<?php
/**
 * Durable reminder state. No recipient or rendered message is persisted here.
 *
 * @package Abientot
 */

namespace Abientot\Reminders;

use Abientot\Repositories\BookingLock;
use Abientot\Support\Db;
use Abientot\Support\TransactionGuard;

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

require_once __DIR__ . '/Settings.php';
require_once __DIR__ . '/Migrator.php';

// phpcs:disable WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- The reminder queue is the plugin's own table; every read must see committed state inside the booking lock.

final class Repository {
	/**
	 * Runs $callback inside the booking lock and one database transaction on verified storage.
	 *
	 * @return mixed The callback's result.
	 */
	public function transaction( callable $callback ) {
		global $wpdb;
		$owned   = ! BookingLock::is_held();
		$started = false;
		if ( $owned && ! BookingLock::acquire() ) {
			throw new \RuntimeException( 'reminder_lock' );
		}
		try {
			if ( get_option( Migrator::OPTION ) !== Migrator::VERSION || ! Migrator::verified() ) {
				throw new \RuntimeException( 'reminder_schema' );
			}
			TransactionGuard::prepare_write();
			$engine = Db::rows( $wpdb->suppress_errors( true ), $wpdb->get_results( $wpdb->prepare( 'SELECT ENGINE FROM information_schema.TABLES WHERE TABLE_SCHEMA=DATABASE() AND TABLE_NAME=%s', $wpdb->options ), ARRAY_A ), 'reminder_read' );
			if ( ! $engine || strtoupper( (string) $engine[0]['ENGINE'] ) !== 'INNODB' ) {
				throw new \RuntimeException( 'reminder_options_engine' );
			}
			Db::done( $wpdb->suppress_errors( true ), $wpdb->query( 'START TRANSACTION' ), 'reminder_write' );
			$started = true;
			$result  = $callback();
			Db::done( $wpdb->suppress_errors( true ), $wpdb->query( 'COMMIT' ), 'reminder_write' );
			$started = false;
			return $result;
		} catch ( \Throwable $error ) {
			if ( $started ) {
				$wpdb->query( 'ROLLBACK' );
			}
			throw $error;
		} finally {
			if ( $owned ) {
				BookingLock::release();
			}
		}
	}

	/** Settings read from the database, bypassing the options cache. */
	public function settings(): array {
		global $wpdb;
		$rows = Db::rows( $wpdb->suppress_errors( true ), $wpdb->get_results( $wpdb->prepare( "SELECT option_value FROM {$wpdb->options} WHERE option_name=%s", Settings::OPTION ), ARRAY_A ), 'reminder_read' );
		return Settings::normalize( $rows ? maybe_unserialize( $rows[0]['option_value'] ) : null );
	}

	/**
	 * Writes an option inside the current transaction.
	 *
	 * @param mixed $value Option value.
	 */
	private function option( string $name, $value ): void {
		global $wpdb;
		Db::done( $wpdb->suppress_errors( true ), $wpdb->query( $wpdb->prepare( "INSERT INTO {$wpdb->options}(option_name,option_value,autoload) VALUES(%s,%s,'off') ON DUPLICATE KEY UPDATE option_value=VALUES(option_value)", $name, maybe_serialize( $value ) ) ), 'reminder_write' );
	}

	private function clear_options(): void {
		foreach ( array( Settings::OPTION, Settings::CURSOR, 'alloptions', 'notoptions' ) as $key ) {
			wp_cache_delete( $key, 'options' );
		}
	}

	public function configure( array $settings, int $now ): array {
		$result = $this->transaction(
			function () use ( $settings, $now ) {
				$old             = $this->settings();
				$new             = Settings::normalize( $settings );
				$new['revision'] = $old['revision'] + 1;
				$this->option( Settings::OPTION, $new );
				$this->option( Settings::CURSOR, 0 );
				if ( ! $new['enabled'] ) {
					$this->invalidate( null, 'disabled', $now );
				}
				return $new;
			}
		);
		$this->clear_options();
		return $result;
	}

