/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package sun.nio.fs;

import java.nio.file.InvalidPathException;

/**

 * A parser of Windows path strings

 */

class WindowsPathParser {

    private WindowsPathParser() { }

    /**

     * The result of a parse operation

     */

    static class Result {

        private final WindowsPathType type;

        private final String root;

        private final String path;

        Result(WindowsPathType type, String root, String path) {

            this.type = type;

            this.root = root;

            this.path = path;

        }

        /**

         * The path type

         */

        WindowsPathType type() {

            return type;

        }

        /**

         * The root component

         */

        String root() {

            return root;

        }

        /**

         * The normalized path (includes root)

         */

        String path() {

            return path;

        }

    }

    /**

     * Parses the given input as a Windows path

     */

    static Result parse(String input) {

        return parse(input, true);

    }

    /**

     * Parses the given input as a Windows path where it is known that the

     * path is already normalized.

     */

    static Result parseNormalizedPath(String input) {

        return parse(input, false);

    }

    /**

     * Parses the given input as a Windows path.

     *

     * @param   requireToNormalize

     *          Indicates if the path requires to be normalized

     */

    private static Result parse(String input, boolean requireToNormalize) {

        String root = "";

        WindowsPathType type = null;

        int len = input.length();

        int off = 0;

        if (len > 1) {

            char c0 = input.charAt(0);

            char c1 = input.charAt(1);

            char c = 0;

            int next = 2;

            if (isSlash(c0) && isSlash(c1)) {

                // UNC: We keep the first two slash, collapse all the

                // following, then take the hostname and share name out,

                // meanwhile collapsing all the redundant slashes.

                type = WindowsPathType.UNC;

                off = nextNonSlash(input, next, len);

                next = nextSlash(input, off, len);

                if (off == next)

                    throw new InvalidPathException(input, "UNC path is missing hostname");

                String host = input.substring(off, next);  //host

                off = nextNonSlash(input, next, len);

                next = nextSlash(input, off, len);

                if (off == next)

                    throw new InvalidPathException(input, "UNC path is missing sharename");

                root = "\\\\" + host + "\\" + input.substring(off, next) + "\\";

                off = next;

            } else {

                if (isLetter(c0) && c1 == ':') {

                    root = input.substring(0, 2);

                    if (len > 2 && isSlash(input.charAt(2))) {

                        off = 3;

                        root += "\\";

                        type = WindowsPathType.ABSOLUTE;

                    } else {

                        off = 2;

                        type = WindowsPathType.DRIVE_RELATIVE;

                    }

                }

            }

        }

        if (off == 0) {

            if (len > 0 && isSlash(input.charAt(0))) {

                type = WindowsPathType.DIRECTORY_RELATIVE;

                root = "\\";

            } else {

                type = WindowsPathType.RELATIVE;

            }

        }

        if (requireToNormalize) {

            StringBuilder sb = new StringBuilder(input.length());

            sb.append(root);

            return new Result(type, root, normalize(sb, input, off));

        } else {

            return new Result(type, root, input);

        }

    }

    /**

     * Remove redundant slashes from the rest of the path, forcing all slashes

     * into the preferred slash.

    */

    private static String normalize(StringBuilder sb, String path, int off) {

        int len = path.length();

        off = nextNonSlash(path, off, len);

        int start = off;

        char lastC = 0;

        while (off < len) {

            char c = path.charAt(off);

            if (isSlash(c)) {

                if (lastC == ' ')

                    throw new InvalidPathException(path,

                                                   "Trailing char <" + lastC + ">",

                                                   off - 1);

                sb.append(path, start, off);

                off = nextNonSlash(path, off, len);

                if (off != len)   //no slash at the end of normalized path

                    sb.append('\\');

                start = off;

            } else {

                if (isInvalidPathChar(c))

                    throw new InvalidPathException(path,

                                                   "Illegal char <" + c + ">",

                                                   off);

                lastC = c;

                off++;

            }

        }

        if (start != off) {

            if (lastC == ' ')

                throw new InvalidPathException(path,

                                               "Trailing char <" + lastC + ">",

                                               off - 1);

            sb.append(path, start, off);

        }

        return sb.toString();

    }

    private static final boolean isSlash(char c) {

        return (c == '\\') || (c == '/');

    }

    private static final int nextNonSlash(String path, int off, int end) {

        while (off < end && isSlash(path.charAt(off))) { off++; }

        return off;

    }

    private static final int nextSlash(String path, int off, int end) {

        char c;

        while (off < end && !isSlash(c=path.charAt(off))) {

            if (isInvalidPathChar(c))

                throw new InvalidPathException(path,

                                               "Illegal character [" + c + "] in path",

                                               off);

            off++;

        }

        return off;

    }

    private static final boolean isLetter(char c) {

        return ((c >= 'a') && (c <= 'z')) || ((c >= 'A') && (c <= 'Z'));

    }

    // Reserved characters for window path name

    private static final String reservedChars = "<>:\"|?*";

    private static final boolean isInvalidPathChar(char ch) {

        return ch < '\u0020' || reservedChars.indexOf(ch) != -1;

    }

}