import type { Document } from '../../bson';
import { MongoInvalidArgumentError, MongoMissingCredentialsError } from '../../error';
import type { HandshakeDocument } from '../connect';
import type { Connection } from '../connection';
import { type AuthContext, AuthProvider } from './auth_provider';
import type { MongoCredentials } from './mongo_credentials';
import { AzureMachineWorkflow } from './mongodb_oidc/azure_machine_workflow';
import { GCPMachineWorkflow } from './mongodb_oidc/gcp_machine_workflow';
import { K8SMachineWorkflow } from './mongodb_oidc/k8s_machine_workflow';
import { TokenCache } from './mongodb_oidc/token_cache';
import { TokenMachineWorkflow } from './mongodb_oidc/token_machine_workflow';

/** Error when credentials are missing. */
const MISSING_CREDENTIALS_ERROR = 'AuthContext must provide credentials.';

/**
 * The information returned by the server on the IDP server.
 * @public
 */
export interface IdPInfo {
  /**
   * A URL which describes the Authentication Server. This identifier should
   * be the iss of provided access tokens, and be viable for RFC8414 metadata
   * discovery and RFC9207 identification.
   */
  issuer: string;
  /** A unique client ID for this OIDC client. */
  clientId: string;
  /** A list of additional scopes to request from IdP. */
  requestScopes?: string[];
}

/**
 * The response from the IdP server with the access token and
 * optional expiration time and refresh token.
 * @public
 */
export interface IdPServerResponse {
  /** The OIDC access token. */
  accessToken: string;
  /** The time when the access token expires. For future use. */
  expiresInSeconds?: number;
  /** The refresh token, if applicable, to be used by the callback to request a new token from the issuer. */
  refreshToken?: string;
}

/**
 * The response required to be returned from the machine or
 * human callback workflows' callback.
 * @public
 */
export interface OIDCResponse {
  /** The OIDC access token. */
  accessToken: string;
  /** The time when the access token expires. For future use. */
  expiresInSeconds?: number;
  /** The refresh token, if applicable, to be used by the callback to request a new token from the issuer. */
  refreshToken?: string;
}

/**
 * The parameters that the driver provides to the user supplied
 * human or machine callback.
 *
 * The version number is used to communicate callback API changes that are not breaking but that
 * users may want to know about and review their implementation. Users may wish to check the version
 * number and throw an error if their expected version number and the one provided do not match.
 * @public
 */
export interface OIDCCallbackParams {
  /** Optional username. */
  username?: string;
  /** The context in which to timeout the OIDC callback. */
  timeoutContext: AbortSignal;
  /** The current OIDC API version. */
  version: 1;
  /** The IdP information returned from the server. */
  idpInfo?: IdPInfo;
  /** The refresh token, if applicable, to be used by the callback to request a new token from the issuer. */
  refreshToken?: string;
}

/**
 * The signature of the human or machine callback functions.
 * @public
 */
export type OIDCCallbackFunction = (params: OIDCCallbackParams) => Promise<OIDCResponse>;

/** The current version of OIDC implementation. */
export const OIDC_VERSION = 1;

type EnvironmentName = 'test' | 'azure' | 'gcp' | 'k8s' | undefined;

/** @internal */
export interface Workflow {
  /**
   * All device workflows must implement this method in order to get the access
   * token and then call authenticate with it.
   */
  execute(
    connection: Connection,
    credentials: MongoCredentials,
    response?: Document
  ): Promise<void>;

  /**
   * Each workflow should specify the correct custom behaviour for reauthentication.
   */
  reauthenticate(connection: Connection, credentials: MongoCredentials): Promise<void>;

  /**
   * Get the document to add for speculative authentication.
   */
  speculativeAuth(connection: Connection, credentials: MongoCredentials): Promise<Document>;
}

/** @internal */
export const OIDC_WORKFLOWS: Map<EnvironmentName, () => Workflow> = new Map();
OIDC_WORKFLOWS.set('test', () => new TokenMachineWorkflow(new TokenCache()));
OIDC_WORKFLOWS.set('azure', () => new AzureMachineWorkflow(new TokenCache()));
OIDC_WORKFLOWS.set('gcp', () => new GCPMachineWorkflow(new TokenCache()));
OIDC_WORKFLOWS.set('k8s', () => new K8SMachineWorkflow(new TokenCache()));

/**
 * OIDC auth provider.
 */
export class MongoDBOIDC extends AuthProvider {
  workflow: Workflow;

  /**
   * Instantiate the auth provider.
   */
  constructor(workflow?: Workflow) {
    super();
    if (!workflow) {
      throw new MongoInvalidArgumentError('No workflow provided to the OIDC auth provider.');
    }
    this.workflow = workflow;
  }

  /**
   * Authenticate using OIDC
   */
  override async auth(authContext: AuthContext): Promise<void> {
    const { connection, reauthenticating, response } = authContext;
    if (response?.speculativeAuthenticate?.done) {
      return;
    }
    const credentials = getCredentials(authContext);
    if (reauthenticating) {
      await this.workflow.reauthenticate(connection, credentials);
    } else {
      await this.workflow.execute(connection, credentials, response);
    }
  }

  /**
   * Add the speculative auth for the initial handshake.
   */
  override async prepare(
    handshakeDoc: HandshakeDocument,
    authContext: AuthContext
  ): Promise<HandshakeDocument> {
    const { connection } = authContext;
    const credentials = getCredentials(authContext);
    const result = await this.workflow.speculativeAuth(connection, credentials);
    return { ...handshakeDoc, ...result };
  }
}

/**
 * Get credentials from the auth context, throwing if they do not exist.
 */
function getCredentials(authContext: AuthContext): MongoCredentials {
  const { credentials } = authContext;
  if (!credentials) {
    throw new MongoMissingCredentialsError(MISSING_CREDENTIALS_ERROR);
  }
  return credentials;
}
