feat: hooks

Osmi/Imports.cs

@@ -20,5 +20,6 @@
 global using UnityEngine;
 
 global using Lang = Language.Language;
+global using ReflectionHelper = Modding.ReflectionHelper;
 global using Logger = Osmi.Utils.Logger;
 global using UObject = UnityEngine.Object;

Osmi/Osmi.cs

@@ -17,5 +17,8 @@ public sealed class Osmi : Mod {
 	public Osmi() =>
 		Instance = this;
 
+	public override void Initialize() =>
+		_ = Ref.GM.StartCoroutine(OsmiHooks.CheckGameInitialized());
+
 	public static bool IsHere() => true;
 }

Osmi/OsmiHooks.cs

@@ -0,0 +1,205 @@
+using Mono.Cecil.Cil;
+
+using MonoMod.Cil;
+using MonoMod.RuntimeDetour;
+using MonoMod.Utils;
+
+using UnityEngine.SceneManagement;
+
+namespace Osmi;
+
+[PublicAPI]
+public static class OsmiHooks {
+	/// <summary>
+	/// Called when entering main menu for the first time <br />
+	/// Hooking new methods after that will result in immediate invocation
+	/// </summary>
+	public static event Action GameInitializedHook {
+		add {
+			if (gameInitializedHookCalled) {
+				value?.Invoke();
+				return;
+			}
+
+			InternalGameInitializedHook += value;
+		}
+		remove => InternalGameInitializedHook -= value;
+	}
+	private static bool gameInitializedHookCalled = false;
+	private static event Action InternalGameInitializedHook = null!;
+
+	internal static IEnumerator CheckGameInitialized() {
+		yield return new WaitUntil(() => GameObject.Find("LogoTitle") != null);
+
+		gameInitializedHookCalled = true;
+		if (InternalGameInitializedHook == null) {
+			yield break;
+		}
+
+		foreach (Action a in InternalGameInitializedHook.GetInvocationList()) {
+			try {
+				a.Invoke();
+			} catch (Exception e) {
+				Logger.LogError(e.ToString());
+			}
+		}
+
+		InternalGameInitializedHook = null!;
+	}
+
+
+	/// <summary>
+	/// Equivalent to <see cref="UIManager.EditMenus"/>,
+	/// but ensure to be called after MAPI finished building menus
+	/// </summary>
+	public static event Action MenuBuildHook = null!;
+
+	private static void OnMenuBuild() {
+		Logger.LogFine($"{nameof(OnMenuBuild)} Invoked");
+
+		if (MenuBuildHook == null) {
+			return;
+		}
+
+		foreach (Action a in MenuBuildHook.GetInvocationList()) {
+			try {
+				a.Invoke();
+			} catch (Exception e) {
+				Logger.LogError(e.ToString());
+			}
+		}
+	}
+
+
+	/// <summary>
+	///	Equivalent to
+	///	<see cref="UnityEngine.SceneManagement.SceneManager.activeSceneChanged"/>,
+	///	but catch all exceptions
+	/// </summary>
+	public static event Action<Scene, Scene> SceneChangeHook = null!;
+
+	private static void OnSceneChange(Scene prev, Scene next) {
+		Logger.LogFine($"{nameof(OnSceneChange)} Invoked");
+
+		if (SceneChangeHook == null) {
+			return;
+		}
+
+		foreach (Action<Scene, Scene> a in SceneChangeHook.GetInvocationList()) {
+			try {
+				a.Invoke(prev, next);
+			} catch (Exception e) {
+				Logger.LogError(e.ToString());
+			}
+		}
+	}
+
+
+	/// <param name="invincible">Invincibility state passed by vanilla code or last hooked method</param>
+	/// <returns>New invincibility state</returns>
+	public delegate bool HitEnemyHandler(HealthManager hm, HitInstance hit, bool invincible);
+
+	/// <summary>
+	/// Called when deciding whether an enemy is invincible to a hit or not
+	/// </summary>
+	public static event HitEnemyHandler HitEnemyHook = null!;
+
+	private static bool OnHitEnemy(bool invincible, HealthManager hm, HitInstance hitInstance) {
+		Logger.LogFine($"{nameof(OnHitEnemy)} Invoked");
+
+		if (HitEnemyHook == null) {
+			return invincible;
+		}
+
+		foreach (HitEnemyHandler a in HitEnemyHook.GetInvocationList()) {
+			try {
+				invincible = a.Invoke(hm, hitInstance, invincible);
+			} catch (Exception e) {
+				Logger.LogError(e.ToString());
+			}
+		}
+
+		return invincible;
+	}
+
+
+	/// <summary>
+	/// Called when game is about to pause <br />
+	/// <see cref="Time.timeScale"/> is still 1f when called
+	/// </summary>
+	public static event Action GamePauseHook = null!;
+
+	private static void OnGamePause() {
+		Logger.LogFine($"{nameof(OnGamePause)} Invoked");
+
+		if (GamePauseHook == null) {
+			return;
+		}
+
+		foreach (Action a in GamePauseHook.GetInvocationList()) {
+			try {
+				a.Invoke();
+			} catch (Exception e) {
+				Logger.LogError(e.ToString());
+			}
+		}
+	}
+
+	/// <summary>
+	/// Called when game is about to unpause <br />
+	/// <see cref="Time.timeScale"/> is still 0f when called
+	/// </summary>
+	public static event Action GameUnpauseHook = null!;
+
+	private static void OnGameUnpause() {
+		Logger.LogFine($"{nameof(OnGameUnpause)} Invoked");
+
+		if (GameUnpauseHook == null) {
+			return;
+		}
+
+		foreach (Action a in GameUnpauseHook.GetInvocationList()) {
+			try {
+				a.Invoke();
+			} catch (Exception e) {
+				Logger.LogError(e.ToString());
+			}
+		}
+	}
+
+
+	static OsmiHooks() {
+		GameInitializedHook += () => UIManager.EditMenus += OnMenuBuild;
+
+		UnityEngine.SceneManagement.SceneManager.activeSceneChanged += OnSceneChange;
+
+		IL.HealthManager.Hit += il => new ILCursor(il)
+			.Goto(0)
+			.GotoNext(i => i.MatchCallvirt<HealthManager>(
+				nameof(HealthManager.IsBlockingByDirection)
+			))
+			.Emit(OpCodes.Ldarg_0) // this
+			.Emit(OpCodes.Ldarg_1) // hitInstance
+			.EmitDelegate(OnHitEnemy);
+
+		_ = new ILHook(
+			ReflectionHelper
+				.GetMethodInfo(typeof(GameManager), nameof(GameManager.PauseGameToggle))
+				.GetStateMachineTarget(),
+			il => new ILCursor(il)
+				.Goto(0)
+				.GotoNext(
+					MoveType.Before,
+					i => i.MatchLdcR4(0f),
+					i => i.MatchCallvirt(typeof(GameManager), "SetTimeScale")
+				)
+				.Emit(OpCodes.Call, ((Delegate) OnGamePause).Method)
+				.GotoNext(
+					MoveType.Before,
+					i => i.MatchLdcR4(1f),
+					i => i.MatchCallvirt(typeof(GameManager), "SetTimeScale")
+				)
+				.Emit(OpCodes.Call, ((Delegate) OnGameUnpause).Method)
+		);
+	}
+}