// Copyright (C) 2024, 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"), 
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// 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 
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// DEALINGS IN THE SOFTWARE.

using System;
using Duplicati.Library.Main.Database;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using Duplicati.Library.Interface;

namespace Duplicati.Library.Main.Operation
{
    internal static class FilelistProcessor
    {
        /// <summary>
        /// The tag used for logging
        /// </summary>
        private static readonly string LOGTAG = Logging.Log.LogTagFromType(typeof(FilelistProcessor));

        /// <summary>
        /// Helper method that verifies uploaded volumes and updates their state in the database.
        /// Throws an error if there are issues with the remote storage
        /// </summary>
        /// <param name="database">The database to compare with</param>
        public static void VerifyLocalList(BackendManager backend, LocalDatabase database)
        {
            var locallist = database.GetRemoteVolumes();
            foreach(var i in locallist)
            {
                switch (i.State)
                {
                    case RemoteVolumeState.Uploaded:
                    case RemoteVolumeState.Verified:
                    case RemoteVolumeState.Deleted:
                        break;

                    case RemoteVolumeState.Temporary:
                    case RemoteVolumeState.Deleting:
                    case RemoteVolumeState.Uploading:
                        Logging.Log.WriteInformationMessage(LOGTAG, "RemovingStaleFile", "Removing remote file listed as {0}: {1}", i.State, i.Name);
                        try
                        {
                            backend.Delete(i.Name, i.Size, true);
                        }
                        catch (Exception ex)
                        {
                            Logging.Log.WriteWarningMessage(LOGTAG, "DeleteFileFailed", ex, "Failed to erase file {0}, treating as deleted: {1}", i.Name, ex.Message);
                        }

                        break;

                    default:
                        Logging.Log.WriteWarningMessage(LOGTAG, "UnknownFileState", null, "Unknown state for remote file listed as {0}: {1}", i.State, i.Name);
                        break;
                }

                backend.FlushDbMessages();
            }
        }

        public static void VerifyRemoteList(BackendManager backend, Options options, LocalDatabase database, IBackendWriter backendWriter, bool latestVolumesOnly, IDbTransaction transaction)
        {
            if (!options.NoBackendverification)
            {
                LocalBackupDatabase backupDatabase = new LocalBackupDatabase(database, options);
                IEnumerable<string> protectedFiles = backupDatabase.GetTemporaryFilelistVolumeNames(latestVolumesOnly, transaction);
                FilelistProcessor.VerifyRemoteList(backend, options, database, backendWriter, protectedFiles);
            }
        }

        /// <summary>
        /// Helper method that verifies uploaded volumes and updates their state in the database.
        /// Throws an error if there are issues with the remote storage
        /// </summary>
        /// <param name="backend">The backend instance to use</param>
        /// <param name="options">The options used</param>
        /// <param name="database">The database to compare with</param>
        /// <param name="log">The log instance to use</param>
        /// <param name="protectedFiles">Filenames that should be exempted from deletion</param>
        public static void VerifyRemoteList(BackendManager backend, Options options, LocalDatabase database, IBackendWriter log, IEnumerable<string> protectedFiles = null)
        {
            var tp = RemoteListAnalysis(backend, options, database, log, protectedFiles);
            long extraCount = 0;
            long missingCount = 0;

            foreach(var n in tp.ExtraVolumes)
            {
                Logging.Log.WriteWarningMessage(LOGTAG, "ExtraUnknownFile", null, "Extra unknown file: {0}", n.File.Name);
                extraCount++;
            }

            foreach(var n in tp.MissingVolumes)
            {
                Logging.Log.WriteWarningMessage(LOGTAG, "MissingFile", null, "Missing file: {0}", n.Name);
                missingCount++;
            }

            if (extraCount > 0)
            {
                var s = string.Format("Found {0} remote files that are not recorded in local storage, please run repair", extraCount);
                Logging.Log.WriteErrorMessage(LOGTAG, "ExtraRemoteFiles", null, s);
                throw new RemoteListVerificationException(s, "ExtraRemoteFiles");
            }

