<?php
/**
 * Implements Special:Emailuser
 *
 * 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 SpecialPage
 */

use MediaWiki\MediaWikiServices;
use MediaWiki\Preferences\MultiUsernameFilter;
use MediaWiki\User\UserNamePrefixSearch;
use MediaWiki\User\UserNameUtils;
use MediaWiki\User\UserOptionsLookup;

/**
 * A special page that allows users to send e-mails to other users
 *
 * @ingroup SpecialPage
 */
class SpecialEmailUser extends UnlistedSpecialPage {
	protected $mTarget;

	/**
	 * @var User|string
	 */
	protected $mTargetObj;

	/** @var UserNameUtils */
	private $userNameUtils;

	/** @var UserNamePrefixSearch */
	private $userNamePrefixSearch;

	/** @var UserOptionsLookup */
	private $userOptionsLookup;

	/**
	 * @param UserNameUtils $userNameUtils
	 * @param UserNamePrefixSearch $userNamePrefixSearch
	 * @param UserOptionsLookup $userOptionsLookup
	 */
	public function __construct(
		UserNameUtils $userNameUtils,
		UserNamePrefixSearch $userNamePrefixSearch,
		UserOptionsLookup $userOptionsLookup
	) {
		parent::__construct( 'Emailuser' );
		$this->userNameUtils = $userNameUtils;
		$this->userNamePrefixSearch = $userNamePrefixSearch;
		$this->userOptionsLookup = $userOptionsLookup;
	}

	public function doesWrites() {
		return true;
	}

	public function getDescription() {
		$target = self::getTarget( $this->mTarget, $this->getUser() );
		if ( !$target instanceof User ) {
			return $this->msg( 'emailuser-title-notarget' )->text();
		}

		return $this->msg( 'emailuser-title-target', $target->getName() )->text();
	}

	protected function getFormFields() {
		$linkRenderer = $this->getLinkRenderer();
		$user = $this->getUser();
		return [
			'From' => [
				'type' => 'info',
				'raw' => 1,
				'default' => $linkRenderer->makeLink(
					$user->getUserPage(),
					$user->getName()
				),
				'label-message' => 'emailfrom',
				'id' => 'mw-emailuser-sender',
			],
			'To' => [
				'type' => 'info',
				'raw' => 1,
				'default' => $linkRenderer->makeLink(
					$this->mTargetObj->getUserPage(),
					$this->mTargetObj->getName()
				),
				'label-message' => 'emailto',
				'id' => 'mw-emailuser-recipient',
			],
			'Target' => [
				'type' => 'hidden',
				'default' => $this->mTargetObj->getName(),
			],
			'Subject' => [
				'type' => 'text',
				'default' => $this->msg( 'defemailsubject', $user->getName() )->inContentLanguage()->text(),
				'label-message' => 'emailsubject',
				'maxlength' => 200,
				'size' => 60,
				'required' => true,
			],
			'Text' => [
				'type' => 'textarea',
				'rows' => 20,
				'label-message' => 'emailmessage',
				'required' => true,
			],
			'CCMe' => [
				'type' => 'check',
				'label-message' => 'emailccme',
				'default' => $this->userOptionsLookup->getBoolOption( $user, 'ccmeonemails' ),
			],
		];
	}

	public function execute( $par ) {
		$out = $this->getOutput();
		$request = $this->getRequest();
		$out->addModuleStyles( 'mediawiki.special' );

		$this->mTarget = $par ?? $request->getVal( 'wpTarget', $request->getVal( 'target', '' ) );

		// Make sure, that HTMLForm uses the correct target.
		$request->setVal( 'wpTarget', $this->mTarget );

		// This needs to be below assignment of $this->mTarget because
		// getDescription() needs it to determine the correct page title.
		$this->setHeaders();
		$this->outputHeader();

		// error out if sending user cannot do this
		$error = self::getPermissionsError(
			$this->getUser(),
			$this->getRequest()->getVal( 'wpEditToken' ),
			$this->getConfig()
		);

		switch ( $error ) {
			case null:
				# Wahey!
				break;
			case 'badaccess':
				throw new PermissionsError( 'sendemail' );
			case 'blockedemailuser':
				throw new UserBlockedError( $this->getUser()->getBlock() );
			case 'actionthrottledtext':
				throw new ThrottledError;
			case 'mailnologin':
			case 'usermaildisabled':
				throw new ErrorPageError( $error, "{$error}text" );
			default:
				# It's a hook error
				list( $title, $msg, $params ) = $error;
				throw new ErrorPageError( $title, $msg, $params );
		}

