TypeUtil.toHex(c, buf);
                        }
                        else
                            buf.append((char)c);
                }
            }
        }

        return buf;
    }

    
Encode a raw URI String and convert any raw spaces to
their "%20" equivalent.
Params:
str – input raw string
Returns:
output with spaces converted to "%20"/**
     * Encode a raw URI String and convert any raw spaces to
     * their "%20" equivalent.
     *
     * @param str input raw string
     * @return output with spaces converted to "%20"
     */
    public static String encodeSpaces(String str)
    {
        return StringUtil.replace(str, " ", "%20");
    }

    
Encode a raw String and convert any specific characters to their URI encoded equivalent.
Params:
str – input raw string
charsToEncode – the list of raw characters that need to be encoded (if encountered)
Returns:
output with specified characters encoded./**
     * Encode a raw String and convert any specific characters to their URI encoded equivalent.
     *
     * @param str input raw string
     * @param charsToEncode the list of raw characters that need to be encoded (if encountered)
     * @return output with specified characters encoded.
     */
    @SuppressWarnings("Duplicates")
    public static String encodeSpecific(String str, String charsToEncode)
    {
        if ((str == null) || (str.length() == 0))
            return null;

        if ((charsToEncode == null) || (charsToEncode.length() == 0))
            return str;

        char[] find = charsToEncode.toCharArray();
        int len = str.length();
        StringBuilder ret = new StringBuilder((int)(len * 0.20d));
        for (int i = 0; i < len; i++)
        {
            char c = str.charAt(i);
            boolean escaped = false;
            for (char f : find)
            {
                if (c == f)
                {
                    escaped = true;
                    ret.append('%');
                    int d = 0xf & ((0xF0 & c) >> 4);
                    ret.append((char)((d > 9 ? ('A' - 10) : '0') + d));
                    d = 0xf & c;
                    ret.append((char)((d > 9 ? ('A' - 10) : '0') + d));
                    break;
                }
            }
            if (!escaped)
            {
                ret.append(c);
            }
        }
        return ret.toString();
    }

    
Decode a raw String and convert any specific URI encoded sequences into characters.
Params:
str – input raw string
charsToDecode – the list of raw characters that need to be decoded (if encountered), leaving all other encoded sequences alone.
Returns:
output with specified characters decoded./**
     * Decode a raw String and convert any specific URI encoded sequences into characters.
     *
     * @param str input raw string
     * @param charsToDecode the list of raw characters that need to be decoded (if encountered), leaving all other encoded sequences alone.
     * @return output with specified characters decoded.
     */
    @SuppressWarnings("Duplicates")
    public static String decodeSpecific(String str, String charsToDecode)
    {
        if ((str == null) || (str.length() == 0))
            return null;

        if ((charsToDecode == null) || (charsToDecode.length() == 0))
            return str;

        int idx = str.indexOf('%');
        if (idx == -1)
        {
            // no hits
            return str;
        }

        char[] find = charsToDecode.toCharArray();
        int len = str.length();
        Utf8StringBuilder ret = new Utf8StringBuilder(len);
        ret.append(str, 0, idx);

        for (int i = idx; i < len; i++)
        {
            char c = str.charAt(i);
            switch (c)
            {
                case '%':
                    if ((i + 2) < len)
                    {
                        char u = str.charAt(i + 1);
                        char l = str.charAt(i + 2);
                        char result = (char)(0xff & (TypeUtil.convertHexDigit(u) * 16 + TypeUtil.convertHexDigit(l)));
                        boolean decoded = false;
                        for (char f : find)
                        {
                            if (f == result)
                            {
                                ret.append(result);
                                decoded = true;
                                break;
                            }
                        }
                        if (decoded)
                        {
                            i += 2;
                        }
                        else
                        {
                            ret.append(c);
                        }
                    }
                    else
                    {
                        throw new IllegalArgumentException("Bad URI % encoding");
                    }
                    break;
                default:
                    ret.append(c);
                    break;
            }
        }
        return ret.toString();
    }