	public function booking( int $id ): ?array {
		global $wpdb;
		$rows = Db::rows(
			$wpdb->suppress_errors( true ),
			$wpdb->get_results(
				$wpdb->prepare(
					"SELECT a.*,c.email AS reminder_email,s.slug AS status_slug,s.blocks_availability FROM {$wpdb->prefix}abientot_appointments a"
					. " INNER JOIN {$wpdb->prefix}abientot_customers c ON c.id=a.customer_id"
					. " INNER JOIN {$wpdb->prefix}abientot_booking_statuses s ON s.id=a.status_id"
					. " INNER JOIN {$wpdb->prefix}abientot_services v ON v.id=a.service_id"
					. " INNER JOIN {$wpdb->prefix}abientot_staff f ON f.id=a.staff_id"
					. " INNER JOIN {$wpdb->prefix}abientot_locations l ON l.id=a.location_id WHERE a.id=%d",
					$id
				),
				ARRAY_A
			),
			'reminder_read'
		);
		return $rows[0] ?? null;
	}

	public static function eligible( ?array $booking, int $now ): bool {
		return $booking
			&& ( $booking['source'] ?? '' ) !== 'import'
			&& (int) $booking['blocks_availability'] === 1
			&& ! in_array( $booking['status_slug'], array( 'cancelled', 'completed', 'no-show', 'no_show' ), true )
			&& is_email( $booking['reminder_email'] )
			&& strtotime( $booking['start_utc'] . ' UTC' ) > $now;
	}

	public static function start_digest( array $booking ): string {
		return hash( 'sha256', $booking['id'] . '|' . $booking['start_utc'] );
	}

	public static function booking_digest( array $booking ): string {
		$data = array();
		foreach ( array( 'id', 'customer_id', 'service_id', 'staff_id', 'location_id', 'start_utc', 'end_utc', 'timezone', 'duration_minutes' ) as $key ) {
			$data[ $key ] = (string) $booking[ $key ];
		}
		$data['email'] = strtolower( trim( $booking['reminder_email'] ) );
		return hash_hmac( 'sha256', wp_json_encode( $data ), wp_salt( 'nonce' ) );
	}

	/**
	 * Cancels open jobs (a job already sending becomes uncertain).
	 *
	 * @param int|null    $appointment One booking, or null for every booking.
	 * @param string|null $keep        Start digest of the occurrence to leave untouched.
	 */
	private function invalidate( ?int $appointment, string $code, int $now, ?string $keep = null ): void {
		global $wpdb;
		Db::done(
			$wpdb->suppress_errors( true ),
			$wpdb->query(
				$wpdb->prepare(
					"UPDATE {$wpdb->prefix}abientot_reminder_queue SET lease_hash=IF(state='sending',lease_hash,NULL),state=IF(state='sending','uncertain','cancelled'),last_code=%s,lease_until=NULL,updated_at=%s"
					. " WHERE ( %d = 1 OR appointment_id=%d ) AND ( %d = 0 OR start_digest<>%s ) AND state IN('pending','retry','leased','sending')",
					$code,
					gmdate( 'Y-m-d H:i:s', $now ),
					null === $appointment ? 1 : 0,
					(int) $appointment,
					null === $keep ? 0 : 1,
					(string) $keep
				)
			),
			'reminder_write'
		);
	}

