/*
 * Copyright 2015 Red Hat, Inc. and/or its affiliates.
 *
 * 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 org.uberfire.commons.regex.util;

import java.util.ArrayList;
import java.util.List;
import java.util.StringTokenizer;

/**
 * PathMatcher implementation for Ant-style path patterns.
 * <p>
 * This code has been borrowed from <a href="http://camel.apache.org">Apache Camel</a>.
 * <p>
 */
public class AntPathMatcher {

    /**
     * Default path separator: "/"
     */
    public static final String DEFAULT_PATH_SEPARATOR = "/";

    private String pathSeparator = DEFAULT_PATH_SEPARATOR;

    /**
     * Tokenize the given String into a String array via a StringTokenizer.
     * Trims tokens and omits empty tokens.
     * <p>
     * The given delimiters string is supposed to consist of any number of
     * delimiter characters. Each of those characters can be used to separate
     * tokens. A delimiter is always a single character; for multi-character
     * delimiters, consider using <code>delimitedListToStringArray</code>
     * @param str the String to tokenize
     * @param delimiters the delimiter characters, assembled as String (each of
     * those characters is individually considered as delimiter).
     * @return an array of the tokens
     * @see java.util.StringTokenizer
     * @see java.lang.String#trim()
     */
    public static String[] tokenizeToStringArray(String str,
                                                 String delimiters) {
        if (str == null) {
            return new String[]{};
        }
        final StringTokenizer st = new StringTokenizer(str,
                                                       delimiters);
        final List<String> tokens = new ArrayList<String>();
        while (st.hasMoreTokens()) {
            final String token = st.nextToken().trim();
            if (token.length() > 0) {
                tokens.add(token);
            }
        }
        return tokens.toArray(new String[tokens.size()]);
    }

    /**
     * Set the path separator to use for pattern parsing. Default is "/", as in
     * Ant.
     */
    public void setPathSeparator(final String pathSeparator) {
        this.pathSeparator = pathSeparator != null ? pathSeparator : DEFAULT_PATH_SEPARATOR;
    }

    public boolean isPattern(final String path) {
        return path.indexOf('*') != -1 || path.indexOf('?') != -1;
    }

    public boolean match(final String pattern,
                         final String path) {
        return doMatch(pattern,
                       path,
                       true);
    }

    public boolean matchStart(final String pattern,
                              final String path) {
        return doMatch(pattern,
                       path,
                       false);
    }

    /**
     * Actually match the given <code>path</code> against the given
     * <code>pattern</code>.
     * @param pattern the pattern to match against
     * @param path the path String to test
     * @param fullMatch whether a full pattern match is required (else a pattern
     * match as far as the given base path goes is sufficient)
     * @return <code>true</code> if the supplied <code>path</code> matched,
     * <code>false</code> if it didn't
     */
    protected boolean doMatch(String pattern,
                              String path,
                              boolean fullMatch) {
        if (path.startsWith(this.pathSeparator) != pattern.startsWith(this.pathSeparator)) {
            return false;
        }

        String[] pattDirs = tokenizeToStringArray(pattern,
                                                  this.pathSeparator);
        String[] pathDirs = tokenizeToStringArray(path,
                                                  this.pathSeparator);

        int pattIdxStart = 0;
        int pattIdxEnd = pattDirs.length - 1;
        int pathIdxStart = 0;
        int pathIdxEnd = pathDirs.length - 1;

        // Match all elements up to the first **
        while (pattIdxStart <= pattIdxEnd && pathIdxStart <= pathIdxEnd) {
            String patDir = pattDirs[pattIdxStart];
            if ("**".equals(patDir)) {
                break;
            }
            if (!matchStrings(patDir,
                              pathDirs[pathIdxStart])) {
                return false;
            }
            pattIdxStart++;
            pathIdxStart++;
        }

        if (pathIdxStart > pathIdxEnd) {
            // Path is exhausted, only match if rest of pattern is * or **'s
            if (pattIdxStart > pattIdxEnd) {
                return pattern.endsWith(this.pathSeparator) ? path.endsWith(this.pathSeparator) : !path
                        .endsWith(this.pathSeparator);
            }
            if (!fullMatch) {
                return true;
            }
            if (pattIdxStart == pattIdxEnd && "*".equals(pattDirs[pattIdxStart])
                    && path.endsWith(this.pathSeparator)) {
                return true;
            }
            for (int i = pattIdxStart; i <= pattIdxEnd; i++) {
                if (!"**".equals(pattDirs[i])) {
                    return false;
                }
            }
            return true;
        } else if (pattIdxStart > pattIdxEnd) {
            // String not exhausted, but pattern is. Failure.
            return false;
        } else if (!fullMatch && "**".equals(pattDirs[pattIdxStart])) {
            // Path start definitely matches due to "**" part in pattern.
            return true;
        }

