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/*
 * Copyright (c) 1997-2020 Oracle and/or its affiliates. All rights reserved.
 * Copyright 2004 The Apache Software Foundation
 *
 * 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 jakarta.security.jacc;

/**
 *
 * @see
 *
 * @author Ron Monzillo
 *
 * @serial exclude
 */
class URLPattern extends Object implements Comparable {

    private static String DEFAULT_PATTERN = "/";

    /* changed to order default pattern / below extension */
    public static final int PT_DEFAULT = 0;
    public static final int PT_EXTENSION = 1;
    public static final int PT_PREFIX = 2;
    public static final int PT_EXACT = 3;

    private int patternType = -1;
    private final String pattern;

    public URLPattern() {
        this.pattern = DEFAULT_PATTERN;
        this.patternType = PT_DEFAULT;
    }

    // Note that the EMPTY_STRING is a legitimate URL_PATTERN
    public URLPattern(String pattern) {
        if (pattern == null) {
            this.pattern = DEFAULT_PATTERN;
            this.patternType = PT_DEFAULT;
        } else {
            this.pattern = pattern;
        }
    }

    public int patternType() {
        if (patternType < 0) {
            if (pattern.startsWith("*.")) {
                patternType = PT_EXTENSION;
            } else if (pattern.startsWith("/") && pattern.endsWith("/*")) {
                patternType = PT_PREFIX;
            } else if (DEFAULT_PATTERN.equals(pattern)) {
                patternType = PT_DEFAULT;
            } else {
                patternType = PT_EXACT;
            }
        }

        return patternType;
    }

    @Override
    public int compareTo(URLPattern that) {
        int refPatternType = this.patternType();

        /*
         * The comparison yields increasing sort order by pattern type. That is, prefix patterns sort before exact patterns.
         * Also shorter length patterns precede longer length patterns. This is important for the URLPatternList
         * canonicalization done by URLPatternSpec.setURLPatternArray
         */
        int result = refPatternType - that.patternType();

        if (result == 0) {

            if (refPatternType == PT_PREFIX || refPatternType == PT_EXACT) {

                result = this.getPatternDepth() - that.getPatternDepth();

                if (result == 0) {
                    result = this.pattern.compareTo(that.pattern);
                }

            } else {
                result = this.pattern.compareTo(that.pattern);
            }
        }

        return result > 0 ? 1 : (result < 0 ? -1 : 0);
    }

    /**
     * Does this pattern imply (that is, match) the argument pattern? This method follows the same rules (in the same order)
     * as those used for mapping requests to Jakarta Servlets.
     *
     * 
     * Two URL patterns match if they are related as follows:
     * 

     * 

     * their pattern values are String equivalent, or
     * 
this pattern is the path-prefix pattern "/*", or
     * 
this pattern is a path-prefix pattern (that is, it starts with "/" and ends with "/*") and the argument pattern
     * starts with the substring of this pattern, minus its last 2 characters, and the next character of the argument
     * pattern, if there is one, is "/", or
     * 
this pattern is an extension pattern (that is, it starts with "*.") and the argument pattern ends with this
     * pattern, or
     * 
the reference pattern is the special default pattern, "/", which matches all argument patterns.
     * 
     *
     * @param that URLPattern to determine if implied by (matched by) this URLPattern to
     */
    public boolean implies(URLPattern that) {

        // Normalize the argument
        if (that == null) {
            that = new URLPattern(null);
        }

        String thatPattern = that.pattern;
        String thisPattern = this.pattern;

        // Check for exact match
        if (thisPattern.equals(thatPattern)) {
            return true;
        }

        // Check for path prefix matching
        if (thisPattern.startsWith("/") && thisPattern.endsWith("/*")) {
            thisPattern = thisPattern.substring(0, thisPattern.length() - 2);

            int length = thisPattern.length();

            if (length == 0) {
                return true; // "/*" is the same as the DEFAULT_PATTERN
            }

            return thatPattern.startsWith(thisPattern) && (thatPattern.length() == length || thatPattern.substring(length).startsWith("/"));
        }

        // Check for suffix matching
        if (thisPattern.startsWith("*.")) {
            int slash = thatPattern.lastIndexOf('/');
            int period = thatPattern.lastIndexOf('.');
            if ((slash >= 0) && (period > slash) && thatPattern.endsWith(thisPattern.substring(1))) {
                return true;
            }

            return false;
        }

        // Check for universal mapping
        if (thisPattern.equals(DEFAULT_PATTERN)) {
            return true;
        }

        return false;
    }

    @Override
    public boolean equals(Object obj) {
        if (!(obj instanceof URLPattern)) {
            return false;
        }
        return this.pattern.equals(((URLPattern) obj).pattern);
    }

    @Override
    public String toString() {
        return pattern;
    }

    public int getPatternDepth() {
        int i = 0;
        int depth = 1;

        while (i >= 0) {

            i = pattern.indexOf("/", i);

            if (i >= 0) {

                if (i == 0 && depth != 1) {
                    throw new IllegalArgumentException("// in pattern");
                }

                i += 1;
            }
        }

        return depth;
    }
}