import pg from 'pg'

import { PostgresTransaction, PostgresTransactionImpl } from './PostgresTransaction.js'
import { Database } from '../../Database.js'
import type { DbBaseConfig, DbConfig } from '../../types.js'

/**
 * Represents a Postgres database connection that extends the Database class.
 * @extends Database<PostgresTransaction>
 */
export class PostgresDatabase extends Database<PostgresTransaction> {
  /**
   * A public static property that represents a connection pool for a PostgreSQL database.
   * This property is used to manage and provide connections to the PostgreSQL database.
   */
  private static pgProvider = pg.Pool
  /**
   * Represents a connection pool to manage multiple client connections to the database.
   */
  public readonly client: pg.Pool
  /**
   * A private property that represents a connection pool for clients.
   * @type {Pool | undefined}
   */
  public readonly readClient?: pg.Pool

  /**
   * Constructor for creating a new instance of a database connection using Postgres.
   * @param {DbConfig<'pg'>} config - The configuration object for the Postgres database.
   * @returns None
   */
  constructor(config: DbConfig<'pg'>) {
    super(config)
    this.client = this.providerFactory(config)
    if (config.readReplica) this.readClient = this.providerFactory(config.readReplica)
  }

  /**
   * Creates a new Postgres transaction using the provided client and read client.
   * @returns {Promise<PostgresTransaction>} A promise that resolves to a new PostgresTransaction object.
   */
  public override async transaction(): Promise<PostgresTransaction> {
    return PostgresTransactionImpl.newTransaction(this.client, this, this.readClient)
  }

  private providerFactory(config: DbBaseConfig) {
    return new PostgresDatabase.pgProvider({
      host: config.host,
      port: config.port,
      user: config.username,
      password: config.password,
      database: config.database,
      max: config.maxConnections,
    })
  }
}