// Copyright Epic Games, Inc. All Rights Reserved.

#if DEBUG
// When enabled the command will not actually submit the changelist, but will act like it did.
// This is for development purposes only and so is only available in the debug config.
//#define UE_DEBUG_DISABLE_SUBMITS
#endif

using EpicGames.Core;
using EpicGames.Perforce;
using Microsoft.Extensions.Logging;
using Microsoft.Win32;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Text.Json;
using System.Threading;
using System.Threading.Tasks;

namespace P4VUtils.Commands
{
	/// <summary>
	/// Contains info about a built exe, generated by our build system (found in .version files)
	/// </summary>
	public class BuildVersion
	{
		public int? MajorVersion { get; set; }
		public int? MinorVersion { get; set; }
		public int? PatchVersion { get; set; }
		public int? Changelist { get; set; }
		public int? CompatibleChangelist { get; set; }
		public int? IsLicenseeVersion { get; set; }
		public int? IsPromotedBuild { get; set; }
		public string? BranchName { get; set; }
		public string? BuildId { get; set; }
	}

	/// <summary>
	/// A partial representation of the .target file generated by our build system. We are only
	/// interested in the BuildVersion info and so the class does not have any other members.
	/// </summary>
	public class TargetBuildVersion
	{
		public BuildVersion? Version { get; set; }
	}

	public static class LoggingUtils
	{
		/// <summary>
		/// This extension is used to write a new line to the logger. 
		/// log.NewLine better shows intent over log.LogInformation("")
		/// </summary>
		public static void NewLine(this ILogger logger)
		{
			logger.LogInformation("");
		}
	}

	[Command("submitandvirtualize", CommandCategory.Content, 0)]
	class SubmitAndVirtualizeCommand : Command
	{
		public override string Description => "Virtualize And Submit";

		public override CustomToolInfo CustomTool => new CustomToolInfo("Virtualize And Submit", "$c %C") { ShowConsole = true, RefreshUI = true };

		public override async Task<int> Execute(string[] args, IReadOnlyDictionary<string, string> configValues, ILogger logger)
		{
			// Parse command lines
			if (args.Length < 3)
			{
				logger.LogError("Error: Not enough args for command, tool is now exiting");
				return 1;
			}

			string clientSpec = args[1];

			List<int> changelistsToSubmit = new List<int>();

			for (int index = 2; index < args.Length; ++index)
			{
				if (!int.TryParse(args[index], out int changeNumber))
				{
					logger.LogError("Error: '{Argument}' is not a numbered changelist, tool is now exiting", args[index]);
					return 1;
				}

				changelistsToSubmit.Add(changeNumber);
			}

			if (changelistsToSubmit.Count == 0)
			{
				logger.LogError("Error: No changelists to submit were provided, tool is now exiting");
				return 1;
			}

			// Connect to perforce and validate

			logger.LogInformation("Connecting to Perforce...");

			// We prefer the native client to avoid the problem where different versions of p4.exe expect
			// or return records with different formatting to each other.
			PerforceSettings settings = new PerforceSettings(PerforceSettings.Default) { PreferNativeClient = true, ClientName = clientSpec };
			using IPerforceConnection perforceConnection = await PerforceConnection.CreateAsync(settings, logger);
			if (perforceConnection == null)
			{
				logger.LogError("Error: Failed to connect to Perforce, tool is now exiting");
				return 1;
			}

			for (int index = 0; index < changelistsToSubmit.Count; ++index)
			{
				logger.NewLine();
				logger.LogInformation("========== Processing change list {Index}/{Count} ==========", index + 1, changelistsToSubmit.Count);

				int changeNumber = changelistsToSubmit[index];
				if(await ProcessChangelist(perforceConnection, changeNumber, logger) == false)
				{
					logger.LogError("\nError: Failed to process CL {Changelist}, tool is now exiting", changeNumber);
					return 1;
				}
			}

			logger.NewLine();
			logger.LogInformation("========== All changelist(s) submitted successfully, tool is now exiting ==========");
			
			return 0;
		}

		public static async Task<bool> ProcessChangelist(IPerforceConnection perforceConnection, int changeNumber, ILogger logger)
		{
			if (perforceConnection == null || perforceConnection.Settings == null || perforceConnection.Settings.ClientName == null)
			{
				logger.LogError("Error: Invalid Perforce connection!");
				return false;
			}

			string clientSpec = perforceConnection.Settings.ClientName;

			logger.LogInformation("Attempting to virtualize and submit changelist {Change} in the workspace {Spec}", changeNumber, clientSpec);

