<?php // phpcs:ignore Squiz.Classes.ClassFileName.NoMatch -- Abstract class; filename intentionally uses 'abstract-class-' prefix.
/**
 * TMDO_Abstract_Notifier — Base for all health-alert notifiers (v2.5.0 M15).
 *
 * Subclasses (Email / Slack / Telegram / Discord) inherit:
 *   - wpdo/health_alert_critical action subscription
 *   - opt-in toggle (`wpdo_{channel}_enabled`)
 *   - 24h-default throttle keyed by md5 fingerprint of summary
 *   - shared subject / body builders (overridable)
 *   - severity subscription (critical_only / critical_and_recommended)
 *
 * Subclass只 implements `actually_send( $subject, $body, $context ): bool`
 * and `channel_id(): string` (used as option-key prefix).
 *
 * @package WP_Data_Optimizer
 */

declare(strict_types=1);

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

/**
 * Abstract base — concrete subclasses below.
 */
abstract class TMDO_Abstract_Notifier {

	/** Default throttle window. */
	public const DEFAULT_THROTTLE_HOURS = 24;

	/**
	 * Channel ID — used as option key prefix (e.g. 'email', 'slack').
	 *
	 * @return string
	 */
	abstract public static function channel_id(): string;

	/**
	 * Channel-specific delivery. Implementations should return false on
	 * transient failure so caller can re-throttle attempts.
	 *
	 * @param string $subject Subject / title (Slack uses as text-prefix).
	 * @param string $body    Body text (channel-specific markdown).
	 * @param array  $context Optional context (recipient/webhook URL/etc.).
	 * @return bool
	 */
	abstract public static function actually_send( string $subject, string $body, array $context ): bool;

	/**
	 * Hook subclass into `wpdo/health_alert_critical`.
	 *
	 * @return void
	 */
	public static function register(): void {
		add_action( 'wpdo/health_alert_critical', array( static::class, 'maybe_send' ), 10, 1 );
	}

	/**
	 * Decide whether to send + throttle + dispatch.
	 *
	 * @param array $summary Summary array from Health_Cron::run().
	 * @return bool
	 */
	public static function maybe_send( array $summary ): bool {
		if ( ! static::is_enabled() ) {
			return false;
		}
		// Severity subscription check.
		$severity_filter = static::severity_filter();
		if ( 'critical_only' === $severity_filter && (int) ( $summary['critical_count'] ?? 0 ) === 0 ) {
			return false;
		}
		// Channel-specific recipient/config sanity check.
		$context = static::build_context();
		if ( null === $context ) {
			return false;
		}
		// Throttle.
		$fingerprint = static::fingerprint( $summary );
		if ( static::is_throttled( $fingerprint ) ) {
			return false;
		}
		// Build + send.
		$subject = static::build_subject( $summary );
		$body    = static::build_body( $summary );
		$sent    = static::actually_send( $subject, $body, $context );
		if ( $sent ) {
			static::mark_sent( $fingerprint );
			if ( class_exists( 'TMDO_Logger' ) ) {
				TMDO_Logger::info(
					sprintf( '%s_alert_sent', static::channel_id() ),
					array(
						'fingerprint' => $fingerprint,
						'critical'    => (int) ( $summary['critical_count'] ?? 0 ),
					)
				);
			}
		}
		return $sent;
	}

	// ─── settings accessors（optional override）────────────────────────

	/**
	 * Whether this notification channel is enabled.
	 *
	 * @return bool
	 */
	public static function is_enabled(): bool {
		return '1' === (string) get_option( static::option_key( 'enabled' ), '0' );
	}

	/**
	 * Throttle window in hours (clamped 1..168).
	 *
	 * @return int
	 */
	public static function throttle_hours(): int {
		$v = (int) get_option( static::option_key( 'throttle_hours' ), self::DEFAULT_THROTTLE_HOURS );
		return max( 1, min( 168, $v ) );
	}

	/**
	 * Severity subscription filter.
	 *
	 * @return string 'critical_only' or 'critical_and_recommended'
	 */
	public static function severity_filter(): string {
		$v = (string) get_option( static::option_key( 'severity' ), 'critical_only' );
		return in_array( $v, array( 'critical_only', 'critical_and_recommended' ), true ) ? $v : 'critical_only';
	}

