/*
 *  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 org.apache.catalina.util;

/**
 * Utility class for working with URIs and URLs.
 */
public final class UriUtil {

    private UriUtil() {
        // Utility class. Hide default constructor
    }


    /**
     * Determine if the character is allowed in the scheme of a URI.
     * See RFC 2396, Section 3.1
     *
     * @param c The character to test
     *
     * @return {@code true} if a the character is allowed, otherwise {code
     *         @false}
     */
    private static boolean isSchemeChar(char c) {
        return Character.isLetterOrDigit(c) || c == '+' || c == '-' || c == '.';
    }


    /**
     * Determine if a URI string has a <code>scheme</code> component.
     *
     * @param uri The URI to test
     *
     * @return {@code true} if a scheme is present, otherwise {code @false}
     */
    public static boolean hasScheme(CharSequence uri) {
        int len = uri.length();
        for(int i=0; i < len ; i++) {
            char c = uri.charAt(i);
            if(c == ':') {
                return i > 0;
            } else if(!UriUtil.isSchemeChar(c)) {
                return false;
            }
        }
        return false;
    }
}
