#region Disclaimer / License
// Copyright (C) 2010, Kenneth Skovhede
// http://www.hexad.dk, opensource@hexad.dk
// 
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
// 
// This library 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
// Lesser General Public License for more details.
// 
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
// 
#endregion
using System;
using System.Collections.Generic;
using System.Text;
using System.Text.RegularExpressions;

namespace Duplicati.Library.Main
{
    /// <summary>
    /// This class is responsible for naming remote files,
    /// and parsing remote filenames
    /// </summary>
    internal class FilenameStrategy
    {

        //In Duplicati 1.0 there is only one manifest file, and it is called manifest or M in short mode
        //Issue# 58 introduced a backup manifest. Since 1.0 does not verify the manifest version number,
        // the name manifest/M is not used, as that prevents 1.0 clients from reading the manifests and volumes.
        //The new names are manifestA and manifestB (A/B in short mode).
        //Future versions of Duplicati always verify the version number to avoid reading/writing data to a format 
        // that is not supported.
        //
        //These are the strings that are used:

        private const string MANIFEST_OLD = "manifest";
        private const string MANIFEST_A = "manifestA";
        private const string MANIFEST_B = "manifestB";

        private const string MANIFEST_OLD_SHORT = "M";
        private const string MANIFEST_A_SHORT = "A";
        private const string MANIFEST_B_SHORT = "B";

        private const string CONTENT = "content";
        private const string SIGNATURE = "signature";
        private const string FULL = "full";
        private const string INCREMENTAL = "inc";

        private const string CONTENT_SHORT = "C";
        private const string SIGNATURE_SHORT = "S";
        private const string FULL_SHORT = "F";
        private const string INCREMENTAL_SHORT = "I";

        private const string VOLUME = "vol";

        private bool m_useShortFilenames;
        private string m_timeSeperator;
        private string m_prefix;

        private Regex m_filenameRegExp;
        private Regex m_shortRegExp;

        /// <summary>
        /// A cache used to ensure that filenames are consistent, 
        /// even if the timezone changes in between filename generation
        /// </summary>
        private Dictionary<DateTime, string> m_timeStringCache;

        public FilenameStrategy(string prefix, string timeSeperator, bool useShortNames)
        {
            m_prefix = prefix;
            m_timeSeperator = timeSeperator;
            m_useShortFilenames = useShortNames;

            m_shortRegExp = new Regex(
                string.Format(@"(?<prefix>{0})\-(?<type>({1}|{2}|{3}|{4}|{5}))(?<inc>({6}|{7}))(?<time>([A-F]|[a-f]|[0-9])+)\.(?<volumegroup>{8}(?<volumenumber>\d+)\.)?(?<extension>.+)",
                    Regex.Escape(m_prefix),
                    CONTENT_SHORT,
                    SIGNATURE_SHORT,
                    MANIFEST_OLD_SHORT,
                    MANIFEST_A_SHORT,
                    MANIFEST_B_SHORT,
                    FULL_SHORT,
                    INCREMENTAL_SHORT,
                    VOLUME
                )
            );
            m_filenameRegExp = new Regex(
                string.Format(@"(?<prefix>{0})\-(?<inc>({1}|{2}))\-(?<type>({3}|{4}|{5}|{6}|{7}))\.(?<time>\d{10}\-\d{11}\-\d{11}.\d{11}{9}\d{11}{9}\d{11}(?<timezone>([\+\-]\d{11}{9}\d{11})|Z)?)\.(?<volumegroup>{8}(?<volumenumber>\d+)\.)?(?<extension>.+)",
                    Regex.Escape(m_prefix),
                    FULL,
                    INCREMENTAL,
                    CONTENT,
                    SIGNATURE,
                    MANIFEST_OLD,
                    MANIFEST_A,
                    MANIFEST_B,
                    VOLUME,
                    Regex.Escape(timeSeperator),
                    "{4}", //We need to insert it because it gets replaced by string.Format
                    "{2}" //Same as above
                )
            );