    
Encode a URI path.
Params:
path – The path the encode
buf – StringBuilder to encode path into (or null)
encode – String of characters to encode. % is always encoded.
Returns:
The StringBuilder or null if no substitutions required./**
     * Encode a URI path.
     *
     * @param path The path the encode
     * @param buf StringBuilder to encode path into (or null)
     * @param encode String of characters to encode. % is always encoded.
     * @return The StringBuilder or null if no substitutions required.
     */
    public static StringBuilder encodeString(StringBuilder buf,
                                             String path,
                                             String encode)
    {
        if (buf == null)
        {
            for (int i = 0; i < path.length(); i++)
            {
                char c = path.charAt(i);
                if (c == '%' || encode.indexOf(c) >= 0)
                {
                    buf = new StringBuilder(path.length() << 1);
                    break;
                }
            }
            if (buf == null)
                return null;
        }

        for (int i = 0; i < path.length(); i++)
        {
            char c = path.charAt(i);
            if (c == '%' || encode.indexOf(c) >= 0)
            {
                buf.append('%');
                StringUtil.append(buf, (byte)(0xff & c), 16);
            }
            else
                buf.append(c);
        }

        return buf;
    }

    /* Decode a URI path and strip parameters
     */
    public static String decodePath(String path)
    {
        return decodePath(path, 0, path.length());
    }

    /* Decode a URI path and strip parameters of UTF-8 path
     */
    public static String decodePath(String path, int offset, int length)
    {
        try
        {
            Utf8StringBuilder builder = null;
            int end = offset + length;
            for (int i = offset; i < end; i++)
            {
                char c = path.charAt(i);
                switch (c)
                {
                    case '%':
                        if (builder == null)
                        {
                            builder = new Utf8StringBuilder(path.length());
                            builder.append(path, offset, i - offset);
                        }
                        if ((i + 2) < end)
                        {
                            char u = path.charAt(i + 1);
                            if (u == 'u')
                            {
                                // TODO remove %u support in jetty-10
                                // this is wrong. This is a codepoint not a char
                                builder.append((char)(0xffff & TypeUtil.parseInt(path, i + 2, 4, 16)));
                                i += 5;
                            }
                            else
                            {
                                builder.append((byte)(0xff & (TypeUtil.convertHexDigit(u) * 16 + TypeUtil.convertHexDigit(path.charAt(i + 2)))));
                                i += 2;
                            }
                        }
                        else
                        {
                            throw new IllegalArgumentException("Bad URI % encoding");
                        }

                        break;

                    case ';':
                        if (builder == null)
                        {
                            builder = new Utf8StringBuilder(path.length());
                            builder.append(path, offset, i - offset);
                        }

                        while (++i < end)
                        {
                            if (path.charAt(i) == '/')
                            {
                                builder.append('/');
                                break;
                            }
                        }

                        break;

                    default:
                        if (builder != null)
                            builder.append(c);
                        break;
                }
            }

            if (builder != null)
                return builder.toString();
            if (offset == 0 && length == path.length())
                return path;
            return path.substring(offset, end);
        }
        catch (NotUtf8Exception e)
        {
            if (LOG.isDebugEnabled())
                LOG.debug("{} {}", path.substring(offset, offset + length), e.toString());
            return decodeISO88591Path(path, offset, length);
        }
        catch (IllegalArgumentException e)
        {
            throw e;
        }
        catch (Exception e)
        {
            throw new IllegalArgumentException("cannot decode URI", e);
        }

    }

    /* Decode a URI path and strip parameters of ISO-8859-1 path
     */
    private static String decodeISO88591Path(String path, int offset, int length)
    {
        StringBuilder builder = null;
        int end = offset + length;
        for (int i = offset; i < end; i++)
        {
            char c = path.charAt(i);
            switch (c)
            {
                case '%':
                    if (builder == null)
                    {
                        builder = new StringBuilder(path.length());
                        builder.append(path, offset, i - offset);
                    }
                    if ((i + 2) < end)
                    {
                        char u = path.charAt(i + 1);
                        if (u == 'u')
                        {
                            // TODO remove %u encoding support in jetty-10
                            // This is wrong. This is a codepoint not a char
                            builder.append((char)(0xffff & TypeUtil.parseInt(path, i + 2, 4, 16)));
                            i += 5;
                        }
                        else
                        {
                            builder.append((char)(0xff & (TypeUtil.convertHexDigit(u) * 16 + TypeUtil.convertHexDigit(path.charAt(i + 2)))));
                            i += 2;
                        }
                    }
                    else
                    {
                        throw new IllegalArgumentException();
                    }

