// ZipConstants.cs
//
// Copyright (C) 2001 Mike Krueger
// Copyright (C) 2004 John Reilly
//
// This file was translated from java, it was part of the GNU Classpath
// Copyright (C) 2001 Free Software Foundation, Inc.
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program 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 for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
//
// Linking this library statically or dynamically with other modules is
// making a combined work based on this library.  Thus, the terms and
// conditions of the GNU General Public License cover the whole
// combination.
// 
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent
// modules, and to copy and distribute the resulting executable under
// terms of your choice, provided that you also meet, for each linked
// independent module, the terms and conditions of the license of that
// module.  An independent module is a module which is not derived from
// or based on this library.  If you modify this library, you may extend
// this exception to your version of the library, but you are not
// obligated to do so.  If you do not wish to do so, delete this
// exception statement from your version.

// HISTORY
//	22-12-2009	DavidPierson	Added AES support

using System;
using System.Globalization;
using System.Text;
using System.Threading;

#if NETCF_1_0 || NETCF_2_0
using System.Globalization;
#endif

namespace PdfSharp.SharpZipLib.Zip
{

    #region Enumerations

    /// <summary>
    /// Determines how entries are tested to see if they should use Zip64 extensions or not.
    /// </summary>
    public enum UseZip64
    {
        /// <summary>
        /// Zip64 will not be forced on entries during processing.
        /// </summary>
        /// <remarks>An entry can have this overridden if required ZipEntry.ForceZip64"</remarks>
        Off,
        /// <summary>
        /// Zip64 should always be used.
        /// </summary>
        On,
        /// <summary>
        /// #ZipLib will determine use based on entry values when added to archive.
        /// </summary>
        Dynamic,
    }

    /// <summary>
    /// The kind of compression used for an entry in an archive
    /// </summary>
    public enum CompressionMethod
    {
        /// <summary>
        /// A direct copy of the file contents is held in the archive
        /// </summary>
        Stored = 0,

        /// <summary>
        /// Common Zip compression method using a sliding dictionary 
        /// of up to 32KB and secondary compression from Huffman/Shannon-Fano trees
        /// </summary>
        Deflated = 8,

        /// <summary>
        /// An extension to deflate with a 64KB window. Not supported by #Zip currently
        /// </summary>
        Deflate64 = 9,

        /// <summary>
        /// BZip2 compression. Not supported by #Zip.
        /// </summary>
        BZip2 = 11,

        /// <summary>
        /// WinZip special for AES encryption, Now supported by #Zip.
        /// </summary>
        WinZipAES = 99,

    }

    /// <summary>
    /// Identifies the encryption algorithm used for an entry
    /// </summary>
    public enum EncryptionAlgorithm
    {
        /// <summary>
        /// No encryption has been used.
        /// </summary>
        None = 0,
        /// <summary>
        /// Encrypted using PKZIP 2.0 or 'classic' encryption.
        /// </summary>
        PkzipClassic = 1,
        /// <summary>
        /// DES encryption has been used.
        /// </summary>
        Des = 0x6601,
        /// <summary>
        /// RC2 encryption has been used for encryption.
        /// </summary>
        RC2 = 0x6602,
        /// <summary>
        /// Triple DES encryption with 168 bit keys has been used for this entry.
        /// </summary>
        TripleDes168 = 0x6603,
        /// <summary>
        /// Triple DES with 112 bit keys has been used for this entry.
        /// </summary>
        TripleDes112 = 0x6609,
        /// <summary>
        /// AES 128 has been used for encryption.
        /// </summary>
        Aes128 = 0x660e,
        /// <summary>
        /// AES 192 has been used for encryption.
        /// </summary>
        Aes192 = 0x660f,
        /// <summary>
        /// AES 256 has been used for encryption.
        /// </summary>
        Aes256 = 0x6610,
        /// <summary>
        /// RC2 corrected has been used for encryption.
        /// </summary>
        RC2Corrected = 0x6702,
        /// <summary>
        /// Blowfish has been used for encryption.
        /// </summary>
        Blowfish = 0x6720,
        /// <summary>
        /// Twofish has been used for encryption.
        /// </summary>
        Twofish = 0x6721,
        /// <summary>
        /// RC4 has been used for encryption.
        /// </summary>
        RC4 = 0x6801,
        /// <summary>
        /// An unknown algorithm has been used for encryption.
        /// </summary>
        Unknown = 0xffff
    }