            ISet<string> doubles;
            Library.Utility.Utility.GetUniqueItems(tp.ParsedVolumes.Select(x => x.File.Name), out doubles);

            if (doubles.Count > 0)
            {
                var s = string.Format("Found remote files reported as duplicates, either the backend module is broken or you need to manually remove the extra copies.\nThe following files were found multiple times: {0}", string.Join(", ", doubles));
                Logging.Log.WriteErrorMessage(LOGTAG, "DuplicateRemoteFiles", null, s);
                throw new RemoteListVerificationException(s, "DuplicateRemoteFiles");
            }

            if (missingCount > 0)
            {
                string s;
                if (!tp.BackupPrefixes.Contains(options.Prefix) && tp.BackupPrefixes.Length > 0)
                    s = string.Format("Found {0} files that are missing from the remote storage, and no files with the backup prefix {1}, but found the following backup prefixes: {2}", missingCount, options.Prefix, string.Join(", ", tp.BackupPrefixes));
                else
                    s = string.Format("Found {0} files that are missing from the remote storage, please run repair", missingCount);

                Logging.Log.WriteErrorMessage(LOGTAG, "MissingRemoteFiles", null, s);
                throw new RemoteListVerificationException(s, "MissingRemoteFiles");
            }
        }

        public struct RemoteAnalysisResult
        {
            public IEnumerable<Volumes.IParsedVolume> ParsedVolumes;
            public IEnumerable<Volumes.IParsedVolume> ExtraVolumes;
            public IEnumerable<Volumes.IParsedVolume> OtherVolumes;
            public IEnumerable<RemoteVolumeEntry> MissingVolumes;
            public IEnumerable<RemoteVolumeEntry> VerificationRequiredVolumes;

            public string[] BackupPrefixes { get { return ParsedVolumes.Union(ExtraVolumes).Union(OtherVolumes).Select(x => x.Prefix).Distinct().ToArray(); } }
        }

        /// <summary>
        /// Creates a temporary verification file.
        /// </summary>
        /// <returns>The verification file.</returns>
        /// <param name="db">The database instance</param>
        /// <param name="stream">The stream to write to</param>
        public static void CreateVerificationFile(LocalDatabase db, System.IO.StreamWriter stream)
        {
            var s = new Newtonsoft.Json.JsonSerializer();
            s.Serialize(stream, db.GetRemoteVolumes().Where(x => x.State != RemoteVolumeState.Temporary).Cast<IRemoteVolume>().ToArray());
        }

        /// <summary>
        /// Uploads the verification file.
        /// </summary>
        /// <param name="backendurl">The backend url</param>
        /// <param name="options">The options to use</param>
        /// <param name="result">The result writer</param>
        /// <param name="db">The attached database</param>
        /// <param name="transaction">An optional transaction object</param>
        public static void UploadVerificationFile(string backendurl, Options options, IBackendWriter result, LocalDatabase db, System.Data.IDbTransaction transaction)
        {
            using(var backend = new BackendManager(backendurl, options, result, db))
            using(var tempfile = new Library.Utility.TempFile())
            {
                var remotename = options.Prefix + "-verification.json";
                using(var stream = new System.IO.StreamWriter(tempfile, false, System.Text.Encoding.UTF8))
                    FilelistProcessor.CreateVerificationFile(db, stream);

                if (options.Dryrun)
                {
                    Logging.Log.WriteDryrunMessage(LOGTAG, "WouldUploadVerificationFile", "Would upload verification file: {0}, size: {1}", remotename, Library.Utility.Utility.FormatSizeString(new System.IO.FileInfo(tempfile).Length));
                }
                else
                {
                    backend.PutUnencrypted(remotename, tempfile);
                    backend.WaitForComplete(db, transaction);
                }
            }
        }

