OV-39: integrate Open AI

backend/package.json

@@ -41,6 +41,7 @@
         "fastify": "4.28.1",
         "knex": "3.1.0",
         "objection": "3.1.4",
+        "openai": "4.56.0",
         "pg": "8.12.0",
         "pino": "9.3.2",
         "pino-pretty": "10.3.1",

backend/src/common/config/base-config.package.ts

@@ -41,6 +41,12 @@ class BaseConfig implements Config {
                     env: 'PORT',
                     default: null,
                 },
+                OPEN_AI_KEY: {
+                    doc: 'Key for Open Ai',
+                    format: String,
+                    env: 'OPEN_AI_KEY',
+                    default: null,
+                },
             },
             DB: {
                 CONNECTION_STRING: {

backend/src/common/config/types/environment-schema.type.ts

@@ -5,6 +5,7 @@ type EnvironmentSchema = {
     APP: {
         PORT: number;
         ENVIRONMENT: ValueOf<typeof AppEnvironment>;
+        OPEN_AI_KEY: string;
     };
     DB: {
         CONNECTION_STRING: string;

backend/src/common/services/open-ai/libs/constants/chat-model.constant.ts

@@ -0,0 +1,3 @@
+const CHAT_MODEL = 'gpt-4o-mini';
+
+export { CHAT_MODEL };

backend/src/common/services/open-ai/libs/constants/constants.ts

@@ -0,0 +1,2 @@
+export { CHAT_MODEL } from './chat-model.constant.js';
+export { MAX_TOKEN } from './max-token.constant.js';

backend/src/common/services/open-ai/libs/constants/max-token.constant.ts

@@ -0,0 +1,3 @@
+const MAX_TOKEN = 16_000;
+
+export { MAX_TOKEN };

backend/src/common/services/open-ai/libs/enums/enums.ts

@@ -0,0 +1 @@
+export { OpenAIRole } from './open-ai-role.enum.js';

backend/src/common/services/open-ai/libs/enums/open-ai-role.enum.ts

@@ -0,0 +1,7 @@
+const OpenAIRole = {
+    USER: 'user',
+    SYSTEM: 'system',
+    ASSISTANT: 'assistant',
+} as const;
+
+export { OpenAIRole };

backend/src/common/services/open-ai/libs/types/message.type.ts

@@ -0,0 +1,10 @@
+import { type ValueOf } from 'shared';
+
+import { type OpenAIRole } from '../enums/enums.js';
+
+type Message = {
+    role: ValueOf<typeof OpenAIRole>;
+    content: string;
+};
+
+export { type Message };

backend/src/common/services/open-ai/libs/types/open-ai-service.type.ts

@@ -0,0 +1,7 @@
+import { type Message } from './message.type.js';
+
+type OpenAIService = {
+    generateText(messages: Message[]): Promise<string>;
+};
+
+export { type OpenAIService };

backend/src/common/services/open-ai/libs/types/types.ts

@@ -0,0 +1,2 @@
+export { type Message } from './message.type.js';
+export { type OpenAIService } from './open-ai-service.type.js';

backend/src/common/services/open-ai/open-ai.service.ts

@@ -0,0 +1,41 @@
+import OpenAI from 'openai';
+
+import { type BaseConfig } from '~/common/config/base-config.package.js';
+
+import { CHAT_MODEL, MAX_TOKEN } from './libs/constants/constants.js';
+import {
+    type Message,
+    type OpenAIService as OpenAIServiceModule,
+} from './libs/types/types.js';
+
+type Constructor = {
+    config: BaseConfig;
+};
+
+class OpenAIService implements OpenAIServiceModule {
+    private config: BaseConfig;
+    private openAi: OpenAI;
+
+    public constructor({ config }: Constructor) {
+        this.config = config;
+        this.openAi = this.initOpenAi();
+    }
+
+    private initOpenAi = (): OpenAI => {
+        return new OpenAI({
+            apiKey: this.config.ENV.APP.OPEN_AI_KEY,
+        });
+    };
+
+    public async generateText(messages: Message[]): Promise<string> {
+        const completion = await this.openAi.chat.completions.create({
+            messages,
+            model: CHAT_MODEL,
+            max_tokens: MAX_TOKEN,
+        });
+
+        return completion.choices[0]?.message.content || '';
+    }
+}
+
+export { OpenAIService };