    /// <summary>
    /// Defines the contents of the general bit flags field for an archive entry.
    /// </summary>
    [Flags]
    public enum GeneralBitFlags : int
    {
        /// <summary>
        /// Bit 0 if set indicates that the file is encrypted
        /// </summary>
        Encrypted = 0x0001,
        /// <summary>
        /// Bits 1 and 2 - Two bits defining the compression method (only for Method 6 Imploding and 8,9 Deflating)
        /// </summary>
        Method = 0x0006,
        /// <summary>
        /// Bit 3 if set indicates a trailing data desciptor is appended to the entry data
        /// </summary>
        Descriptor = 0x0008,
        /// <summary>
        /// Bit 4 is reserved for use with method 8 for enhanced deflation
        /// </summary>
        ReservedPKware4 = 0x0010,
        /// <summary>
        /// Bit 5 if set indicates the file contains Pkzip compressed patched data.
        /// Requires version 2.7 or greater.
        /// </summary>
        Patched = 0x0020,
        /// <summary>
        /// Bit 6 if set indicates strong encryption has been used for this entry.
        /// </summary>
        StrongEncryption = 0x0040,
        /// <summary>
        /// Bit 7 is currently unused
        /// </summary>
        Unused7 = 0x0080,
        /// <summary>
        /// Bit 8 is currently unused
        /// </summary>
        Unused8 = 0x0100,
        /// <summary>
        /// Bit 9 is currently unused
        /// </summary>
        Unused9 = 0x0200,
        /// <summary>
        /// Bit 10 is currently unused
        /// </summary>
        Unused10 = 0x0400,
        /// <summary>
        /// Bit 11 if set indicates the filename and 
        /// comment fields for this file must be encoded using UTF-8.
        /// </summary>
        UnicodeText = 0x0800,
        /// <summary>
        /// Bit 12 is documented as being reserved by PKware for enhanced compression.
        /// </summary>
        EnhancedCompress = 0x1000,
        /// <summary>
        /// Bit 13 if set indicates that values in the local header are masked to hide
        /// their actual values, and the central directory is encrypted.
        /// </summary>
        /// <remarks>
        /// Used when encrypting the central directory contents.
        /// </remarks>
        HeaderMasked = 0x2000,
        /// <summary>
        /// Bit 14 is documented as being reserved for use by PKware
        /// </summary>
        ReservedPkware14 = 0x4000,
        /// <summary>
        /// Bit 15 is documented as being reserved for use by PKware
        /// </summary>
        ReservedPkware15 = 0x8000
    }

    #endregion

    /// <summary>
    /// This class contains constants used for Zip format files
    /// </summary>
    internal sealed class ZipConstants
    {
        #region Versions
        /// <summary>
        /// The version made by field for entries in the central header when created by this library
        /// </summary>
        /// <remarks>
        /// This is also the Zip version for the library when comparing against the version required to extract
        /// for an entry.  See ZipEntry.CanDecompress.
        /// </remarks>
        public const int VersionMadeBy = 51; // was 45 before AES

        /// <summary>
        /// The version made by field for entries in the central header when created by this library
        /// </summary>
        /// <remarks>
        /// This is also the Zip version for the library when comparing against the version required to extract
        /// for an entry.  See ZipInputStream.CanDecompressEntry.
        /// </remarks>
        [Obsolete("Use VersionMadeBy instead")]
        public const int VERSION_MADE_BY = 51;

        /// <summary>
        /// The minimum version required to support strong encryption
        /// </summary>
        public const int VersionStrongEncryption = 50;

        /// <summary>
        /// The minimum version required to support strong encryption
        /// </summary>
        [Obsolete("Use VersionStrongEncryption instead")]
        public const int VERSION_STRONG_ENCRYPTION = 50;

        /// <summary>
        /// Version indicating AES encryption
        /// </summary>
        public const int VERSION_AES = 51;

        /// <summary>
        /// The version required for Zip64 extensions (4.5 or higher)
        /// </summary>
        public const int VersionZip64 = 45;
        #endregion

        #region Header Sizes
        /// <summary>
        /// Size of local entry header (excluding variable length fields at end)
        /// </summary>
        public const int LocalHeaderBaseSize = 30;