		// Make sure, that a submitted form isn't submitted to a subpage (which could be
		// a non-existing username)
		$context = new DerivativeContext( $this->getContext() );
		$context->setTitle( $this->getPageTitle() ); // Remove subpage
		$this->setContext( $context );

		// A little hack: HTMLForm will check $this->mTarget only, if the form was posted, not
		// if the user opens Special:EmailUser/Florian (e.g.). So check, if the user did that
		// and show the "Send email to user" form directly, if so. Show the "enter username"
		// form, otherwise.
		$this->mTargetObj = self::getTarget( $this->mTarget, $this->getUser() );
		if ( !$this->mTargetObj instanceof User ) {
			$this->userForm( $this->mTarget );
		} else {
			$this->sendEmailForm();
		}
	}

	/**
	 * Validate target User
	 *
	 * @param string $target Target user name
	 * @param User $sender User sending the email
	 * @return User|string User object on success or a string on error
	 */
	public static function getTarget( $target, User $sender ) {
		if ( $target == '' ) {
			wfDebug( "Target is empty." );

			return 'notarget';
		}

		$nu = User::newFromName( $target );
		$error = self::validateTarget( $nu, $sender );

		return $error ?: $nu;
	}

	/**
	 * Validate target User
	 *
	 * @param User $target Target user
	 * @param User $sender User sending the email
	 * @return string Error message or empty string if valid.
	 * @since 1.30
	 */
	public static function validateTarget( $target, User $sender ) {
		if ( !$target instanceof User || !$target->getId() ) {
			wfDebug( "Target is invalid user." );

			return 'notarget';
		}

		if ( !$target->isEmailConfirmed() ) {
			wfDebug( "User has no valid email." );

			return 'noemail';
		}

		if ( !$target->canReceiveEmail() ) {
			wfDebug( "User does not allow user emails." );

			return 'nowikiemail';
		}

		if ( !$target->getOption( 'email-allow-new-users' ) && $sender->isNewbie() ) {
			wfDebug( "User does not allow user emails from new users." );

			return 'nowikiemail';
		}

		$muteList = $target->getOption( 'email-blacklist', '' );
		if ( $muteList ) {
			$muteList = MultiUsernameFilter::splitIds( $muteList );
			$senderId = MediaWikiServices::getInstance()
				->getCentralIdLookup()
				->centralIdFromLocalUser( $sender );
			if ( $senderId !== 0 && in_array( $senderId, $muteList ) ) {
				wfDebug( "User does not allow user emails from this user." );

				return 'nowikiemail';
			}
		}

		return '';
	}

	/**
	 * Check whether a user is allowed to send email
	 *
	 * @param User $user
	 * @param string $editToken
	 * @param Config|null $config optional for backwards compatibility
	 * @return null|string|array Null on success, string on error, or array on
	 *  hook error
	 */
	public static function getPermissionsError( $user, $editToken, Config $config = null ) {
		if ( $config === null ) {
			wfDebug( __METHOD__ . ' called without a Config instance passed to it' );
			$config = MediaWikiServices::getInstance()->getMainConfig();
		}
		if ( !$config->get( 'EnableEmail' ) || !$config->get( 'EnableUserEmail' ) ) {
			return 'usermaildisabled';
		}

		// Run this before checking 'sendemail' permission
		// to show appropriate message to anons (T160309)
		if ( !$user->isEmailConfirmed() ) {
			return 'mailnologin';
		}

		if ( !MediaWikiServices::getInstance()
				->getPermissionManager()
				->userHasRight( $user, 'sendemail' )
		) {
			return 'badaccess';
		}

		if ( $user->isBlockedFromEmailuser() ) {
			wfDebug( "User is blocked from sending e-mail." );

			return "blockedemailuser";
		}

		// Check the ping limiter without incrementing it - we'll check it
		// again later and increment it on a successful send
		if ( $user->pingLimiter( 'emailuser', 0 ) ) {
			wfDebug( "Ping limiter triggered." );

			return 'actionthrottledtext';
		}

		$hookErr = false;

