<?php
/**
 * Sign-in event log.
 *
 * @package Rahkar\WP
 */

declare( strict_types = 1 );

namespace Rahkar\WP\Modules\OtpAuth;

use Rahkar\WP\Database\Schema;
use Rahkar\WP\Support\Settings;

defined( 'ABSPATH' ) || exit;

/**
 * What was sent, to whom, through which gateway, and what came back.
 *
 * The store owner needs this for three real questions: did this customer's code
 * actually go out, is a gateway failing, and is somebody hammering the form. The
 * general log cannot answer them — it is a stream of messages, not rows that can
 * be counted by result and gateway.
 *
 * What it deliberately does not hold is the code. A table of codes keyed by
 * phone number is a working key to every account on the store; rows here carry
 * the outcome and the provider's reason, and are pruned on a retention window.
 */
final class OtpLog {

	public const EVENT_SEND      = 'send';
	public const EVENT_VERIFY    = 'verify';
	public const EVENT_THROTTLED = 'throttled';
	public const EVENT_LOGIN     = 'login';
	public const EVENT_SIGNUP    = 'signup';
	public const EVENT_PASSWORD  = 'password';

	/** An alert sent to the administrators; not a customer event. */
	public const EVENT_ALERT = 'alert';

	/** The failsafe stepped in or stood down. */
	public const EVENT_FAILSAFE = 'failsafe';

	public const RESULT_OK         = 'ok';
	public const RESULT_TEMPORARY  = 'temporary';
	public const RESULT_PERMANENT  = 'permanent';
	public const RESULT_TEST       = 'test_mode';
	public const RESULT_NO_GATEWAY = 'no_gateway';
	public const RESULT_WRONG      = 'wrong_code';
	public const RESULT_EXPIRED    = 'expired';
	public const RESULT_BLOCKED    = 'blocked';
	public const RESULT_FAILED     = 'failed';

	/**
	 * Send results that mean the customer got nothing from that attempt.
	 */
	public const FAILED_SENDS = [
		self::RESULT_TEMPORARY,
		self::RESULT_PERMANENT,
		self::RESULT_NO_GATEWAY,
	];

	/**
	 * Rows per page on the log screen.
	 */
	public const PER_PAGE = 50;

	/**
	 * Default retention, in days.
	 */
	public const DEFAULT_DAYS = 30;

	/**
	 * Write one row.
	 *
	 * Never lets a failure reach the caller: the log is a record of the sign-in,
	 * and a missing table must not become a customer who cannot sign in.
	 *
	 * @param string               $event  One of the EVENT_* constants.
	 * @param string               $result One of the RESULT_* constants.
	 * @param array<string, mixed> $row    Optional `phone`, `user_id`, `gateway`, `via`, `message`, `ip`.
	 */
	public static function record( string $event, string $result, array $row = [] ): void {
		global $wpdb;

		$ip = array_key_exists( 'ip', $row ) ? (string) $row['ip'] : RateLimiter::clientIp();

		$suppress = $wpdb->suppress_errors( true );

		// phpcs:ignore WordPress.DB.DirectDatabaseQuery
		$wpdb->insert(
			Schema::table( 'otp_log' ),
			[
				'event'      => substr( $event, 0, 16 ),
				'result'     => substr( $result, 0, 16 ),
				'phone'      => substr( (string) ( $row['phone'] ?? '' ), 0, 32 ),
				'user_id'    => max( 0, (int) ( $row['user_id'] ?? 0 ) ),
				'gateway'    => substr( (string) ( $row['gateway'] ?? '' ), 0, 32 ),
				'via'        => substr( (string) ( $row['via'] ?? '' ), 0, 16 ),
				// Provider errors can be long and can echo request content back;
				// truncated rather than let a strict server reject the insert.
				'message'    => mb_substr( (string) ( $row['message'] ?? '' ), 0, 250 ),
				'ip'         => substr( $ip, 0, 45 ),
				'created_at' => gmdate( 'Y-m-d H:i:s' ),
			],
			[ '%s', '%s', '%s', '%d', '%s', '%s', '%s', '%s', '%s' ]
		);

		$wpdb->suppress_errors( $suppress );
	}

	/**
	 * Rows matching the filters, newest first.
	 *
	 * @param array<string, string> $filters `phone`, `event`, `result`, `gateway`.
	 * @param int                   $limit   Rows.
	 * @param int                   $offset  Rows to skip.
	 *
	 * @return list<array<string, mixed>>
	 */
	public static function search( array $filters, int $limit, int $offset = 0 ): array {
		global $wpdb;

		[ $where, $args ] = self::where( $filters );

