<?php

namespace RoosterLMS\Invitations;

use RoosterLMS\Core\Clock;
use RoosterLMS\Data\Db;
use RoosterLMS\Data\SqlPart;
use RoosterLMS\Domain\Services;
use RoosterLMS\Earlier\Audience;
use RoosterLMS\I18n\Language;
use RoosterLMS\I18n\Names;
use RoosterLMS\Messages\LogObject;
use RoosterLMS\Messages\LogState;
use RoosterLMS\Messages\MessageLog;
use RoosterLMS\Messages\Tracking;
use RoosterLMS\Notify\NotificationKey;

defined( 'ABSPATH' ) || exit;

final class Sender {

	public const HOOK = 'rooster_lms/invitation_batch';

	public const GROUP = 'rooster-lms';

	public const BATCH = 50;

	public static function enqueue( int $invitation_id, int $after ): void {
		if ( ! function_exists( 'as_enqueue_async_action' ) || ! did_action( 'action_scheduler_init' ) ) {
			return;
		}
		$args = array(
			'invitation' => $invitation_id,
			'after'      => $after,
		);
		if ( function_exists( 'as_has_scheduled_action' ) && as_has_scheduled_action( self::HOOK, $args, self::GROUP ) ) {
			return;
		}
		as_enqueue_async_action( self::HOOK, $args, self::GROUP );
	}

	public static function unschedule( int $invitation_id ): void {
		if ( ! function_exists( 'as_get_scheduled_actions' ) || ! function_exists( 'as_unschedule_action' ) || ! did_action( 'action_scheduler_init' ) || ! class_exists( '\ActionScheduler_Store' ) ) {
			return;
		}
		$actions = as_get_scheduled_actions(
			array(
				'hook'     => self::HOOK,
				'group'    => self::GROUP,
				'status'   => \ActionScheduler_Store::STATUS_PENDING,
				'per_page' => 50,
			)
		);
		foreach ( is_array( $actions ) ? $actions : array() as $action ) {
			$args = $action instanceof \ActionScheduler_Action ? $action->get_args() : array();
			if ( (int) ( $args['invitation'] ?? 0 ) === $invitation_id ) {
				as_unschedule_action( self::HOOK, $args, self::GROUP );
			}
		}
	}

	public static function run( $invitation = 0, $after = 0 ): void {
		$out = self::run_batch( (int) $invitation, (int) $after );
		if ( $out['more'] ) {
			self::enqueue( (int) $invitation, $out['last'] );
		}
	}

