// Copyright (C) 2026, The Duplicati Team
// https://duplicati.com, hello@duplicati.com
// 
// Permission is hereby granted, free of charge, to any person obtaining a 
// copy of this software and associated documentation files (the "Software"), 
// to deal in the Software without restriction, including without limitation 
// the rights to use, copy, modify, merge, publish, distribute, sublicense, 
// and/or sell copies of the Software, and to permit persons to whom the 
// Software is furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in 
// all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS 
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
// DEALINGS IN THE SOFTWARE.

using System;
using System.IO;
using System.Linq;
using System.Collections.Generic;
using Duplicati.Library.Common.IO;
using Duplicati.Library.Utility;
using System.IO.Compression;
using Duplicati.Library.Interface;

namespace Duplicati.CommandLine.RecoveryTool
{
    public static class Restore
    {
        private static readonly ISystemIO systemIO = SystemIO.IO_OS;

        public static int Run(List<string> args, Dictionary<string, string> options, Library.Utility.IFilter filter)
        {
            if (args.Count != 2 && args.Count != 3)
            {
                Console.WriteLine("Invalid argument count ({0} expected 2 or 3): {1}{2}", args.Count, Environment.NewLine, string.Join(Environment.NewLine, args));
                return 100;
            }

            var folder = Path.GetFullPath(args[1]);

            if (!Directory.Exists(folder))
            {
                Console.WriteLine("Folder not found: {0}", folder);
                return 100;
            }

            Directory.SetCurrentDirectory(folder);

            options.TryGetValue("targetpath", out var targetpath);
            options.TryGetValue("indexfile", out var ixfile);
            if (string.IsNullOrWhiteSpace(ixfile))
                ixfile = "index.txt";

            ixfile = Path.GetFullPath(ixfile);
            if (!File.Exists(ixfile))
            {
                Console.WriteLine("Index file not found, perhaps you need to run the index command?");
                return 100;
            }


            string filelist;
            if (args.Count == 2)
            {
                var time = List.ParseListFiles(folder).First();
                filelist = time.Value;

                Console.WriteLine("Using set 0 with timestamp {0}", time.Key.ToLocalTime());
            }
            else
            {
                filelist = List.SelectListFile(args[2], folder);
            }

            Library.Main.Volumes.VolumeReaderBase.UpdateOptionsFromManifest(Path.GetExtension(filelist).Trim('.'), filelist, new Duplicati.Library.Main.Options(options));

            options.TryGetValue("blocksize", out var blocksize_str);
            options.TryGetValue("block-hash-algorithm", out var blockhash_str);
            options.TryGetValue("block-hash-algorithm", out var filehash_str);
            var offset = 0L;
            if (options.TryGetValue("offset", out var offset_str))
                offset = long.Parse(offset_str);


            long blocksize = string.IsNullOrWhiteSpace(blocksize_str) ? 0 : Library.Utility.Sizeparser.ParseSize(blocksize_str);

            if (blocksize <= 0)
            {
                Console.WriteLine("Invalid blocksize: {0}, try setting --blocksize manually", blocksize);
                return 100;
            }

            if (string.IsNullOrWhiteSpace(blockhash_str))
                throw new Duplicati.Library.Interface.UserInformationException(string.Format("Block hash algorithm not valid: {0}", blockhash_str), "BlockHashAlgorithmNotSupported");
            if (string.IsNullOrWhiteSpace(filehash_str))
                throw new Duplicati.Library.Interface.UserInformationException(string.Format("File hash algorithm not valid: {0}", filehash_str), "FileHashAlgorithmNotSupported");

            var useIndexMap = !Library.Utility.Utility.ParseBoolOption(options, "reduce-memory-use");
            var disableFileVerify = Library.Utility.Utility.ParseBoolOption(options, "disable-file-verify");

            var startedCount = 0L;
            var restoredCount = 0L;
            var errorCount = 0L;
            var fileErrors = 0L;
            var totalSize = 0L;

            using (var blockhasher = HashFactory.CreateHasher(blockhash_str))
            using (var filehasher = HashFactory.CreateHasher(filehash_str))
            using (var mru = new CompressedFileMRUCache(options))
            {
                var hashesprblock = blocksize / (blockhasher.HashSize / 8);

