import { MongoClient, Db } from "mongodb";
import { setDb } from "./index";
import { validateConfig, validateMongoUri } from "../utils/validation";

class MongoDBClient {
  private client: MongoClient | null = null;
  private db: Db | null = null;

  private extractDatabaseName(uri: string): string | null {
    try {
      const url = new URL(uri);
      const dbName = url.pathname.slice(1);
      return dbName || null;
    } catch {
      return null;
    }
  }

  async connect(uri?: string, databaseName?: string): Promise<void> {
    if (this.client) {
      return;
    }

    const mongodbUri = uri || process.env.MONGO_URI || process.env.MONGODB_URI;
    validateConfig("MONGO_URI", mongodbUri);
    validateMongoUri(mongodbUri!);

    try {
      this.client = new MongoClient(mongodbUri!);
      await this.client.connect();

      const dbNameFromUri = this.extractDatabaseName(mongodbUri!);
      const dbName =
        databaseName || process.env.TALKPILOT_DB_NAME || dbNameFromUri;

      if (!dbName) {
        throw new Error(
          "[core-db] Database name not specified. Please pass databaseName to connect(), " +
            "add it to the URI, or set TALKPILOT_DB_NAME.",
        );
      }

      this.db = this.client.db(dbName);
      setDb(this.db);
      console.info(`[core-db] TalkPilot MongoDB connected: ${dbName}`);
    } catch (error) {
      console.error("[core-db] TalkPilot connection failed", error);
      throw error;
    }
  }

  async disconnect(): Promise<void> {
    if (this.client) {
      try {
        await this.client.close();
        this.client = null;
        this.db = null;
        console.info("MongoDB disconnected successfully");
      } catch (error) {
        console.error("[core-db] Disconnection failed", error);
        throw error;
      }
    }
  }

  getDb(): Db {
    if (!this.db) {
      throw new Error("Database not initialized. Call connect() first.");
    }
    return this.db;
  }

  isConnected(): boolean {
    return this.client !== null && this.client !== undefined;
  }
}

export const mongodbClient = new MongoDBClient();