        /// <summary>
        /// Size of local entry header (excluding variable length fields at end)
        /// </summary>
        [Obsolete("Use LocalHeaderBaseSize instead")]
        public const int LOCHDR = 30;

        /// <summary>
        /// Size of Zip64 data descriptor
        /// </summary>
        public const int Zip64DataDescriptorSize = 24;

        /// <summary>
        /// Size of data descriptor
        /// </summary>
        public const int DataDescriptorSize = 16;

        /// <summary>
        /// Size of data descriptor
        /// </summary>
        [Obsolete("Use DataDescriptorSize instead")]
        public const int EXTHDR = 16;

        /// <summary>
        /// Size of central header entry (excluding variable fields)
        /// </summary>
        public const int CentralHeaderBaseSize = 46;

        /// <summary>
        /// Size of central header entry
        /// </summary>
        [Obsolete("Use CentralHeaderBaseSize instead")]
        public const int CENHDR = 46;

        /// <summary>
        /// Size of end of central record (excluding variable fields)
        /// </summary>
        public const int EndOfCentralRecordBaseSize = 22;

        /// <summary>
        /// Size of end of central record (excluding variable fields)
        /// </summary>
        [Obsolete("Use EndOfCentralRecordBaseSize instead")]
        public const int ENDHDR = 22;

        /// <summary>
        /// Size of 'classic' cryptographic header stored before any entry data
        /// </summary>
        public const int CryptoHeaderSize = 12;

        /// <summary>
        /// Size of cryptographic header stored before entry data
        /// </summary>
        [Obsolete("Use CryptoHeaderSize instead")]
        public const int CRYPTO_HEADER_SIZE = 12;
        #endregion

        #region Header Signatures

        /// <summary>
        /// Signature for local entry header
        /// </summary>
        public const int LocalHeaderSignature = 'P' | ('K' << 8) | (3 << 16) | (4 << 24);

        /// <summary>
        /// Signature for local entry header
        /// </summary>
        [Obsolete("Use LocalHeaderSignature instead")]
        public const int LOCSIG = 'P' | ('K' << 8) | (3 << 16) | (4 << 24);

        /// <summary>
        /// Signature for spanning entry
        /// </summary>
        public const int SpanningSignature = 'P' | ('K' << 8) | (7 << 16) | (8 << 24);

        /// <summary>
        /// Signature for spanning entry
        /// </summary>
        [Obsolete("Use SpanningSignature instead")]
        public const int SPANNINGSIG = 'P' | ('K' << 8) | (7 << 16) | (8 << 24);

        /// <summary>
        /// Signature for temporary spanning entry
        /// </summary>
        public const int SpanningTempSignature = 'P' | ('K' << 8) | ('0' << 16) | ('0' << 24);

        /// <summary>
        /// Signature for temporary spanning entry
        /// </summary>
        [Obsolete("Use SpanningTempSignature instead")]
        public const int SPANTEMPSIG = 'P' | ('K' << 8) | ('0' << 16) | ('0' << 24);

        /// <summary>
        /// Signature for data descriptor
        /// </summary>
        /// <remarks>
        /// This is only used where the length, Crc, or compressed size isnt known when the
        /// entry is created and the output stream doesnt support seeking.
        /// The local entry cannot be 'patched' with the correct values in this case
        /// so the values are recorded after the data prefixed by this header, as well as in the central directory.
        /// </remarks>
        public const int DataDescriptorSignature = 'P' | ('K' << 8) | (7 << 16) | (8 << 24);

        /// <summary>
        /// Signature for data descriptor
        /// </summary>
        /// <remarks>
        /// This is only used where the length, Crc, or compressed size isnt known when the
        /// entry is created and the output stream doesnt support seeking.
        /// The local entry cannot be 'patched' with the correct values in this case
        /// so the values are recorded after the data prefixed by this header, as well as in the central directory.
        /// </remarks>
        [Obsolete("Use DataDescriptorSignature instead")]
        public const int EXTSIG = 'P' | ('K' << 8) | (7 << 16) | (8 << 24);

        /// <summary>
        /// Signature for central header
        /// </summary>
        [Obsolete("Use CentralHeaderSignature instead")]
        public const int CENSIG = 'P' | ('K' << 8) | (1 << 16) | (2 << 24);