                Console.WriteLine("Building lookup table for file hashes");
                // Source OS can have different directory separator
                string sourceDirsep = null;
                using (HashLookupHelper lookup = new HashLookupHelper(ixfile, mru, (int)blocksize, blockhasher.HashSize / 8, useIndexMap))
                {
                    var filecount = 0L;

                    if (!string.IsNullOrWhiteSpace(targetpath))
                        Console.WriteLine("Computing restore path");

                    string largestprefix = GetLargestPrefix(from f in List.EnumerateFilesInDList(filelist, filter, options) select f.Path, out sourceDirsep, out filecount);

                    Console.WriteLine("Restoring {0} files to {1}", filecount, string.IsNullOrWhiteSpace(targetpath) ? "original position" : targetpath);

                    if (!string.IsNullOrEmpty(largestprefix))
                        Console.WriteLine("Removing common prefix {0} from files", largestprefix);

                    var i = 0L;

                    // Allocate buffers for block and blocklist hashes
                    var buffer = new byte[blocksize];
                    var blocklistbuffer = new byte[blocksize];
                    foreach (var f in List.EnumerateFilesInDList(filelist, filter, options))
                    {
                        if (i < offset)
                        {
                            Console.WriteLine($"Skipping {i}: {f.Path} ({Utility.FormatSizeString(f.Size)})");
                            i++;
                            continue;
                        }

                        startedCount++;
                        try
                        {
                            var targetfile = MapToRestorePath(f.Path, largestprefix, targetpath, sourceDirsep);
                            if (!systemIO.DirectoryExists(systemIO.PathGetDirectoryName(targetfile)))
                                systemIO.DirectoryCreate(systemIO.PathGetDirectoryName(targetfile));

                            Console.Write($"{i} ({Utility.FormatSizeString(totalSize)}): {targetfile} ({Utility.FormatSizeString(f.Size)})");
                            totalSize += f.Size;

                            using (var tf = new Library.Utility.TempFile())
                            {
                                using (var sw = File.OpenWrite(tf))
                                {
                                    if (f.BlocklistHashes == null)
                                    {
                                        if (f.Size > 0)
                                            lookup.WriteHash(sw, f.Hash, buffer);
                                    }
                                    else
                                    {
                                        var blhi = 0L;
                                        foreach (var blh in f.BlocklistHashes)
                                        {
                                            Console.Write(" {0}", blhi);
                                            var blockhashoffset = blhi * hashesprblock * blocksize;

                                            try
                                            {
                                                var bi = 0;
                                                foreach (var h in lookup.ReadBlocklistHashes(blh, blocklistbuffer))
                                                {
                                                    try
                                                    {
                                                        sw.Position = blockhashoffset + (bi * blocksize);
                                                        lookup.WriteHash(sw, h, buffer);
                                                    }
                                                    catch (Exception ex)
                                                    {
                                                        errorCount++;
                                                        Console.WriteLine("Failed to read hash: {0}{1}{2}", h, Environment.NewLine, ex);
                                                    }

                                                    bi++;
                                                }
                                            }
                                            catch (Exception ex)
                                            {
                                                errorCount++;
                                                Console.WriteLine("Failed to read Blocklist hash: {0}{1}{2}", blh, Environment.NewLine, ex);
                                            }

                                            blhi++;
                                        }
                                    }
                                }

                                restoredCount++;

                                if (disableFileVerify)
                                {
                                    Console.WriteLine(" done! (not verified)");
                                    if (systemIO.FileExists(targetfile))
                                        systemIO.FileCopy(tf, targetfile, true);
                                    else
                                        systemIO.FileMove(tf, targetfile);
                                }
                                else
                                {
                                    string fh;
                                    using (var fs = File.OpenRead(tf))
                                        fh = Convert.ToBase64String(filehasher.ComputeHash(fs));

                                    if (fh == f.Hash)
                                    {
                                        Console.WriteLine(" done!");
                                        if (systemIO.FileExists(targetfile))
                                            systemIO.FileCopy(tf, targetfile, true);
                                        else
                                            systemIO.FileMove(tf, targetfile);
                                    }
                                    else
                                    {
                                        fileErrors++;
                                        Console.Write(" - Restored file hash mismatch");
                                        if (systemIO.FileExists(targetfile))
                                            Console.WriteLine(" - not overwriting existing file: {0}", targetfile);
                                        else
                                            Console.WriteLine(" - restoring file in damaged condition");
                                    }
                                }
                            }
                        }
                        catch (Exception ex)
                        {
                            errorCount++;
                            Console.WriteLine(" error: {0}", ex);
                        }
                        i++;
                    }
                }
            }

