// Copyright (C) 2025, The Duplicati Team
// https://duplicati.com, hello@duplicati.com
//
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// The above copyright notice and this permission notice shall be included in
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//
// 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
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using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Threading;
using System.Xml.Linq;
using Duplicati.Library.Utility;
using Duplicati.Proprietary.DiskImage;
using Duplicati.Proprietary.DiskImage.General;
using NUnit.Framework;

#nullable enable

namespace Duplicati.UnitTest.DiskImage
{
    /// <summary>
    /// macOS implementation of <see cref="IDiskImageHelper"/> using hdiutil and standard macOS tools.
    /// </summary>
    internal class MacOSDiskImageHelper : IDiskImageHelper
    {
        /// <inheritdoc />
        public string CreateDisk(string imagePath, long sizeB)
        {
            // Ensure the directory exists
            var directory = Path.GetDirectoryName(imagePath);
            if (!string.IsNullOrEmpty(directory) && !Directory.Exists(directory))
                Directory.CreateDirectory(directory);

            // Delete existing image if it exists
            if (File.Exists(imagePath))
                try
                {
                    CleanupDisk(imagePath);
                }
                catch
                {
                    // Ignore errors during cleanup
                }

            // Create a raw disk image using hdiutil
            // Use UDIF format with "Free Space" filesystem (unformatted)
            RunProcess("hdiutil", $"create -size {sizeB} -type UDIF -layout NONE -o \"{imagePath}\"");

            var output = RunProcess("hdiutil", $"attach -nomount -noautofsck \"{imagePath}\"");

            // Parse the disk device from output (e.g., "/dev/disk4")
            var diskDevice = output.Trim().Split(new[] { '\r', '\n' }, StringSplitOptions.RemoveEmptyEntries).FirstOrDefault()?.Trim()
                ?? throw new InvalidOperationException("Failed to get disk device from hdiutil attach output");

            // Return the raw device path for direct I/O
            return diskDevice.Replace("/dev/disk", "/dev/rdisk");
        }

        private string[] GetPartitionNames(string diskIdentifier)
        {
            var output = RunProcess("diskutil", $"list -plist {diskIdentifier}");

            var plist = XDocument.Parse(output);
            var rootDict = plist.Element("plist")?.Element("dict");
            if (rootDict == null)
                return [];

            // Find the disk in AllDisksAndPartitions
            var allDisksAndPartitions = PlistHelper.GetArrayElement(rootDict, "AllDisksAndPartitions");
            if (allDisksAndPartitions == null)
                return [];

            // Normalize disk identifier - plist stores just "disk4" but we might have "/dev/disk4" or "/dev/rdisk4"
            var normalizedId = diskIdentifier.Replace("/dev/rdisk", "disk").Replace("/dev/disk", "disk");

            var diskElement = allDisksAndPartitions.Elements("dict")
                .FirstOrDefault(d => PlistHelper.GetStringValue(d, "DeviceIdentifier") == normalizedId);

            if (diskElement == null)
                return [];

            var partitions = new List<string>();

            // Check for regular partitions
            var partitionsArray = PlistHelper.GetArrayElement(diskElement, "Partitions");
            if (partitionsArray != null)
            {
                foreach (var partition in partitionsArray.Elements("dict"))
                {
                    var deviceIdentifier = PlistHelper.GetStringValue(partition, "DeviceIdentifier");
                    if (!string.IsNullOrWhiteSpace(deviceIdentifier))
                        partitions.Add(deviceIdentifier);
                }
            }

            // Check for APFS volumes
            var apfsVolumes = PlistHelper.GetArrayElement(diskElement, "APFSVolumes");
            if (apfsVolumes != null)
            {
                foreach (var volume in apfsVolumes.Elements("dict"))
                {
                    var deviceIdentifier = PlistHelper.GetStringValue(volume, "DeviceIdentifier");
                    if (!string.IsNullOrWhiteSpace(deviceIdentifier))
                        partitions.Add(deviceIdentifier);
                }
            }

            return [.. partitions];
        }

        private string[] GetMountPoints(string diskIdentifier)
        {
            var partitions = GetPartitionNames(diskIdentifier);
            var mountPoints = new System.Collections.Generic.List<string>();

            foreach (var partition in partitions)
            {
                var output = RunProcess("diskutil", $"info -plist /dev/{partition}");
                var plist = XDocument.Parse(output);
                var dict = plist.Element("plist")?.Element("dict");
                if (dict == null)
                    continue;

