// Copyright (C) 2025, The Duplicati Team
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//
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using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Versioning;
using System.Text.RegularExpressions;
using Duplicati.Library.Snapshots;
using Duplicati.Library.Snapshots.Windows;

namespace Duplicati.Library.Modules.Builtin
{
    /// <summary>
    /// Provides options for Hyper-V backup.
    /// </summary>
    public class HyperVOptions : Interface.IGenericSourceModule
    {
        /// <summary>
        /// The tag used for logging
        /// </summary>
        private static readonly string LOGTAG = Logging.Log.LogTagFromType<HyperVOptions>();
        private const string m_HyperVPathGuidRegExp = @"\%HYPERV\%\\(?<id>[0-9a-fA-F]{8}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{12})(\\(?<path>.*))?";
        private const string m_HyperVPathAllMarker = @"%HYPERV%";

        private const string IGNORE_CONSISTENCY_WARNING_OPTION = "hyperv-ignore-client-warning";

        #region IGenericModule Members

        /// <summary>
        /// Gets the key identifier for this module.
        /// </summary>
        public string Key
        {
            get { return "hyperv-options"; }
        }

        /// <summary>
        /// Gets the display name for this module.
        /// </summary>
        public string DisplayName
        {
            get { return Strings.HyperVOptions.DisplayName; }
        }

        /// <summary>
        /// Gets the description of this module.
        /// </summary>
        public string Description
        {
            get { return Strings.HyperVOptions.Description; }
        }

        /// <summary>
        /// Gets whether this module should be loaded by default.
        /// </summary>
        public bool LoadAsDefault
        {
            get { return OperatingSystem.IsWindows(); }
        }

        /// <summary>
        /// Gets the list of supported command line arguments.
        /// </summary>
        public IList<Interface.ICommandLineArgument> SupportedCommands
            => new List<Interface.ICommandLineArgument>
            {
                new Interface.CommandLineArgument(IGNORE_CONSISTENCY_WARNING_OPTION, Interface.CommandLineArgument.ArgumentType.Boolean, Strings.HyperVOptions.IgnoreConsistencyWarningShort, Strings.HyperVOptions.IgnoreConsistencyWarningLong)
            };

        /// <summary>
        /// Configures the module with the provided command line options.
        /// </summary>
        /// <param name="commandlineOptions">The command line options dictionary.</param>
        public void Configure(IDictionary<string, string> commandlineOptions)
        {
            // Do nothing. Implementation needed for IGenericModule interface.
        }

        #endregion

        #region Implementation of IGenericSourceModule
        /// <summary>
        /// Parses the source paths for Hyper-V backups.
        /// </summary>
        /// <param name="paths">The source paths.</param>
        /// <param name="filter">The filter string.</param>
        /// <param name="commandlineOptions">The command line options.</param>
        /// <returns>A dictionary of changed options.</returns>
        public Dictionary<string, string> ParseSourcePaths(ref string[] paths, ref string filter, Dictionary<string, string> commandlineOptions)
        {
            // Early exit in case we are non-windows to prevent attempting to load Windows-only components
            if (!OperatingSystem.IsWindows())
            {
                Logging.Log.WriteWarningMessage(LOGTAG, "HyperVWindowsOnly", null, "Hyper-V backup works only on Windows OS");

                if (paths != null)
                    paths = paths.Where(x => !x.Equals(m_HyperVPathAllMarker, StringComparison.OrdinalIgnoreCase) && !Regex.IsMatch(x, m_HyperVPathGuidRegExp, RegexOptions.IgnoreCase | RegexOptions.CultureInvariant)).ToArray();

                if (!string.IsNullOrEmpty(filter))
                {
                    var filters = filter.Split(new string[] { System.IO.Path.PathSeparator.ToString() }, StringSplitOptions.RemoveEmptyEntries);
                    var remainingfilters = filters.Where(x => !Regex.IsMatch(x, m_HyperVPathGuidRegExp, RegexOptions.IgnoreCase | RegexOptions.CultureInvariant)).ToArray();
                    filter = string.Join(System.IO.Path.PathSeparator.ToString(), remainingfilters);
                }

                return new Dictionary<string, string>();
            }

            // Windows, do the real stuff!
            return RealParseSourcePaths(ref paths, ref filter, commandlineOptions);
        }