                    break;

                case ';':
                    if (builder == null)
                    {
                        builder = new StringBuilder(path.length());
                        builder.append(path, offset, i - offset);
                    }
                    while (++i < end)
                    {
                        if (path.charAt(i) == '/')
                        {
                            builder.append('/');
                            break;
                        }
                    }
                    break;

                default:
                    if (builder != null)
                        builder.append(c);
                    break;
            }
        }

        if (builder != null)
            return builder.toString();
        if (offset == 0 && length == path.length())
            return path;
        return path.substring(offset, end);
    }

    
Add two encoded URI path segments.
Handles null and empty paths, path and query params
(eg ?a=b or ;JSESSIONID=xxx) and avoids duplicate '/'
Params:
p1 – URI path segment (should be encoded)
p2 – URI path segment (should be encoded)
Returns:
Legally combined path segments./**
     * Add two encoded URI path segments.
     * Handles null and empty paths, path and query params
     * (eg ?a=b or ;JSESSIONID=xxx) and avoids duplicate '/'
     *
     * @param p1 URI path segment (should be encoded)
     * @param p2 URI path segment (should be encoded)
     * @return Legally combined path segments.
     */
    public static String addEncodedPaths(String p1, String p2)
    {
        if (p1 == null || p1.length() == 0)
        {
            if (p1 != null && p2 == null)
                return p1;
            return p2;
        }
        if (p2 == null || p2.length() == 0)
            return p1;

        int split = p1.indexOf(';');
        if (split < 0)
            split = p1.indexOf('?');
        if (split == 0)
            return p2 + p1;
        if (split < 0)
            split = p1.length();

        StringBuilder buf = new StringBuilder(p1.length() + p2.length() + 2);
        buf.append(p1);

        if (buf.charAt(split - 1) == '/')
        {
            if (p2.startsWith(URIUtil.SLASH))
            {
                buf.deleteCharAt(split - 1);
                buf.insert(split - 1, p2);
            }
            else
                buf.insert(split, p2);
        }
        else
        {
            if (p2.startsWith(URIUtil.SLASH))
                buf.insert(split, p2);
            else
            {
                buf.insert(split, '/');
                buf.insert(split + 1, p2);
            }
        }

        return buf.toString();
    }

    
Add two Decoded URI path segments.
Handles null and empty paths.  Path and query params (eg ?a=b or
;JSESSIONID=xxx) are not handled
Params:
p1 – URI path segment (should be decoded)
p2 – URI path segment (should be decoded)
Returns:
Legally combined path segments./**
     * Add two Decoded URI path segments.
     * Handles null and empty paths.  Path and query params (eg ?a=b or
     * ;JSESSIONID=xxx) are not handled
     *
     * @param p1 URI path segment (should be decoded)
     * @param p2 URI path segment (should be decoded)
     * @return Legally combined path segments.
     */
    public static String addPaths(String p1, String p2)
    {
        if (p1 == null || p1.length() == 0)
        {
            if (p1 != null && p2 == null)
                return p1;
            return p2;
        }
        if (p2 == null || p2.length() == 0)
            return p1;

        boolean p1EndsWithSlash = p1.endsWith(SLASH);
        boolean p2StartsWithSlash = p2.startsWith(SLASH);

        if (p1EndsWithSlash && p2StartsWithSlash)
        {
            if (p2.length() == 1)
                return p1;
            if (p1.length() == 1)
                return p2;
        }