        // up to last '**'
        while (pattIdxStart <= pattIdxEnd && pathIdxStart <= pathIdxEnd) {
            String patDir = pattDirs[pattIdxEnd];
            if ("**".equals(patDir)) {
                break;
            }
            if (!matchStrings(patDir,
                              pathDirs[pathIdxEnd])) {
                return false;
            }
            pattIdxEnd--;
            pathIdxEnd--;
        }
        if (pathIdxStart > pathIdxEnd) {
            // String is exhausted
            for (int i = pattIdxStart; i <= pattIdxEnd; i++) {
                if (!"**".equals(pattDirs[i])) {
                    return false;
                }
            }
            return true;
        }

        while (pattIdxStart != pattIdxEnd && pathIdxStart <= pathIdxEnd) {
            int patIdxTmp = -1;
            for (int i = pattIdxStart + 1; i <= pattIdxEnd; i++) {
                if ("**".equals(pattDirs[i])) {
                    patIdxTmp = i;
                    break;
                }
            }
            if (patIdxTmp == pattIdxStart + 1) {
                // '**/**' situation, so skip one
                pattIdxStart++;
                continue;
            }
            // Find the pattern between padIdxStart & padIdxTmp in str between
            // strIdxStart & strIdxEnd
            int patLength = patIdxTmp - pattIdxStart - 1;
            int strLength = pathIdxEnd - pathIdxStart + 1;
            int foundIdx = -1;

            strLoop:
            for (int i = 0; i <= strLength - patLength; i++) {
                for (int j = 0; j < patLength; j++) {
                    String subPat = pattDirs[pattIdxStart + j + 1];
                    String subStr = pathDirs[pathIdxStart + i + j];
                    if (!matchStrings(subPat,
                                      subStr)) {
                        continue strLoop;
                    }
                }
                foundIdx = pathIdxStart + i;
                break;
            }

            if (foundIdx == -1) {
                return false;
            }

            pattIdxStart = patIdxTmp;
            pathIdxStart = foundIdx + patLength;
        }

        for (int i = pattIdxStart; i <= pattIdxEnd; i++) {
            if (!"**".equals(pattDirs[i])) {
                return false;
            }
        }

        return true;
    }

    /**
     * Tests whether or not a string matches against a pattern. The pattern may
     * contain two special characters:<br>
     * '*' means zero or more characters<br>
     * '?' means one and only one character
     * @param pattern pattern to match against. Must not be <code>null</code>.
     * @param str string which must be matched against the pattern. Must not be
     * <code>null</code>.
     * @return <code>true</code> if the string matches against the pattern, or
     * <code>false</code> otherwise.
     */
    private boolean matchStrings(String pattern,
                                 String str) {
        char[] patArr = pattern.toCharArray();
        char[] strArr = str.toCharArray();
        int patIdxStart = 0;
        int patIdxEnd = patArr.length - 1;
        int strIdxStart = 0;
        int strIdxEnd = strArr.length - 1;
        char ch;

        boolean containsStar = false;
        for (char c : patArr) {
            if (c == '*') {
                containsStar = true;
                break;
            }
        }

        if (!containsStar) {
            // No '*'s, so we make a shortcut
            if (patIdxEnd != strIdxEnd) {
                return false; // Pattern and string do not have the same size
            }
            for (int i = 0; i <= patIdxEnd; i++) {
                ch = patArr[i];
                if (ch != '?') {
                    if (ch != strArr[i]) {
                        return false;
                        // Character mismatch
                    }
                }
            }
            return true; // String matches against pattern
        }

        if (patIdxEnd == 0) {
            return true; // Pattern contains only '*', which matches anything
        }

        // Process characters before first star
        while ((ch = patArr[patIdxStart]) != '*' && strIdxStart <= strIdxEnd) {
            if (ch != '?') {
                if (ch != strArr[strIdxStart]) {
                    return false;
                    // Character mismatch
                }
            }
            patIdxStart++;
            strIdxStart++;
        }
        if (strIdxStart > strIdxEnd) {
            // All characters in the string are used. Check if only '*'s are
            // left in the pattern. If so, we succeeded. Otherwise failure.
            for (int i = patIdxStart; i <= patIdxEnd; i++) {
                if (patArr[i] != '*') {
                    return false;
                }
            }
            return true;
        }

