// Copyright 1998-2017 Epic Games, Inc. All Rights Reserved.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace UnrealBuildTool
{
	/// <summary>
	/// Stores custom build steps to be executed by a project or plugin
	/// </summary>
	public class CustomBuildSteps
	{
		SortedDictionary<UnrealTargetPlatform, string[]> HostPlatformToCommands = new SortedDictionary<UnrealTargetPlatform,string[]>();

		/// <summary>
		/// Construct a custom build steps object from a Json object.
		/// </summary>
		public CustomBuildSteps(JsonObject RawObject)
		{
			foreach(string HostPlatformName in RawObject.KeyNames)
			{
				UnrealTargetPlatform HostPlatform;
				if(Enum.TryParse(HostPlatformName, true, out HostPlatform))
				{
					HostPlatformToCommands.Add(HostPlatform, RawObject.GetStringArrayField(HostPlatformName));
				}
			}
		}

		/// <summary>
		/// Reads a list of build steps from a Json project or plugin descriptor
		/// </summary>
		/// <param name="RawObject">The json descriptor object</param>
		/// <param name="FieldName">Name of the field to read</param>
		/// <param name="OutBuildSteps">Output variable to store the sorted dictionary that was read</param>
		/// <returns>True if the field was read (and OutBuildSteps is set), false otherwise.</returns>
		public static bool TryRead(JsonObject RawObject, string FieldName, out CustomBuildSteps OutBuildSteps)
		{
			JsonObject BuildStepsObject;
			if(RawObject.TryGetObjectField(FieldName, out BuildStepsObject))
			{
				OutBuildSteps = new CustomBuildSteps(BuildStepsObject);
				return true;
			}
			else
			{
				OutBuildSteps = null;
				return false;
			}
		}

		/// <summary>
		/// Reads a list of build steps from a Json project or plugin descriptor
		/// </summary>
		/// <param name="Writer">Writer to receive json output</param>
		/// <param name="FieldName">Name of the field to read</param>
		/// <returns>True if the field was read (and OutBuildSteps is set), false otherwise.</returns>
		public void Write(JsonWriter Writer, string FieldName)
		{
			Writer.WriteObjectStart(FieldName);
			foreach(KeyValuePair<UnrealTargetPlatform, string[]> Pair in HostPlatformToCommands)
			{
				Writer.WriteArrayStart(Pair.Key.ToString());
				foreach(string Line in Pair.Value)
				{
					Writer.WriteValue(Line);
				}
				Writer.WriteArrayEnd();
			}
			Writer.WriteObjectEnd();
		}

		/// <summary>
		/// Determines whether there are custom build steps for the given host platform
		/// </summary>
		/// <param name="HostPlatform">The host platform to check for</param>
		/// <returns>True if the host platform exists</returns>
		public bool HasHostPlatform(UnrealTargetPlatform HostPlatform)
		{
			string[] Commands;
			return HostPlatformToCommands.TryGetValue(HostPlatform, out Commands) && Commands.Length > 0;
		}

		/// <summary>
		/// Tries to get the commands for a given host platform
		/// </summary>
		/// <param name="HostPlatform">The host platform to look for</param>
		/// <param name="Variables">Lookup of additional environment variables to expand</param>
		/// <param name="OutCommands">Array of commands</param>
		/// <returns>True if a list of commands was generated</returns>
		public bool TryGetCommands(UnrealTargetPlatform HostPlatform, Dictionary<string, string> Variables, out string[] OutCommands)
		{
			string[] Commands;
			if(HostPlatformToCommands.TryGetValue(HostPlatform, out Commands) && Commands.Length > 0)
			{
				OutCommands = Commands.Select(x => Utils.ExpandVariables(x, Variables)).ToArray();
				return true;
			}
			else
			{
				OutCommands = null;
				return false;
			}
		}
	}
}