        StringBuilder buf = new StringBuilder(p1.length() + p2.length() + 2);
        buf.append(p1);

        if (p1.endsWith(SLASH))
        {
            if (p2.startsWith(SLASH))
                buf.setLength(buf.length() - 1);
        }
        else
        {
            if (!p2.startsWith(SLASH))
                buf.append(SLASH);
        }
        buf.append(p2);

        return buf.toString();
    }

    
Add a path and a query string
Params:
path – The path which may already contain contain a query
query – The query string or null if no query to be added
Returns:
The path with any non null query added after a '?' or '&' as appropriate./** Add a path and a query string
     * @param path The path which may already contain contain a query
     * @param query The query string or null if no query to be added
     * @return The path with any non null query added after a '?' or '&amp;' as appropriate.
     */
    public static String addPathQuery(String path, String query)
    {
        if (query == null)
            return path;
        if (path.indexOf('?') >= 0)
            return path + '&' + query;
        return path + '?' + query;
    }

    
Given a URI, attempt to get the last segment.
 If this is a jar:file:// style URI, then the JAR filename is returned (not the deep !/path location) 
Params:
uri – the URI to look in
Returns:
the last segment./**
     * Given a URI, attempt to get the last segment.
     * <p>
     * If this is a {@code jar:file://} style URI, then
     * the JAR filename is returned (not the deep {@code !/path} location)
     * </p>
     *
     * @param uri the URI to look in
     * @return the last segment.
     */
    public static String getUriLastPathSegment(URI uri)
    {
        String ssp = uri.getSchemeSpecificPart();
        // strip off deep jar:file: reference information
        int idx = ssp.indexOf("!/");
        if (idx != -1)
        {
            ssp = ssp.substring(0, idx);
        }

        // Strip off trailing '/' if present
        if (ssp.endsWith("/"))
        {
            ssp = ssp.substring(0, ssp.length() - 1);
        }

        // Only interested in last segment
        idx = ssp.lastIndexOf('/');
        if (idx != -1)
        {
            ssp = ssp.substring(idx + 1);
        }

        return ssp;
    }

    
Return the parent Path.
Treat a URI like a directory path and return the parent directory.
Params:
p – the path to return a parent reference to
Returns:
the parent path of the URI/**
     * Return the parent Path.
     * Treat a URI like a directory path and return the parent directory.
     *
     * @param p the path to return a parent reference to
     * @return the parent path of the URI
     */
    public static String parentPath(String p)
    {
        if (p == null || URIUtil.SLASH.equals(p))
            return null;
        int slash = p.lastIndexOf('/', p.length() - 2);
        if (slash >= 0)
            return p.substring(0, slash + 1);
        return null;
    }

    
Convert a decoded path to a canonical form.

All instances of "." and ".." are factored out.


Null is returned if the path tries to .. above its root.

Params:
path – the path to convert, decoded, with path separators '/' and no queries.
Returns:
the canonical path, or null if path traversal above root./**
     * Convert a decoded path to a canonical form.
     * <p>
     * All instances of "." and ".." are factored out.
     * </p>
     * <p>
     * Null is returned if the path tries to .. above its root.
     * </p>
     *
     * @param path the path to convert, decoded, with path separators '/' and no queries.
     * @return the canonical path, or null if path traversal above root.
     */
    public static String canonicalPath(String path)
    {
        if (path == null || path.isEmpty())
            return path;

        boolean slash = true;
        int end = path.length();
        int i = 0;

        loop:
        while (i < end)
        {
            char c = path.charAt(i);
            switch (c)
            {
                case '/':
                    slash = true;
                    break;

                case '.':
                    if (slash)
                        break loop;
                    slash = false;
                    break;

                default:
                    slash = false;
            }

            i++;
        }

        if (i == end)
            return path;

        StringBuilder canonical = new StringBuilder(path.length());
        canonical.append(path, 0, i);

        int dots = 1;
        i++;
        while (i <= end)
        {
            char c = i < end ? path.charAt(i) : '\0';
            switch (c)
            {
                case '\0':
                case '/':
                    switch (dots)
                    {
                        case 0:
                            if (c != '\0')
                                canonical.append(c);
                            break;

                        case 1:
                            break;

                        case 2:
                            if (canonical.length() < 2)
                                return null;
                            canonical.setLength(canonical.length() - 1);
                            canonical.setLength(canonical.lastIndexOf("/") + 1);
                            break;

                        default:
                            while (dots-- > 0)
                            {
                                canonical.append('.');
                            }
                            if (c != '\0')
                                canonical.append(c);
                    }

                    slash = true;
                    dots = 0;
                    break;

                case '.':
                    if (dots > 0)
                        dots++;
                    else if (slash)
                        dots = 1;
                    else
                        canonical.append('.');
                    slash = false;
                    break;

                default:
                    while (dots-- > 0)
                    {
                        canonical.append('.');
                    }
                    canonical.append(c);
                    dots = 0;
                    slash = false;
            }

            i++;
        }
        return canonical.toString();
    }

    
Convert a path to a cananonical form.