			// First we need to find the packages in the changelist
			string[]? localFilePaths = await FindPackagesInChangelist(perforceConnection, changeNumber, logger);
			if (localFilePaths == null)
			{
				return false;
			}

			if (localFilePaths.Length > 0)
			{
				// If the changelist has shelved files then the submit will fail, so if we have package files that
				// need to be checked for virtualization we don't want to have the potentially long virtualization
				// process run (during which the user will alt-tab) only for it to fail at the end.
				// So we should check for shelved files now and early out before the virtualization process runs.
				if (await DoesChangelistHaveShelvedFiles(perforceConnection, changeNumber) == true)
				{
					logger.LogError("Error: Changelist {Change} has shelved files and cannot be submitted", changeNumber);
					return false;
				}

				logger.LogInformation("Found {Amount} package(s) that may need virtualization", localFilePaths.Length);

				// Now sort the package paths by their project (it is unlikely but a user could be submitting content
				// from multiple projects that the same time)

				Dictionary<string, List<string>> projects = SortPackagesIntoProjects(localFilePaths, logger);

				logger.LogInformation("The packages are distributed between {Amount} project(s)", projects.Count);

				// Find engine per project
				IReadOnlyDictionary<string, string> engineInstalls = EnumerateEngineInstallations(logger);

				foreach (KeyValuePair<string, List<string>> project in projects)
				{
					string projectPath = project.Key;
					string engineRoot = GetEngineRootForProject(projectPath, logger);
					if (!String.IsNullOrEmpty(engineRoot))
					{
						logger.NewLine();
						logger.LogInformation("Attempting to virtualize packages in project '{Project}' using the engine installation '{Engine}'", project.Key, engineRoot);
						// @todo Many projects can share the same engine install, and technically UnrealVirtualizationTool
						// supports the virtualization files from many projects at the same time. We could consider doing
						// this pass per engine install rather than per project? At the very least we should only 'build'
						// the tool once per engine

						Task<bool> compileResult = ValidateOrBuildVirtualizationTool(engineRoot, logger);

						string tempFilesPath = await WritePackageFileList(project.Value, logger);

						// Check if the compilation of the tool succeeded or not
						if (await compileResult == false)
						{
							return false;
						}

						// Even though this will have been done while we were waiting for BuildVirtualizationTool to complete 
						// we want to log that it was done after so that the output log makes sense to the user, otherwise 
						// they will end up thinking that they are waiting on the PackageList to be written rather than on
						// the tool to be built.
						logger.LogInformation("PackageList was written to '{Path}'", tempFilesPath);

						if (await RunVirtualizationTool(engineRoot, projectPath, clientSpec, tempFilesPath, logger) == false)
						{
							return false;
						};

						// @todo Make sure this always gets cleaned up when we go out of scope
						File.Delete(tempFilesPath);
					}
					else
					{
						logger.LogError("Error: Failed to find engine root for project {Project}", project.Key);
						return false;
					}
				}

				logger.NewLine();
				logger.LogInformation("All packages have been virtualized");

				//@todo ideally we should get the tags back from UnrealVirtualizationTool
				ChangeRecord? changeRecord = await StampChangelistDescription(perforceConnection, changeNumber, logger);
				if (changeRecord == null)
				{
					return false;
				}

				logger.LogInformation("Attempting to submit changelist {Number}...", changeNumber);

#if !UE_DEBUG_DISABLE_SUBMITS
				if (await SubmitChangelist(perforceConnection, changeNumber, logger) == false)
				{
					// If the final submit failed we remove the virtualization tag, even though the changelist is technically
					// virtualized at this point and submitting it would be safe.
					// This is to keep the behavior the same as the native code paths.
					logger.LogInformation("Removing virtualization tags from the changelist...");
					PerforceResponse updateResponse = await perforceConnection.TryUpdateChangeAsync(UpdateChangeOptions.None, changeRecord, CancellationToken.None);
					if (!updateResponse.Succeeded)
					{
						logger.LogError("Error: Failed to remove the virtualization tags!");
					}
					logger.LogInformation("Virtualization tags have been removed.");

					return false;
				}
#else
				// Dummy pretend submit for debugging purposes, allows developer iteration without actually submitting
				logger.LogInformation("Successfully submited changelist {Change}", changeNumber);
#endif // !UE_DEBUG_DISABLE_SUBMITS
			}
			else
			{
				logger.LogInformation("The changelist does not contain any package files, submitting as normal...");