		// phpcs:disable WordPress.DB.DirectDatabaseQuery, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, WordPress.DB.PreparedSQLPlaceholders.ReplacementsWrongNumber, PluginCheck.Security.DirectDB.UnescapedDBParameter -- $where is built in where() from literal fragments; every value is a bound placeholder.
		$rows = $wpdb->get_results(
			$wpdb->prepare(
				"SELECT * FROM %i {$where} ORDER BY id DESC LIMIT %d OFFSET %d",
				array_merge( [ Schema::table( 'otp_log' ) ], $args, [ max( 1, min( 500, $limit ) ), max( 0, $offset ) ] )
			),
			ARRAY_A
		);
		// phpcs:enable WordPress.DB.DirectDatabaseQuery, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, WordPress.DB.PreparedSQLPlaceholders.ReplacementsWrongNumber, PluginCheck.Security.DirectDB.UnescapedDBParameter

		return is_array( $rows ) ? array_values( $rows ) : [];
	}

	/**
	 * How many rows match the filters.
	 *
	 * @param array<string, string> $filters See {@see self::search()}.
	 */
	public static function count( array $filters ): int {
		global $wpdb;

		[ $where, $args ] = self::where( $filters );

		// phpcs:disable WordPress.DB.DirectDatabaseQuery, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, WordPress.DB.PreparedSQLPlaceholders.ReplacementsWrongNumber, PluginCheck.Security.DirectDB.UnescapedDBParameter -- $where is built in where() from literal fragments; every value is a bound placeholder.
		$count = $wpdb->get_var(
			$wpdb->prepare(
				"SELECT COUNT(*) FROM %i {$where}",
				array_merge( [ Schema::table( 'otp_log' ) ], $args )
			)
		);
		// phpcs:enable WordPress.DB.DirectDatabaseQuery, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, WordPress.DB.PreparedSQLPlaceholders.ReplacementsWrongNumber, PluginCheck.Security.DirectDB.UnescapedDBParameter

		return (int) $count;
	}

	/**
	 * How many real sends in a row have failed, most recent first.
	 *
	 * Test-mode rows are skipped rather than counted either way: a tester seeing
	 * codes on screen says nothing about whether the gateway works.
	 */
	public static function consecutiveFailures(): int {
		global $wpdb;

		// phpcs:ignore WordPress.DB.DirectDatabaseQuery
		$results = $wpdb->get_col(
			$wpdb->prepare(
				'SELECT result FROM %i WHERE event = %s AND result <> %s ORDER BY id DESC LIMIT 100',
				Schema::table( 'otp_log' ),
				self::EVENT_SEND,
				self::RESULT_TEST
			)
		);

		$failures = 0;

		foreach ( (array) $results as $result ) {
			if ( self::RESULT_OK === $result ) {
				break;
			}

			++$failures;
		}

		return $failures;
	}

	/**
	 * Delete rows past the retention window.
	 *
	 * @return int Rows removed.
	 */
	public static function purge(): int {
		global $wpdb;

		$days = self::retentionDays();

		if ( $days <= 0 ) {
			return 0;
		}

		// phpcs:ignore WordPress.DB.DirectDatabaseQuery
		$removed = $wpdb->query(
			$wpdb->prepare(
				'DELETE FROM %i WHERE created_at < %s LIMIT 5000',
				Schema::table( 'otp_log' ),
				gmdate( 'Y-m-d H:i:s', time() - $days * DAY_IN_SECONDS )
			)
		);

		return (int) $removed;
	}

	/**
	 * Days rows are kept for. Zero keeps them forever.
	 */
	public static function retentionDays(): int {
		return max( 0, (int) Settings::get( OtpAuthModule::SLUG . '.log_days', self::DEFAULT_DAYS ) );
	}

	/**
	 * The WHERE clause and its arguments for a set of filters.
	 *
	 * @param array<string, string> $filters See {@see self::search()}.
	 *
	 * @return array{0: string, 1: list<string>}
	 */
	private static function where( array $filters ): array {
		global $wpdb;

		$clauses = [];
		$args    = [];

		if ( '' !== ( $filters['phone'] ?? '' ) ) {
			$clauses[] = 'phone LIKE %s';
			$args[]    = '%' . $wpdb->esc_like( $filters['phone'] ) . '%';
		}

		foreach ( [ 'event', 'result', 'gateway' ] as $column ) {
			if ( '' !== ( $filters[ $column ] ?? '' ) ) {
				$clauses[] = $column . ' = %s';
				$args[]    = $filters[ $column ];
			}
		}

		return [ [] === $clauses ? '' : 'WHERE ' . implode( ' AND ', $clauses ), $args ];
	}
}