        /// <summary>
        /// Parses the source paths for Hyper-V backups (real implementation).
        /// </summary>
        /// <param name="paths">The source paths.</param>
        /// <param name="filter">The filter string.</param>
        /// <param name="commandlineOptions">The command line options.</param>
        /// <param name="hypervUtility">The Hyper-V utility instance.</param>
        /// <returns>A dictionary of changed options.</returns>
        // Make sure the JIT does not attempt to inline this call and thus load
        // referenced types from System.Management here
        [System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.NoInlining)]
        [SupportedOSPlatform("windows")]
        public Dictionary<string, string> RealParseSourcePaths(ref string[] paths, ref string filter, Dictionary<string, string> commandlineOptions, IHyperVUtility hypervUtility = null)
        {
            var changedOptions = new Dictionary<string, string>();
            var hypervFilters = new List<string>();

            if (!string.IsNullOrEmpty(filter))
            {
                var filters = filter.Split(new string[] { System.IO.Path.PathSeparator.ToString() }, StringSplitOptions.RemoveEmptyEntries);

                hypervFilters = filters.Where(x => Regex.IsMatch(x, m_HyperVPathGuidRegExp, RegexOptions.IgnoreCase | RegexOptions.CultureInvariant)).ToList();
                var remainingfilters = filters.Where(x => !Regex.IsMatch(x, m_HyperVPathGuidRegExp, RegexOptions.IgnoreCase | RegexOptions.CultureInvariant)).ToArray();
                filter = string.Join(System.IO.Path.PathSeparator.ToString(), remainingfilters);
            }

            hypervUtility ??= new HyperVUtility();

            if (paths == null || !ContainFilesForBackup(paths) || !hypervUtility.IsHyperVInstalled)
                return changedOptions;

            if (commandlineOptions.Keys.Contains("vss-exclude-writers"))
            {
                var excludedWriters = commandlineOptions["vss-exclude-writers"].Split(';').Where(x => !string.IsNullOrWhiteSpace(x) && x.Trim().Length > 0).Select(x => new Guid(x)).ToArray();

                if (excludedWriters.Contains(hypervUtility.HyperVWriterGuid))
                {
                    Logging.Log.WriteWarningMessage(LOGTAG, "CannotExcludeHyperVVSSWriter", null, "Excluded writers for VSS cannot contain Hyper-V writer when backuping Hyper-V virtual machines. Removing \"{0}\" to continue", hypervUtility.HyperVWriterGuid.ToString());
                    changedOptions["vss-exclude-writers"] = string.Join(";", excludedWriters.Where(x => x != hypervUtility.HyperVWriterGuid));
                }
            }

            if (!commandlineOptions.Keys.Contains("snapshot-policy") || !commandlineOptions["snapshot-policy"].Equals("required", StringComparison.OrdinalIgnoreCase))
            {
                Logging.Log.WriteWarningMessage(LOGTAG, "MustSetSnapshotPolicy", null, "Snapshot policy have to be set to \"required\" when backuping Hyper-V virtual machines. Changing to \"required\" to continue", Logging.LogMessageType.Warning);
                changedOptions["snapshot-policy"] = "required";
            }

            if (!hypervUtility.IsVSSWriterSupported && !Library.Utility.Utility.ParseBoolOption(commandlineOptions, IGNORE_CONSISTENCY_WARNING_OPTION))
                Logging.Log.WriteWarningMessage(LOGTAG, "HyperVOnServerOnly", null, "This is client version of Windows. Hyper-V VSS writer is present only on Server version. Backup will continue, but will be crash consistent only in opposite to application consistent in Server version");

            Logging.Log.WriteInformationMessage(LOGTAG, "StartingHyperVQuery", "Starting to gather Hyper-V information");
            var provider = Utility.Utility.ParseEnumOption(changedOptions.AsReadOnly(), "snapshot-provider", WindowsSnapshot.DEFAULT_WINDOWS_SNAPSHOT_QUERY_PROVIDER);
            hypervUtility.QueryHyperVGuestsInfo(provider, true);

            if (hypervUtility.Guests == null || hypervUtility.Guests.Count == 0)
            {
                Logging.Log.WriteWarningMessage(LOGTAG, "NoHyperVMachinesFound", null, "No Hyper-V virtual machines found.");
                return changedOptions;
            }

            Logging.Log.WriteInformationMessage(LOGTAG, "HyperVMachineCount", "Found {0} virtual machines on Hyper-V", hypervUtility.Guests?.Count);
            foreach (var guest in hypervUtility.Guests)
                Logging.Log.WriteProfilingMessage(LOGTAG, "FoundHyperVMachine", "Found VM name {0}, ID {1}, files {2}", guest.Name, guest.ID, string.Join(";", guest.DataPaths));

            var guestsForBackup = new List<HyperVGuest>();
            var conditionalPathsForBackup = new List<(string ID, string Path)>();

            if (paths.Contains(m_HyperVPathAllMarker, StringComparer.OrdinalIgnoreCase))
                guestsForBackup = hypervUtility.Guests;
            else
            {
                var guestEntries = paths.Where(x => Regex.IsMatch(x, m_HyperVPathGuidRegExp, RegexOptions.IgnoreCase | RegexOptions.CultureInvariant))
                    .Select(x =>
                    {
                        var m = Regex.Match(x, m_HyperVPathGuidRegExp, RegexOptions.IgnoreCase | RegexOptions.CultureInvariant);
                        return (ID: m.Groups["id"].Value, Path: m.Groups["path"].Value);
                    });

