<?php
/**
 * TMDO_Telegram_Notifier — Telegram bot channel (v2.5.0 M15).
 *
 * Settings: wpdo_telegram_enabled, wpdo_telegram_bot_token,
 * wpdo_telegram_chat_id, wpdo_telegram_throttle_hours, wpdo_telegram_severity.
 *
 * Bot token is sensitive: stored as-is in wp_options for now (admin-only).
 * Future hardening: integrate TMDO_Crypto encryption (note in v2.5+).
 *
 * @package WP_Data_Optimizer
 */

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

/**
 * Telegram channel.
 */
class TMDO_Telegram_Notifier extends TMDO_Abstract_Notifier {

	/**
	 * Channel identifier used as option key prefix.
	 *
	 * @return string
	 */
	public static function channel_id(): string {
		return 'telegram';
	}

	/**
	 * Build Telegram-specific context (bot token + chat ID).
	 *
	 * @return array|null Null if token or chat ID is missing or invalid.
	 */
	public static function build_context(): ?array {
		$token = class_exists( 'TMDO_Crypto' )
			? TMDO_Crypto::get_option( 'wpdo_telegram_bot_token' )
			: (string) get_option( 'wpdo_telegram_bot_token', '' );
		$chat  = (string) get_option( 'wpdo_telegram_chat_id', '' );
		if ( '' === $token || '' === $chat ) {
			return null;
		}
		// Bot tokens are formatted as 123456:ABC-DEF...; minimal validation.
		if ( ! preg_match( '/^\d+:[A-Za-z0-9_\-]{20,}$/', $token ) ) {
			return null;
		}
		return array(
			'token'   => $token,
			'chat_id' => $chat,
		);
	}

	/**
	 * Send alert via Telegram Bot API.
	 *
	 * @param string $subject Alert subject / title.
	 * @param string $body    Alert body text.
	 * @param array  $context Channel context (token, chat_id).
	 * @return bool True on HTTP 2xx response.
	 */
	public static function actually_send( string $subject, string $body, array $context ): bool {
		$token = (string) ( $context['token'] ?? '' );
		$chat  = (string) ( $context['chat_id'] ?? '' );
		if ( '' === $token || '' === $chat ) {
			return false;
		}
		// Telegram MarkdownV2 has many escaped chars; use plain text mode for safety.
		$text = "🚨 {$subject}\n\n{$body}";
		// Telegram message limit = 4096 chars.
		$text = substr( $text, 0, 4000 );

		$url  = sprintf( 'https://api.telegram.org/bot%s/sendMessage', rawurlencode( $token ) );
		$resp = wp_remote_post(
			$url,
			array(
				'headers'  => array( 'Content-Type' => 'application/json' ),
				'body'     => wp_json_encode(
					array(
						'chat_id' => $chat,
						'text'    => $text,
					)
				),
				'timeout'  => 5,
				'blocking' => true,
			)
		);
		if ( is_wp_error( $resp ) ) {
			return false;
		}
		$code = (int) wp_remote_retrieve_response_code( $resp );
		return $code >= 200 && $code < 300;
	}
}