feat(plugins): Consolidate flush and validate plugins (#970)

Author: delucis

src/core/initialize.ts

@@ -7,9 +7,8 @@
  */
 
 import { ProcessGameConfig } from './game';
-import type { Game } from '../types';
 import * as plugins from '../plugins/main';
-import type { PartialGameState, State, Ctx } from '../types';
+import type { Ctx, Game, PartialGameState, State } from '../types';
 
 /**
  * Creates the initial game state.
@@ -61,7 +60,7 @@ export function InitializeGame({
   };
 
   initial = game.flow.init(initial);
-  initial = plugins.Flush(initial, { game });
+  [initial] = plugins.FlushAndValidate(initial, { game });
 
   // Initialize undo stack.
   if (!game.disableUndo) {

src/core/reducer.ts

@@ -130,22 +130,19 @@ function initializeDeltalog(
 
 /**
  * Update plugin state after move/event & check if plugins consider the action to be valid.
- * @param newState Latest version of state in the reducer.
- * @param oldState Initial value of state when reducer started its work.
+ * @param state Current version of state in the reducer.
+ * @param oldState State to revert to in case of error.
  * @param pluginOpts Plugin configuration options.
  * @returns Tuple of the new state updated after flushing plugins and the old
  * state augmented with an error if a plugin declared the action invalid.
  */
 function flushAndValidatePlugins(
-  newState: State,
+  state: State,
   oldState: State,
   pluginOpts: { game: Game; isClient?: boolean }
 ): [State, TransientState?] {
-  newState = plugins.Flush(newState, pluginOpts);
-  const isInvalid = plugins.IsInvalid(newState, pluginOpts);
+  const [newState, isInvalid] = plugins.FlushAndValidate(state, pluginOpts);
   if (!isInvalid) return [newState];
-  const { plugin, message } = isInvalid;
-  error(`plugin declared action invalid: ${plugin} - ${message}`);
   return [
     newState,
     WithError(oldState, ActionErrorType.PluginActionInvalid, isInvalid),

src/plugins/main.ts

@@ -21,6 +21,7 @@ import type {
   ActionShape,
   PlayerID,
 } from '../types';
+import { error } from '../core/logger';
 
 interface PluginOpts {
   game: Game;
@@ -166,7 +167,7 @@ export const Enhance = (
 /**
  * Allows plugins to update their state after a move / event.
  */
-export const Flush = (state: State, opts: PluginOpts): State => {
+const Flush = (state: State, opts: PluginOpts): State => {
   // We flush the events plugin first, then custom plugins and the core plugins.
   // This means custom plugins cannot use the events API but will be available in event hooks.
   // Note that plugins are flushed in reverse, to allow custom plugins calling each other.
@@ -246,7 +247,7 @@ export const NoClient = (state: State, opts: PluginOpts): boolean => {
  * Allows plugins to indicate if the entire action should be thrown out
  * as invalid. This will cancel the entire state update.
  */
-export const IsInvalid = (
+const IsInvalid = (
   state: State,
   opts: PluginOpts
 ): false | { plugin: string; message: string } => {
@@ -270,6 +271,19 @@ export const IsInvalid = (
   return firstInvalidReturn || false;
 };
 
+/**
+ * Update plugin state after move/event & check if plugins consider the update to be valid.
+ * @returns Tuple of `[updatedState]` or `[originalState, invalidError]`.
+ */
+export const FlushAndValidate = (state: State, opts: PluginOpts) => {
+  const updatedState = Flush(state, opts);
+  const isInvalid = IsInvalid(updatedState, opts);
+  if (!isInvalid) return [updatedState] as const;
+  const { plugin, message } = isInvalid;
+  error(`${plugin} plugin declared action invalid:\n${message}`);
+  return [state, isInvalid] as const;
+};
+
 /**
  * Allows plugins to customize their data for specific players.
  * For example, a plugin may want to share no data with the client, or