	public static function run_batch( int $invitation_id, int $after = 0 ): array {
		$out  = array(
			'sent'       => 0,
			'failed'     => 0,
			'suppressed' => 0,
			'capped'     => 0,
			'more'       => false,
			'last'       => $after,
		);
		$rows = self::candidates( $invitation_id, $after );
		if ( array() === $rows ) {
			self::finish( $invitation_id );
			return $out;
		}
		$inv = Invitation::from_row( self::invitation_columns( $rows[0] ) );
		if ( InvitationState::SENDING !== $inv->state ) {
			return $out;
		}
		$cap      = Audience::weekly_cap();
		$expiry   = RsvpService::token_expiry( $inv );
		$now      = Clock::now();
		$send     = array();
		$states   = array();
		$tokens   = array();
		$logs     = array();
		$previous = array();
		$default  = Names::default_language();
		foreach ( $rows as $row ) {
			$id              = (int) $row['id'];
			$out['last']     = $id;
			$previous[ $id ] = array( null === $row['prev_sent_at'] ? null : (string) $row['prev_sent_at'], (int) $row['prev_version'] );
			$user_id         = (int) $row['user_id'];
			$address         = $user_id > 0 ? (string) ( $row['user_email'] ?? '' ) : (string) $row['email'];
			if ( 1 === (int) $row['unsub'] || 0 === (int) $row['consent'] ) {
				$states[ $id ] = InviteeState::SUPPRESSED->value;
				$logs[]        = array( $user_id, (string) $row['email_hash'], LogState::SUPPRESSED, 1 === (int) $row['unsub'] ? 'unsubscribed' : 'consent', '' );
				++$out['suppressed'];
				continue;
			}
			if ( $cap > 0 && (int) $row['recent'] >= $cap ) {
				++$out['capped'];
				continue;
			}
			if ( '' === $address || false === is_email( $address ) || ( $user_id > 0 && null === $row['user_email'] ) ) {
				$states[ $id ] = InviteeState::FAILED->value;
				$logs[]        = array( $user_id, (string) $row['email_hash'], LogState::FAILED, 'address', '' );
				++$out['failed'];
				continue;
			}
			$seed  = (string) ( $row['token_seed'] ?? '' );
			$token = Tokens::for_invitee( $id, $seed );
			if ( '' === $token || ! hash_equals( (string) ( $row['token_hash'] ?? '' ), Tokens::hash( $token ) ) ) {
				$seed          = Tokens::seed();
				$token         = Tokens::for_invitee( $id, $seed );
				$tokens[ $id ] = array( Tokens::hash( $token ), $seed );
			}
			$states[ $id ] = InviteeState::SENT->value;
			$lang          = Language::normalize( (string) ( $user_id > 0 && '' !== (string) ( $row['person_lang'] ?? '' ) ? $row['person_lang'] : $row['lang'] ) );
			$send[ $id ]   = array(
				'to'      => $address,
				'token'   => $token,
				'user_id' => $user_id,
				'first'   => $user_id > 0 ? (string) ( $row['display_name'] ?? '' ) : (string) $row['first_name'],
				'lang'    => '' !== $lang && in_array( $lang, Names::languages(), true ) ? $lang : $default,
				'hash'    => (string) $row['email_hash'],
			);
		}
		self::write_states( $inv, $states, $tokens, array_keys( $send ), $expiry, $now );
		cache_users( array_values( array_filter( array_map( static fn( array $m ): int => (int) $m['user_id'], $send ) ) ) );
		$template = self::template_id( $inv );
		$tracked  = Tracking::on();
		$marks    = array();
		$failed   = array();
		self::with_from_name(
			static function () use ( $send, $tracked, $template, $inv, &$marks, &$logs, &$out, &$failed ): void {
				foreach ( $send as $id => $mail ) {
					$log     = $tracked ? MessageLog::add( $template, NotificationKey::INVITATION->value, $mail['user_id'], $mail['to'], LogObject::INVITATION, $inv->id, LogState::PREPARED, '', $mail['lang'] ) : 0;
					$first   = self::first_name( $mail['user_id'], $mail['first'] );
					$message = InvitationMail::message( $inv, $mail['user_id'], $first, $mail['lang'], $mail['token'], $log );
					$ok      = Services::notifier()->deliver( $mail['to'], $message['subject'], $message['html'], 0, $mail['lang'], array(), $message['headers'], NotificationKey::INVITATION->value, $mail['user_id'] );
					if ( $log > 0 ) {
						$marks[ $log ] = $ok ? LogState::SENT : LogState::FAILED;
					} else {
						$logs[] = array( $mail['user_id'], $mail['hash'], $ok ? LogState::SENT : LogState::FAILED, $ok ? '' : 'mail', $mail['lang'] );
					}
					if ( $ok ) {
						++$out['sent'];
						self::announce( $inv, $id, $mail );
						continue;
					}
					$failed[] = $id;
				}
			}
		);
		if ( array() !== $failed ) {
			global $wpdb;
			$at_case = SqlPart::of( '' );
			$version_case = SqlPart::of( '' );
			foreach ( $failed as $id ) {
				$at_case = $at_case->add( null === $previous[ $id ][0] ? SqlPart::of( ' WHEN %d THEN NULL', $id ) : SqlPart::of( ' WHEN %d THEN %s', $id, $previous[ $id ][0] ) );
				$version_case = $version_case->add( SqlPart::of( ' WHEN %d THEN %d', $id, $previous[ $id ][1] ) );
			}
			Db::query( SqlPart::of( 'UPDATE %i SET state = %d, token_hash = NULL, token_seed = NULL, ', Db::table( 'invitees' ), InviteeState::FAILED->value )->add( 'sent_at = CASE id' )->add( $at_case )->add( ' ELSE sent_at END, sent_version = CASE id' )->add( $version_case )->add( ' ELSE sent_version END WHERE id IN (' . implode( ',', array_map( 'intval', $failed ) ) . ')' ) );
			$out['failed'] += count( $failed );
		}
		MessageLog::add_hashed( $template, NotificationKey::INVITATION->value, LogObject::INVITATION, $inv->id, $logs );
		MessageLog::mark_many( $marks );
		\RoosterLMS\Messages\Events::flush();
		$out['more'] = count( $rows ) >= self::BATCH;
		if ( ! $out['more'] ) {
			self::finish( $invitation_id );
		}
		return $out;
	}