            //The short filenames are UTC so there is no timezone attached
            if (!m_useShortFilenames)
                m_timeStringCache = new Dictionary<DateTime, string>();
        }

        public FilenameStrategy(Options options)
            : this(options.BackupPrefix, options.TimeSeperatorChar, options.UseShortFilenames)
        {
        }

        public string GenerateFilename(BackupEntryBase type)
        {
            string t;
            if (type is ManifestEntry && ((ManifestEntry)type).IsPrimary)
                t = m_useShortFilenames ? MANIFEST_A_SHORT : MANIFEST_A;
            else if (type is ManifestEntry && !((ManifestEntry)type).IsPrimary)
                t = m_useShortFilenames ? MANIFEST_B_SHORT : MANIFEST_B;
            else if (type is ContentEntry)
                t = m_useShortFilenames ? CONTENT_SHORT : CONTENT;
            else if (type is SignatureEntry)
                t = m_useShortFilenames ? SIGNATURE_SHORT : SIGNATURE;
            else
                throw new Exception(string.Format(Strings.FilenameStrategy.InvalidEntryTypeError, type));

            string filename;
            if (!m_useShortFilenames)
            {
                //Make sure the same DateTime is always the same string
                if (!m_timeStringCache.ContainsKey(type.Time))
                    m_timeStringCache[type.Time] = type.Time.ToString("yyyy-MM-ddTHH:mm:ssK");

                string datetime = m_timeStringCache[type.Time].Replace(":", m_timeSeperator);
                filename = m_prefix + "-" + (type.IsFull ? FULL : INCREMENTAL) + "-" + t + "." + datetime;
            }
            else
            {
                filename = m_prefix + "-" + t + (type.IsFull ? FULL_SHORT : INCREMENTAL_SHORT) + (type.Time.ToUniversalTime().Ticks / TimeSpan.TicksPerSecond).ToString("X");
            }

            if (type is ManifestEntry)
                return filename;
            else
                return filename + "." + VOLUME + ((PayloadEntryBase)type).Volumenumber.ToString();
        }

        public BackupEntryBase ParseFilename(Duplicati.Library.Interface.IFileEntry fe)
        {
            Match m = m_filenameRegExp.Match(fe.Name);
            if (!m.Success)
                m = m_shortRegExp.Match(fe.Name);
            if (!m.Success)
                return null;
            if (m.Value != fe.Name)
                return null; //Accept only full matches

            bool isFull = m.Groups["inc"].Value == FULL || m.Groups["inc"].Value == FULL_SHORT;
            bool isShortName = m.Groups["inc"].Value.Length == 1;
            string timeString = m.Groups["time"].Value;
            DateTime time;
            if (isShortName)
                time = new DateTime(long.Parse(timeString, System.Globalization.NumberStyles.HexNumber) * TimeSpan.TicksPerSecond, DateTimeKind.Utc).ToLocalTime();
            else
                time = DateTime.Parse(timeString.Replace(m_timeSeperator, ":"));

            string extension = m.Groups["extension"].Value;

            int volNumber = -1;
            if (m.Groups["volumenumber"].Success)
                volNumber = int.Parse(m.Groups["volumenumber"].Value);

            string compression = extension;
            string encryption = null;

            int dotIndex = compression.IndexOf(".");
            if (dotIndex > 0)
            {
                encryption = compression.Substring(dotIndex + 1);
                compression = compression.Substring(0, dotIndex);
            }

            if (Array.IndexOf<string>(new string[] { MANIFEST_OLD , MANIFEST_OLD_SHORT ,MANIFEST_A , MANIFEST_A_SHORT, MANIFEST_B, MANIFEST_B_SHORT },  m.Groups["type"].Value) >= 0)
                return new ManifestEntry(fe.Name, fe, time, isFull, timeString, encryption, m.Groups["type"].Value != MANIFEST_B && m.Groups["type"].Value != MANIFEST_B_SHORT);
            else if (m.Groups["type"].Value == SIGNATURE || m.Groups["type"].Value == SIGNATURE_SHORT)
                return new SignatureEntry(fe.Name, fe, time, isFull, timeString, encryption, compression, volNumber);
            else if (m.Groups["type"].Value == CONTENT || m.Groups["type"].Value == CONTENT_SHORT)
                return new ContentEntry(fe.Name, fe, time, isFull, timeString, encryption, compression, volNumber);
            else
                return null;
        }

        public bool UseShortNames { get { return m_useShortFilenames; } }
        public string Prefix { get { return m_prefix; } }
    }
}