import { drizzle, type NodePgDatabase } from "drizzle-orm/node-postgres";
import { Pool, type PoolConfig } from "pg";
import { identityAdapterSchema } from "./schema.js";

export type IdentityDrizzleDatabase = NodePgDatabase<typeof identityAdapterSchema>;

export type IdentityDatabaseErrorCode = "IDENTITY_DATABASE_CONFIGURATION_INVALID";

/** Never carries the offending connection string, host, or underlying driver error. */
export class IdentityDatabaseError extends Error {
  readonly code: IdentityDatabaseErrorCode;

  constructor(code: IdentityDatabaseErrorCode) {
    super("Identity database configuration is invalid.");
    this.name = "IdentityDatabaseError";
    this.code = code;
    this.stack = `${this.name}: ${this.message}`;
    Object.freeze(this);
  }
}

export interface IdentityDatabaseOptions {
  readonly connectionTimeoutMs?: number;
}

export interface IdentityDatabaseHandle {
  readonly close: () => Promise<void>;
  readonly db: IdentityDrizzleDatabase;
}

function validateConnectionString(connectionString: string): string {
  if (connectionString.trim().length === 0) {
    throw new IdentityDatabaseError("IDENTITY_DATABASE_CONFIGURATION_INVALID");
  }
  let protocol: string;
  try {
    protocol = new URL(connectionString).protocol;
  } catch {
    throw new IdentityDatabaseError("IDENTITY_DATABASE_CONFIGURATION_INVALID");
  }
  if (protocol !== "postgres:" && protocol !== "postgresql:") {
    throw new IdentityDatabaseError("IDENTITY_DATABASE_CONFIGURATION_INVALID");
  }
  return connectionString;
}

/**
 * Explicitly constructs the Core-owned Drizzle database instance used by the identity factory.
 * Building the `pg.Pool` performs no network I/O until a query is issued, and this function is
 * only ever invoked by explicit caller code — never during module import.
 */
export function createIdentityDrizzleDatabase(
  connectionString: string,
  options: IdentityDatabaseOptions = {},
): IdentityDatabaseHandle {
  const validatedConnectionString = validateConnectionString(connectionString);
  const poolConfig: PoolConfig = { connectionString: validatedConnectionString };
  if (options.connectionTimeoutMs !== undefined) {
    poolConfig.connectionTimeoutMillis = options.connectionTimeoutMs;
  }

  const pool = new Pool(poolConfig);
  const db = drizzle(pool, { schema: identityAdapterSchema });

  return Object.freeze({
    close: () => pool.end(),
    db,
  });
}