            if (fileErrors > 0 || restoredCount != startedCount)
                Console.WriteLine($"Restored {restoredCount} files of {startedCount} attempted ({Library.Utility.Utility.FormatSizeString(totalSize)}); {fileErrors} files had verification errors");
            else
                Console.WriteLine($"Restored {restoredCount} files ({Library.Utility.Utility.FormatSizeString(totalSize)})");

            if (errorCount > 0)
                Console.WriteLine("Errors: {0}", errorCount);

            return errorCount != 0 || restoredCount != startedCount || fileErrors > 0
                ? 1
                : 0;
        }

        public static string GetLargestPrefix(IEnumerable<string> filePaths, out string sourceDirsep, out long filecount)
        {
            // Get dir separator like in LocalRestoreDatabase.GetLargestPrefix():
            string largestprefix = filePaths.OrderByDescending(p => p.Length).FirstOrDefault() ?? string.Empty;
            sourceDirsep = Util.GuessDirSeparator(largestprefix);


            string[] dirsepSplit = new string[] { sourceDirsep };
            string[] largestprefixparts = largestprefix.Split(dirsepSplit, StringSplitOptions.None);

            // Because only files are in the list, need to remove filename from prefix
            // Otherwise, in case of a single file the prefix is not a directory
            if (largestprefixparts.Length > 0)
                Array.Resize(ref largestprefixparts, largestprefixparts.Length - 1);
            largestprefix = string.Join(sourceDirsep, largestprefixparts);

            filecount = 0;
            foreach (var path in filePaths)
            {
                if (largestprefix.Length > 1)
                {
                    // Unix paths starting with / have an empty string in paths[0]
                    // Completely empty strings should not combine with that, so should have no parts at all
                    var parts = path.Length == 0 ? new string[0] : path.Split(dirsepSplit, StringSplitOptions.None);

                    var ni = 0;
                    for (; ni < Math.Min(parts.Length, largestprefixparts.Length); ni++)
                        if (!Library.Utility.Utility.ClientFilenameStringComparer.Equals(parts[ni], largestprefixparts[ni]))
                            break;

                    if (ni != largestprefixparts.Length)
                    {
                        if (ni == 0)
                        {
                            largestprefixparts = new string[0];
                            largestprefix = string.Empty;
                        }
                        else
                        {
                            // Only the first ni parts match
                            Array.Resize(ref largestprefixparts, ni);
                            largestprefix = string.Join(sourceDirsep, largestprefixparts);
                        }
                    }
                }
                filecount++;
            }
            return largestprefixparts.Length == 0 ? "" : Util.AppendDirSeparator(largestprefix, sourceDirsep);
        }

        public static string MapToRestorePath(string path, string prefixpath, string restorepath, string sourceDirsep)
        {
            if (sourceDirsep != null && sourceDirsep != Util.DirectorySeparatorString && sourceDirsep != Util.AltDirectorySeparatorString)
            {
                // Replace directory separator in source and prefix path
                path = path.Replace(sourceDirsep, Util.DirectorySeparatorString);
                if (!string.IsNullOrWhiteSpace(prefixpath))
                {
                    prefixpath = prefixpath.Replace(sourceDirsep, Util.DirectorySeparatorString);
                }
            }
            if (string.IsNullOrWhiteSpace(restorepath))
                return path;

            if (string.IsNullOrWhiteSpace(prefixpath))
            {
                //Special case, restoring to new folder, but files are from different drives
                // So we use the format <restore path> / <drive letter> / <source path>
                // To avoid generating paths with a colon
                if (path.Substring(1, 1) == ":")
                    prefixpath = path.Substring(0, 1) + path.Substring(2);

                return systemIO.PathCombine(restorepath, prefixpath);
            }

            return systemIO.PathCombine(restorepath, path.Substring(prefixpath.Length));
        }



        private class HashLookupHelper : IDisposable
        {
            private const int LOOKUP_TABLE_SIZE = 2048;

            private readonly CompressedFileMRUCache m_cache;
            private readonly int m_hashsize;
            private readonly int m_blocksize;
            private Stream m_indexfile;
            private readonly List<string> m_lookup = new List<string>();
            private readonly List<long> m_offsets = new List<long>();
            private readonly Dictionary<string, string> m_indexMap;
            private readonly byte[] m_linebuf = new byte[128];
            private readonly byte[] m_newline = Environment.NewLine.Select(x => (byte)x).ToArray();