        /// <summary>
        /// Signature for central header
        /// </summary>
        public const int CentralHeaderSignature = 'P' | ('K' << 8) | (1 << 16) | (2 << 24);

        /// <summary>
        /// Signature for Zip64 central file header
        /// </summary>
        public const int Zip64CentralFileHeaderSignature = 'P' | ('K' << 8) | (6 << 16) | (6 << 24);

        /// <summary>
        /// Signature for Zip64 central file header
        /// </summary>
        [Obsolete("Use Zip64CentralFileHeaderSignature instead")]
        public const int CENSIG64 = 'P' | ('K' << 8) | (6 << 16) | (6 << 24);

        /// <summary>
        /// Signature for Zip64 central directory locator
        /// </summary>
        public const int Zip64CentralDirLocatorSignature = 'P' | ('K' << 8) | (6 << 16) | (7 << 24);

        /// <summary>
        /// Signature for archive extra data signature (were headers are encrypted).
        /// </summary>
        public const int ArchiveExtraDataSignature = 'P' | ('K' << 8) | (6 << 16) | (7 << 24);

        /// <summary>
        /// Central header digitial signature
        /// </summary>
        public const int CentralHeaderDigitalSignature = 'P' | ('K' << 8) | (5 << 16) | (5 << 24);

        /// <summary>
        /// Central header digitial signature
        /// </summary>
        [Obsolete("Use CentralHeaderDigitalSignaure instead")]
        public const int CENDIGITALSIG = 'P' | ('K' << 8) | (5 << 16) | (5 << 24);

        /// <summary>
        /// End of central directory record signature
        /// </summary>
        public const int EndOfCentralDirectorySignature = 'P' | ('K' << 8) | (5 << 16) | (6 << 24);

        /// <summary>
        /// End of central directory record signature
        /// </summary>
        [Obsolete("Use EndOfCentralDirectorySignature instead")]
        public const int ENDSIG = 'P' | ('K' << 8) | (5 << 16) | (6 << 24);
        #endregion

#if true//NETCF_1_0 || NETCF_2_0
        // This isn't so great but is better than nothing.
        // Trying to work out an appropriate OEM code page would be good.
        // 850 is a good default for English speakers particularly in Europe.
#if SILVERLIGHT || NETFX_CORE || UWP
        // TODO Do we need this for PDFsharp? If so, make it work.
        static int defaultCodePage = 65001;
#else
        static int defaultCodePage = CultureInfo.CurrentCulture.TextInfo.ANSICodePage;
#endif
#else
	    /// <remarks>
	    /// Get OEM codepage from NetFX, which parses the NLP file with culture info table etc etc.
	    /// But sometimes it yields the special value of 1 which is nicknamed <c>CodePageNoOEM</c> in <see cref="Encoding"/> sources (might also mean <c>CP_OEMCP</c>, but Encoding puts it so).
	    /// This was observed on Ukranian and Hindu systems.
	    /// Given this value, <see cref="Encoding.GetEncoding(int)"/> throws an <see cref="ArgumentException"/>.
	    /// So replace it with some fallback, e.g. 437 which is the default codepage in a console in a default Windows installation.
	    /// </remarks>
	    static int defaultCodePage =
            // these values cause ArgumentException in subsequent calls to Encoding::GetEncoding()
            ((Thread.CurrentThread.CurrentCulture.TextInfo.OEMCodePage == 1) || (Thread.CurrentThread.CurrentCulture.TextInfo.OEMCodePage == 2) || (Thread.CurrentThread.CurrentCulture.TextInfo.OEMCodePage == 3) || (Thread.CurrentThread.CurrentCulture.TextInfo.OEMCodePage == 42))
            ? 437 // The default OEM encoding in a console in a default Windows installation, as a fallback.
	        : Thread.CurrentThread.CurrentCulture.TextInfo.OEMCodePage;  
#endif