	/**
	 * Build channel-specific context (e.g. webhook URL or recipient address).
	 * Return null to skip send (e.g. invalid email or empty webhook).
	 *
	 * @return array|null
	 */
	public static function build_context(): ?array {
		return array();
	}

	// ─── shared subject / body builders ───────────────────────────────

	/**
	 * Build alert subject line.
	 *
	 * @param array $summary Summary array from Health_Cron::run().
	 * @return string
	 */
	public static function build_subject( array $summary ): string {
		$site  = (string) get_option( 'blogname', 'WordPress' );
		$crit  = (int) ( $summary['critical_count'] ?? 0 );
		$first = '';
		foreach ( (array) ( $summary['tests'] ?? array() ) as $slug => $t ) {
			if ( 'critical' === ( $t['status'] ?? '' ) ) {
				$first = $slug;
				break;
			}
		}
		return sprintf( '[%s] WPDO 警告：%d 項 critical (%s)', $site, $crit, $first );
	}

	/**
	 * Generic plain-text body. Subclasses can override to add channel-specific
	 * formatting (Slack mrkdwn, Discord markdown, Telegram MarkdownV2, etc.).
	 *
	 * @param array $summary Summary.
	 * @return string
	 */
	public static function build_body( array $summary ): string {
		$lines   = array();
		$lines[] = sprintf( '站台：%s', home_url( '/' ) );
		$lines[] = sprintf( '檢查時間：%s UTC', (string) ( $summary['ran_at'] ?? '?' ) );
		$lines[] = sprintf(
			'結果：%d critical / %d recommended',
			(int) ( $summary['critical_count'] ?? 0 ),
			(int) ( $summary['recommended_count'] ?? 0 )
		);
		$lines[] = '';
		$lines[] = '失敗的檢查：';
		foreach ( (array) ( $summary['tests'] ?? array() ) as $slug => $t ) {
			if ( in_array( ( $t['status'] ?? '' ), array( 'critical', 'recommended' ), true ) ) {
				$lines[] = sprintf(
					'  [%s] %s — %s',
					strtoupper( (string) ( $t['status'] ?? '' ) ),
					$slug,
					(string) ( $t['description'] ?? '' )
				);
			}
		}
		$lines[] = '';
		$lines[] = '查看詳情：' . admin_url( 'tools.php?page=wp-data-optimizer&tab=doctor' );
		return implode( "\n", $lines );
	}

	// ─── private helpers ─────────────────────────────────────────────

	/**
	 * Per-channel option key (e.g. wpdo_email_enabled, wpdo_slack_webhook).
	 *
	 * @param string $field 'enabled' / 'throttle_hours' / 'severity' / etc.
	 * @return string
	 */
	protected static function option_key( string $field ): string {
		return sprintf( 'wpdo_%s_%s', static::channel_id(), $field );
	}

	/**
	 * Stable fingerprint from the alert content for deduplication.
	 *
	 * @param array $summary Summary array from Health_Cron::run().
	 * @return string md5 hash.
	 */
	protected static function fingerprint( array $summary ): string {
		$relevant = array(
			'critical_count' => (int) ( $summary['critical_count'] ?? 0 ),
			'first_critical' => null,
		);
		foreach ( (array) ( $summary['tests'] ?? array() ) as $slug => $t ) {
			if ( 'critical' === ( $t['status'] ?? '' ) ) {
				$relevant['first_critical'] = $slug;
				break;
			}
		}
		return md5( wp_json_encode( $relevant ) );
	}

	/**
	 * Check whether an alert with this fingerprint was recently sent.
	 *
	 * @param string $fingerprint Alert fingerprint (md5).
	 * @return bool
	 */
	protected static function is_throttled( string $fingerprint ): bool {
		$key = sprintf( 'wpdo_%s_sent_%s', static::channel_id(), $fingerprint );
		return false !== get_transient( $key );
	}

	/**
	 * Record that an alert was sent (sets throttle transient).
	 *
	 * @param string $fingerprint Alert fingerprint (md5).
	 * @return void
	 */
	protected static function mark_sent( string $fingerprint ): void {
		$key = sprintf( 'wpdo_%s_sent_%s', static::channel_id(), $fingerprint );
		set_transient( $key, time(), static::throttle_hours() * HOUR_IN_SECONDS );
	}
}