	public static function remind_batch( Invitation $inv, int $after = 0 ): array {
		global $wpdb;
		$out = array(
			'sent'    => 0,
			'skipped' => 0,
			'more'    => false,
			'last'    => $after,
		);
		if ( ! $inv->asks() || $inv->is_cancelled() || '' === $inv->sent_at ) {
			return $out;
		}
		$sql  = SqlPart::of( 'SELECT /* outside-tx */ i.id, i.user_id, i.email_hash, i.email, i.first_name, i.lang, i.token_hash, i.token_seed, u.user_email, u.display_name, p.lang AS person_lang, ' )->add( SendRules::consent_sql() )->add( ' AS consent, ' )->add( SendRules::unsubscribed_sql() )->add( ' AS unsub' )->add( SqlPart::of( ' FROM %i i LEFT JOIN %i u ON u.ID = i.user_id LEFT JOIN %i p ON p.user_id = i.user_id WHERE i.invitation_id = %d AND i.id > %d AND i.state = %d AND i.answer = %d AND i.source <> %d AND i.token_hash IS NOT NULL ORDER BY i.id LIMIT %d', Db::table( 'invitees' ), $wpdb->users, Db::table( 'people' ), $inv->id, max( 0, $after ), InviteeState::SENT->value, RsvpAnswer::NONE->value, InviteeSource::NEWSLETTER->value, self::BATCH ) );
		$rows = Db::rows( $sql );
		cache_users( array_values( array_filter( array_map( static fn( array $r ): int => (int) $r['user_id'], $rows ) ) ) );
		$template = self::template_id( $inv );
		$default  = Names::default_language();
		$logs     = array();
		self::with_from_name(
			static function () use ( $rows, $inv, $default, &$logs, &$out ): void {
				foreach ( $rows as $row ) {
					$id          = (int) $row['id'];
					$out['last'] = $id;
					$user_id     = (int) $row['user_id'];
					$address     = $user_id > 0 ? (string) ( $row['user_email'] ?? '' ) : (string) $row['email'];
					$token       = Tokens::for_invitee( $id, (string) ( $row['token_seed'] ?? '' ) );
					if ( 1 === (int) $row['unsub'] || 0 === (int) $row['consent'] || '' === $token || ! hash_equals( (string) $row['token_hash'], Tokens::hash( $token ) ) || false === is_email( $address ) ) {
						++$out['skipped'];
						continue;
					}
					$lang    = Language::normalize( (string) ( $user_id > 0 && '' !== (string) ( $row['person_lang'] ?? '' ) ? $row['person_lang'] : $row['lang'] ) );
					$lang    = '' !== $lang && in_array( $lang, Names::languages(), true ) ? $lang : $default;
					$first   = self::first_name( $user_id, $user_id > 0 ? (string) ( $row['display_name'] ?? '' ) : (string) $row['first_name'] );
					$message = InvitationMail::message( $inv, $user_id, $first, $lang, $token, 0, true );
					$ok      = Services::notifier()->deliver( $address, $message['subject'], $message['html'], 0, $lang, array(), $message['headers'], NotificationKey::INVITATION->value, $user_id );
					$logs[]  = array( $user_id, (string) $row['email_hash'], $ok ? LogState::SENT : LogState::FAILED, $ok ? 'reminder' : 'mail', $lang );
					if ( ! $ok ) {
						++$out['skipped'];
						continue;
					}
					++$out['sent'];
					do_action( 'rooster_lms_invitation_reminded', $inv->id, $id, $user_id, $inv->version );
				}
			}
		);
		MessageLog::add_hashed( $template, NotificationKey::INVITATION->value, LogObject::INVITATION, $inv->id, $logs );
		$out['more'] = count( $rows ) >= self::BATCH;
		return $out;
	}

