import { drizzle, type NodePgDatabase } from "drizzle-orm/node-postgres";
import { Pool, type PoolConfig } from "pg";
import {
  type DatabaseTransportPolicy,
  databaseTlsConnectionOptions,
} from "../database/transport.js";
import { authorizationSchema } from "./schema.js";

export type AuthorizationDrizzleDatabase = NodePgDatabase<typeof authorizationSchema>;

export type AuthorizationDatabaseErrorCode = "AUTHORIZATION_DATABASE_CONFIGURATION_INVALID";

const maximumPostgresTimeoutMs = 2_147_483_647;

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

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

export interface AuthorizationDatabaseOptions {
  readonly connectionTimeoutMs?: number;
  /** Bounds both `query_timeout` and `statement_timeout`, mirroring
   * `core/src/identity/database.ts`: `connectionTimeoutMs` alone only bounds establishing a
   * connection, not a hung query already running on one. */
  readonly operationTimeoutMs?: number;
  /** The validated transport policy (`core/src/database/transport.js`). Passed explicitly by
   * every production executable; omitted by single-domain unit/integration factories that use
   * the disposable loopback database, which keeps the pre-existing plaintext behavior. */
  readonly transport?: DatabaseTransportPolicy;
}

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

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

/** Mirrors `core/src/identity/database.ts`'s timeout validation exactly: an explicit timeout must
 * be a positive safe integer no larger than PostgreSQL's own maximum, or it is rejected as invalid
 * configuration rather than silently passed through to `pg`. */
function validateTimeout(value: unknown): number | undefined {
  if (value === undefined) {
    return undefined;
  }
  if (
    typeof value !== "number" ||
    !Number.isSafeInteger(value) ||
    value <= 0 ||
    value > maximumPostgresTimeoutMs
  ) {
    throw new AuthorizationDatabaseError("AUTHORIZATION_DATABASE_CONFIGURATION_INVALID");
  }
  return value;
}

/**
 * Explicitly constructs the Core-owned Drizzle database instance backing the authorization store.
 * 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 createAuthorizationDrizzleDatabase(
  connectionString: string,
  options: AuthorizationDatabaseOptions = {},
): AuthorizationDatabaseHandle {
  const validatedConnectionString = validateConnectionString(connectionString);
  const validatedConnectionTimeoutMs = validateTimeout(options.connectionTimeoutMs);
  const validatedOperationTimeoutMs = validateTimeout(options.operationTimeoutMs);
  const ssl =
    options.transport === undefined
      ? undefined
      : databaseTlsConnectionOptions(validatedConnectionString, options.transport);
  const poolConfig: PoolConfig = {
    connectionString: validatedConnectionString,
    ...(ssl === undefined ? {} : { ssl }),
    ...(validatedConnectionTimeoutMs === undefined
      ? {}
      : { connectionTimeoutMillis: validatedConnectionTimeoutMs }),
    ...(validatedOperationTimeoutMs === undefined
      ? {}
      : {
          query_timeout: validatedOperationTimeoutMs,
          statement_timeout: validatedOperationTimeoutMs,
        }),
  };

  const pool = new Pool(poolConfig);
  // Same rationale as core/src/identity/database.ts: pg's own documentation requires an error
  // listener on the pool, or a server-initiated termination of an idle client becomes an
  // unhandled Node.js error and can crash the process.
  pool.on("error", () => undefined);
  const db = drizzle(pool, { schema: authorizationSchema });

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

/**
 * A typed Drizzle view over an externally owned pool — for example one shared with the identity
 * schema via `createValidatedPostgresPool` (`core/src/database/pool.ts`). Unlike
 * `createAuthorizationDrizzleDatabase`, this function never constructs, registers an error
 * listener on, or closes a pool itself: the caller retains that responsibility exactly once,
 * regardless of how many typed views it creates over the same pool.
 */
export function createAuthorizationDrizzleView(pool: Pool): AuthorizationDrizzleDatabase {
  return drizzle(pool, { schema: authorizationSchema });
}