        /// <summary>
        /// Default encoding used for string conversion.  0 gives the default system OEM code page.
        /// Dont use unicode encodings if you want to be Zip compatible!
        /// Using the default code page isnt the full solution necessarily
        /// there are many variable factors, codepage 850 is often a good choice for
        /// European users, however be careful about compatibility.
        /// </summary>
        public static int DefaultCodePage
        {
            get
            {
                return defaultCodePage;
            }
            set
            {
                if ((value < 0) || (value > 65535) ||
                    (value == 1) || (value == 2) || (value == 3) || (value == 42))
                {
                    throw new ArgumentOutOfRangeException("value");
                }

                defaultCodePage = value;
            }
        }

        /// <summary>
        /// Convert a portion of a byte array to a string.
        /// </summary>		
        /// <param name="data">
        /// Data to convert to string
        /// </param>
        /// <param name="count">
        /// Number of bytes to convert starting from index 0
        /// </param>
        /// <returns>
        /// data[0]..data[count - 1] converted to a string
        /// </returns>
        public static string ConvertToString(byte[] data, int count)
        {
            if (data == null)
            {
                return string.Empty;
            }

#if SILVERLIGHT || NETFX_CORE
            return Encoding.GetEncoding("utf-8").GetString(data, 0, count);
#else
            return Encoding.GetEncoding(DefaultCodePage).GetString(data, 0, count);
#endif
        }

        /// <summary>
        /// Convert a byte array to string
        /// </summary>
        /// <param name="data">
        /// Byte array to convert
        /// </param>
        /// <returns>
        /// <paramref name="data">data</paramref>converted to a string
        /// </returns>
        public static string ConvertToString(byte[] data)
        {
            if (data == null)
            {
                return string.Empty;
            }
            return ConvertToString(data, data.Length);
        }

        /// <summary>
        /// Convert a byte array to string
        /// </summary>
        /// <param name="flags">The applicable general purpose bits flags</param>
        /// <param name="data">
        /// Byte array to convert
        /// </param>
        /// <param name="count">The number of bytes to convert.</param>
        /// <returns>
        /// <paramref name="data">data</paramref>converted to a string
        /// </returns>
        public static string ConvertToStringExt(int flags, byte[] data, int count)
        {
            if (data == null)
            {
                return string.Empty;
            }

            if ((flags & (int)GeneralBitFlags.UnicodeText) != 0)
            {
                return Encoding.UTF8.GetString(data, 0, count);
            }
            else
            {
                return ConvertToString(data, count);
            }
        }

        /// <summary>
        /// Convert a byte array to string
        /// </summary>
        /// <param name="data">
        /// Byte array to convert
        /// </param>
        /// <param name="flags">The applicable general purpose bits flags</param>
        /// <returns>
        /// <paramref name="data">data</paramref>converted to a string
        /// </returns>
        public static string ConvertToStringExt(int flags, byte[] data)
        {
            if (data == null)
            {
                return string.Empty;
            }

            if ((flags & (int)GeneralBitFlags.UnicodeText) != 0)
            {
                return Encoding.UTF8.GetString(data, 0, data.Length);
            }
            else
            {
                return ConvertToString(data, data.Length);
            }
        }

        /// <summary>
        /// Convert a string to a byte array
        /// </summary>
        /// <param name="str">
        /// String to convert to an array
        /// </param>
        /// <returns>Converted array</returns>
        public static byte[] ConvertToArray(string str)
        {
            if (str == null)
            {
                return new byte[0];
            }

#if SILVERLIGHT || NETFX_CORE
            return Encoding.GetEncoding("utf-8").GetBytes(str);
#else
            return Encoding.GetEncoding(DefaultCodePage).GetBytes(str);
#endif
        }

        /// <summary>
        /// Convert a string to a byte array
        /// </summary>
        /// <param name="flags">The applicable <see cref="GeneralBitFlags">general purpose bits flags</see></param>
        /// <param name="str">
        /// String to convert to an array
        /// </param>
        /// <returns>Converted array</returns>
        public static byte[] ConvertToArray(int flags, string str)
        {
            if (str == null)
            {
                return new byte[0];
            }

            if ((flags & (int)GeneralBitFlags.UnicodeText) != 0)
            {
                return Encoding.UTF8.GetBytes(str);
            }
            else
            {
                return ConvertToArray(str);
            }
        }


        /// <summary>
        /// Initialise default instance of <see cref="ZipConstants">ZipConstants</see>
        /// </summary>
        /// <remarks>
        /// Private to prevent instances being created.
        /// </remarks>
        ZipConstants()
        {
            // Do nothing
        }
    }
}