<?php
/**
 * Email notification channel via wp_mail.
 *
 * @package Bookline
 */

declare( strict_types=1 );

namespace Bookline\Infrastructure\Notification;

use Bookline\Domain\Notification\EscapeFormat;
use Bookline\Domain\Notification\NotificationChannel;
use Bookline\Domain\Notification\NotificationTemplate;
use Bookline\Domain\Notification\Recipient;
use Bookline\Domain\Notification\RenderedMessage;
use Bookline\Domain\Notification\SendResult;
use Bookline\Domain\Notification\TemplateRenderer;
use Bookline\Domain\Notification\VariableBag;
use Bookline\Infrastructure\Settings\SettingsStore;
use Closure;

/**
 * Core email channel.
 *
 * @since 0.1.0
 */
final class EmailChannel implements NotificationChannel {

	/**
	 * Optional mailer override for tests: fn(string,string,string,array,array): bool.
	 *
	 * @var Closure|null
	 */
	private ?Closure $mailer;

	/**
	 * Constructor.
	 *
	 * @param TemplateRenderer    $renderer Template renderer.
	 * @param SettingsStore       $settings Settings.
	 * @param ThemeTemplateLoader $themes   Theme overrides.
	 * @param Closure|null        $mailer   Optional mailer.
	 */
	public function __construct(
		private readonly TemplateRenderer $renderer,
		private readonly SettingsStore $settings,
		private readonly ThemeTemplateLoader $themes,
		?Closure $mailer = null,
	) {
		$this->mailer = $mailer;
	}

	/**
	 * {@inheritDoc}
	 */
	public function id(): string {
		return 'email';
	}

	/**
	 * {@inheritDoc}
	 */
	public function label(): string {
		return function_exists( '__' ) ? __( 'Email', 'buildler' ) : 'Email';
	}

	/**
	 * {@inheritDoc}
	 */
	public function is_configured(): bool {
		return true;
	}

	/**
	 * {@inheritDoc}
	 *
	 * @param NotificationTemplate $template Template.
	 */
	public function supports( NotificationTemplate $template ): bool {
		return 'email' === $template->channel();
	}

	/**
	 * {@inheritDoc}
	 *
	 * @param NotificationTemplate $template Template.
	 * @param VariableBag          $bag      Bag.
	 */
	public function render( NotificationTemplate $template, VariableBag $bag ): RenderedMessage {
		$subject_src = (string) ( $template->subject() ?? '' );
		$body_src    = $this->themes->load_body( $template->key() ) ?? (string) ( $template->body() ?? '' );

		$subject = $this->renderer->replace( $subject_src, $bag, EscapeFormat::Text );
		$html    = $this->renderer->replace( $body_src, $bag, EscapeFormat::Html );
		$text    = $this->html_to_text( $this->renderer->replace( $body_src, $bag, EscapeFormat::Text ) );

		$message = new RenderedMessage( $subject, $html, $text, null );

		if ( function_exists( 'apply_filters' ) ) {
			/**
			 * Filter a rendered notification message.
			 *
			 * @param RenderedMessage      $message  Message.
			 * @param NotificationTemplate $template Template.
			 *
			 * @since 0.1.0
			 */
			$filtered = apply_filters( 'bookline/notification/rendered', $message, $template );
			if ( $filtered instanceof RenderedMessage ) {
				return $filtered;
			}
		}

		return $message;
	}

	/**
	 * {@inheritDoc}
	 *
	 * @param RenderedMessage $message   Message.
	 * @param Recipient       $recipient Recipient.
	 */
	public function send( RenderedMessage $message, Recipient $recipient ): SendResult {
		$headers = [
			'Content-Type: text/html; charset=UTF-8',
			'From: ' . $this->from_header(),
		];

		$mailer = $this->mailer;
		if ( null !== $mailer ) {
			$ok = (bool) $mailer(
				$recipient->address(),
				$message->subject(),
				$message->body_html(),
				$headers,
				[]
			);
			return $ok ? SendResult::ok( 'test' ) : SendResult::fail( 'Mailer returned false.', true );
		}

		if ( ! function_exists( 'wp_mail' ) ) {
			return SendResult::fail( 'wp_mail is unavailable.', false );
		}

		$ok = wp_mail(
			$recipient->address(),
			$message->subject(),
			$message->body_html(),
			$headers
		);

		if ( $ok ) {
			return SendResult::ok();
		}

		return SendResult::fail( 'wp_mail returned false.', true );
	}

	/**
	 * From header using settings with site defaults.
	 */
	private function from_header(): string {
		$name  = (string) $this->settings->get( 'notifications.from_name' );
		$email = (string) $this->settings->get( 'notifications.from_email' );

		if ( '' === $name && function_exists( 'get_bloginfo' ) ) {
			$name = (string) get_bloginfo( 'name' );
		}
		if ( '' === $email && function_exists( 'get_option' ) ) {
			$email = (string) get_option( 'admin_email' );
		}
		if ( '' === $name ) {
			$name = 'Buildler';
		}
		if ( '' === $email ) {
			$email = 'noreply@example.com';
		}

		return sprintf( '%s <%s>', $this->strip_header( $name ), $this->strip_header( $email ) );
	}

	/**
	 * Strip CR/LF from header values.
	 *
	 * @param string $value Value.
	 */
	private function strip_header( string $value ): string {
		return str_replace( [ "\r", "\n" ], '', $value );
	}

	/**
	 * Produce a plain-text alternative from HTML source after text-mode substitution.
	 *
	 * @param string $html HTML or near-HTML.
	 */
	private function html_to_text( string $html ): string {
		$text = preg_replace( '/<br\s*\/?>/i', "\n", $html ) ?? $html;
		$text = preg_replace( '/<\/p>/i', "\n\n", $text ) ?? $text;
		if ( function_exists( 'wp_strip_all_tags' ) ) {
			$text = wp_strip_all_tags( $text );
		} else {
			$text = preg_replace( '/<[^>]+>/', '', $text ) ?? $text;
		}
		return trim( html_entity_decode( $text, ENT_QUOTES | ENT_HTML5, 'UTF-8' ) );
	}
}