				if (await SubmitChangelist(perforceConnection, changeNumber, logger) == false)
				{
					return false;
				}
			}
		
			return true;
		}

		/// <summary>
		/// Checks to see if a precompiled version of the UnrealVirtualizationTool exists and if so
		/// if it is valid for us to use this.
		/// If we cannot use a precompiled version of the tool then we will request that it be 
		/// compiled locally.
		/// </summary>
		/// <param name="engineRoot">Root path of the engine we want to build the tool for</param>
		/// <param name="logger">Interface for logging</param>
		/// <returns>True if the UnrealVirtualizationTool.exe exists in a form that we can use, otherwise false</returns>
		private static async Task<bool> ValidateOrBuildVirtualizationTool(string engineRoot, ILogger logger)
		{
			// Check to see if the precompiled binaries for the  editor and virtualization tool are available

			if (!IsSourceCodeAvaliable(engineRoot))
			{
				if (DoesEngineToolExist(engineRoot, "UnrealVirtualizationTool"))
				{
					logger.LogInformation("Using a precompiled binary version of UnrealVirtualizationTool");
					return true;
				}
				else
				{
					logger.LogError("Error: No source code and no precompiled binary of UnrealVirtualizationTool found");
					return false;
				}
			}
			else
			{
				// Since we have no good way to determine if an exe was from the PCB or not, if we have
				// source code we will just have to build the tool anyway for safety.
				// Once this is fixed we should use the old logic which was to use the PCB version of
				// UnrealVirtualizationTool if the editor was a PCB version and only to recompile it 
				// once we detect that the editor has been compiled locally.

				// We must try to build the tool locally, if the user does not have a valid code compilation 
				// tool chain installed then UnrealBuildTool will give them errors.
				return await BuildVirtualizationTool(engineRoot, logger);
			}
		}

		/// <summary>
		/// Checks to see if the user has source code synced or not.
		/// To make this assumption we check to see if we can find the UnrealBuildTool project. If we can
		/// then it is a fair bet that the user can compile code, if they do not have the project then
		/// they probably can't.
		/// </summary>
		/// <param name="engineRoot">Root path of the engine we want to build the tool for</param>
		/// <returns>True if source code is present, otherwise false</returns>
		private static bool IsSourceCodeAvaliable(string engineRoot)
		{
			string versionPath = String.Format(@"{0}\Engine\Source\Programs\UnrealBuildTool\UnrealBuildTool.csproj", engineRoot);

			if (System.IO.File.Exists(versionPath))
			{
				return true;
			}
			else
			{
				return false;
			}
		}

		/// <summary>
		/// Checks if the given tool exists in the engine binaries or not
		/// </summary>
		/// <param name="engineRoot">Root path of the engine we want to build the tool for</param>
		/// <param name="toolName">The name of the tool to look for</param>
		/// <returns>TRue if the exe for the tool already exists, otherwise false</returns>
		private static bool DoesEngineToolExist(string engineRoot, string toolName)
		{
			string toolPath = String.Format(@"{0}\Engine\Binaries\Win64\{1}.exe", engineRoot, toolName);

			if (System.IO.File.Exists(toolPath))
			{
				return true;
			}
			else
			{
				return false;
			}
		}

		/// <summary>
		/// Compiles UnrealVirtualizationTool via RunUBT.bat
		/// </summary>
		/// <param name="engineRoot">Root path of the engine we want to build the tool for</param>
		/// <param name="logger">Interface for logging</param>
		/// <returns>True if the tool built successfully, otherwise false</returns>
		private static async Task<bool> BuildVirtualizationTool(string engineRoot, ILogger logger)
		{
			logger.LogInformation("Building UnrealVirtualizationTool...");

			string buildBatchFile = Path.Combine(engineRoot, @"Engine\Build\BatchFiles\RunUBT.bat");
			StringBuilder arguments = new StringBuilder($"{buildBatchFile.QuoteArgument()}");
			arguments.Append(" UnrealVirtualizationTool Win64 development -Progress");

			string shellFileName = Environment.GetEnvironmentVariable("COMSPEC") ?? "C:\\Windows\\System32\\cmd.exe";
			string shellArguments = $"/d/s/c \"{arguments}\"";

			using (MemoryStream bufferedOutput = new MemoryStream())
			using (ManagedProcessGroup Group = new ManagedProcessGroup())
			using (ManagedProcess Process = new ManagedProcess(Group, shellFileName, shellArguments, null, null, System.Diagnostics.ProcessPriorityClass.Normal))
			{
				await Process.CopyToAsync(bufferedOutput, CancellationToken.None);