All instances of "." and ".." are factored out.


Null is returned if the path tries to .. above its root.

Params:
path – the path to convert (expects URI/URL form, encoded, and with path separators '/')
Returns:
the canonical path, or null if path traversal above root./**
     * Convert a path to a cananonical form.
     * <p>
     * All instances of "." and ".." are factored out.
     * </p>
     * <p>
     * Null is returned if the path tries to .. above its root.
     * </p>
     *
     * @param path the path to convert (expects URI/URL form, encoded, and with path separators '/')
     * @return the canonical path, or null if path traversal above root.
     */
    public static String canonicalEncodedPath(String path)
    {
        if (path == null || path.isEmpty())
            return path;

        boolean slash = true;
        int end = path.length();
        int i = 0;

        loop:
        while (i < end)
        {
            char c = path.charAt(i);
            switch (c)
            {
                case '/':
                    slash = true;
                    break;

                case '.':
                    if (slash)
                        break loop;
                    slash = false;
                    break;

                case '?':
                    return path;

                default:
                    slash = false;
            }

            i++;
        }

        if (i == end)
            return path;

        StringBuilder canonical = new StringBuilder(path.length());
        canonical.append(path, 0, i);

        int dots = 1;
        i++;
        while (i <= end)
        {
            char c = i < end ? path.charAt(i) : '\0';
            switch (c)
            {
                case '\0':
                case '/':
                case '?':
                    switch (dots)
                    {
                        case 0:
                            if (c != '\0')
                                canonical.append(c);
                            break;

                        case 1:
                            if (c == '?')
                                canonical.append(c);
                            break;

                        case 2:
                            if (canonical.length() < 2)
                                return null;
                            canonical.setLength(canonical.length() - 1);
                            canonical.setLength(canonical.lastIndexOf("/") + 1);
                            if (c == '?')
                                canonical.append(c);
                            break;
                        default:
                            while (dots-- > 0)
                            {
                                canonical.append('.');
                            }
                            if (c != '\0')
                                canonical.append(c);
                    }

                    slash = true;
                    dots = 0;
                    break;

                case '.':
                    if (dots > 0)
                        dots++;
                    else if (slash)
                        dots = 1;
                    else
                        canonical.append('.');
                    slash = false;
                    break;

                default:
                    while (dots-- > 0)
                    {
                        canonical.append('.');
                    }
                    canonical.append(c);
                    dots = 0;
                    slash = false;
            }

            i++;
        }
        return canonical.toString();
    }

    
Convert a path to a compact form.
All instances of "//" and "///" etc. are factored out to single "/"
Params:
path – the path to compact
Returns:
the compacted path/**
     * Convert a path to a compact form.
     * All instances of "//" and "///" etc. are factored out to single "/"
     *
     * @param path the path to compact
     * @return the compacted path
     */
    public static String compactPath(String path)
    {
        if (path == null || path.length() == 0)
            return path;

        int state = 0;
        int end = path.length();
        int i = 0;

        loop:
        while (i < end)
        {
            char c = path.charAt(i);
            switch (c)
            {
                case '?':
                    return path;
                case '/':
                    state++;
                    if (state == 2)
                        break loop;
                    break;
                default:
                    state = 0;
            }
            i++;
        }

        if (state < 2)
            return path;