        /// <summary>
        /// Helper method that verifies uploaded volumes and updates their state in the database.
        /// Throws an error if there are issues with the remote storage
        /// </summary>
        /// <param name="backend">The backend instance to use</param>
        /// <param name="options">The options used</param>
        /// <param name="database">The database to compare with</param>
        /// <param name="protectedFiles">Filenames that should be exempted from deletion</param>
        public static RemoteAnalysisResult RemoteListAnalysis(BackendManager backend, Options options, LocalDatabase database, IBackendWriter log, IEnumerable<string> protectedFiles)
        {
            var rawlist = backend.List();
            var lookup = new Dictionary<string, Volumes.IParsedVolume>();
            protectedFiles = protectedFiles ?? Enumerable.Empty<string>();

            var remotelist = (from n in rawlist
                                       let p = Volumes.VolumeBase.ParseFilename(n)
                                        where p != null && p.Prefix == options.Prefix
                                       select p).ToList();

            var otherlist = (from n in rawlist
                                let p = Volumes.VolumeBase.ParseFilename(n)
                                where p != null && p.Prefix != options.Prefix
                                select p).ToList();

            var unknownlist = (from n in rawlist
                                        let p = Volumes.VolumeBase.ParseFilename(n)
                                        where p == null
                                        select n).ToList();

            var filesets = (from n in remotelist
                                     where n.FileType == RemoteVolumeType.Files orderby n.Time descending
                                     select n).ToList();

            log.KnownFileCount = remotelist.Count;
            long knownFileSize = remotelist.Select(x => Math.Max(0, x.File.Size)).Sum();
            log.KnownFileSize = knownFileSize;
            log.UnknownFileCount = unknownlist.Count;
            log.UnknownFileSize = unknownlist.Select(x => Math.Max(0, x.Size)).Sum();
            log.BackupListCount = database.FilesetTimes.Count();
            log.LastBackupDate = filesets.Count == 0 ? new DateTime(0) : filesets[0].Time.ToLocalTime();

            CheckQuota(backend, options, log, knownFileSize);

            foreach (var s in remotelist)
                lookup[s.File.Name] = s;

            var missing = new List<RemoteVolumeEntry>();
            var missingHash = new List<Tuple<long, RemoteVolumeEntry>>();
            var cleanupRemovedRemoteVolumes = new HashSet<string>();

            foreach(var e in database.DuplicateRemoteVolumes())
            {
                if (e.Value == RemoteVolumeState.Uploading || e.Value == RemoteVolumeState.Temporary)
                    database.UnlinkRemoteVolume(e.Key, e.Value);
                else
                    throw new RemoteListVerificationException(string.Format("The remote volume {0} appears in the database with state {1} and a deleted state, cannot continue", e.Key, e.Value.ToString()), "AmbiguousStateRemoteFiles");
            }

            var locallist = database.GetRemoteVolumes();
            foreach(var i in locallist)
            {
                Volumes.IParsedVolume r;
                var remoteFound = lookup.TryGetValue(i.Name, out r);
                var correctSize = remoteFound && i.Size >= 0 && (i.Size == r.File.Size || r.File.Size < 0);

                lookup.Remove(i.Name);

                switch (i.State)
                {
                    case RemoteVolumeState.Deleted:
                        if (remoteFound)
                            Logging.Log.WriteInformationMessage(LOGTAG, "IgnoreRemoteDeletedFile", "ignoring remote file listed as {0}: {1}", i.State, i.Name);

                        break;

