<?php
/**
 * A thin Telegram Bot API client. Every call returns an array the caller can act on:
 * ok, http code, Telegram's description, the result, and retry_after on a 429 — a rate-limited
 * message is rescheduled, never dropped and never retried in a tight loop.
 *
 * @package Orderchirp
 */

namespace Orderchirp;

defined( 'ABSPATH' ) || exit;

final class Telegram_Api {

	/**
	 * Bot token.
	 *
	 * @var string
	 */
	private $token;

	/**
	 * Constructor.
	 *
	 * @param string $token Bot token.
	 */
	public function __construct( $token ) {
		$this->token = (string) $token;
	}

	/**
	 * For the configured bot.
	 *
	 * @return Telegram_Api
	 */
	public static function from_settings() {
		return new self( (string) Settings::get( 'bot_token' ) );
	}

	/**
	 * Call a Bot API method.
	 *
	 * @param string              $method Method, e.g. sendMessage.
	 * @param array<string,mixed> $params Parameters.
	 * @param int                 $timeout Seconds.
	 * @return array{ok:bool,code:int,description:string,result:mixed,retry_after:int,network:bool}
	 */
	public function call( $method, array $params = array(), $timeout = 15 ) {
		/**
		 * Base URL of the Bot API. Changed only to point at a self-hosted Bot API server.
		 *
		 * @param string $base Default https://api.telegram.org.
		 */
		$base     = (string) apply_filters( 'orderchirp_telegram_api_base', 'https://api.telegram.org' );
		$response = wp_remote_post(
			rtrim( $base, '/' ) . '/bot' . $this->token . '/' . $method,
			array(
				'timeout' => $timeout,
				'headers' => array( 'Content-Type' => 'application/json' ),
				'body'    => wp_json_encode( $params ),
			)
		);
		if ( is_wp_error( $response ) ) {
			return array(
				'ok'          => false,
				'code'        => 0,
				'description' => self::redact( $response->get_error_message(), $this->token ),
				'result'      => null,
				'retry_after' => 0,
				'network'     => true,
			);
		}
		return self::parse_response( (int) wp_remote_retrieve_response_code( $response ), (string) wp_remote_retrieve_body( $response ) );
	}

	/**
	 * Turn an HTTP answer into the result array. A body that is not Telegram's JSON is a failure.
	 *
	 * @param int    $code HTTP status.
	 * @param string $body Body.
	 * @return array{ok:bool,code:int,description:string,result:mixed,retry_after:int,network:bool}
	 */
	public static function parse_response( $code, $body ) {
		$data = json_decode( $body, true );
		if ( ! is_array( $data ) || ! array_key_exists( 'ok', $data ) ) {
			return array(
				'ok'          => false,
				'code'        => $code,
				'description' => 'Unexpected answer from Telegram (HTTP ' . $code . ')',
				'result'      => null,
				'retry_after' => 0,
				'network'     => $code >= 500 || 0 === $code,
			);
		}
		$ok          = true === $data['ok'];
		$retry_after = 0;
		if ( isset( $data['parameters']['retry_after'] ) ) {
			$retry_after = max( 1, (int) $data['parameters']['retry_after'] );
		}
		return array(
			'ok'          => $ok,
			'code'        => isset( $data['error_code'] ) ? (int) $data['error_code'] : $code,
			'description' => isset( $data['description'] ) ? (string) $data['description'] : '',
			'result'      => isset( $data['result'] ) ? $data['result'] : null,
			'retry_after' => $retry_after,
			'network'     => ! $ok && $code >= 500,
		);
	}

	/**
	 * Whether a failure means the person blocked the bot or deleted their account, so the chat
	 * must be forgotten rather than retried.
	 *
	 * @param array{ok:bool,code:int,description:string} $result Result of call().
	 * @return bool
	 */
	public static function chat_is_gone( array $result ) {
		if ( $result['ok'] ) {
			return false;
		}
		if ( 403 === (int) $result['code'] ) {
			return true;
		}
		return 400 === (int) $result['code'] && false !== stripos( (string) $result['description'], 'chat not found' );
	}

	/**
	 * Remove the bot token from text that may be logged or shown (an HTTP error message can
	 * contain the full request URL).
	 *
	 * @param string $text  Text.
	 * @param string $token Token.
	 * @return string
	 */
	public static function redact( $text, $token ) {
		$text = (string) $text;
		if ( '' !== (string) $token ) {
			$text = str_replace( (string) $token, '***', $text );
		}
		return (string) preg_replace( '/bot\d{5,16}:[A-Za-z0-9_-]{30,64}/', 'bot***', $text );
	}

	/**
	 * Send a plain-text message.
	 *
	 * @param string|int            $chat_id Chat.
	 * @param string                $text    Text.
	 * @param array<int,array>|null $buttons Optional rows of URL buttons: [[['text'=>..,'url'=>..]]].
	 * @return array{ok:bool,code:int,description:string,result:mixed,retry_after:int,network:bool}
	 */
	public function send_message( $chat_id, $text, $buttons = null ) {
		$params = array(
			'chat_id'              => (string) $chat_id,
			'text'                 => (string) $text,
			'link_preview_options' => array( 'is_disabled' => true ),
		);
		if ( $buttons ) {
			$params['reply_markup'] = array( 'inline_keyboard' => $buttons );
		}
		return $this->call( 'sendMessage', $params );
	}
}