				// We only show the output if there was an error to avoid showing too much
				// info to the user when they are invoking this from p4v.
				// We need to print everything from stdout and stderr as stderr alone often 
				// does not contain all of the build failure info. (note that ManagedProcess is
				// merging the two streams by default)
				if (Process.ExitCode != 0)
				{
					bufferedOutput.Seek(0, SeekOrigin.Begin);

					using (Stream stdOutput = Console.OpenStandardOutput())
					{
						await bufferedOutput.CopyToAsync(stdOutput, CancellationToken.None);
					}

					logger.LogError("Error: Failed to build UnrealVirtualizationTool");
					return false;
				}
			}

			logger.LogInformation("UnrealVirtualizationTool built successfully");
			return true;
		}

		/// <summary>
		/// Runs the UnrealVirtualizationTool
		/// </summary>
		/// <param name="engineRoot">Root path of the engine we want to run the tool from</param>
		/// <param name="projectPath">The absolute path of the project file for the packages in the package list</param>
		/// <param name="clientSpec">The perforce client spec that the files are in</param>
		/// <param name="packageListPath">A path to a text file containing the paths of the packages to be virtualized</param>
		/// <param name="logger">Interface for logging</param>
		/// <returns></returns>
		private static async Task<bool> RunVirtualizationTool(string engineRoot, string projectPath, string clientSpec, string packageListPath, ILogger logger)
		{
			logger.LogInformation("Running UnrealVirtualizationTool...");

			string toolPath = Path.Combine(engineRoot, @"Engine\Binaries\Win64\UnrealVirtualizationTool.exe");
			string toolArgs = string.Format("\"{0}\" -MinimalLogging -ClientSpecName={1} -Mode=PackageList -Path=\"{2}\"", projectPath, clientSpec, packageListPath);

			using (Stream stdOutput = Console.OpenStandardOutput())
			using (ManagedProcessGroup Group = new ManagedProcessGroup())
			using (ManagedProcess Process = new ManagedProcess(Group, toolPath, toolArgs, null, null, System.Diagnostics.ProcessPriorityClass.Normal))
			{
				await Process.CopyToAsync(stdOutput, CancellationToken.None);

				if (Process.ExitCode != 0)
				{
					logger.LogError("Error: UnrealVirtualizationTool failed!");
					return false;
				}
			}

			return true;
		}

		/// <summary>
		/// Writes out a list of package paths to a text file stored in the users 
		/// temp directory.
		/// The name of the file will be a randomly generated GUID making file name
		/// collisions unlikely.
		/// Each path will be written to it's own line inside of the files
		/// </summary>
		/// <param name="packagePaths">A list of package file paths to be written to the file</param>
		/// <param name="logger">Interface for logging</param>
		/// <returns>The path of the file once it has been written</returns>
		private static async Task<string> WritePackageFileList(List<string> packagePaths, ILogger logger)
		{
			// We pass the list of packages to the tool via a file as the number of package 
			// paths can potentially be huge and exceed the cmdline length. 
			// So currently we write the files to a UnrealVirtualizationTool directory under the temp directory
			string tempDirectory = Path.Combine(Path.GetTempPath(), "UnrealVirtualizationTool");
			Directory.CreateDirectory(tempDirectory);

			string tempFilesPath = Path.Combine(tempDirectory, Guid.NewGuid().ToString() + ".txt");

			using (StreamWriter Writer = new StreamWriter(tempFilesPath))
			{
				foreach (string line in packagePaths)
				{
					await Writer.WriteLineAsync(line);
				}
			}

			return NormalizeFilename(tempFilesPath);
		}

		/// <summary>
		/// Sorts the given package paths by the unreal project that they are found to be in.
		/// If a package is found to not be in a project it will currently raise a warning 
		/// but not prevent further execution.
		/// </summary>
		/// <param name="packagePaths">A list of absolute file paths pointing to package files</param>
		/// <param name="logger">Interface for logging</param>
		/// <returns>A dictionary where the key is the path of an unreal project and the value is a list of packages in that project</returns>
		private static Dictionary<string, List<string>> SortPackagesIntoProjects(string[] packagePaths, ILogger logger)
		{
			Dictionary<string, List<string>> projects = new Dictionary<string, List<string>>();
			foreach (string path in packagePaths)
			{
				string normalizedPath = NormalizeFilename(path);
				string projectFilePath = FindProjectForPackage(normalizedPath, logger);

