Add function handling for OpenAI model

for now it's querying only time, but in the future there will be more commands

src/funcitonManager.ts

@@ -0,0 +1,83 @@
+import { ChatCompletionFunctions, ChatCompletionRequestMessageFunctionCall } from "openai";
+import config from "./config";
+
+type parameterMap = {
+  string: string,
+  number: number,
+};
+
+type nameTypeMap = {[name: string]: keyof parameterMap} | Record<string, never>;
+
+type OpenAIFunctionRequestData<T extends nameTypeMap> = {
+  [name in keyof T]: T[name];
+};
+
+/**
+ * Represents the function that can be ran by the OpenAI model
+ */
+export interface OpenAIFunction<T extends nameTypeMap = nameTypeMap> {
+  name: string,
+  description?: string,
+  parameters: {
+    type: "object",
+    properties: T extends Record<string, never> ? Record<string, never> : {
+      [name in T[string]]: {
+        type: T[name],
+        description?: string,
+      }
+    },
+    required?: Array<keyof T>,
+  },
+}
+
+export abstract class OpenAIFunction<T extends nameTypeMap = nameTypeMap> {
+  getSettings(): ChatCompletionFunctions {
+    return {
+      name: this.name,
+      description: this.description,
+      parameters: this.parameters,
+    };
+  }
+
+  abstract execute(data: OpenAIFunctionRequestData<T>): string;
+}
+
+/*
+ * Manages functions for the OpenAI
+ **/
+export default class FunctionManager {
+  store = new Map<string, OpenAIFunction>();
+
+  constructor() {
+    this.store.set("getTime", new GetTime());
+  }
+
+  public getFunctions(): ChatCompletionFunctions[] {
+    const rvalue: ChatCompletionFunctions[] = [];
+    for (const [, value] of this.store) {
+      rvalue.push(value.getSettings());
+    }
+    return rvalue;
+  }
+
+  public handleFunction(request: ChatCompletionRequestMessageFunctionCall) {
+    
+    const parsedArguments = JSON.parse(request.arguments ?? "");
+    return this.store.get(request.name ?? "")?.execute(parsedArguments);
+  }
+}
+
+// buildins
+
+class GetTime extends OpenAIFunction<Record<string, never>> {
+  name = "getTime";
+  description = "Gets current date and time with a timezone attached";
+  parameters = {
+    type: "object" as const,
+    properties: {} as Record<string, never>,
+  };
+
+  execute(): string {
+    return `${Intl.DateTimeFormat().resolvedOptions().timeZone}): ${new Date().toLocaleString("en-US", config.calendarConfig)}`;
+  }
+}