                foreach ((var guestID, var path) in guestEntries)
                {
                    var foundGuest = hypervUtility.Guests.Where(x => x.ID == new Guid(guestID));

                    if (foundGuest.Count() != 1)
                        throw new Duplicati.Library.Interface.UserInformationException(string.Format("Hyper-V guest specified in source with ID {0} cannot be found", guestID), "HyperVGuestNotFound");

                    if (string.IsNullOrWhiteSpace(path))
                        guestsForBackup.Add(foundGuest.First());
                    else
                        conditionalPathsForBackup.Add((guestID, path));
                }
            }

            var guestStatus = new Dictionary<string, bool>(StringComparer.OrdinalIgnoreCase);
            var pathFilters = new List<(string ID, string Filter)>();

            foreach (var filterExp in hypervFilters)
            {
                var m = Regex.Match(filterExp, m_HyperVPathGuidRegExp, RegexOptions.IgnoreCase | RegexOptions.CultureInvariant);
                (var id, var path) = (m.Groups["id"].Value, m.Groups["path"].Value);
                if (string.IsNullOrWhiteSpace(path))
                {
                    if (!guestStatus.ContainsKey(id))
                        guestStatus[id] = filterExp.StartsWith("-", StringComparison.Ordinal) ? false : true;
                }
                else
                {
                    pathFilters.Add((id, filterExp[0] + path));
                }
            }

            guestsForBackup = guestsForBackup
                .Where(x => !guestStatus.ContainsKey(x.ID.ToString()) || guestStatus[x.ID.ToString()])
                .DistinctBy(x => x.ID)
                .ToList();

            var includedGuestIds = guestsForBackup.Select(x => x.ID.ToString()).ToHashSet(StringComparer.OrdinalIgnoreCase);

            pathFilters = pathFilters
                .Where(x => includedGuestIds.Contains(x.ID))
                .DistinctBy(x => x.ID)
                .ToList();

            conditionalPathsForBackup = conditionalPathsForBackup
                .Where(x => includedGuestIds.Contains(x.ID))
                .DistinctBy(x => x.ID)
                .ToList();

            var filterhandler = pathFilters.Select(x => x.Filter)
                .Concat(filter.Split(new[] { System.IO.Path.PathSeparator }, StringSplitOptions.RemoveEmptyEntries))
                .Where(x => !string.IsNullOrWhiteSpace(x))
                .Select(x => Utility.FilterExpression.StringToIFilter(x))
                .Append(new Utility.FilterExpression())
                .Aggregate((a, b) => Utility.FilterExpression.Combine(a, b));

            var pathsForBackup = new List<string>(paths.Where(x => !x.Equals(m_HyperVPathAllMarker, StringComparison.OrdinalIgnoreCase) && !Regex.IsMatch(x, m_HyperVPathGuidRegExp, RegexOptions.IgnoreCase | RegexOptions.CultureInvariant)));
            pathsForBackup.AddRange(conditionalPathsForBackup.Select(x => x.Path).Where(x => !string.IsNullOrWhiteSpace(x)));

            foreach (var guestForBackup in guestsForBackup)
                foreach (var pathForBackup in guestForBackup.DataPaths)
                {
                    if (!filterhandler.Matches(pathForBackup, out _, out _))
                    {
                        Logging.Log.WriteInformationMessage(LOGTAG, "IncludeHyperV", "For VM {0} - adding {1}", guestForBackup.Name, pathForBackup);
                        pathsForBackup.Add(pathForBackup);
                    }
                    else
                        Logging.Log.WriteInformationMessage(LOGTAG, "ExcludeByFilter", "Excluding {0} based on excluding filters", pathForBackup);
                }

            paths = pathsForBackup
                .Distinct(Utility.Utility.ClientFilenameStringComparer).OrderBy(a => a).ToArray();

            return changedOptions;
        }

        /// <summary>
        /// Determines whether the paths contain files for Hyper-V backup.
        /// </summary>
        /// <param name="paths">The paths to check.</param>
        /// <returns>True if the paths contain Hyper-V files for backup.</returns>
        public bool ContainFilesForBackup(string[] paths)
        {
            if (paths == null || !OperatingSystem.IsWindows())
                return false;

            return paths.Where(x => !string.IsNullOrWhiteSpace(x)).Any(x => x.Equals(m_HyperVPathAllMarker, StringComparison.OrdinalIgnoreCase) || Regex.IsMatch(x, m_HyperVPathGuidRegExp, RegexOptions.IgnoreCase | RegexOptions.CultureInvariant));
        }

        #endregion
    }
}