		Hooks::runner()->onUserCanSendEmail( $user, $hookErr );
		Hooks::runner()->onEmailUserPermissionsErrors( $user, $editToken, $hookErr );

		if ( $hookErr ) {
			return $hookErr;
		}

		return null;
	}

	/**
	 * Form to ask for target user name.
	 *
	 * @param string $name User name submitted.
	 */
	protected function userForm( $name ) {
		$htmlForm = HTMLForm::factory( 'ooui', [
			'Target' => [
				'type' => 'user',
				'exists' => true,
				'required' => true,
				'label' => $this->msg( 'emailusername' )->text(),
				'id' => 'emailusertarget',
				'autofocus' => true,
				'value' => $name,
			]
		], $this->getContext() );

		$htmlForm
			->setSubmitCallback( [ $this, 'sendEmailForm' ] )
			->setFormIdentifier( 'userForm' )
			->setId( 'askusername' )
			->setWrapperLegendMsg( 'emailtarget' )
			->setSubmitTextMsg( 'emailusernamesubmit' )
			->show();
	}

	public function sendEmailForm() {
		$out = $this->getOutput();

		$ret = $this->mTargetObj;
		if ( !$ret instanceof User ) {
			if ( $this->mTarget != '' ) {
				// Messages used here: notargettext, noemailtext, nowikiemailtext
				$ret = ( $ret == 'notarget' ) ? 'emailnotarget' : ( $ret . 'text' );
				return Status::newFatal( $ret );
			}
			return false;
		}

		$htmlForm = HTMLForm::factory( 'ooui', $this->getFormFields(), $this->getContext() );
		// By now we are supposed to be sure that $this->mTarget is a user name
		$htmlForm
			->addPreText( $this->msg( 'emailpagetext', $this->mTarget )->parse() )
			->setSubmitTextMsg( 'emailsend' )
			->setSubmitCallback( [ __CLASS__, 'submit' ] )
			->setFormIdentifier( 'sendEmailForm' )
			->setWrapperLegendMsg( 'email-legend' )
			->loadData();

		if ( !$this->getHookRunner()->onEmailUserForm( $htmlForm ) ) {
			return false;
		}

		$result = $htmlForm->show();

		if ( $result === true || ( $result instanceof Status && $result->isGood() ) ) {
			$out->setPageTitle( $this->msg( 'emailsent' ) );
			$out->addWikiMsg( 'emailsenttext', $this->mTarget );
			$out->returnToMain( false, $ret->getUserPage() );
		}
		return true;
	}

	/**
	 * Really send a mail. Permissions should have been checked using
	 * getPermissionsError(). It is probably also a good
	 * idea to check the edit token and ping limiter in advance.
	 *
	 * @param array $data
	 * @param IContextSource $context
	 * @return Status|false
	 * @throws MWException if EmailUser hook sets the error to something unsupported
	 */
	public static function submit( array $data, IContextSource $context ) {
		$config = $context->getConfig();

		$sender = $context->getUser();
		$target = self::getTarget( $data['Target'], $sender );
		if ( !$target instanceof User ) {
			// Messages used here: notargettext, noemailtext, nowikiemailtext
			return Status::newFatal( $target . 'text' );
		}

		$toAddress = MailAddress::newFromUser( $target );
		$fromAddress = MailAddress::newFromUser( $sender );
		$subject = $data['Subject'];
		$text = $data['Text'];

		// Add a standard footer and trim up trailing newlines
		$text = rtrim( $text ) . "\n\n-- \n";
		$text .= $context->msg(
			'emailuserfooter',
			$fromAddress->name,
			$toAddress->name
		)->inContentLanguage()->text();

		if ( $config->get( 'EnableSpecialMute' ) ) {
			$specialMutePage = SpecialPage::getTitleFor( 'Mute', $sender->getName() );
			$text .= "\n" . $context->msg(
				'specialmute-email-footer',
				$specialMutePage->getCanonicalURL(),
				$sender->getName()
			)->inContentLanguage()->text();
		}

		// Check and increment the rate limits
		if ( $sender->pingLimiter( 'emailuser' ) ) {
			throw new ThrottledError();
		}

		// Services that are needed, will be injected once this is moved to EmailUserUtils
		// service, see T265541
		$hookRunner = Hooks::runner();
		$emailer = MediaWikiServices::getInstance()->getEmailer();