	private function sync_locked( int $id, int $now ): void {
		global $wpdb;
		$config  = $this->settings();
		$booking = $this->booking( $id );
		if ( ! $config['enabled'] || ! self::eligible( $booking, $now ) ) {
			$this->invalidate( $id, $config['enabled'] ? 'booking_unavailable' : 'disabled', $now );
			return;
		}
		$start  = self::start_digest( $booking );
		$digest = self::booking_digest( $booking );
		$this->invalidate( $id, 'booking_changed', $now, $start );
		$due   = gmdate( 'Y-m-d H:i:s', strtotime( $booking['start_utc'] . ' UTC' ) - $config['lead_hours'] * HOUR_IN_SECONDS );
		$stamp = gmdate( 'Y-m-d H:i:s', $now );
		$rows  = Db::rows( $wpdb->suppress_errors( true ), $wpdb->get_results( $wpdb->prepare( "SELECT * FROM {$wpdb->prefix}abientot_reminder_queue WHERE appointment_id=%d AND start_digest=%s FOR UPDATE", $id, $start ), ARRAY_A ), 'reminder_read' );
		if ( ! $rows ) {
			Db::done( $wpdb->suppress_errors( true ), $wpdb->query( $wpdb->prepare( "INSERT INTO {$wpdb->prefix}abientot_reminder_queue(appointment_id,start_digest,booking_digest,due_at,next_attempt_at,state,attempts,created_at,updated_at) VALUES(%d,%s,%s,%s,%s,'pending',0,%s,%s)", $id, $start, $digest, $due, $due, $stamp, $stamp ) ), 'reminder_write' );
			return;
		}
		$row = $rows[0];
		if ( in_array( $row['state'], array( 'sent', 'uncertain', 'failed', 'expired' ), true ) || ( $row['state'] === 'cancelled' && ! in_array( $row['last_code'], array( 'disabled', 'booking_changed', 'booking_unavailable' ), true ) ) ) {
			return;
		}
		if ( $row['state'] === 'sending' || $row['state'] === 'leased' ) {
			if ( ! hash_equals( $row['booking_digest'], $digest ) ) {
				Db::done( $wpdb->suppress_errors( true ), $wpdb->query( $wpdb->prepare( "UPDATE {$wpdb->prefix}abientot_reminder_queue SET lease_hash=IF(state='sending',lease_hash,NULL),state=%s,last_code='booking_changed',lease_until=NULL,updated_at=%s WHERE id=%d", $row['state'] === 'sending' ? 'uncertain' : 'cancelled', $stamp, $row['id'] ) ), 'reminder_write' );
			} else {
				Db::done( $wpdb->suppress_errors( true ), $wpdb->query( $wpdb->prepare( "UPDATE {$wpdb->prefix}abientot_reminder_queue SET updated_at=%s WHERE id=%d", $stamp, $row['id'] ) ), 'reminder_write' );
			}
			return;
		}
		$next = $row['state'] === 'retry' ? max( $due, $row['next_attempt_at'] ) : $due;
		Db::done( $wpdb->suppress_errors( true ), $wpdb->query( $wpdb->prepare( "UPDATE {$wpdb->prefix}abientot_reminder_queue SET booking_digest=%s,due_at=%s,next_attempt_at=%s,state=%s,updated_at=%s WHERE id=%d", $digest, $due, $next, $row['state'] === 'retry' ? 'retry' : 'pending', $stamp, $row['id'] ) ), 'reminder_write' );
	}

	public function sync( int $id, int $now ): void {
		$this->transaction(
			function () use ( $id, $now ) {
				$this->sync_locked( $id, $now );
			}
		);
	}

	public function reconcile( int $now, int $limit = 100 ): void {
		global $wpdb;
		$limit = max( 1, min( 100, $limit ) );
		$this->transaction(
			function () use ( $now, $limit, $wpdb ) {
				$stamp = gmdate( 'Y-m-d H:i:s', $now );
				Db::done( $wpdb->suppress_errors( true ), $wpdb->query( $wpdb->prepare( "UPDATE {$wpdb->prefix}abientot_reminder_queue SET state=IF(state='sending','uncertain','retry'),last_code='lease_expired',next_attempt_at=%s,lease_hash=NULL,lease_until=NULL,updated_at=%s WHERE state IN('leased','sending') AND lease_until<=%s", $stamp, $stamp, $stamp ) ), 'reminder_write' );
				if ( ! $this->settings()['enabled'] ) {
					$this->invalidate( null, 'disabled', $now );
					return;
				}
				$cursorrows = Db::rows( $wpdb->suppress_errors( true ), $wpdb->get_results( $wpdb->prepare( "SELECT option_value FROM {$wpdb->options} WHERE option_name=%s", Settings::CURSOR ), ARRAY_A ), 'reminder_read' );
				$cursor     = max( 0, (int) ( $cursorrows[0]['option_value'] ?? 0 ) );
				$rows       = Db::rows( $wpdb->suppress_errors( true ), $wpdb->get_results( $wpdb->prepare( "SELECT id FROM {$wpdb->prefix}abientot_appointments WHERE id>%d AND start_utc>%s AND source<>'import' ORDER BY id LIMIT %d", $cursor, $stamp, $limit ), ARRAY_A ), 'reminder_read' );
				foreach ( $rows as $row ) {
					$this->sync_locked( (int) $row['id'], $now );
				}
				$this->option( Settings::CURSOR, count( $rows ) === $limit ? (int) end( $rows )['id'] : 0 );
				$audit = Db::rows( $wpdb->suppress_errors( true ), $wpdb->get_results( $wpdb->prepare( "SELECT appointment_id FROM {$wpdb->prefix}abientot_reminder_queue WHERE state IN('pending','retry','leased','sending') GROUP BY appointment_id ORDER BY MIN(updated_at),appointment_id LIMIT %d", $limit ), ARRAY_A ), 'reminder_read' );
				foreach ( $audit as $row ) {
					$this->sync_locked( (int) $row['appointment_id'], $now );
				}
			}
		);
		$this->clear_options();
	}