            public HashLookupHelper(string indexfile, CompressedFileMRUCache cache, int blocksize, int hashsize, bool useIndexMap)
            {
                m_cache = cache;
                m_blocksize = blocksize;
                m_hashsize = hashsize;
                m_indexfile = File.OpenRead(indexfile);

                if (useIndexMap)
                {
                    m_indexMap = new Dictionary<string, string>();
                    Console.WriteLine("Building in-memory index table ... ");

                    m_indexfile.Position = 0;
                    foreach (var n in AllFileLines())
                        m_indexMap[n.Key] = n.Value;

                    Console.WriteLine("Index table has {0} unique hashes", m_indexMap.Count);
                }
                else
                {
                    // Build index ....
                    var hashes = 0L;
                    string prev = null;
                    m_indexfile.Position = 0;
                    foreach (var n in AllFileLines())
                    {
                        if (n.Key != prev)
                        {
                            hashes++;
                            prev = n.Key;
                        }
                    }

                    Console.WriteLine("Index file has {0} hashes in total", hashes);

                    var lookuptablesize = Math.Max(1, Math.Min(LOOKUP_TABLE_SIZE, hashes) - 1);
                    var lookupincrements = hashes / lookuptablesize;

                    Console.WriteLine("Building lookup table with {0} entries, giving increments of {1}", lookuptablesize, lookupincrements);

                    m_indexfile.Position = 0;
                    prev = null;
                    var prevoff = 0L;
                    var hc = 0L;

                    foreach (var n in AllFileLines())
                    {
                        if (n.Key != prev)
                        {
                            if ((hc % lookupincrements) == 0)
                            {
                                m_lookup.Add(n.Key);
                                m_offsets.Add(prevoff);
                            }

                            hc++;
                            prev = n.Key;
                            prevoff = m_indexfile.Position;
                        }
                    }
                }
            }

            private string ReadNextLine()
            {
                var p = m_indexfile.Position;
                var max = m_indexfile.Read(m_linebuf, 0, m_linebuf.Length);
                if (max == 0)
                    return null;

                var lfi = 0;
                for (int i = 0; i < max; i++)
                    if (m_linebuf[i] == m_newline[lfi])
                    {
                        if (lfi == m_newline.Length - 1)
                        {
                            m_indexfile.Position = p + i + 1;
                            return System.Text.Encoding.Default.GetString(m_linebuf, 0, i - m_newline.Length + 1);

                        }
                        else
                        {
                            lfi++;
                        }
                    }
                    else
                    {
                        lfi = 0;
                    }

                throw new Exception(string.Format("Unexpected long line starting at offset {0}, read {1} bytes without a newline", p, m_linebuf.Length));
            }

            private IEnumerable<KeyValuePair<string, string>> AllFileLines()
            {
                while (true)
                {
                    var str = ReadNextLine();
                    if (str == null)
                        break;

                    if (str.Length == 0)
                        continue;

                    var ix = str.IndexOf(", ", StringComparison.Ordinal);
                    if (ix < 0)
                        Console.WriteLine("Failed to parse line starting at offset {0} in index file, string: {1}", m_indexfile.Position - str.Length - m_newline.Length, str);
                    yield return new KeyValuePair<string, string>(str.Substring(0, ix), str.Substring(ix + 2));
                }
            }

            public IEnumerable<string> ReadBlocklistHashes(string hash, byte[] buffer)
            {
                var bytes = ReadHash(hash, buffer);
                for (var i = 0; i < bytes; i += m_hashsize)
                    yield return Convert.ToBase64String(buffer, i, m_hashsize);
            }

            public int ReadHash(string hash, byte[] buffer)
            {
                // Use in-memory map if available
                if (m_indexMap != null)
                {
                    if (!m_indexMap.TryGetValue(hash, out var filename))
                        throw new Exception(string.Format("Unable to locate block with hash: {0}", hash));

                    using (var fs = m_cache.ReadBlock(filename, hash))
                        return Duplicati.Library.Utility.Utility.ForceStreamRead(fs, buffer, buffer.Length);
                }
                else
                {
                    var ix = m_lookup.BinarySearch(hash, StringComparer.Ordinal);
                    if (ix < 0)
                    {
                        ix = ~ix;
                        if (ix != 0)
                            ix--;
                    }

                    m_indexfile.Position = m_offsets[ix];

                    foreach (var v in AllFileLines())
                    {
                        if (v.Key == hash)
                            using (var fs = m_cache.ReadBlock(v.Value, hash))
                                return Duplicati.Library.Utility.Utility.ForceStreamRead(fs, buffer, buffer.Length);


