From cba206efeca261f3b26d51aaeb87fa634ca6b08c Mon Sep 17 00:00:00 2001
From: YoshiRulz <OSSYoshiRulz@gmail.com>
Date: Sun, 4 Dec 2022 04:06:58 +1000
Subject: [PATCH] Add `IUserDataApi.Keys`/`userdata.get_keys`

---
 src/BizHawk.Client.Common/Api/Classes/UserDataApi.cs   | 10 ++++++++++
 .../Api/Interfaces/IUserDataApi.cs                     | 10 +++++++++-
 .../lua/CommonLibs/UserDataLuaLibrary.cs               |  9 +++++++++
 3 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/src/BizHawk.Client.Common/Api/Classes/UserDataApi.cs b/src/BizHawk.Client.Common/Api/Classes/UserDataApi.cs
index 794351e479..91e1d0e45f 100644
--- a/src/BizHawk.Client.Common/Api/Classes/UserDataApi.cs
+++ b/src/BizHawk.Client.Common/Api/Classes/UserDataApi.cs
@@ -1,4 +1,6 @@
 using System;
+using System.Collections.Generic;
+using System.Linq;
 
 namespace BizHawk.Client.Common
 {
@@ -6,6 +8,14 @@ namespace BizHawk.Client.Common
 	{
 		private readonly IMovieSession _movieSession;
 
+#if NET6_0
+		public IReadOnlySet<string> Keys
+			=> throw new NotImplementedException();
+#else
+		public IReadOnlyCollection<string> Keys
+			=> _movieSession.UserBag.Keys.ToList();
+#endif
+
 		public UserDataApi(IMovieSession movieSession) => _movieSession = movieSession;
 
 		/// <exception cref="InvalidOperationException">type of <paramref name="value"/> cannot be used in userdata</exception>
diff --git a/src/BizHawk.Client.Common/Api/Interfaces/IUserDataApi.cs b/src/BizHawk.Client.Common/Api/Interfaces/IUserDataApi.cs
index 840c894078..497aff23b2 100644
--- a/src/BizHawk.Client.Common/Api/Interfaces/IUserDataApi.cs
+++ b/src/BizHawk.Client.Common/Api/Interfaces/IUserDataApi.cs
@@ -1,7 +1,15 @@
-namespace BizHawk.Client.Common
+using System.Collections.Generic;
+
+namespace BizHawk.Client.Common
 {
 	public interface IUserDataApi : IExternalApi
 	{
+#if NET6_0
+		IReadOnlySet<string> Keys { get; }
+#else
+		IReadOnlyCollection<string> Keys { get; }
+#endif
+
 		void Set(string name, object value);
 		object Get(string key);
 		void Clear();
diff --git a/src/BizHawk.Client.Common/lua/CommonLibs/UserDataLuaLibrary.cs b/src/BizHawk.Client.Common/lua/CommonLibs/UserDataLuaLibrary.cs
index 3ae6ba90c8..59b9dd4136 100644
--- a/src/BizHawk.Client.Common/lua/CommonLibs/UserDataLuaLibrary.cs
+++ b/src/BizHawk.Client.Common/lua/CommonLibs/UserDataLuaLibrary.cs
@@ -1,6 +1,9 @@
 using System;
+using System.Collections.Generic;
 using System.ComponentModel;
 
+using NLua;
+
 // ReSharper disable UnusedMember.Global
 namespace BizHawk.Client.Common
 {
@@ -37,5 +40,11 @@ namespace BizHawk.Client.Common
 		[LuaMethod("containskey", "returns whether or not there is an entry for the given key")]
 		public bool ContainsKey([LuaArbitraryStringParam] string key)
 			=> APIs.UserData.ContainsKey(key);
+
+		[LuaMethodExample("console.writeline(#userdata.get_keys());")]
+		[LuaMethod("get_keys", "returns a list-like table of valid keys")]
+		[return: LuaArbitraryStringParam]
+		public LuaTable GetKeys()
+			=> _th.ListToTable((List<string>) APIs.UserData.Keys); //HACK cast will succeed as long as impl. returns Dictionary<K, V>.Keys.ToList() as IROC<K>
 	}
 }