	public function claim( int $now ): ?array {
		global $wpdb;
		return $this->transaction(
			function () use ( $now, $wpdb ) {
				if ( ! $this->settings()['enabled'] ) {
					return null;
				}
				$rows = Db::rows( $wpdb->suppress_errors( true ), $wpdb->get_results( $wpdb->prepare( "SELECT * FROM {$wpdb->prefix}abientot_reminder_queue WHERE state IN('pending','retry') AND next_attempt_at<=%s ORDER BY next_attempt_at,id LIMIT 1 FOR UPDATE", gmdate( 'Y-m-d H:i:s', $now ) ), ARRAY_A ), 'reminder_read' );
				if ( ! $rows ) {
					return null;
				}
				$row = $rows[0];
				$this->sync_locked( (int) $row['appointment_id'], $now );
				$fresh = $this->job( (int) $row['id'] );
				if ( ! in_array( $fresh['state'], array( 'pending', 'retry' ), true ) || $fresh['next_attempt_at'] > gmdate( 'Y-m-d H:i:s', $now ) ) {
					return null;
				}
				$raw  = bin2hex( random_bytes( 32 ) );
				$hash = hash( 'sha256', $raw );
				Db::done( $wpdb->suppress_errors( true ), $wpdb->query( $wpdb->prepare( "UPDATE {$wpdb->prefix}abientot_reminder_queue SET state='leased',lease_hash=%s,lease_until=%s,updated_at=%s WHERE id=%d", $hash, gmdate( 'Y-m-d H:i:s', $now + 300 ), gmdate( 'Y-m-d H:i:s', $now ), $row['id'] ) ), 'reminder_write' );
				$fresh['lease'] = $raw;
				return $fresh;
			}
		);
	}

	public function job( int $id ): ?array {
		global $wpdb;
		$rows = Db::rows( $wpdb->suppress_errors( true ), $wpdb->get_results( $wpdb->prepare( "SELECT * FROM {$wpdb->prefix}abientot_reminder_queue WHERE id=%d", $id ), ARRAY_A ), 'reminder_read' );
		return $rows[0] ?? null;
	}

	/** The lease is not permission to send under an older configuration. */
	public function begin_send( array $job, int $now ): ?array {
		global $wpdb;
		return $this->transaction(
			function () use ( $job, $now, $wpdb ) {
				$row = $this->job( (int) $job['id'] );
				if ( ! $row || $row['state'] !== 'leased' || ! hash_equals( (string) $row['lease_hash'], hash( 'sha256', $job['lease'] ) ) || strtotime( $row['lease_until'] . ' UTC' ) <= $now ) {
					return null;
				}
				$this->sync_locked( (int) $row['appointment_id'], $now );
				$row = $this->job( (int) $row['id'] );
				if ( $row['state'] !== 'leased' ) {
					return null;
				}
				$config = $this->settings();
				if ( ! $config['enabled'] ) {
					return null;
				}
				$booking = $this->booking( (int) $row['appointment_id'] );
				$due     = gmdate( 'Y-m-d H:i:s', strtotime( $booking['start_utc'] . ' UTC' ) - $config['lead_hours'] * HOUR_IN_SECONDS );
				$stamp   = gmdate( 'Y-m-d H:i:s', $now );
				if ( $due > $stamp ) {
					// No transport has started: release only this lease, preserving previous attempts.
					$state = ( $job['state'] ?? '' ) === 'retry' ? 'retry' : 'pending';
					Db::done( $wpdb->suppress_errors( true ), $wpdb->query( $wpdb->prepare( "UPDATE {$wpdb->prefix}abientot_reminder_queue SET state=%s,due_at=%s,next_attempt_at=%s,lease_hash=NULL,lease_until=NULL,updated_at=%s WHERE id=%d", $state, $due, max( $due, $row['next_attempt_at'] ), $stamp, $row['id'] ) ), 'reminder_write' );
					return null;
				}
				Db::done( $wpdb->suppress_errors( true ), $wpdb->query( $wpdb->prepare( "UPDATE {$wpdb->prefix}abientot_reminder_queue SET state='sending',due_at=%s,attempts=attempts+1,updated_at=%s WHERE id=%d", $due, $stamp, $row['id'] ) ), 'reminder_write' );
				return $config;
			}
		);
	}

