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

using EpicGames.BuildGraph;
using EpicGames.Perforce;
using Microsoft.Extensions.Logging.Abstractions;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Xml;
using EpicGames.Core;
using UnrealBuildBase;
using UnrealBuildTool;
using Microsoft.Extensions.Logging;

namespace AutomationTool.Tasks
{
	/// <summary>
	/// Parameters for a task that compiles a C# project
	/// </summary>
	public class FindModifiedFilesTaskParameters
	{
		/// <summary>
		///  List of file specifications separated by semicolon (default is ...)
		/// </summary>
		[TaskParameter(Optional=true, ValidationType = TaskParameterValidationType.FileSpec)]
		public string Path = "...";

		/// <summary>
		/// The configuration to compile.
		/// </summary>
		[TaskParameter(Optional = true)]
		public int Change;

		/// <summary>
		/// The configuration to compile.
		/// </summary>
		[TaskParameter(Optional = true)]
		public int MinChange;

		/// <summary>
		/// The configuration to compile.
		/// </summary>
		[TaskParameter(Optional = true)]
		public int MaxChange;

		/// <summary>
		/// The file to write to
		/// </summary>
		[TaskParameter(Optional = true)]
		public FileReference Output;
	}

	/// <summary>
	/// Compiles C# project files, and their dependencies.
	/// </summary>
	[TaskElement("FindModifiedFiles", typeof(FindModifiedFilesTaskParameters))]
	public class FindModifiedFilesTask : BgTaskImpl
	{
		/// <summary>
		/// Parameters for the task
		/// </summary>
		FindModifiedFilesTaskParameters Parameters;

		/// <summary>
		/// Constructor.
		/// </summary>
		/// <param name="InParameters">Parameters for this task</param>
		public FindModifiedFilesTask(FindModifiedFilesTaskParameters InParameters)
		{
			Parameters = InParameters;
		}

		/// <summary>
		/// Execute the task.
		/// </summary>
		/// <param name="Job">Information about the current job</param>
		/// <param name="BuildProducts">Set of build products produced by this node.</param>
		/// <param name="TagNameToFileSet">Mapping from tag names to the set of files they include</param>
		public override async Task ExecuteAsync(JobContext Job, HashSet<FileReference> BuildProducts, Dictionary<string, HashSet<FileReference>> TagNameToFileSet)
		{
			using IPerforceConnection Connection = await PerforceConnection.CreateAsync(CommandUtils.P4Settings, Log.Logger);

			SortedSet<string> AllLocalFiles = new SortedSet<string>();
			foreach (string Path in Parameters.Path.Split(";"))
			{
				StringBuilder Filter = new StringBuilder($"//{Connection.Settings.ClientName}/{Path}");
				if (Parameters.Change > 0)
				{
					Filter.Append($"@={Parameters.Change}");
				}
				else if (Parameters.MinChange > 0)
				{
					if (Parameters.MaxChange > 0)
					{
						Filter.Append($"@{Parameters.MinChange},{Parameters.MaxChange}");
					}
					else
					{
						Filter.Append($"@>={Parameters.MinChange}");
					}
				}
				else
				{
					throw new AutomationException("Change or MinChange must be specified to FindModifiedFiles task");
				}

				StreamRecord StreamRecord = await Connection.GetStreamAsync(CommandUtils.P4Env.Branch, true);
				PerforceViewMap ViewMap = PerforceViewMap.Parse(StreamRecord.View);

				HashSet<string> LocalFiles = new HashSet<string>();

				List<FilesRecord> Files = await Connection.FilesAsync(FilesOptions.None, Filter.ToString());
				foreach (FilesRecord File in Files)
				{
					string LocalFile;
					if (ViewMap.TryMapFile(File.DepotFile, StringComparison.OrdinalIgnoreCase, out LocalFile))
					{
						LocalFiles.Add(LocalFile);
					}
					else
					{
						Logger.LogInformation("Unable to map {DepotFile} to workspace; skipping.", File.DepotFile);
					}
				}

				Logger.LogInformation("Found {NumFiles} modified files matching {Filter}", LocalFiles.Count, Filter.ToString());
				foreach (string LocalFile in LocalFiles)
				{
					Logger.LogInformation("  {LocalFile}", LocalFile);
				}
				AllLocalFiles.UnionWith(LocalFiles);
			}

			Logger.LogInformation("Found {NumFiles} total modified files", AllLocalFiles.Count);
			if (Parameters.Output != null)
			{
				await FileReference.WriteAllLinesAsync(Parameters.Output, AllLocalFiles);
				Logger.LogInformation("Written {OutputFile}", Parameters.Output);
			}
		}

		/// <summary>
		/// Output this task out to an XML writer.
		/// </summary>
		public override void Write(XmlWriter Writer)
		{
			Write(Writer, Parameters);
		}

		/// <summary>
		/// Find all the tags which are used as inputs to this task
		/// </summary>
		/// <returns>The tag names which are read by this task</returns>
		public override IEnumerable<string> FindConsumedTagNames()
		{
			//			return FindTagNamesFromFilespec(Parameters.Project);
			return Enumerable.Empty<string>();
		}

		/// <summary>
		/// Find all the tags which are modified by this task
		/// </summary>
		/// <returns>The tag names which are modified by this task</returns>
		public override IEnumerable<string> FindProducedTagNames()
		{
			return Enumerable.Empty<string>();
/*			foreach (string TagName in FindTagNamesFromList(Parameters.Tag))
			{
				yield return TagName;
			}

			foreach (string TagName in FindTagNamesFromList(Parameters.TagReferences))
			{
				yield return TagName;
			}*/
		}
	}
}