        StringBuilder buf = new StringBuilder(path.length());
        buf.append(path, 0, i);

        loop2:
        while (i < end)
        {
            char c = path.charAt(i);
            switch (c)
            {
                case '?':
                    buf.append(path, i, end);
                    break loop2;
                case '/':
                    if (state++ == 0)
                        buf.append(c);
                    break;
                default:
                    state = 0;
                    buf.append(c);
            }
            i++;
        }

        return buf.toString();
    }

    
Params:
uri – URI
Returns:
True if the uri has a scheme/**
     * @param uri URI
     * @return True if the uri has a scheme
     */
    public static boolean hasScheme(String uri)
    {
        for (int i = 0; i < uri.length(); i++)
        {
            char c = uri.charAt(i);
            if (c == ':')
                return true;
            if (!(c >= 'a' && c <= 'z' ||
                c >= 'A' && c <= 'Z' ||
                (i > 0 && (c >= '0' && c <= '9' ||
                    c == '.' ||
                    c == '+' ||
                    c == '-'))))
            {
                break;
            }
        }
        return false;
    }

    
Create a new URI from the arguments, handling IPv6 host encoding and default ports
Params:
scheme – the URI scheme
server – the URI server
port – the URI port
path – the URI path
query – the URI query
Returns:
A String URI/**
     * Create a new URI from the arguments, handling IPv6 host encoding and default ports
     *
     * @param scheme the URI scheme
     * @param server the URI server
     * @param port the URI port
     * @param path the URI path
     * @param query the URI query
     * @return A String URI
     */
    public static String newURI(String scheme, String server, int port, String path, String query)
    {
        StringBuilder builder = newURIBuilder(scheme, server, port);
        builder.append(path);
        if (query != null && query.length() > 0)
            builder.append('?').append(query);
        return builder.toString();
    }

    
Create a new URI StringBuilder from the arguments, handling IPv6 host encoding and default ports
Params:
scheme – the URI scheme
server – the URI server
port – the URI port
Returns:
a StringBuilder containing URI prefix/**
     * Create a new URI StringBuilder from the arguments, handling IPv6 host encoding and default ports
     *
     * @param scheme the URI scheme
     * @param server the URI server
     * @param port the URI port
     * @return a StringBuilder containing URI prefix
     */
    public static StringBuilder newURIBuilder(String scheme, String server, int port)
    {
        StringBuilder builder = new StringBuilder();
        appendSchemeHostPort(builder, scheme, server, port);
        return builder;
    }

    
Append scheme, host and port URI prefix, handling IPv6 address encoding and default ports
Params:
url – StringBuilder to append to
scheme – the URI scheme
server – the URI server
port – the URI port/**
     * Append scheme, host and port URI prefix, handling IPv6 address encoding and default ports
     *
     * @param url StringBuilder to append to
     * @param scheme the URI scheme
     * @param server the URI server
     * @param port the URI port
     */
    public static void appendSchemeHostPort(StringBuilder url, String scheme, String server, int port)
    {
        url.append(scheme).append("://").append(HostPort.normalizeHost(server));

        if (port > 0)
        {
            switch (scheme)
            {
                case "http":
                    if (port != 80)
                        url.append(':').append(port);
                    break;

                case "https":
                    if (port != 443)
                        url.append(':').append(port);
                    break;

                default:
                    url.append(':').append(port);
            }
        }
    }

    
Append scheme, host and port URI prefix, handling IPv6 address encoding and default ports
Params:
url – StringBuffer to append to
scheme – the URI scheme
server – the URI server
port – the URI port/**
     * Append scheme, host and port URI prefix, handling IPv6 address encoding and default ports
     *
     * @param url StringBuffer to append to
     * @param scheme the URI scheme
     * @param server the URI server
     * @param port the URI port
     */
    public static void appendSchemeHostPort(StringBuffer url, String scheme, String server, int port)
    {
        synchronized (url)
        {
            url.append(scheme).append("://").append(HostPort.normalizeHost(server));

            if (port > 0)
            {
                switch (scheme)
                {
                    case "http":
                        if (port != 80)
                            url.append(':').append(port);
                        break;

                    case "https":
                        if (port != 443)
                            url.append(':').append(port);
                        break;

                    default:
                        url.append(':').append(port);
                }
            }
        }
    }

    public static boolean equalsIgnoreEncodings(String uriA, String uriB)
    {
        int lenA = uriA.length();
        int lenB = uriB.length();
        int a = 0;
        int b = 0;

        while (a < lenA && b < lenB)
        {
            int oa = uriA.charAt(a++);
            int ca = oa;
            if (ca == '%')
            {
                ca = lenientPercentDecode(uriA, a);
                if (ca == (-1))
                {
                    ca = '%';
                }
                else
                {
                    a += 2;
                }
            }

            int ob = uriB.charAt(b++);
            int cb = ob;
            if (cb == '%')
            {
                cb = lenientPercentDecode(uriB, b);
                if (cb == (-1))
                {
                    cb = '%';
                }
                else
                {
                    b += 2;
                }
            }