                        if (StringComparer.Ordinal.Compare(hash, v.Key) < 0)
                            break;
                    }

                    throw new Exception(string.Format("Unable to locate block with hash: {0}", hash));
                }
            }

            public void WriteHash(Stream sw, string hash, byte[] buffer)
            {
                var h = ReadHash(hash, buffer);
                sw.Write(buffer, 0, h);
            }


            public void Dispose()
            {
                if (m_indexfile != null)
                    m_indexfile.Dispose();
                m_indexfile = null;
            }
        }

        private class WrappedZipReader : IArchiveReader
        {
            private readonly ZipArchive m_zip;
            public WrappedZipReader(Stream stream)
            {
                m_zip = new ZipArchive(stream, ZipArchiveMode.Read, true);
            }

            public void Dispose()
            {
                m_zip.Dispose();
            }

            public bool FileExists(string file) => throw new NotImplementedException();

            public DateTime GetLastWriteTime(string file) => throw new NotImplementedException();

            public string[] ListFiles(string prefix) => throw new NotImplementedException();

            public IEnumerable<KeyValuePair<string, long>> ListFilesWithSize(string prefix) => throw new NotImplementedException();

            public Stream OpenRead(string file) => m_zip.GetEntry(file).Open();
        }

        private class CompressedFileMRUCache : IDisposable
        {
            private Dictionary<string, Library.Interface.IArchiveReader> m_lookup = new Dictionary<string, Library.Interface.IArchiveReader>();
            private Dictionary<string, Stream> m_streams = new Dictionary<string, Stream>();
            private List<string> m_mru = new List<string>();
            private readonly Dictionary<string, string> m_options;
            private readonly bool m_useWrappedZip;

            private readonly int MAX_OPEN_ARCHIVES = 200;

            public CompressedFileMRUCache(Dictionary<string, string> options)
            {
                m_options = options;
                m_useWrappedZip = !Library.Utility.Utility.ParseBoolOption(options, "disable-wrapped-zip");
                if (options.TryGetValue("max-open-archives", out var maxopenarchives))
                    MAX_OPEN_ARCHIVES = int.Parse(maxopenarchives);
            }

            public Stream ReadBlock(string filename, string hash)
            {
                if (!m_lookup.TryGetValue(filename, out var cf) || !m_streams.ContainsKey(filename))
                {
                    var stream = new FileStream(filename, FileMode.Open, FileAccess.Read, FileShare.Read | FileShare.Delete);
                    var ext = Path.GetExtension(filename).Trim('.');

                    cf = m_useWrappedZip && ext.Equals("zip", StringComparison.OrdinalIgnoreCase)
                        ? new WrappedZipReader(stream)
                        : Library.DynamicLoader.CompressionLoader.GetModule(ext, stream, Library.Interface.ArchiveMode.Read, m_options);

                    if (cf == null)
                    {
                        stream.Dispose();
                        throw new Exception(string.Format("Unable to decompress {0}, no such compression module {1}", filename, Path.GetExtension(filename).Trim('.')));
                    }
                    m_lookup[filename] = cf;
                    m_streams[filename] = stream;
                }

                if (m_mru.Count == 0 || m_mru[0] != filename)
                {
                    m_mru.Remove(filename);
                    m_mru.Insert(0, filename);
                }

                while (m_mru.Count > MAX_OPEN_ARCHIVES)
                {
                    var f = m_mru.Last();
                    (m_lookup[f] as IDisposable)?.Dispose();
                    m_lookup.Remove(f);
                    m_streams[f].Dispose();
                    m_streams.Remove(f);
                    m_mru.Remove(f);
                }

                return cf.OpenRead(Library.Utility.Utility.Base64PlainToBase64Url(hash));
            }

            #region IDisposable implementation

            public void Dispose()
            {
                foreach (var v in m_lookup.Values)
                    try { (v as IDisposable)?.Dispose(); }
                    catch { }

                foreach (var v in m_streams.Values)
                    try { v.Dispose(); }
                    catch { }

                m_lookup = null;
                m_streams = null;
                m_mru = null;
            }

            #endregion
        }
    }
}