                // Check if this is an APFS Physical Store
                var contentType = PlistHelper.GetStringValue(dict, "Content");
                var isApfsPhysicalStore = contentType == "Apple_APFS";

                if (isApfsPhysicalStore)
                {
                    // For APFS, get the container and then get volumes from it
                    var containerId = PlistHelper.GetStringValue(dict, "APFSContainerReference");
                    if (!string.IsNullOrEmpty(containerId))
                    {
                        // Get volumes from the container (they are like disk5s1, disk5s2, etc.)
                        var containerVolumes = GetApfsContainerVolumes(containerId);
                        foreach (var volume in containerVolumes)
                        {
                            var volumeOutput = RunProcess("diskutil", $"info -plist {volume}");
                            var volumePlist = XDocument.Parse(volumeOutput);
                            var volumeDict = volumePlist.Element("plist")?.Element("dict");
                            if (volumeDict != null)
                            {
                                var mountPoint = PlistHelper.GetStringValue(volumeDict, "MountPoint");
                                if (!string.IsNullOrEmpty(mountPoint))
                                    mountPoints.Add(mountPoint);
                            }
                        }
                    }
                }
                else
                {
                    // Regular partition - extract mount point directly
                    var mountPoint = PlistHelper.GetStringValue(dict, "MountPoint");
                    if (!string.IsNullOrEmpty(mountPoint))
                        mountPoints.Add(mountPoint);
                }
            }

            return [.. mountPoints];
        }

        private string[] GetApfsContainerVolumes(string containerId)
        {
            var output = RunProcess("diskutil", $"list -plist {containerId}");

            var plist = XDocument.Parse(output);
            var rootDict = plist.Element("plist")?.Element("dict");
            if (rootDict == null)
                return [];

            var allDisksAndPartitions = PlistHelper.GetArrayElement(rootDict, "AllDisksAndPartitions");
            if (allDisksAndPartitions == null)
                return [];

            // Normalize container id - plist stores just "disk4" but we might have "/dev/disk4" or "/dev/rdisk4"
            var normalizedId = containerId.Replace("/dev/rdisk", "disk").Replace("/dev/disk", "disk");

            var container = allDisksAndPartitions.Elements("dict")
                .FirstOrDefault(d => PlistHelper.GetStringValue(d, "DeviceIdentifier") == normalizedId);

            if (container == null)
                return [];

            var volumes = new List<string>();
            var apfsVolumes = PlistHelper.GetArrayElement(container, "APFSVolumes");
            if (apfsVolumes != null)
            {
                foreach (var volume in apfsVolumes.Elements("dict"))
                {
                    var deviceIdentifier = PlistHelper.GetStringValue(volume, "DeviceIdentifier");
                    if (!string.IsNullOrWhiteSpace(deviceIdentifier))
                        volumes.Add(deviceIdentifier);
                }
            }

            return [.. volumes];
        }

        /// <inheritdoc />
        public string[] InitializeDisk(string diskIdentifier, PartitionTableType tableType, (FileSystemType, long)[] partitions)
        {
            if (tableType == PartitionTableType.Unknown)
                return []; // No partition table, so nothing to initialize

            // Use diskutil to partition the disk with the specified scheme
            // "Free Space" means no filesystem, just the partition table
            var partitionStrings = partitions.Length > 0 ? partitions.Select((p, i) =>
            {
                var fsType = p.Item1 switch
                {
                    FileSystemType.NTFS => throw new NotSupportedException("NTFS is not natively supported on macOS for creating partitions. Use ExFAT or FAT32 instead."),
                    FileSystemType.FAT32 => "\"MS-DOS FAT32\"",
                    FileSystemType.ExFAT => "ExFAT",
                    FileSystemType.HFSPlus => "HFS+",
                    FileSystemType.APFS => "APFS",
                    _ => throw new ArgumentException($"Unsupported filesystem type on macOS: {p.Item1}", nameof(partitions))
                };

                var sizeArg = p.Item2 > 0 ? $"{p.Item2}" : "0";
                return $"{fsType} \"Partition {i + 1}\" {sizeArg}";
            })
            : ["\"Free Space\" \"\" 0"];
            var partitionArgs = string.Join(" ", partitionStrings);