                    case RemoteVolumeState.Temporary:
                    case RemoteVolumeState.Deleting:
                        if (remoteFound)
                        {
                            Logging.Log.WriteInformationMessage(LOGTAG, "RemoveUnwantedRemoteFile", "removing remote file listed as {0}: {1}", i.State, i.Name);
                            backend.Delete(i.Name, i.Size, true);
                        }
                        else
                        {
                            if (i.DeleteGracePeriod > DateTime.UtcNow)
                            {
                                Logging.Log.WriteInformationMessage(LOGTAG, "KeepDeleteRequest", "keeping delete request for {0} until {1}", i.Name, i.DeleteGracePeriod.ToLocalTime());
                            }
                            else
                            {
                                if (i.State == RemoteVolumeState.Temporary && protectedFiles.Any(pf => pf == i.Name))
                                {
                                    Logging.Log.WriteInformationMessage(LOGTAG, "KeepIncompleteFile", "keeping protected incomplete remote file listed as {0}: {1}", i.State, i.Name);
                                }
                                else
                                {
                                    Logging.Log.WriteInformationMessage(LOGTAG, "RemoteUnwantedMissingFile", "removing file listed as {0}: {1}", i.State, i.Name);
                                    cleanupRemovedRemoteVolumes.Add(i.Name);
                                }
                            }
                        }
                        break;
                    case RemoteVolumeState.Uploading:
                        if (remoteFound && correctSize && r.File.Size >= 0)
                        {
                            Logging.Log.WriteInformationMessage(LOGTAG, "PromotingCompleteFile", "promoting uploaded complete file from {0} to {2}: {1}", i.State, i.Name, RemoteVolumeState.Uploaded);
                            database.UpdateRemoteVolume(i.Name, RemoteVolumeState.Uploaded, i.Size, i.Hash);
                        }
                        else if (!remoteFound)
                        {
                            if (protectedFiles.Any(pf => pf == i.Name))
                            {
                                Logging.Log.WriteInformationMessage(LOGTAG, "KeepIncompleteFile", "keeping protected incomplete remote file listed as {0}: {1}", i.State, i.Name);
                                database.UpdateRemoteVolume(i.Name, RemoteVolumeState.Temporary, i.Size, i.Hash, false, new TimeSpan(0), null);
                            }
                            else
                            {
                                Logging.Log.WriteInformationMessage(LOGTAG, "SchedulingMissingFileForDelete", "scheduling missing file for deletion, currently listed as {0}: {1}", i.State, i.Name);
                                cleanupRemovedRemoteVolumes.Add(i.Name);
                                database.UpdateRemoteVolume(i.Name, RemoteVolumeState.Deleting, i.Size, i.Hash, false, TimeSpan.FromHours(2), null);
                            }
                        }
                        else
                        {
                            if (protectedFiles.Any(pf => pf == i.Name))
                            {
                                Logging.Log.WriteInformationMessage(LOGTAG, "KeepIncompleteFile", "keeping protected incomplete remote file listed as {0}: {1}", i.State, i.Name);
                            }
                            else
                            {
                                Logging.Log.WriteInformationMessage(LOGTAG, "Remove incomplete file", "removing incomplete remote file listed as {0}: {1}", i.State, i.Name);
                                backend.Delete(i.Name, i.Size, true);
                            }
                        }
                        break;

                    case RemoteVolumeState.Uploaded:
                        if (!remoteFound)
                            missing.Add(i);
                        else if (correctSize)
                            database.UpdateRemoteVolume(i.Name, RemoteVolumeState.Verified, i.Size, i.Hash);
                        else
                            missingHash.Add(new Tuple<long, RemoteVolumeEntry>(r.File.Size, i));

                        break;

                    case RemoteVolumeState.Verified:
                        if (!remoteFound)
                            missing.Add(i);
                        else if (!correctSize)
                            missingHash.Add(new Tuple<long, RemoteVolumeEntry>(r.File.Size, i));

                        break;

                    default:
                        Logging.Log.WriteWarningMessage(LOGTAG, "UnknownFileState", null, "unknown state for remote file listed as {0}: {1}", i.State, i.Name);
                        break;
                }

                backend.FlushDbMessages();
            }

            // cleanup deleted volumes in DB en block
            database.RemoveRemoteVolumes(cleanupRemovedRemoteVolumes, null);

            foreach(var i in missingHash)
                Logging.Log.WriteWarningMessage(LOGTAG, "MissingRemoteHash", null, "remote file {1} is listed as {0} with size {2} but should be {3}, please verify the sha256 hash \"{4}\"", i.Item2.State, i.Item2.Name, i.Item1, i.Item2.Size, i.Item2.Hash);