            // Don't match on encoded slash
            if (ca == '/' && oa != ob)
                return false;

            if (ca != cb)
                return false;
        }
        return a == lenA && b == lenB;
    }

    private static int lenientPercentDecode(String str, int offset)
    {
        if (offset >= str.length())
            return -1;

        if (StringUtil.isHex(str, offset, 2))
        {
            return TypeUtil.parseInt(str, offset, 2, 16);
        }
        else
        {
            return -1;
        }
    }

    public static boolean equalsIgnoreEncodings(URI uriA, URI uriB)
    {
        if (uriA.equals(uriB))
            return true;

        if (uriA.getScheme() == null)
        {
            if (uriB.getScheme() != null)
                return false;
        }
        else if (!uriA.getScheme().equalsIgnoreCase(uriB.getScheme()))
            return false;

        if ("jar".equalsIgnoreCase(uriA.getScheme()))
        {
            // at this point we know that both uri's are "jar:"
            URI uriAssp = URI.create(uriA.getSchemeSpecificPart());
            URI uriBssp = URI.create(uriB.getSchemeSpecificPart());
            return equalsIgnoreEncodings(uriAssp, uriBssp);
        }

        if (uriA.getAuthority() == null)
        {
            if (uriB.getAuthority() != null)
                return false;
        }
        else if (!uriA.getAuthority().equals(uriB.getAuthority()))
            return false;

        return equalsIgnoreEncodings(uriA.getPath(), uriB.getPath());
    }

    
Params:
uri – A URI to add the path to
path – A decoded path element
Returns:
URI with path added./**
     * @param uri A URI to add the path to
     * @param path A decoded path element
     * @return URI with path added.
     */
    public static URI addPath(URI uri, String path)
    {
        String base = uri.toASCIIString();
        StringBuilder buf = new StringBuilder(base.length() + path.length() * 3);
        buf.append(base);
        if (buf.charAt(base.length() - 1) != '/')
            buf.append('/');

        int offset = path.charAt(0) == '/' ? 1 : 0;
        encodePath(buf, path, offset);

        return URI.create(buf.toString());
    }

    
Combine two query strings into one. Each query string should not contain the beginning '?' character, but may contain multiple parameters separated by the '&' character. 
Params:
query1 – the first query string.
query2 – the second query string.
Returns:
the combination of the two query strings./**
     * Combine two query strings into one. Each query string should not contain the beginning '?' character, but
     * may contain multiple parameters separated by the '{@literal &}' character.
     * @param query1 the first query string.
     * @param query2 the second query string.
     * @return the combination of the two query strings.
     */
    public static String addQueries(String query1, String query2)
    {
        if (StringUtil.isEmpty(query1))
            return query2;
        if (StringUtil.isEmpty(query2))
            return query1;
        return query1 + '&' + query2;
    }

    public static URI getJarSource(URI uri)
    {
        try
        {
            if (!"jar".equals(uri.getScheme()))
                return uri;
            // Get SSP (retaining encoded form)
            String s = uri.getRawSchemeSpecificPart();
            int bangSlash = s.indexOf("!/");
            if (bangSlash >= 0)
                s = s.substring(0, bangSlash);
            return new URI(s);
        }
        catch (URISyntaxException e)
        {
            throw new IllegalArgumentException(e);
        }
    }

    public static String getJarSource(String uri)
    {
        if (!uri.startsWith("jar:"))
            return uri;
        int bangSlash = uri.indexOf("!/");
        return (bangSlash >= 0) ? uri.substring(4, bangSlash) : uri.substring(4);
    }
}