            // Normalize disk identifier for diskutil command (it expects "disk4", not "/dev/rdisk4")
            var normalizedDiskId = diskIdentifier.Replace("/dev/rdisk", "disk").Replace("/dev/disk", "disk");
            RunProcess("diskutil", $"partitionDisk {normalizedDiskId} {tableType.ToString().ToUpperInvariant()} {partitionArgs}");

            if (partitions.Length == 0)
                return [];

            return GetMountPoints(diskIdentifier);
        }

        /// <inheritdoc />
        public string[] Mount(string diskIdentifier, string? baseMountPath = null, bool readOnly = false, FileSystemType[]? fileSystemTypes = null)
        {
            // Check if already mounted
            try
            {
                var existingMountPoints = GetMountPoints(diskIdentifier);
                if (existingMountPoints.Length > 0 && existingMountPoints.All(mp => mp.StartsWith(baseMountPath ?? "/Volumes/")))
                {
                    return existingMountPoints;
                }
            }
            catch
            {
                // Ignore errors and try mounting
            }

            // Get the list of partitions first to ensure we target the correct disk
            var partitions = GetPartitionNames(diskIdentifier);

            List<string> mountPoints = [];
            foreach (var partition in partitions)
            {
                var output = RunProcess("diskutil", $"info -plist /dev/{partition}");
                var plist = XDocument.Parse(output);
                var dict = plist.Element("plist")?.Element("dict");
                if (dict == null)
                    continue;

                // Check if this is an APFS Physical Store
                var contentType = PlistHelper.GetStringValue(dict, "Content");
                var isApfsPhysicalStore = contentType == "Apple_APFS";

                if (isApfsPhysicalStore)
                {
                    // For APFS, get the container and mount volumes from it
                    var containerId = PlistHelper.GetStringValue(dict, "APFSContainerReference");
                    if (!string.IsNullOrEmpty(containerId))
                    {
                        // Get volumes from the container (they are like disk5s1, disk5s2, etc.)
                        var containerVolumes = GetApfsContainerVolumes(containerId);
                        foreach (var volume in containerVolumes)
                        {
                            MountVolume(volume, baseMountPath, mountPoints, readOnly);
                        }
                    }
                }
                else
                {
                    // Regular partition - mount directly
                    MountVolume(partition, baseMountPath, mountPoints, readOnly);
                }
            }

            return mountPoints.Count == 0 ? WaitForMountPoints(diskIdentifier) : [.. mountPoints];
        }

        /// <summary>
        /// Mounts a single volume/partition with optional custom mount point.
        /// </summary>
        /// <param name="volume">The volume identifier (e.g., "disk4s1").</param>
        /// <param name="baseMountPath">Optional base path for mounting.</param>
        /// <param name="mountPoints">List to collect mount points.</param>
        /// <param name="readOnly">Indicates whether the volume should be mounted as read-only.</param>
        private void MountVolume(string volume, string? baseMountPath, List<string> mountPoints, bool readOnly)
        {
            var dir = "";
            var mountArgs = readOnly ? "-readOnly" : "";
            if (baseMountPath is not null)
            {
                dir = Path.Combine(baseMountPath, volume);
                Directory.CreateDirectory(dir); // diskutil will mount to this directory instead of /Volumes/ if it exists, so create it ahead of time
                var readOnlyArg = readOnly ? " -readOnly" : "";
                mountArgs = $"{readOnlyArg} -mountPoint \"{dir}\"";
            }

