lua: Change CompletionRequested handler to use an event table. (#5280)

docs/chatterino.d.ts

@@ -75,6 +75,13 @@ declare module c2 {
     handler: (ctx: CommandContext) => void
   ): boolean;
 
+  class CompletionEvent {
+    query: string;
+    full_text_content: string;
+    cursor_position: number;
+    is_first_word: boolean;
+  }
+
   class CompletionList {
     values: String[];
     hide_others: boolean;
@@ -84,12 +91,7 @@ declare module c2 {
     CompletionRequested = "CompletionRequested",
   }
 
-  type CbFuncCompletionsRequested = (
-    query: string,
-    full_text_content: string,
-    cursor_position: number,
-    is_first_word: boolean
-  ) => CompletionList;
+  type CbFuncCompletionsRequested = (ev: CompletionEvent) => CompletionList;
   type CbFunc<T> = T extends EventType.CompletionRequested
     ? CbFuncCompletionsRequested
     : never;

docs/wip-plugins.md

@@ -167,7 +167,7 @@ Limitations/known issues:
 
 #### `register_callback("CompletionRequested", handler)`
 
-Registers a callback (`handler`) to process completions. The callback gets the following parameters:
+Registers a callback (`handler`) to process completions. The callback takes a single table with the following entries:
 
 - `query`: The queried word.
 - `full_text_content`: The whole input.
@@ -190,8 +190,8 @@ end
 
 c2.register_callback(
     "CompletionRequested",
-    function(query, full_text_content, cursor_position, is_first_word)
-        if ("!join"):startswith(query) then
+    function(event)
+        if ("!join"):startswith(event.query) then
             ---@type CompletionList
             return { hide_others = true, values = { "!join" } }
         end