	private static function with_from_name( callable $mails ): void {
		$from = trim( (string) \RoosterLMS\Core\Settings::get( 'inv_from_name' ) );
		if ( '' === $from ) {
			$mails();
			return;
		}
		$name = static fn(): string => $from;
		add_filter( 'wp_mail_from_name', $name, 10 );
		try {
			$mails();
		} finally {
			remove_filter( 'wp_mail_from_name', $name, 10 );
		}
	}

	private static function template_id( Invitation $inv ): int {
		if ( '' !== $inv->subject || '' !== $inv->body ) {
			return 0;
		}
		$t = MessagesBridge::template( $inv->template_id );
		return null === $t ? 0 : $t->id;
	}

	private static function candidates( int $invitation_id, int $after ): array {
		global $wpdb;
		$sql = SqlPart::of( 'SELECT /* outside-tx */ i.id, i.user_id, i.email_hash, i.email, i.first_name, i.lang, i.source, i.state AS invitee_state, i.token_hash, i.token_seed, i.sent_at AS prev_sent_at, i.sent_version AS prev_version, u.user_email, u.display_name, p.lang AS person_lang, v.id AS inv_id, v.kind, v.course_id, v.unit_id, v.occurrence_id, v.template_id, v.announcement_id, v.version, v.attachment_ids, v.rsvp, v.rsvp_until, v.yes_action, v.places, v.state AS inv_state, v.scheduled_at, v.sent_at AS inv_sent_at, v.subject, v.body, v.lang AS inv_lang, v.created_by, v.created_at, v.target_cohort_id, ' )->add( SendRules::consent_sql() )->add( ' AS consent, ' )->add( SendRules::unsubscribed_sql() )->add( ' AS unsub, ' )->add( SendRules::recent_sql() )->add( ' AS recent' )->add( SqlPart::of( ' FROM %i i JOIN %i v ON v.id = i.invitation_id LEFT JOIN %i u ON u.ID = i.user_id LEFT JOIN %i p ON p.user_id = i.user_id WHERE i.invitation_id = %d AND i.id > %d AND ', Db::table( 'invitees' ), Db::table( 'invitations' ), $wpdb->users, Db::table( 'people' ), $invitation_id, max( 0, $after ) ) )->add( SendRules::due_sql( 'v.version' ) )->add( SqlPart::of( ' ORDER BY i.id LIMIT %d', self::BATCH ) );
		return Db::rows( $sql );
	}

	private static function invitation_columns( array $row ): array {
		return array(
			'id'               => $row['inv_id'],
			'kind'             => $row['kind'],
			'course_id'        => $row['course_id'],
			'unit_id'          => $row['unit_id'],
			'occurrence_id'    => $row['occurrence_id'],
			'template_id'      => $row['template_id'],
			'announcement_id'  => $row['announcement_id'],
			'version'          => $row['version'],
			'attachment_ids'   => $row['attachment_ids'],
			'rsvp'             => $row['rsvp'],
			'rsvp_until'       => $row['rsvp_until'],
			'yes_action'       => $row['yes_action'],
			'places'           => $row['places'],
			'state'            => $row['inv_state'],
			'scheduled_at'     => $row['scheduled_at'],
			'sent_at'          => $row['inv_sent_at'],
			'subject'          => $row['subject'],
			'body'             => $row['body'],
			'lang'             => $row['inv_lang'],
			'created_by'       => $row['created_by'],
			'created_at'       => $row['created_at'],
			'target_cohort_id' => $row['target_cohort_id'],
		);
	}