            // Unmount first in case it's already mounted somewhere else, to ensure it gets mounted to the correct location
            var oldMp = GetMountPointFromPlist(RunProcess("diskutil", $"info -plist /dev/{volume}"));
            if (oldMp is not null && !oldMp.StartsWith(baseMountPath ?? "/Volumes/"))
                RunProcess("diskutil", $"unmount force /dev/{volume}");

            RunProcess("diskutil", $"mount -nobrowse {mountArgs} /dev/{volume}");

            // Verify the mount
            var mp = RunProcess("diskutil", $"info -plist /dev/{volume}");
            var mountPoint = GetMountPointFromPlist(mp);
            if (!string.IsNullOrEmpty(mountPoint))
            {
                mountPoints.Add(mountPoint);

                if (!mountPoint.StartsWith(baseMountPath ?? "/Volumes/"))
                {
                    Console.WriteLine($"Warning: Volume /dev/{volume} did not mount to expected location. Output: {mp}");
                }
            }
            else
            {
                Console.WriteLine($"Warning: Volume /dev/{volume} did not report a mount point after mounting. Output: {mp}");
            }
        }

        /// <summary>
        /// Extracts the mount point from diskutil info -plist output.
        /// </summary>
        private string? GetMountPointFromPlist(string plistOutput)
        {
            try
            {
                var plist = XDocument.Parse(plistOutput);
                var dict = plist.Element("plist")?.Element("dict");
                if (dict == null)
                    return null;

                var mountPoint = PlistHelper.GetStringValue(dict, "MountPoint");
                // Return null if not mounted (empty string indicates not mounted)
                return string.IsNullOrWhiteSpace(mountPoint) ? null : mountPoint;
            }
            catch
            {
                return null;
            }
        }

        /// <summary>
        /// Waits for mount points to be fully established after a mount operation.
        /// Uses exponential backoff starting from a short delay to minimize wait time
        /// in the common case while still handling slow mounts.
        ///
        /// After mounting (especially after raw partition table writes during restore),
        /// macOS may need time to fully recognize filesystems and establish mount points
        /// in /Volumes/. Without this retry loop, mount points may be:
        /// - Not yet available (empty array)
        /// - In a transient location like /private/var/ instead of /Volumes/
        /// - Mounted but with empty directories (filesystem not yet recognized)
        /// </summary>
        /// <param name="diskIdentifier">The disk identifier to check mount points for.</param>
        /// <returns>An array of mount point paths.</returns>
        private string[] WaitForMountPoints(string diskIdentifier)
        {
            const int maxRetries = 10;
            const int initialDelayMs = 100;
            const int maxDelayMs = 1000;

            var delayMs = initialDelayMs;
            for (int i = 0; i < maxRetries; i++)
            {
                var mountPoints = GetMountPoints(diskIdentifier);

                if (mountPoints.Length > 0)
                {
                    // Check if any mount points are in a transient location (not under /Volumes/)
                    if (mountPoints.Any(mp => !mp.StartsWith("/Volumes/")))
                    {
                        Thread.Sleep(delayMs);
                        delayMs = Math.Min(delayMs * 2, maxDelayMs);
                        continue;
                    }

                    // Check if all mount points have filesystem entries (not empty)
                    var allNonEmpty = mountPoints.All(mp =>
                    {
                        try { return Directory.GetFileSystemEntries(mp).Length > 0; }
                        catch { return false; }
                    });

                    if (allNonEmpty || i == maxRetries - 1)
                        return mountPoints;
                }

                Thread.Sleep(delayMs);
                delayMs = Math.Min(delayMs * 2, maxDelayMs);
            }

            // Final attempt - return whatever we have
            return GetMountPoints(diskIdentifier);
        }

        public void Unmount(string diskIdentifier)
        {
            int retryCount = 3;
            for (int i = 0; i < retryCount; i++)
            {
                try
                {
                    // Unmount all volumes on the disk
                    RunProcess("diskutil", $"unmountDisk {diskIdentifier}");
                }
                catch
                {
                    // Sometimes an unmount is issued too fast after writing data, which makes diskutil throw an errory.
                    Thread.Sleep(500);
                }
            }
        }

