<?php
/**
 * Primary authentication provider interface
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 * @ingroup Auth
 */

namespace MediaWiki\Auth;

use StatusValue;
use User;

/**
 * A primary authentication provider is responsible for associating the submitted
 * authentication data with a MediaWiki account.
 *
 * When multiple primary authentication providers are configured for a site, they
 * act as alternatives; the first one that recognizes the data will handle it,
 * and further primary providers are not called (although they all get a chance
 * to prevent actions).
 *
 * For login, the PrimaryAuthenticationProvider takes form data and determines
 * which authenticated user (if any) corresponds to that form data. It might
 * do this on the basis of a username and password in that data, or by
 * interacting with an external authentication service (e.g. using OpenID),
 * or by some other mechanism.
 *
 * (A PrimaryAuthenticationProvider would not be appropriate for something like
 * HTTP authentication, OAuth, or SSL client certificates where each HTTP
 * request contains all the information needed to identify the user. In that
 * case you'll want to be looking at a \MediaWiki\Session\SessionProvider
 * instead.)
 *
 * For account creation, the PrimaryAuthenticationProvider takes form data and
 * stores some authentication details which will allow it to verify a login by
 * that user in the future. This might for example involve saving it in the
 * database in a table that can be joined to the user table, or sending it to
 * some external service for account creation, or authenticating the user with
 * some remote service and then recording that the remote identity is linked to
 * the local account.
 * The creation of the local user (i.e. calling User::addToDatabase()) is handled
 * by AuthManager once the primary authentication provider returns a PASS
 * from begin/continueAccountCreation; do not try to do it yourself.
 *
 * For account linking, the PrimaryAuthenticationProvider verifies the user's
 * identity at some external service (typically by redirecting the user and
 * asking the external service to verify) and then records which local account
 * is linked to which remote accounts. It should keep track of this and be able
 * to enumerate linked accounts via getAuthenticationRequests(ACTION_REMOVE).
 *
 * This interface also provides methods for changing authentication data such
 * as passwords, and callbacks that are invoked after login / account creation
 * / account linking succeeded or failed.
 *
 * @ingroup Auth
 * @since 1.27
 * @see https://www.mediawiki.org/wiki/Manual:SessionManager_and_AuthManager
 */
interface PrimaryAuthenticationProvider extends AuthenticationProvider {
	/** Provider can create accounts */
	const TYPE_CREATE = 'create';
	/** Provider can link to existing accounts elsewhere */
	const TYPE_LINK = 'link';
	/** Provider cannot create or link to accounts */
	const TYPE_NONE = 'none';

	/**
	 * @inheritDoc
	 *
	 * Of the requests returned by this method, exactly one should have
	 * {@link AuthenticationRequest::$required} set to REQUIRED.
	 */
	public function getAuthenticationRequests( $action, array $options );

	/**
	 * Start an authentication flow
	 *
	 * @param AuthenticationRequest[] $reqs
	 * @return AuthenticationResponse Expected responses:
	 *  - PASS: The user is authenticated. Secondary providers will now run.
	 *  - FAIL: The user is not authenticated. Fail the authentication process.
	 *  - ABSTAIN: These $reqs are not handled. Some other primary provider may handle it.
	 *  - UI: The $reqs are accepted, no other primary provider will run.
	 *    Additional AuthenticationRequests are needed to complete the process.
	 *  - REDIRECT: The $reqs are accepted, no other primary provider will run.
	 *    Redirection to a third party is needed to complete the process.
	 */
	public function beginPrimaryAuthentication( array $reqs );

	/**
	 * Continue an authentication flow
	 * @param AuthenticationRequest[] $reqs
	 * @return AuthenticationResponse Expected responses:
	 *  - PASS: The user is authenticated. Secondary providers will now run.
	 *  - FAIL: The user is not authenticated. Fail the authentication process.
	 *  - UI: Additional AuthenticationRequests are needed to complete the process.
	 *  - REDIRECT: Redirection to a third party is needed to complete the process.
	 */
	public function continuePrimaryAuthentication( array $reqs );

	/**
	 * Post-login callback
	 *
	 * This will be called at the end of any login attempt, regardless of whether this provider was
	 * the one that handled it. It will not be called for unfinished login attempts that fail by
	 * the session timing out.
	 *
	 * @param User|null $user User that was attempted to be logged in, if known.
	 *   This may become a "UserValue" in the future, or User may be refactored
	 *   into such.
	 * @param AuthenticationResponse $response Authentication response that will be returned
	 *   (PASS or FAIL)
	 */
	public function postAuthentication( $user, AuthenticationResponse $response );

	/**
	 * Test whether the named user exists
	 *
	 * Single-sign-on providers can use this to reserve a username for autocreation.
	 *
	 * @param string $username MediaWiki username
	 * @param int $flags Bitfield of User:READ_* constants
	 * @return bool
	 */
	public function testUserExists( $username, $flags = User::READ_NORMAL );