				if (!String.IsNullOrEmpty(projectFilePath))
				{
					if (!projects.ContainsKey(projectFilePath))
					{
						projects.Add(projectFilePath, new List<string>());
					}

					projects[projectFilePath].Add(normalizedPath);
				}
				else
				{
					// @todo Re-evaluate if we want this warning at some point in the future. 
					// Technically submitting a package file not under a project could have valid use cases
					// but if the user called this command it would indicate that they expect that they are
					// submitting packages in a valid project.
					// So for now we give a warning so that it is easier to catch cases where packages are
					// thought not to be part of a project even if they are.
					logger.LogWarning("Unable to find a valid project for the package '{Path}'", normalizedPath);
				}
			}

			return projects;
		}

		private static async Task<bool> SubmitChangelist(IPerforceConnection perforceConnection, int changeNumber, ILogger logger)
		{
			PerforceResponseList<SubmitRecord> submitResponses = await TrySubmitAsync(perforceConnection, changeNumber, SubmitOptions.None, CancellationToken.None);

			bool successfulSubmit = submitResponses.All(x => x.Succeeded);
			if (successfulSubmit)
			{
				// The submit request will return a number of records. One for the original changelist (null)
				// one for each submitted file (all null) and the last record detailing the submitted changelist.
				// So we can just grab the submitted changelist number from the last record.

				PerforceResponse<SubmitRecord> submittedResponse = submitResponses[submitResponses.Count - 1];
				logger.LogInformation("Successfully submited CL {SrcCL} as CL {DstCL}", changeNumber, submittedResponse.Data.SubmittedChangeNumber);
				
				return true;
			}
			else
			{
				// Log every response that was a failure and has an error message associated with it
				logger.LogError("Error: Submit failed due to:");
				foreach (PerforceResponse<SubmitRecord> response in submitResponses)
				{
					if (response.Failed && response.Error != null)
					{
						logger.LogError("\t{Message}", response.Error.Data.ToString());
					}
				}

				return false;
			}
		}

		/// <summary>
		/// Adds the virtualization tags to a changelist description which is used to show that the virtualization
		/// process has been run on it, before it was submitted.
		/// </summary>
		/// <param name="perforceConnection">A valid connection to perforce to use</param>
		/// <param name="changeNumber">The changelist we should be stamping</param>
		/// <param name="logger">Interface for logging</param>
		/// <returns>If the stamp succeeded then it returns a ChangeRecord representing the changelist as it was before it was stamped, returns null on failure</returns>
		private static async Task<ChangeRecord?> StampChangelistDescription(IPerforceConnection perforceConnection, int changeNumber, ILogger logger)
		{
			logger.LogInformation("Adding virtualization tags to changelist description...");

			ChangeRecord changeRecord;
			try
			{
				changeRecord = await perforceConnection.GetChangeAsync(GetChangeOptions.None, changeNumber);
			}
			catch (Exception)
			{
				logger.LogError("Error: Failed to get the description {Change} so we can edit it", changeNumber);
				return null;
			}

			string? originalDescription = changeRecord.Description;

			// @todo Should be getting the tag from the virtualization tool!
			changeRecord.Description += "\n#virtualized\n";

			PerforceResponse updateResponse = await perforceConnection.TryUpdateChangeAsync(UpdateChangeOptions.None, changeRecord, CancellationToken.None);
			if (updateResponse.Succeeded)
			{
				// Restore the original description so we are returning the original ChangeRecord
				changeRecord.Description = originalDescription;
				return changeRecord;
			}
			else
			{
				logger.LogError("Error: Failed to edit the description of {Change} due to\n{Message}", changeNumber, updateResponse.Error!.ToString());
				return null;
			}
		}

		/// <summary>
		/// Find all of the unreal packages in a single perforce changelist and return them as local file paths on the users machine.
		/// </summary>
		/// <param name="perforceConnection">A valid connection to perforce. This should have the correct client spec for the given changelist number</param>
		/// <param name="changeNumber">The changelist we should look in</param>
		/// <param name="logger">Interface for logging</param>
		/// <returns>A list of all the packages in the given changelist, in local file path format</returns>
		private static async Task<string[]?> FindPackagesInChangelist(IPerforceConnection perforceConnection, int changeNumber, ILogger logger)
		{
			logger.LogInformation("Finding files in changelist {Change}...", changeNumber);
			DescribeRecord changeRecord;
			try
			{
				changeRecord = await perforceConnection.DescribeAsync(changeNumber, CancellationToken.None);
			}
			catch (Exception)
			{
				logger.LogError("Error: Failed to find changelist {Change}", changeNumber);
				return null;
			}

			if (changeRecord.Files.Count == 0)
			{
				logger.LogError("Error: Changelist {Change} is empty, cannot submit", changeNumber);
				return null;
			}

			// @todo Should we check if the changelist has shelved files and error at this point since
			// we know that the user will not be able to submit it?