	/** Fresh read immediately before transport; a snapshot is never a recipient fallback. */
	public function deliverable( array $job, int $now ): bool {
		$row     = $this->job( (int) $job['id'] );
		$booking = $this->booking( (int) $job['appointment_id'] );
		$config  = $this->settings();
		return ! BookingLock::is_held()
			&& $config['enabled']
			&& $row
			&& $row['state'] === 'sending'
			&& hash_equals( (string) $row['lease_hash'], hash( 'sha256', $job['lease'] ) )
			&& self::eligible( $booking, $now )
			&& strtotime( $booking['start_utc'] . ' UTC' ) - $config['lead_hours'] * HOUR_IN_SECONDS <= $now
			&& hash_equals( $row['booking_digest'], self::booking_digest( $booking ) );
	}

	/** Only the worker which has positively skipped transport may recover its own marker. */
	public function finish_unsent( array $job, int $now ): void {
		global $wpdb;
		$this->transaction(
			function () use ( $job, $now, $wpdb ) {
				$row = $this->job( (int) $job['id'] );
				if ( ! $row || ! in_array( $row['state'], array( 'sending', 'uncertain' ), true ) || ! hash_equals( (string) $row['lease_hash'], hash( 'sha256', $job['lease'] ) ) ) {
					return;
				}
				$config   = $this->settings();
				$booking  = $this->booking( (int) $row['appointment_id'] );
				$stamp    = gmdate( 'Y-m-d H:i:s', $now );
				$attempts = max( 0, (int) $row['attempts'] - 1 );
				$state    = 'cancelled';
				$code     = 'booking_unavailable';
				$due      = $row['due_at'];
				$next     = $row['next_attempt_at'];
				$digest   = $row['booking_digest'];
				if ( ! $config['enabled'] ) {
					$code = 'disabled';
				} elseif ( self::eligible( $booking, $now ) && hash_equals( $row['start_digest'], self::start_digest( $booking ) ) ) {
					// Timing/contact changes can be retried safely: this owner never called transport.
					$due    = gmdate( 'Y-m-d H:i:s', strtotime( $booking['start_utc'] . ' UTC' ) - $config['lead_hours'] * HOUR_IN_SECONDS );
					$next   = max( $due, $row['next_attempt_at'] );
					$digest = self::booking_digest( $booking );
					$state  = $attempts > 0 ? 'retry' : 'pending';
					$code   = '';
				} elseif ( $booking && ! hash_equals( $row['start_digest'], self::start_digest( $booking ) ) ) {
					$code = 'booking_changed';
				}
				Db::done( $wpdb->suppress_errors( true ), $wpdb->query( $wpdb->prepare( "UPDATE {$wpdb->prefix}abientot_reminder_queue SET state=%s,last_code=%s,attempts=%d,booking_digest=%s,due_at=%s,next_attempt_at=%s,lease_hash=NULL,lease_until=NULL,updated_at=%s WHERE id=%d", $state, $code, $attempts, $digest, $due, $next, $stamp, $row['id'] ) ), 'reminder_write' );
			}
		);
	}