		$error = false;
		if ( !$hookRunner->onEmailUser( $toAddress, $fromAddress, $subject, $text, $error ) ) {
			if ( $error instanceof Status ) {
				return $error;
			} elseif ( $error === false || $error === '' || $error === [] ) {
				// Possibly to tell HTMLForm to pretend there was no submission?
				return false;
			} elseif ( $error === true ) {
				// Hook sent the mail itself and indicates success?
				return Status::newGood();
			} elseif ( is_array( $error ) ) {
				$status = Status::newGood();
				foreach ( $error as $e ) {
					$status->fatal( $e );
				}
				return $status;
			} elseif ( $error instanceof MessageSpecifier ) {
				return Status::newFatal( $error );
			} else {
				// Setting $error to something else was deprecated in 1.29 and
				// removed in 1.36, and so an exception is now thrown
				$type = is_object( $error ) ? get_class( $error ) : gettype( $error );
				throw new MWException(
					'EmailUser hook set $error to unsupported type ' . $type
				);
			}
		}

		if ( $config->get( 'UserEmailUseReplyTo' ) ) {
			/**
			 * Put the generic wiki autogenerated address in the From:
			 * header and reserve the user for Reply-To.
			 *
			 * This is a bit ugly, but will serve to differentiate
			 * wiki-borne mails from direct mails and protects against
			 * SPF and bounce problems with some mailers (see below).
			 */
			$mailFrom = new MailAddress(
				$config->get( 'PasswordSender' ),
				$context->msg( 'emailsender' )->inContentLanguage()->text()
			);
			$replyTo = $fromAddress;
		} else {
			/**
			 * Put the sending user's e-mail address in the From: header.
			 *
			 * This is clean-looking and convenient, but has issues.
			 * One is that it doesn't as clearly differentiate the wiki mail
			 * from "directly" sent mails.
			 *
			 * Another is that some mailers (like sSMTP) will use the From
			 * address as the envelope sender as well. For open sites this
			 * can cause mails to be flunked for SPF violations (since the
			 * wiki server isn't an authorized sender for various users'
			 * domains) as well as creating a privacy issue as bounces
			 * containing the recipient's e-mail address may get sent to
			 * the sending user.
			 */
			$mailFrom = $fromAddress;
			$replyTo = null;
		}

		$status = Status::wrap( $emailer->send(
			$toAddress,
			$mailFrom,
			$subject,
			$text,
			null,
			[ 'replyTo' => $replyTo ]
		) );

		if ( !$status->isGood() ) {
			return $status;
		}

		// if the user requested a copy of this mail, do this now,
		// unless they are emailing themselves, in which case one
		// copy of the message is sufficient.
		if ( $data['CCMe'] && $toAddress != $fromAddress ) {
			$ccTo = $fromAddress;
			$ccFrom = $fromAddress;
			$ccSubject = $context->msg( 'emailccsubject' )->plaintextParams(
				$target->getName(),
				$subject
			)->text();
			$ccText = $text;

			$hookRunner->onEmailUserCC( $ccTo, $ccFrom, $ccSubject, $ccText );

			if ( $config->get( 'UserEmailUseReplyTo' ) ) {
				$mailFrom = new MailAddress(
					$config->get( 'PasswordSender' ),
					$context->msg( 'emailsender' )->inContentLanguage()->text()
				);
				$replyTo = $ccFrom;
			} else {
				$mailFrom = $ccFrom;
				$replyTo = null;
			}

			$ccStatus = $emailer->send(
				$ccTo,
				$mailFrom,
				$ccSubject,
				$ccText,
				null,
				[ 'replyTo' => $replyTo ]
			);
			$status->merge( $ccStatus );
		}

		$hookRunner->onEmailUserComplete( $toAddress, $fromAddress, $subject, $text );

		return $status;
	}

	/**
	 * Return an array of subpages beginning with $search that this special page will accept.
	 *
	 * @param string $search Prefix to search for
	 * @param int $limit Maximum number of results to return (usually 10)
	 * @param int $offset Number of results to skip (usually 0)
	 * @return string[] Matching subpages
	 */
	public function prefixSearchSubpages( $search, $limit, $offset ) {
		$search = $this->userNameUtils->getCanonical( $search );
		if ( !$search ) {
			// No prefix suggestion for invalid user
			return [];
		}
		// Autocomplete subpage as user list - public to allow caching
		return $this->userNamePrefixSearch
			->search( UserNamePrefixSearch::AUDIENCE_PUBLIC, $search, $limit, $offset );
	}

	protected function getGroupName() {
		return 'users';
	}
}