<?php
/**
 * Base class for a notification channel.
 *
 * Every channel receives the same message array and formats it for its
 * service:
 *
 *     event       Alert type (e.g. "critical").
 *     title       One-line headline.
 *     intro       Optional sentence under the headline.
 *     items       List of { title, subtitle, detail } rows.
 *     more        How many rows were left out of `items`.
 *     url         Link into the admin.
 *     link_label  Text for that link.
 *     site        Store name.
 *
 * @package ProfitEngine
 */

declare( strict_types=1 );

namespace ProfitEngine\Notifications\Channels;

use WP_Error;

defined( 'ABSPATH' ) || exit;

/**
 * Shared delivery helpers.
 */
abstract class Channel {

	/**
	 * Request timeout in seconds. Sends run in the background, never at checkout.
	 */
	protected const TIMEOUT = 10;

	/**
	 * Send a message.
	 *
	 * @param array<string,mixed> $message Message.
	 * @param array<string,mixed> $config  Channel config.
	 * @return true|WP_Error
	 */
	abstract public function send( array $message, array $config );

	/**
	 * POST JSON and treat any 2xx as success.
	 *
	 * Uses wp_safe_remote_post(), which refuses local and private network
	 * addresses, so a webhook URL can't be pointed at the server itself.
	 *
	 * @param string              $url     URL.
	 * @param array<string,mixed> $payload Body.
	 * @param array<string,string> $headers Extra headers.
	 * @return true|WP_Error
	 */
	protected function post_json( string $url, array $payload, array $headers = array() ) {
		$body = (string) wp_json_encode( $payload );
		return $this->post_raw( $url, $body, $headers );
	}

	/**
	 * POST an already-encoded JSON body.
	 *
	 * @param string               $url     URL.
	 * @param string               $body    JSON body.
	 * @param array<string,string> $headers Extra headers.
	 * @return true|WP_Error
	 */
	protected function post_raw( string $url, string $body, array $headers = array() ) {
		$response = wp_safe_remote_post(
			$url,
			array(
				'timeout'     => self::TIMEOUT,
				'redirection' => 0,
				'headers'     => array_merge( array( 'Content-Type' => 'application/json; charset=utf-8' ), $headers ),
				'body'        => $body,
			)
		);

		if ( is_wp_error( $response ) ) {
			return $response;
		}

		$code = (int) wp_remote_retrieve_response_code( $response );
		if ( $code >= 200 && $code < 300 ) {
			return true;
		}

		$detail = trim( wp_strip_all_tags( (string) wp_remote_retrieve_body( $response ) ) );
		return new WP_Error(
			'profit_engine_notification_http',
			/* translators: 1: HTTP status code, 2: response text from the service. */
			sprintf( __( 'The service answered HTTP %1$d. %2$s', 'profit-engine' ), $code, mb_substr( $detail, 0, 200 ) ),
			array( 'code' => $code )
		);
	}

	/**
	 * The message as plain text lines (for services without rich layouts).
	 *
	 * @param array<string,mixed> $message Message.
	 * @return string[]
	 */
	protected function item_lines( array $message ): array {
		$lines = array();
		foreach ( (array) ( $message['items'] ?? array() ) as $item ) {
			$name    = (string) ( $item['title'] ?? '' );
			$sku     = (string) ( $item['subtitle'] ?? '' );
			$detail  = (string) ( $item['detail'] ?? '' );
			$lines[] = $name . ( '' !== $sku ? " ({$sku})" : '' ) . ( '' !== $detail ? " — {$detail}" : '' );
		}
		if ( ! empty( $message['more'] ) ) {
			/* translators: %d: number of further rows not listed. */
			$lines[] = sprintf( __( '…and %d more', 'profit-engine' ), (int) $message['more'] );
		}
		return $lines;
	}
}