            return new RemoteAnalysisResult()
            {
                ParsedVolumes = remotelist,
                OtherVolumes = otherlist,
                ExtraVolumes = lookup.Values,
                MissingVolumes = missing,
                VerificationRequiredVolumes = missingHash.Select(x => x.Item2)
            };
        }

        private static void CheckQuota(BackendManager backend, Options options, IBackendWriter log, long knownFileSize)
        {
            // TODO: We should query through the backendmanager
            using (var bk = DynamicLoader.BackendLoader.GetBackend(backend.BackendUrl, options.RawOptions))
                if (bk is IQuotaEnabledBackend enabledBackend && !options.QuotaDisable)
                {
                    Library.Interface.IQuotaInfo quota = enabledBackend.Quota;
                    if (quota != null)
                    {
                        log.TotalQuotaSpace = quota.TotalQuotaSpace;
                        log.FreeQuotaSpace = quota.FreeQuotaSpace;

                        // Check to see if there should be a warning or error about the quota
                        // Since this processor may be called multiple times during a backup
                        // (both at the start and end, for example), the log keeps track of
                        // whether a quota error or warning has been sent already.
                        // Note that an error can still be sent later even if a warning was sent earlier.
                        if (!log.ReportedQuotaError && quota.FreeQuotaSpace == 0)
                        {
                            log.ReportedQuotaError = true;
                            Logging.Log.WriteErrorMessage(LOGTAG, "BackendQuotaExceeded", null, "Backend quota has been exceeded: Using {0} of {1} ({2} available)", Library.Utility.Utility.FormatSizeString(knownFileSize), Library.Utility.Utility.FormatSizeString(quota.TotalQuotaSpace), Library.Utility.Utility.FormatSizeString(quota.FreeQuotaSpace));
                        }
                        else if (!log.ReportedQuotaWarning && !log.ReportedQuotaError && quota.FreeQuotaSpace >= 0) // Negative value means the backend didn't return the quota info
                        {
                            // Warnings are sent if the available free space is less than the given percentage of the total backup size.
                            double warningThreshold = options.QuotaWarningThreshold / (double)100;
                            if (quota.FreeQuotaSpace < warningThreshold * knownFileSize)
                            {
                                log.ReportedQuotaWarning = true;
                                Logging.Log.WriteWarningMessage(LOGTAG, "BackendQuotaNear", null, "Backend quota is close to being exceeded: Using {0} of {1} ({2} available)", Library.Utility.Utility.FormatSizeString(knownFileSize), Library.Utility.Utility.FormatSizeString(quota.TotalQuotaSpace), Library.Utility.Utility.FormatSizeString(quota.FreeQuotaSpace));
                            }
                        }
                    }
                }

            log.AssignedQuotaSpace = options.QuotaSize;
            if (log.AssignedQuotaSpace != -1)
            {
                // Check assigned quota
                if (!log.ReportedQuotaError && knownFileSize > log.AssignedQuotaSpace)
                {
                    log.ReportedQuotaError = true;
                    Logging.Log.WriteErrorMessage(LOGTAG, "AssignedQuotaExceeded", null, "Assigned quota has been exceeded: Using {0} of {1}", Library.Utility.Utility.FormatSizeString(knownFileSize), Library.Utility.Utility.FormatSizeString(log.AssignedQuotaSpace));
                }
                else if (!log.ReportedQuotaWarning && !log.ReportedQuotaError)
                {
                    // Warnings are sent if the available free space is less than the given percentage of the total backup size.
                    double warningThreshold = options.QuotaWarningThreshold / (double)100;
                    long freeSpace = log.AssignedQuotaSpace - knownFileSize;
                    if (freeSpace < warningThreshold * knownFileSize)
                    {
                        log.ReportedQuotaWarning = true;
                        Logging.Log.WriteWarningMessage(LOGTAG, "AssignedQuotaNear", null, "Assigned quota is close to being exceeded: Using {0} of {1}", Library.Utility.Utility.FormatSizeString(knownFileSize), Library.Utility.Utility.FormatSizeString(log.AssignedQuotaSpace));
                    }
                }
            }
        }
    }
}