        /// <inheritdoc />
        public void FlushDisk(string diskIdentifier)
        {
            // On macOS, use sync to flush all filesystem buffers
            RunProcess("sync", "");
        }

        /// <inheritdoc />
        public void CleanupDisk(string imagePath, string? diskIdentifier = null)
        {
            if (diskIdentifier is null)
            {
                var output = RunProcess("hdiutil", $"info");

                diskIdentifier = output
                    .Split("================================================")
                    .Skip(1) // Skip the header
                    .Select(d =>
                    {
                        var lines = d
                            .Split('\n')
                            .Select(l => l.Trim())
                            .Where(l => l.Length > 0)
                            .ToList();
                        var imagePathLine = lines.FirstOrDefault(l => l.StartsWith("image-path"));
                        if (imagePathLine == null)
                            return null;

                        var path = imagePathLine.Split([':'], 2)[1].Trim();
                        if (!string.Equals(path, imagePath, StringComparison.OrdinalIgnoreCase))
                            return null;

                        var deviceLine = lines.FirstOrDefault(l => l.StartsWith("/dev/"));
                        if (deviceLine == null)
                            return null;

                        var device = deviceLine
                            .Split(['\t'], 2)[0]
                            .Trim();

                        return device;
                    })
                    .FirstOrDefault(d => d != null);
            }

            if (diskIdentifier is null)
                throw new InvalidOperationException($"Failed to determine disk identifier for {imagePath} during cleanup");

            try
            {
                RunProcess("diskutil", $"eject {diskIdentifier}");
            }
            catch (Exception ex)
            {
                Console.WriteLine($"Warning: Failed to detach disk image: {ex.Message}");
            }

            try
            {
                if (File.Exists(imagePath))
                    File.Delete(imagePath);
            }
            catch (Exception ex)
            {
                Console.WriteLine($"Warning: Failed to delete disk image file: {ex.Message}");
            }
        }

        /// <inheritdoc />
        public bool HasRequiredPrivileges()
        {
            // Root is not required for virtual disks.
            return true;
        }

        /// <inheritdoc />
        public PartitionTableGeometry GetPartitionTable(string diskIdentifier)
        {
            var output = RunProcess("diskutil", $"info -plist {diskIdentifier}");

            var plist = XDocument.Parse(output);
            var dict = plist.Element("plist")?.Element("dict");
            if (dict == null)
                throw new InvalidOperationException($"Failed to parse diskutil info plist for {diskIdentifier}");

            // Verify disk identifier
            var deviceIdentifier = PlistHelper.GetStringValue(dict, "DeviceIdentifier");
            if (!diskIdentifier.EndsWith(deviceIdentifier ?? "", StringComparison.OrdinalIgnoreCase))
                throw new InvalidOperationException($"Disk identifier mismatch in diskutil info output: {diskIdentifier} doesn't end with {deviceIdentifier}");

            // Determine partition table type
            var contentType = PlistHelper.GetStringValue(dict, "Content");
            var tableType = contentType switch
            {
                "GUID_partition_scheme" => PartitionTableType.GPT,
                "FDisk_partition_scheme" => PartitionTableType.MBR,
                _ => PartitionTableType.Unknown
            };

            // Get size and sector size
            var size = PlistHelper.GetLongValue(dict, "TotalSize");
            var sectorSize = (int)PlistHelper.GetLongValue(dict, "DeviceBlockSize");

            if (size == 0 || sectorSize == 0)
                throw new InvalidOperationException($"Failed to retrieve partition table information for disk {diskIdentifier}");

            return new PartitionTableGeometry
            {
                Type = tableType,
                Size = size,
                SectorSize = sectorSize
                // Ignore the rest for now.
            };
        }

        /// <inheritdoc />
        public PartitionGeometry[] GetPartitions(string diskIdentifier)
        {
            var names = GetPartitionNames(diskIdentifier);

            var partitions = new List<PartitionGeometry>();
            foreach (var name in names)
            {
                var output = RunProcess("diskutil", $"info -plist /dev/{name}");

                var plist = XDocument.Parse(output);
                var dict = plist.Element("plist")?.Element("dict");
                if (dict == null)
                    continue;

