<?php
/**
 * Optional weekly health digest via wp_mail (local only).
 *
 * @package Keepwatch
 */

namespace Keepwatch\Mail;

use Keepwatch\Admin\Menu;
use Keepwatch\Checks\Registry;
use Keepwatch\Checks\Result;
use Keepwatch\Settings;

defined( 'ABSPATH' ) || exit;

/**
 * Sends a plain-text summary of open checks once a week when the setting is on.
 */
final class WeeklyEmail {

	public const HOOK = 'keepwatch_weekly_email';

	/**
	 * Register the cron callback.
	 */
	public function register(): void {
		add_action( self::HOOK, array( $this, 'send' ) );
	}

	/**
	 * Schedule the weekly event if missing.
	 */
	public static function schedule(): void {
		if ( ! wp_next_scheduled( self::HOOK ) ) {
			wp_schedule_event( time() + DAY_IN_SECONDS, 'weekly', self::HOOK );
		}
	}

	/**
	 * Clear the scheduled event.
	 */
	public static function unschedule(): void {
		wp_clear_scheduled_hook( self::HOOK );
	}

	/**
	 * Build and send the digest. No-op when disabled or recipient is missing.
	 */
	public function send(): void {
		if ( ! Settings::weekly_email_enabled() ) {
			return;
		}

		$to = Settings::weekly_email_recipient();
		if ( '' === $to || ! is_email( $to ) ) {
			return;
		}

		$groups  = Registry::run( Registry::checks() );
		$summary = Registry::summary( $groups );
		$subject = self::subject( $summary );
		$body    = self::body( $groups, $summary );

		wp_mail( $to, $subject, $body );
	}

	/**
	 * Email subject line.
	 *
	 * @param array{good: int, recommended: int, critical: int} $summary Counts.
	 */
	public static function subject( array $summary ): string {
		$site = wp_specialchars_decode( get_bloginfo( 'name' ), ENT_QUOTES );
		if ( $summary['critical'] > 0 ) {
			return sprintf(
				/* translators: 1: site name, 2: critical count */
				__( '[Keepwatch] %1$s: %2$d critical issue(s)', 'keepwatch' ),
				$site,
				$summary['critical']
			);
		}
		if ( $summary['recommended'] > 0 ) {
			return sprintf(
				/* translators: 1: site name, 2: recommended count */
				__( '[Keepwatch] %1$s: %2$d recommended fix(es)', 'keepwatch' ),
				$site,
				$summary['recommended']
			);
		}
		return sprintf(
			/* translators: %s: site name */
			__( '[Keepwatch] %s: all checks passed', 'keepwatch' ),
			$site
		);
	}

	/**
	 * Plain-text body.
	 *
	 * @param array<string, Result[]>                           $groups  Grouped results.
	 * @param array{good: int, recommended: int, critical: int} $summary Counts.
	 */
	public static function body( array $groups, array $summary ): string {
		$labels = Menu::group_labels();
		$lines  = array(
			sprintf(
				/* translators: 1: critical count, 2: recommended count, 3: passed count */
				__( 'Keepwatch weekly summary — critical: %1$d, recommended: %2$d, passed: %3$d', 'keepwatch' ),
				$summary['critical'],
				$summary['recommended'],
				$summary['good']
			),
			'',
		);

		$open = 0;
		foreach ( $groups as $group => $results ) {
			$group_lines = array();
			foreach ( $results as $result ) {
				if ( Result::GOOD === $result->status ) {
					continue;
				}
				++$open;
				$prefix        = Result::CRITICAL === $result->status ? '[!]' : '[-]';
				$group_lines[] = $prefix . ' ' . $result->label;
				if ( '' !== $result->description ) {
					$group_lines[] = '    ' . $result->description;
				}
			}
			if ( array() === $group_lines ) {
				continue;
			}
			$heading = isset( $labels[ $group ] ) ? $labels[ $group ] : $group;
			$lines[] = '== ' . $heading . ' ==';
			foreach ( $group_lines as $line ) {
				$lines[] = $line;
			}
			$lines[] = '';
		}

		if ( 0 === $open ) {
			$lines[] = __( 'Everything looks good this week.', 'keepwatch' );
			$lines[] = '';
		}

		$lines[] = sprintf(
			/* translators: %s: dashboard URL */
			__( 'Open Keepwatch: %s', 'keepwatch' ),
			admin_url( 'tools.php?page=' . Menu::SLUG )
		);
		$lines[] = __( 'You can turn this email off under Tools > Keepwatch > Email alerts.', 'keepwatch' );

		return implode( "\n", $lines );
	}
}