import { Injectable, OnModuleDestroy, OnModuleInit } from "@nestjs/common";
import { Pool, PoolClient, QueryResult, QueryResultRow } from "pg";

@Injectable()
export class DbService implements OnModuleInit, OnModuleDestroy {
  private pool!: Pool;

  onModuleInit() {
    const connectionString = process.env.DATABASE_URL;
    if (!connectionString) {
      throw new Error("DATABASE_URL is required (monolito Postgres)");
    }
    const sslOff = process.env.DB_SSL === "false";
    this.pool = new Pool({
      connectionString,
      ssl: sslOff ? undefined : { rejectUnauthorized: false },
    });
  }

  async onModuleDestroy() {
    await this.pool?.end();
  }

  query<T extends QueryResultRow = QueryResultRow>(
    text: string,
    params?: unknown[],
  ): Promise<QueryResult<T>> {
    return this.pool.query<T>(text, params);
  }

  async withClient<T>(fn: (client: PoolClient) => Promise<T>): Promise<T> {
    const client = await this.pool.connect();
    try {
      return await fn(client);
    } finally {
      client.release();
    }
  }
}