			// Find the depth paths in the changelist that point to package files
			string[] depotPackagePaths = changeRecord.Files.Select(x => x.DepotFile).Where(x => IsPackagePath(x)).ToArray();

			// We can early out if there are no packages in the changelist
			if (depotPackagePaths.Length == 0)
			{
				return depotPackagePaths;
			}

			// Now convert from depot paths to local paths on the users machine
			List<WhereRecord> whereRecords = await perforceConnection.WhereAsync(depotPackagePaths, CancellationToken.None).ToListAsync();

			return whereRecords.Select(x => x.Path).ToArray();
		}

		/// <summary>
		/// Returns if a changelist has shelved files or not
		/// </summary>
		/// <param name="perforceConnection">A valid connection to perforce. This should have the correct client spec for the given changelist number</param>
		/// <param name="changeNumber">The changelist we should look in</param>
		/// <returns>True if the changelist contains shelved files, otherwise false</returns>
		private static async Task<bool> DoesChangelistHaveShelvedFiles(IPerforceConnection perforceConnection, int changeNumber)
		{
			List<DescribeRecord> responses = await perforceConnection.DescribeAsync(DescribeOptions.Shelved, -1, new int[] { changeNumber }, CancellationToken.None);

			if (responses.Count == 1)
			{
				return responses[0].Files.Count != 0;
			}
			else
			{
				return false;
			}
		}

		/// <summary>
		/// Finds the unreal project file for a given unreal package
		/// </summary>
		/// <param name="packagePath">The package to find the project for</param>
		/// <param name="logger">Interface for logging</param>
		/// <returns>The path of the projects .uproject file if found, an empty string if no valid project file was found</returns>
		private static string FindProjectForPackage(string packagePath, ILogger logger)
		{
			// @todo note that this function mirrors FUnrealVirtualizationToolApp::TryFindProject
			// both will not work correctly with some plugin setups, this is known and will be
			// fixed later when FUnrealVirtualizationToolApp is also fixed.
			packagePath = NormalizeFilename(packagePath);

			int contentIndex = packagePath.LastIndexOf("/content/", StringComparison.OrdinalIgnoreCase);
			if (contentIndex == -1)
			{
				logger.LogWarning("'{Path}' is not under a content directory", packagePath);
				return string.Empty;
			}

			while (contentIndex != -1)
			{
				// Assume that the project directory is the parent of the /content/ directory
				string projectDirectory = packagePath[..contentIndex];

				string[] projectFiles = Directory.GetFiles(projectDirectory, "*.uproject");

				if (projectFiles.Length == 0)
				{
					// If there was no project file, the package could be in a plugin, so lets check for that
					string pluginDirectory = projectDirectory;
					string[] pluginFiles = Directory.GetFiles(pluginDirectory, "*.uplugin");

					if (pluginFiles.Length == 1)
					{
						// We have a valid plugin file, so we should be able to find a /plugins/ directory which will be just below the project directory
						int pluginIndex = pluginDirectory.LastIndexOf("/plugins/", StringComparison.OrdinalIgnoreCase);
						if (pluginIndex != -1)
						{
							// We found the plugin root directory so the one above it should be the project directory
							projectDirectory = pluginDirectory[..pluginIndex];
							projectFiles = Directory.GetFiles(projectDirectory, "*.uproject");
						}
					}
					else if (pluginFiles.Length > 1)
					{
						logger.LogWarning("Found multiple .uplugin files for '{Path}' at '{PluginDir}'", packagePath, pluginDirectory);
						return string.Empty;
					}
				}

				if (projectFiles.Length == 1)
				{
					return NormalizeFilename(projectFiles[0]);
				}
				else if (projectFiles.Length > 1)
				{
					logger.LogWarning("Found multiple .uproject files for '{Path}' at '{ProjectDir}'", packagePath, projectDirectory);
					return string.Empty;
				}

				// Could be more than one content directory in the path so lets keep looking
				contentIndex = packagePath.LastIndexOf("/content/", contentIndex, StringComparison.OrdinalIgnoreCase);
			}