                // Verify device node
                var deviceNode = PlistHelper.GetStringValue(dict, "DeviceNode");
                if (!string.Equals(deviceNode, $"/dev/{name}", StringComparison.OrdinalIgnoreCase))
                    throw new InvalidOperationException($"Partition identifier mismatch in diskutil info output: expected /dev/{name}, got {deviceNode}");

                // Extract partition number from name (e.g., "disk4s1" -> 1)
                var partitionNumber = int.TryParse(
                    name.LastIndexOf('s') >= 0 ? name[(name.LastIndexOf('s') + 1)..] : "",
                    out int num) ? num : -1;

                // Parse filesystem type
                var fsPersonality = PlistHelper.GetStringValue(dict, "FilesystemPersonality");
                var filesystemType = fsPersonality switch
                {
                    "MS-DOS FAT32" => FileSystemType.FAT32,
                    "ExFAT" => FileSystemType.ExFAT,
                    "HFS+" => FileSystemType.HFSPlus,
                    "APFS" => FileSystemType.APFS,
                    _ => FileSystemType.Unknown
                };

                // Parse volume UUID
                Guid? volumeGuid = null;
                var volumeUuid = PlistHelper.GetStringValue(dict, "VolumeUUID");
                if (Guid.TryParse(volumeUuid, out Guid parsedGuid))
                    volumeGuid = parsedGuid;

                PartitionGeometry partition = new()
                {
                    Number = partitionNumber,
                    Type = PartitionType.Unknown,
                    StartOffset = PlistHelper.GetLongValue(dict, "PartitionMapPartitionOffset"),
                    Size = PlistHelper.GetLongValue(dict, "TotalSize"),
                    Name = PlistHelper.GetStringValue(dict, "VolumeName"),
                    FilesystemType = filesystemType,
                    VolumeGuid = volumeGuid,
                    TableType = PartitionTableType.Unknown
                };

                partitions.Add(partition);
            }

            return partitions.ToArray();
        }

        public string ReAttach(string imagePath, string diskIdentifier, PartitionTableType tableType, bool readOnly = false)
        {
            // Eject can fail if issued too fast after writing data, which makes diskutil throw an error. Retry a few times with a delay to mitigate this.
            RunProcess("diskutil", $"eject {diskIdentifier}", retryCount: 3);
            var reattachoutput = RunProcess("hdiutil", $"attach -nomount -noautofsck -readonly \"{imagePath}\"");
            if (tableType == PartitionTableType.Unknown)
                return reattachoutput.Split('\n').First().Trim();
            else
                return reattachoutput
                    .Split('\n')
                    .Select(x => x.Trim()
                        .Split(' ')
                        .Where(y => !string.IsNullOrEmpty(y))
                        .Select(y => y.Trim())
                        .ToArray()
                    )
                    .Where(x => x.Length > 0 && x[^1].EndsWith("_partition_scheme"))
                    .First().First();
        }

        public static string RunProcess(string fileName, string arguments, int retryCount = 0)
        {
            for (int i = 0; i <= retryCount; i++)
            {
                var result = ProcessRunner.RunProcessAsync(fileName, arguments, 30_000).Await();


                if (result.ExitCode != 0)
                    if (i < retryCount)
                    {
                        Console.WriteLine($"Warning: Process {fileName} with arguments {arguments} exited with code {result.ExitCode}. Retrying... Attempt {i + 1} of {retryCount}");
                        Thread.Sleep(500);
                        continue;
                    }
                    else
                        throw new InvalidOperationException($"Process {fileName} with arguments {arguments} exited with code {result.ExitCode}: {result.Error}. Output: {result.Output}");

                return result.Output;
            }

            // This should never be hit due to the retry loop logic, but is required to satisfy the compiler.
            throw new InvalidOperationException($"Failed to run process {fileName} with arguments {arguments} after retries. This should not happen.");
        }

        /// <inheritdoc />
        public void Dispose()
        {
            // Nothing to dispose
            GC.SuppressFinalize(this);
        }

    }
}