	private static function write_states( Invitation $inv, array $states, array $tokens, array $sent, string $expiry, string $now ): void {
		if ( array() === $states ) {
			return;
		}
		global $wpdb;
		$state_case = SqlPart::of( '' );
		foreach ( $states as $id => $state ) {
			$state_case = $state_case->add( SqlPart::of( ' WHEN %d THEN %d', $id, $state ) );
		}
		$sql = SqlPart::of( 'UPDATE ' )->add( SqlPart::of( '%i', Db::table( 'invitees' ) ) )->add( ' SET state = CASE id' )->add( $state_case )->add( ' ELSE state END' );
		if ( array() !== $tokens ) {
			$hash_case = SqlPart::of( '' );
			$seed_case = SqlPart::of( '' );
			foreach ( $tokens as $id => $pair ) {
				$hash_case = $hash_case->add( SqlPart::of( ' WHEN %d THEN %s', $id, $pair[0] ) );
				$seed_case = $seed_case->add( SqlPart::of( ' WHEN %d THEN %s', $id, $pair[1] ) );
			}
			$sql = $sql->add( SqlPart::of( ', token_hash = CASE id' )->add( $hash_case )->add( ' ELSE token_hash END, token_seed = CASE id' )->add( $seed_case )->add( ' ELSE token_seed END' ) );
		}
		if ( array() !== $sent ) {
			$ids  = array_map( 'intval', $sent );
			$sql = $sql->add( SqlPart::of( ', token_expires_at = CASE WHEN id IN (' . implode( ',', array_fill( 0, count( $ids ), '%d' ) ) . ') THEN %s ELSE token_expires_at END', array_merge( $ids, array( $expiry ) ) )->add( SqlPart::of( ', sent_version = CASE WHEN id IN (' . implode( ',', array_fill( 0, count( $ids ), '%d' ) ) . ') THEN %d ELSE sent_version END', array_merge( $ids, array( $inv->version ) ) ) )->add( SqlPart::of( ', sent_at = CASE WHEN id IN (' . implode( ',', array_fill( 0, count( $ids ), '%d' ) ) . ') THEN %s ELSE sent_at END', array_merge( $ids, array( $now ) ) ) ) );
		}
		$ids  = array_map( 'intval', array_keys( $states ) );
		$sql = $sql->add( SqlPart::of( ' WHERE id IN (' . implode( ',', array_fill( 0, count( $ids ), '%d' ) ) . ')', $ids ) );
		Db::query( $sql );
	}

	private static function finish( int $invitation_id ): void {
		$done = Db::query( 'UPDATE %i SET state = %d, updated_at = %s WHERE id = %d AND state = %d', Db::table( 'invitations' ), InvitationState::SENT->value, Clock::now(), $invitation_id, InvitationState::SENDING->value );
		InvitationRepository::forget( $invitation_id );
		if ( $done > 0 ) {
			do_action( 'rooster_lms_invitation_finished', $invitation_id );
		}
	}

	private static function announce( Invitation $inv, int $id, array $mail ): void {
		$user_id = (int) $mail['user_id'];
		do_action( 'rooster_lms_invitation_sent', $inv->id, $id, $user_id, $inv->version );
		Events::fire(
			'invitation_sent',
			array(
				'user_id'       => $user_id,
				'email_hash'    => (string) $mail['hash'],
				'lang'          => (string) $mail['lang'],
				'course_id'     => $inv->course_id,
				'unit_id'       => $inv->unit_id,
				'occurrence_id' => $inv->occurrence_id,
				'invitation_id' => $inv->id,
				'invitee_id'    => $id,
				'version'       => $inv->version,
			)
		);
	}

	private static function first_name( int $user_id, string $first ): string {
		if ( $user_id <= 0 ) {
			return $first;
		}
		$user = get_userdata( $user_id );
		return $user instanceof \WP_User && '' !== (string) $user->first_name ? (string) $user->first_name : $first;
	}
}