			// We found one or more content directories but none of them contained a project file
			logger.LogWarning("FFailed to find project file for '{Package}'", packagePath);
			return string.Empty;
		}

		private static string GetEngineRootForProject(string projectFilePath, ILogger logger)
		{
			string engineIdentifier = GetEngineIdentifierForProject(projectFilePath, logger);
			if (!String.IsNullOrEmpty(engineIdentifier))
			{
				string engineRoot = GetEngineRootDirFromIdentifier(engineIdentifier, logger);
				if (!String.IsNullOrEmpty(engineRoot))
				{
					return engineRoot;
				}
				else 
				{
					logger.LogWarning("Unable to find an engine root for installation {Identifier}, will attempt to find the engine via the directory hierarchy", engineIdentifier);
				}	
			}

			return FindEngineFromPath(projectFilePath);
		}

		// The following functions mirror code found @Engine\Source\Runtime\CoreUObject\Private\Misc\PackageName.cpp
		#region CoreUObject PackageName 

		private static bool IsPackagePath(string path)
		{
			return IsBinaryPackagePath(path) || IsTextPackagePath(path);
		}
		
		private static bool IsBinaryPackagePath(string path)
		{
			return path.EndsWith(".uasset", StringComparison.OrdinalIgnoreCase) || path.EndsWith(".umap", StringComparison.OrdinalIgnoreCase);
		}

		private static bool IsTextPackagePath(string path)
		{
			return path.EndsWith(".utxt", StringComparison.OrdinalIgnoreCase) || path.EndsWith(".utxtmap", StringComparison.OrdinalIgnoreCase);
		}

		#endregion

		// The following functions mirror code found @Engine\Source\Runtime\Core\Private\Misc\Paths.cpp
		#region Paths

		private static string NormalizeFilename(string path)
		{
			return path.Replace('\\', '/');
		}

		private static string NormalizeDirectoryName(string path)
		{
			path = path.Replace('\\', '/');

			if (path.EndsWith('/'))
			{
				path = path.Remove(path.Length - 1, 1);
			}

			return path;
		}

		#endregion

		// The following functions mirror code found @Engine\Source\Developer\DesktopPlatform\Private\DesktopPlatformBase.cpp
		#region DesktopPlatform DesktopPlatformBase

		// Note that for the C# versions we only support the modern way of associating
		// projects with engine installation, via the 'EngineAssociation' entry in
		// the .uproject file.

		private static string GetEngineIdentifierForProject(string projectFilePath, ILogger logger)
		{
			try
			{
				JsonObject root = JsonObject.Read(new FileReference(projectFilePath));
				string engineIdentifier = root.GetStringField("EngineAssociation");
				if (!String.IsNullOrEmpty(engineIdentifier))
				{
					// @todo what if it is a path? (native code has support for this
					// possibly for an older version)
					return engineIdentifier;
				}
			}
			catch (Exception ex)
			{
				logger.LogError("Error: Failed to parse {File} to find the engine association due to: {Reason}", projectFilePath, ex.Message);
			}

			// @todo In the native version if there is no identifier we will try to
			// find the engine root in the directory hierarchy then either find it
			// identifier or register one if needed.

			return string.Empty;
		}

		private static string FindEngineFromPath(string path)
		{
			string? directoryName = Path.GetDirectoryName(path);
			
			if (!String.IsNullOrEmpty(directoryName))
			{
				DirectoryInfo? directoryToSearch = new DirectoryInfo(directoryName);

				while (directoryToSearch != null)
				{
					if (IsValidRootDirectory(directoryToSearch.ToString()))
					{
						return NormalizeDirectoryName(directoryToSearch.ToString());
					}

					directoryToSearch = Directory.GetParent(directoryToSearch.ToString());
				}
			}

			return string.Empty;
		}

		private static string GetEngineRootDirFromIdentifier(string engineIdentifier, ILogger logger)
		{
			IReadOnlyDictionary<string, string> engineInstalls = EnumerateEngineInstallations(logger);

			if (engineInstalls.TryGetValue(engineIdentifier, out string? engineRoot))
			{
				return engineRoot;
			}
			else
			{
				return string.Empty;
			}
		}

		private static string GetEngineIdentifierFromRootDir(string rootDirectory, ILogger logger)
		{
			rootDirectory = NormalizeDirectoryName(rootDirectory);
			
