<?php
/**
 * Slack, via an incoming webhook.
 *
 * @package ProfitEngine
 */

declare( strict_types=1 );

namespace ProfitEngine\Notifications\Channels;

defined( 'ABSPATH' ) || exit;

/**
 * Posts a Block Kit message to a Slack incoming webhook.
 */
class SlackChannel extends Channel {

	/**
	 * Send a message.
	 *
	 * @param array<string,mixed> $message Message.
	 * @param array<string,mixed> $config  Channel config.
	 * @return true|\WP_Error
	 */
	public function send( array $message, array $config ) {
		$title = $this->escape( (string) $message['title'] );
		$body  = '' !== (string) ( $message['intro'] ?? '' ) ? $this->escape( (string) $message['intro'] ) . "\n" : '';
		foreach ( $this->item_lines( $message ) as $line ) {
			$body .= '• ' . $this->escape( $line ) . "\n";
		}

		$blocks = array(
			array(
				'type' => 'header',
				'text' => array(
					'type' => 'plain_text',
					'text' => mb_substr( (string) $message['title'], 0, 150 ),
				),
			),
		);
		if ( '' !== trim( $body ) ) {
			$blocks[] = array(
				'type' => 'section',
				'text' => array(
					'type' => 'mrkdwn',
					'text' => mb_substr( $body, 0, 2900 ),
				),
			);
		}
		$blocks[] = array(
			'type'     => 'context',
			'elements' => array(
				array(
					'type' => 'mrkdwn',
					'text' => sprintf( '<%s|%s> · %s', esc_url_raw( (string) $message['url'] ), $this->escape( (string) $message['link_label'] ), $this->escape( (string) $message['site'] ) ),
				),
			),
		);

		return $this->post_json(
			(string) $config['webhook_url'],
			array(
				'text'   => $title, // Notification preview text.
				'blocks' => $blocks,
			)
		);
	}

	/**
	 * Escape the three characters Slack treats as control characters.
	 *
	 * @param string $text Text.
	 */
	private function escape( string $text ): string {
		return str_replace( array( '&', '<', '>' ), array( '&amp;', '&lt;', '&gt;' ), $text );
	}
}