        // Process characters after last star
        while ((ch = patArr[patIdxEnd]) != '*' && strIdxStart <= strIdxEnd) {
            if (ch != '?') {
                if (ch != strArr[strIdxEnd]) {
                    return false;
                    // Character mismatch
                }
            }
            patIdxEnd--;
            strIdxEnd--;
        }
        if (strIdxStart > strIdxEnd) {
            // All characters in the string are used. Check if only '*'s are
            // left in the pattern. If so, we succeeded. Otherwise failure.
            for (int i = patIdxStart; i <= patIdxEnd; i++) {
                if (patArr[i] != '*') {
                    return false;
                }
            }
            return true;
        }

        // process pattern between stars. padIdxStart and patIdxEnd point
        // always to a '*'.
        while (patIdxStart != patIdxEnd && strIdxStart <= strIdxEnd) {
            int patIdxTmp = -1;
            for (int i = patIdxStart + 1; i <= patIdxEnd; i++) {
                if (patArr[i] == '*') {
                    patIdxTmp = i;
                    break;
                }
            }
            if (patIdxTmp == patIdxStart + 1) {
                // Two stars next to each other, skip the first one.
                patIdxStart++;
                continue;
            }
            // Find the pattern between padIdxStart & padIdxTmp in str between
            // strIdxStart & strIdxEnd
            int patLength = patIdxTmp - patIdxStart - 1;
            int strLength = strIdxEnd - strIdxStart + 1;
            int foundIdx = -1;
            strLoop:
            for (int i = 0; i <= strLength - patLength; i++) {
                for (int j = 0; j < patLength; j++) {
                    ch = patArr[patIdxStart + j + 1];
                    if (ch != '?') {
                        if (ch != strArr[strIdxStart + i + j]) {
                            continue strLoop;
                        }
                    }
                }

                foundIdx = strIdxStart + i;
                break;
            }

            if (foundIdx == -1) {
                return false;
            }

            patIdxStart = patIdxTmp;
            strIdxStart = foundIdx + patLength;
        }

        // All characters in the string are used. Check if only '*'s are left
        // in the pattern. If so, we succeeded. Otherwise failure.
        for (int i = patIdxStart; i <= patIdxEnd; i++) {
            if (patArr[i] != '*') {
                return false;
            }
        }

        return true;
    }

    /**
     * Given a pattern and a full path, determine the pattern-mapped part.
     * <p>
     * For example:
     * <ul>
     * <li>'<code>/docs/cvs/commit.html</code>' and '
     * <code>/docs/cvs/commit.html</code> -> ''</li>
     * <li>'<code>/docs/*</code>' and '<code>/docs/cvs/commit</code> -> '
     * <code>cvs/commit</code>'</li>
     * <li>'<code>/docs/cvs/*.html</code>' and '
     * <code>/docs/cvs/commit.html</code> -> '<code>commit.html</code>'</li>
     * <li>'<code>/docs/**</code>' and '<code>/docs/cvs/commit</code> -> '
     * <code>cvs/commit</code>'</li>
     * <li>'<code>/docs/**\/*.html</code>' and '
     * <code>/docs/cvs/commit.html</code> -> '<code>cvs/commit.html</code>'</li>
     * <li>'<code>/*.html</code>' and '<code>/docs/cvs/commit.html</code> -> '
     * <code>docs/cvs/commit.html</code>'</li>
     * <li>'<code>*.html</code>' and '<code>/docs/cvs/commit.html</code> -> '
     * <code>/docs/cvs/commit.html</code>'</li>
     * <li>'<code>*</code>' and '<code>/docs/cvs/commit.html</code> -> '
     * <code>/docs/cvs/commit.html</code>'</li>
     * </ul>
     * <p>
     * Assumes that {@link #match} returns <code>true</code> for '
     * <code>pattern</code>' and '<code>path</code>', but does
     * <strong>not</strong> enforce this.
     */
    public String extractPathWithinPattern(String pattern,
                                           String path) {
        final String[] patternParts = tokenizeToStringArray(pattern,
                                                            this.pathSeparator);
        final String[] pathParts = tokenizeToStringArray(path,
                                                         this.pathSeparator);

        final StringBuilder buffer = new StringBuilder();

        // Add any path parts that have a wildcarded pattern part.
        int puts = 0;
        for (int i = 0; i < patternParts.length; i++) {
            final String patternPart = patternParts[i];
            if ((patternPart.indexOf('*') > -1 || patternPart.indexOf('?') > -1) && pathParts.length >= i + 1) {
                if (puts > 0 || (i == 0 && !pattern.startsWith(this.pathSeparator))) {
                    buffer.append(this.pathSeparator);
                }
                buffer.append(pathParts[i]);
                puts++;
            }
        }

        // Append any trailing path parts.
        for (int i = patternParts.length; i < pathParts.length; i++) {
            if (puts > 0 || i > 0) {
                buffer.append(this.pathSeparator);
            }
            buffer.append(pathParts[i]);
        }

        return buffer.toString();
    }
}