			IReadOnlyDictionary<string, string> engineInstalls = EnumerateEngineInstallations(logger);

			foreach (KeyValuePair<string, string> pair in engineInstalls)
			{
				if (String.Equals(pair.Value,rootDirectory, StringComparison.OrdinalIgnoreCase))
				{
					return pair.Key;
				}
			}

			return String.Empty;
		}

		private static bool IsValidRootDirectory(string rootDirectory)
		{
			// Check that there's an Engine\Binaries directory underneath the root
			string engineBinariesDirectory = Path.Combine(rootDirectory, "Engine/Binaries");

			if (!Directory.Exists(engineBinariesDirectory))
			{
				return false;
			}

			// Also check there's an Engine\Build directory. This will filter out anything
			// //that has an engine-like directory structure but doesn't allow building
			// code projects - like the launcher.

			string engineBuildDirectory = Path.Combine(rootDirectory, "Engine/Build");

			if (!Directory.Exists(engineBuildDirectory))
			{
				return false;
			}

			return true;
		}

		private static IReadOnlyDictionary<string, string> EnumerateEngineInstallations(ILogger logger)
		{
			Dictionary<string, string> launcherEngineInstalls = EnumerateLauncherEngineInstallations(logger);
			Dictionary<string, string> customEngineInstalls = EnumerateCustomEngineInstallations(logger);

			Dictionary<string, string> allInstalls = new Dictionary<string, string>();

			foreach (KeyValuePair<string, string> pair in launcherEngineInstalls)
			{
				allInstalls.Add(pair.Key, pair.Value);
			}

			foreach (KeyValuePair<string, string> pair in customEngineInstalls)
			{
				allInstalls.Add(pair.Key, pair.Value);
			}

			return allInstalls;
		}

		private static Dictionary<string, string> EnumerateLauncherEngineInstallations(ILogger logger)
		{
			Dictionary<string, string> installations = new Dictionary<string, string>();

			try
			{
				string installedListFilePath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.CommonApplicationData), "Epic/UnrealEngineLauncher/LauncherInstalled.dat");

				if (JsonObject.TryRead(new FileReference(installedListFilePath), out JsonObject? rawObject))
				{
					JsonObject[] installationArray = rawObject.GetObjectArrayField("InstallationList");
					foreach (JsonObject installObject in installationArray)
					{
						string appName = installObject.GetStringField("AppName");
						if (appName.StartsWith("UE_", StringComparison.Ordinal))
						{
							appName = appName.Remove(0, 3);
							string installPath = NormalizeDirectoryName(installObject.GetStringField("InstallLocation"));

							installations.Add(appName, installPath);
						}
					}
				}
			}
			catch (Exception ex)
			{
				logger.LogWarning("EnumerateLauncherEngineInstallations: {Message}", ex.Message);
				installations.Clear();
			}

			return installations;
		}

		private static Dictionary<string, string> EnumerateCustomEngineInstallations(ILogger logger)
		{
			Dictionary<string, string> installations = new Dictionary<string, string>();

			if (OperatingSystem.IsWindows())
			{
				try
				{
					using RegistryKey? subKey = Registry.CurrentUser.OpenSubKey("SOFTWARE\\Epic Games\\Unreal Engine\\Builds", false);
					if (subKey != null)
					{
						foreach (string installName in subKey.GetValueNames())
						{
							string? installPath = subKey.GetValue(installName) as string;
							if (!String.IsNullOrEmpty(installPath))
							{
								installations.Add(installName, NormalizeDirectoryName(installPath));
							}
						}
					}
				}
				catch (Exception ex)
				{
					logger.LogWarning("EnumerateCustomEngineInstallations: {Message}", ex.Message);
					installations.Clear();
				}
			}

			return installations;
		}

		#endregion

		// The following code acts as an extension to code found @Engine\Source\Programs\Shared\EpicGames.Perforce\PerforceConnection.cs
		#region PerforceConnection

		// @todo None of the submit functions in PerforceConnection.cs seem to report submit errors in a way that we can inform the user
		// so this is a custom version that returns the entire response list as different submit errors will return different error
		// responses. We should fix the API in PerforceConnection so that other areas of code can get better submit error reporting.
		private static async Task<PerforceResponseList<SubmitRecord>> TrySubmitAsync(IPerforceConnection connection, int changeNumber, SubmitOptions options, CancellationToken cancellationToken = default)
		{
			List<string> arguments = new List<string>();
			if ((options & SubmitOptions.ReopenAsEdit) != 0)
			{
				arguments.Add("-r");
			}
			arguments.Add($"-c{changeNumber}");

			return (await connection.CommandAsync<SubmitRecord>("submit", arguments, null, cancellationToken));
		}

		#endregion
	}
}