	/**
	 * Test whether the named user can authenticate with this provider
	 *
	 * Should return true if the provider has any data for this user which can be used to
	 * authenticate it, even if the user is temporarily prevented from authentication somehow.
	 *
	 * @param string $username MediaWiki username
	 * @return bool
	 */
	public function testUserCanAuthenticate( $username );

	/**
	 * Normalize the username for authentication
	 *
	 * Any two inputs that would result in the same user being authenticated
	 * should return the same string here, while inputs that would result in
	 * different users should return different strings.
	 *
	 * If possible, the best thing to do here is to return the canonicalized
	 * name of the local user account that would be used. If not, return
	 * something that would be invalid as a local username (e.g. wrap an email
	 * address in "<>", or append "#servicename" to the username passed to a
	 * third-party service).
	 *
	 * If the provider doesn't use a username at all in its
	 * AuthenticationRequests, return null. If the name is syntactically
	 * invalid, it's probably best to return null.
	 *
	 * @param string $username
	 * @return string|null
	 */
	public function providerNormalizeUsername( $username );

	/**
	 * Revoke the user's credentials
	 *
	 * This may cause the user to no longer exist for the provider, or the user
	 * may continue to exist in a "disabled" state.
	 *
	 * The intention is that the named account will never again be usable for
	 * normal login (i.e. there is no way to undo the revocation of access).
	 *
	 * @param string $username
	 */
	public function providerRevokeAccessForUser( $username );

	/**
	 * Determine whether a property can change
	 * @see AuthManager::allowsPropertyChange()
	 * @param string $property
	 * @return bool
	 */
	public function providerAllowsPropertyChange( $property );

	/**
	 * Validate a change of authentication data (e.g. passwords)
	 *
	 * Return StatusValue::newGood( 'ignored' ) if you don't support this
	 * AuthenticationRequest type.
	 *
	 * @param AuthenticationRequest $req
	 * @param bool $checkData If false, $req hasn't been loaded from the
	 *  submission so checks on user-submitted fields should be skipped.
	 *  $req->username is considered user-submitted for this purpose, even
	 *  if it cannot be changed via $req->loadFromSubmission.
	 * @return StatusValue
	 */
	public function providerAllowsAuthenticationDataChange(
		AuthenticationRequest $req, $checkData = true
	);

	/**
	 * Change or remove authentication data (e.g. passwords)
	 *
	 * If $req was returned for AuthManager::ACTION_CHANGE, the corresponding
	 * credentials should result in a successful login in the future.
	 *
	 * If $req was returned for AuthManager::ACTION_REMOVE, the corresponding
	 * credentials should no longer result in a successful login.
	 *
	 * It can be assumed that providerAllowsAuthenticationDataChange with $checkData === true
	 * was called before this, and passed. This method should never fail (other than throwing an
	 * exception).
	 *
	 * @param AuthenticationRequest $req
	 */
	public function providerChangeAuthenticationData( AuthenticationRequest $req );

	/**
	 * Fetch the account-creation type
	 * @return string One of the TYPE_* constants
	 */
	public function accountCreationType();

	/**
	 * Determine whether an account creation may begin
	 *
	 * Called from AuthManager::beginAccountCreation()
	 *
	 * @note No need to test if the account exists, AuthManager checks that
	 * @param User $user User being created (not added to the database yet).
	 *   This may become a "UserValue" in the future, or User may be refactored
	 *   into such.
	 * @param User $creator User doing the creation. This may become a
	 *   "UserValue" in the future, or User may be refactored into such.
	 * @param AuthenticationRequest[] $reqs
	 * @return StatusValue
	 */
	public function testForAccountCreation( $user, $creator, array $reqs );

	/**
	 * Start an account creation flow
	 * @param User $user User being created (not added to the database yet).
	 *   This may become a "UserValue" in the future, or User may be refactored
	 *   into such.
	 * @param User $creator User doing the creation. This may become a
	 *   "UserValue" in the future, or User may be refactored into such.
	 * @param AuthenticationRequest[] $reqs
	 * @return AuthenticationResponse Expected responses:
	 *  - PASS: The user may be created. Secondary providers will now run.
	 *  - FAIL: The user may not be created. Fail the creation process.
	 *  - ABSTAIN: These $reqs are not handled. Some other primary provider may handle it.
	 *  - UI: The $reqs are accepted, no other primary provider will run.
	 *    Additional AuthenticationRequests are needed to complete the process.
	 *  - REDIRECT: The $reqs are accepted, no other primary provider will run.
	 *    Redirection to a third party is needed to complete the process.
	 */
	public function beginPrimaryAccountCreation( $user, $creator, array $reqs );

	/**
	 * Continue an account creation flow
	 * @param User $user User being created (not added to the database yet).
	 *   This may become a "UserValue" in the future, or User may be refactored
	 *   into such.
	 * @param User $creator User doing the creation. This may become a
	 *   "UserValue" in the future, or User may be refactored into such.
	 * @param AuthenticationRequest[] $reqs
	 * @return AuthenticationResponse Expected responses:
	 *  - PASS: The user may be created. Secondary providers will now run.
	 *  - FAIL: The user may not be created. Fail the creation process.
	 *  - UI: Additional AuthenticationRequests are needed to complete the process.
	 *  - REDIRECT: Redirection to a third party is needed to complete the process.
	 */
	public function continuePrimaryAccountCreation( $user, $creator, array $reqs );

