/*

 * Copyright (c) 2008, 2013, Oracle and/or its affiliates. All rights reserved.

 * 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.Path;

import java.io.File;

import java.net.URI;

import java.net.URISyntaxException;

import java.util.Arrays;

/**

 * Unix specific Path <--> URI conversion

 */

class UnixUriUtils {

    private UnixUriUtils() { }

    /**

     * Converts URI to Path

     */

    static Path fromUri(UnixFileSystem fs, URI uri) {

        if (!uri.isAbsolute())

            throw new IllegalArgumentException("URI is not absolute");

        if (uri.isOpaque())

            throw new IllegalArgumentException("URI is not hierarchical");

        String scheme = uri.getScheme();

        if ((scheme == null) || !scheme.equalsIgnoreCase("file"))

            throw new IllegalArgumentException("URI scheme is not \"file\"");

        if (uri.getAuthority() != null)

            throw new IllegalArgumentException("URI has an authority component");

        if (uri.getFragment() != null)

            throw new IllegalArgumentException("URI has a fragment component");

        if (uri.getQuery() != null)

            throw new IllegalArgumentException("URI has a query component");

        // compatibility with java.io.File

        if (!uri.toString().startsWith("file:///"))

            return new File(uri).toPath();

        // transformation use raw path

        String p = uri.getRawPath();

        int len = p.length();

        if (len == 0)

            throw new IllegalArgumentException("URI path component is empty");

        // transform escaped octets and unescaped characters to bytes

        if (p.endsWith("/") && len > 1)

            len--;

        byte[] result = new byte[len];

        int rlen = 0;

        int pos = 0;

        while (pos < len) {

            char c = p.charAt(pos++);

            byte b;

            if (c == '%') {

                assert (pos+2) <= len;

                char c1 = p.charAt(pos++);

                char c2 = p.charAt(pos++);

                b = (byte)((decode(c1) << 4) | decode(c2));

                if (b == 0)

                    throw new IllegalArgumentException("Nul character not allowed");

            } else {

                assert c < 0x80;

                b = (byte)c;

            }

            result[rlen++] = b;

        }

        if (rlen != result.length)

            result = Arrays.copyOf(result, rlen);

        return new UnixPath(fs, result);

    }

    /**

     * Converts Path to URI

     */

    static URI toUri(UnixPath up) {

        byte[] path = up.toAbsolutePath().asByteArray();

        StringBuilder sb = new StringBuilder("file:///");

        assert path[0] == '/';

        for (int i=1; i<path.length; i++) {

            char c = (char)(path[i] & 0xff);

            if (match(c, L_PATH, H_PATH)) {

                sb.append(c);

            } else {

               sb.append('%');

               sb.append(hexDigits[(c >> 4) & 0x0f]);

               sb.append(hexDigits[(c) & 0x0f]);

            }

        }

        // trailing slash if directory

        if (sb.charAt(sb.length()-1) != '/') {

            try {

                 if (UnixFileAttributes.get(up, true).isDirectory())

                     sb.append('/');

            } catch (UnixException x) {

                // ignore

            }

        }

        try {

            return new URI(sb.toString());

        } catch (URISyntaxException x) {

            throw new AssertionError(x);  // should not happen

        }

    }

    // The following is copied from java.net.URI

    // Compute the low-order mask for the characters in the given string

    private static long lowMask(String chars) {

        int n = chars.length();

        long m = 0;

        for (int i = 0; i < n; i++) {

            char c = chars.charAt(i);

            if (c < 64)

                m |= (1L << c);

        }

        return m;

    }

    // Compute the high-order mask for the characters in the given string

    private static long highMask(String chars) {

        int n = chars.length();

        long m = 0;

        for (int i = 0; i < n; i++) {

            char c = chars.charAt(i);

            if ((c >= 64) && (c < 128))

                m |= (1L << (c - 64));

        }

        return m;

    }

    // Compute a low-order mask for the characters

    // between first and last, inclusive

    private static long lowMask(char first, char last) {

        long m = 0;

        int f = Math.max(Math.min(first, 63), 0);

        int l = Math.max(Math.min(last, 63), 0);

        for (int i = f; i <= l; i++)

            m |= 1L << i;

        return m;

    }

    // Compute a high-order mask for the characters

    // between first and last, inclusive

    private static long highMask(char first, char last) {

        long m = 0;

        int f = Math.max(Math.min(first, 127), 64) - 64;

        int l = Math.max(Math.min(last, 127), 64) - 64;

        for (int i = f; i <= l; i++)

            m |= 1L << i;

        return m;

    }

    // Tell whether the given character is permitted by the given mask pair

    private static boolean match(char c, long lowMask, long highMask) {

        if (c < 64)

            return ((1L << c) & lowMask) != 0;

        if (c < 128)

            return ((1L << (c - 64)) & highMask) != 0;

        return false;

    }

    // decode

    private static int decode(char c) {

        if ((c >= '0') && (c <= '9'))

            return c - '0';

        if ((c >= 'a') && (c <= 'f'))

            return c - 'a' + 10;

        if ((c >= 'A') && (c <= 'F'))

            return c - 'A' + 10;

        throw new AssertionError();

    }

    // digit    = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" |

    //            "8" | "9"

    private static final long L_DIGIT = lowMask('0', '9');

    private static final long H_DIGIT = 0L;

    // upalpha  = "A" | "B" | "C" | "D" | "E" | "F" | "G" | "H" | "I" |

    //            "J" | "K" | "L" | "M" | "N" | "O" | "P" | "Q" | "R" |

    //            "S" | "T" | "U" | "V" | "W" | "X" | "Y" | "Z"

    private static final long L_UPALPHA = 0L;

    private static final long H_UPALPHA = highMask('A', 'Z');

    // lowalpha = "a" | "b" | "c" | "d" | "e" | "f" | "g" | "h" | "i" |

    //            "j" | "k" | "l" | "m" | "n" | "o" | "p" | "q" | "r" |

    //            "s" | "t" | "u" | "v" | "w" | "x" | "y" | "z"

    private static final long L_LOWALPHA = 0L;

    private static final long H_LOWALPHA = highMask('a', 'z');

    // alpha         = lowalpha | upalpha

    private static final long L_ALPHA = L_LOWALPHA | L_UPALPHA;

    private static final long H_ALPHA = H_LOWALPHA | H_UPALPHA;

    // alphanum      = alpha | digit

    private static final long L_ALPHANUM = L_DIGIT | L_ALPHA;

    private static final long H_ALPHANUM = H_DIGIT | H_ALPHA;

    // mark          = "-" | "_" | "." | "!" | "~" | "*" | "'" |

    //                 "(" | ")"

    private static final long L_MARK = lowMask("-_.!~*'()");

    private static final long H_MARK = highMask("-_.!~*'()");

    // unreserved    = alphanum | mark

    private static final long L_UNRESERVED = L_ALPHANUM | L_MARK;

    private static final long H_UNRESERVED = H_ALPHANUM | H_MARK;

    // pchar         = unreserved | escaped |

    //                 ":" | "@" | "&" | "=" | "+" | "$" | ","

    private static final long L_PCHAR

        = L_UNRESERVED | lowMask(":@&=+$,");

    private static final long H_PCHAR

        = H_UNRESERVED | highMask(":@&=+$,");

   // All valid path characters

   private static final long L_PATH = L_PCHAR | lowMask(";/");

   private static final long H_PATH = H_PCHAR | highMask(";/");

        '0', '1', '2', '3', '4', '5', '6', '7',

        '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'

    };

}