	public function finish( array $job, string $outcome, int $now ): void {
		if ( $outcome === 'not_deliverable' ) {
			$this->finish_unsent( $job, $now );
			return;
		}
		global $wpdb;
		$this->transaction(
			function () use ( $job, $outcome, $now, $wpdb ) {
				$row = $this->job( (int) $job['id'] );
				if ( ! $row || $row['state'] !== 'sending' || ! hash_equals( (string) $row['lease_hash'], hash( 'sha256', $job['lease'] ) ) ) {
					return;
				}
				if ( $outcome === 'sent' ) {
					$state = 'sent';
				} elseif ( $outcome === 'transport_false' ) {
					$state = (int) $row['attempts'] >= 3 ? 'failed' : 'retry';
				} else {
					$state = 'uncertain';
				}
				$next  = gmdate( 'Y-m-d H:i:s', $now + ( (int) $row['attempts'] === 1 ? 300 : 900 ) );
				$stamp = gmdate( 'Y-m-d H:i:s', $now );
				Db::done( $wpdb->suppress_errors( true ), $wpdb->query( $wpdb->prepare( "UPDATE {$wpdb->prefix}abientot_reminder_queue SET state=%s,last_code=%s,next_attempt_at=%s,sent_at=IF(%d=1,%s,NULL),lease_hash=NULL,lease_until=NULL,updated_at=%s WHERE id=%d", $state, $outcome, $next, $state === 'sent' ? 1 : 0, $stamp, $stamp, $row['id'] ) ), 'reminder_write' );
			}
		);
	}

	public function intervene( int $id, string $operation, bool $acknowledged, int $now ): void {
		global $wpdb;
		$this->transaction(
			function () use ( $id, $operation, $acknowledged, $now, $wpdb ) {
				$row = $this->job( $id );
				if ( ! $row || ! in_array( $row['state'], array( 'failed', 'uncertain' ), true ) ) {
					throw new \DomainException( 'reminder_state' );
				}
				$stamp = gmdate( 'Y-m-d H:i:s', $now );
				if ( $operation === 'retry' ) {
					if ( ! $acknowledged ) {
						throw new \DomainException( 'reminder_acknowledgement' );
					}
					$booking = $this->booking( (int) $row['appointment_id'] );
					if ( ! $this->settings()['enabled'] || ! self::eligible( $booking, $now ) || ! hash_equals( $row['start_digest'], self::start_digest( $booking ) ) ) {
						throw new \DomainException( 'reminder_ineligible' );
					}
					Db::done( $wpdb->suppress_errors( true ), $wpdb->query( $wpdb->prepare( "UPDATE {$wpdb->prefix}abientot_reminder_queue SET state='retry',attempts=0,booking_digest=%s,next_attempt_at=%s,last_code='manager_retry',lease_hash=NULL,lease_until=NULL,updated_at=%s WHERE id=%d", self::booking_digest( $booking ), $stamp, $stamp, $id ) ), 'reminder_write' );
				} elseif ( $operation === 'dismiss' ) {
					Db::done( $wpdb->suppress_errors( true ), $wpdb->query( $wpdb->prepare( "UPDATE {$wpdb->prefix}abientot_reminder_queue SET state='cancelled',last_code='manager_dismissed',updated_at=%s WHERE id=%d", $stamp, $id ) ), 'reminder_write' );
				} else {
					throw new \DomainException( 'reminder_operation' );
				}
			}
		);
	}

	public function page( int $page ): array {
		global $wpdb;
		$count = Db::rows( $wpdb->suppress_errors( true ), $wpdb->get_results( "SELECT COUNT(*) AS total FROM {$wpdb->prefix}abientot_reminder_queue", ARRAY_A ), 'reminder_read' );
		$total = (int) $count[0]['total'];
		$pages = max( 1, (int) ceil( $total / 20 ) );
		$page  = max( 1, min( $pages, $page ) );
		return array(
			'rows'  => Db::rows( $wpdb->suppress_errors( true ), $wpdb->get_results( $wpdb->prepare( "SELECT * FROM {$wpdb->prefix}abientot_reminder_queue ORDER BY id DESC LIMIT 20 OFFSET %d", ( $page - 1 ) * 20 ), ARRAY_A ), 'reminder_read' ),
			'total' => $total,
			'page'  => $page,
			'pages' => $pages,
		);
	}
}