	/**
	 * Post-creation callback
	 *
	 * Called after the user is added to the database, before secondary
	 * authentication providers are run. Only called if this provider was the one that issued
	 * a PASS.
	 *
	 * @param User $user User being created (has been added to the database now).
	 *   This may become a "UserValue" in the future, or User may be refactored
	 *   into such.
	 * @param User $creator User doing the creation. This may become a
	 *   "UserValue" in the future, or User may be refactored into such.
	 * @param AuthenticationResponse $response PASS response returned earlier
	 * @return string|null 'newusers' log subtype to use for logging the
	 *   account creation. If null, either 'create' or 'create2' will be used
	 *   depending on $creator.
	 */
	public function finishAccountCreation( $user, $creator, AuthenticationResponse $response );

	/**
	 * Post-creation callback
	 *
	 * This will be called at the end of any account creation attempt, regardless of whether this
	 * provider was the one that handled it. It will not be called if the account creation process
	 * results in a session timeout (possibly after a successful user creation, while a secondary
	 * provider is waiting for a response).
	 *
	 * @param User $user User that was attempted to be created.
	 *   This may become a "UserValue" in the future, or User may be refactored
	 *   into such.
	 * @param User $creator User doing the creation. This may become a
	 *   "UserValue" in the future, or User may be refactored into such.
	 * @param AuthenticationResponse $response Authentication response that will be returned
	 *   (PASS or FAIL)
	 */
	public function postAccountCreation( $user, $creator, AuthenticationResponse $response );

	/**
	 * Determine whether an account may be created
	 *
	 * @param User $user User being created (not added to the database yet).
	 *   This may become a "UserValue" in the future, or User may be refactored
	 *   into such.
	 * @param bool|string $autocreate False if this is not an auto-creation, or
	 *  the source of the auto-creation passed to AuthManager::autoCreateUser().
	 * @param array $options
	 *  - flags: (int) Bitfield of User:READ_* constants, default User::READ_NORMAL
	 *  - creating: (bool) If false (or missing), this call is only testing if
	 *    a user could be created. If set, this (non-autocreation) is for
	 *    actually creating an account and will be followed by a call to
	 *    testForAccountCreation(). In this case, the provider might return
	 *    StatusValue::newGood() here and let the later call to
	 *    testForAccountCreation() do a more thorough test.
	 * @return StatusValue
	 */
	public function testUserForCreation( $user, $autocreate, array $options = [] );

	/**
	 * Post-auto-creation callback
	 * @param User $user User being created (has been added to the database now).
	 *   This may become a "UserValue" in the future, or User may be refactored
	 *   into such.
	 * @param string $source The source of the auto-creation passed to
	 *  AuthManager::autoCreateUser().
	 */
	public function autoCreatedAccount( $user, $source );

	/**
	 * Start linking an account to an existing user
	 * @param User $user User being linked.
	 *   This may become a "UserValue" in the future, or User may be refactored
	 *   into such.
	 * @param AuthenticationRequest[] $reqs
	 * @return AuthenticationResponse Expected responses:
	 *  - PASS: The user is linked.
	 *  - FAIL: The user is not linked. Fail the linking process.
	 *  - ABSTAIN: These $reqs are not handled. Some other primary provider may handle it.
	 *  - UI: The $reqs are accepted, no other primary provider will run.
	 *    Additional AuthenticationRequests are needed to complete the process.
	 *  - REDIRECT: The $reqs are accepted, no other primary provider will run.
	 *    Redirection to a third party is needed to complete the process.
	 */
	public function beginPrimaryAccountLink( $user, array $reqs );

	/**
	 * Continue linking an account to an existing user
	 * @param User $user User being linked.
	 *   This may become a "UserValue" in the future, or User may be refactored
	 *   into such.
	 * @param AuthenticationRequest[] $reqs
	 * @return AuthenticationResponse Expected responses:
	 *  - PASS: The user is linked.
	 *  - FAIL: The user is not linked. Fail the linking process.
	 *  - UI: Additional AuthenticationRequests are needed to complete the process.
	 *  - REDIRECT: Redirection to a third party is needed to complete the process.
	 */
	public function continuePrimaryAccountLink( $user, array $reqs );

	/**
	 * Post-link callback
	 *
	 * This will be called at the end of any account linking attempt, regardless of whether this
	 * provider was the one that handled it.
	 *
	 * @param User $user User that was attempted to be linked.
	 *   This may become a "UserValue" in the future, or User may be refactored
	 *   into such.
	 * @param AuthenticationResponse $response Authentication response that will be returned
	 *   (PASS or FAIL)
	 */
	public function postAccountLink( $user, AuthenticationResponse $response );

}