<?php
/**
 * Client for the smsportal.app API (the only routes a WordPress key may use).
 *
 * Contract: docs/integrations/wordpress-connect.md.
 *
 * @package Smsportal
 */

namespace Smsportal;

use WP_Error;

defined( 'ABSPATH' ) || exit;

/**
 * Sends SMS and reads the connection state. Errors are WP_Error with one of the codes:
 * smsportal_not_connected, smsportal_unauthorized (401, connection removed),
 * smsportal_limit_reached (429 with hasReachedLimit: the account's plan limit, do not retry),
 * smsportal_rate_limited (other 429), smsportal_rejected (other 4xx, do not retry),
 * smsportal_unavailable (network or 5xx, retry later).
 */
class Api {

	const SEND_TIMEOUT = 10;

	/**
	 * The overview waits for this call, so it gives up early.
	 */
	const INFO_TIMEOUT = 3;

	const MAX_REASON_LENGTH = 200;
	const RETRYABLE_4XX     = array( 408, 425 );

	const INFO_TRANSIENT = 'smsportal_connection_info';
	const INFO_TTL       = MINUTE_IN_SECONDS;

	/**
	 * Remembered "smsportal.app unavailable" answer, so a down server does not slow every page view.
	 */
	const INFO_ERROR_TRANSIENT = 'smsportal_connection_info_error';
	const INFO_ERROR_TTL       = MINUTE_IN_SECONDS;

	/**
	 * Send one SMS.
	 *
	 * @param string   $to         Recipient (E.164).
	 * @param string   $message    Text.
	 * @param string   $request_id Idempotency key, unique per smsportal account.
	 * @param int|null $expires_at Unix time after which the SMS must not be sent, or null.
	 * @return array{sms_batch_id:string,duplicate:bool}|WP_Error
	 */
	public static function send( string $to, string $message, string $request_id, ?int $expires_at ) {
		$payload = array(
			'recipients' => array( $to ),
			'message'    => $message,
			'requestId'  => $request_id,
		);
		if ( null !== $expires_at ) {
			$payload['expiresAt'] = gmdate( 'Y-m-d\TH:i:s\Z', $expires_at );
		}

		$body = self::request( 'POST', '/api/v1/gateway/send-sms', self::SEND_TIMEOUT, $payload );
		if ( is_wp_error( $body ) ) {
			return $body;
		}

		$data     = isset( $body['data'] ) && is_array( $body['data'] ) ? $body['data'] : array();
		$batch_id = isset( $data['smsBatchId'] ) && is_scalar( $data['smsBatchId'] ) ? (string) $data['smsBatchId'] : '';
		if ( '' === $batch_id ) {
			return self::fail( 'smsportal_unavailable', __( 'smsportal.app sent an unexpected answer.', '85pl-android-sms-api' ), 0 );
		}
		return array(
			'sms_batch_id' => $batch_id,
			'duplicate'    => ! empty( $data['duplicate'] ),
		);
	}

	/**
	 * Phone and usage state of the connection. Answers are cached for 60 seconds; so is
	 * "smsportal.app unavailable" (other errors, e.g. a rejected key, are not).
	 *
	 * @return array<string,mixed>|WP_Error
	 */
	public static function connection_info() {
		if ( ! Connection::is_connected() ) {
			return new WP_Error( 'smsportal_not_connected', __( 'This site is not connected to smsportal.app.', '85pl-android-sms-api' ) );
		}
		$cached = get_transient( self::INFO_TRANSIENT );
		if ( is_array( $cached ) ) {
			return $cached;
		}
		$failed = get_transient( self::INFO_ERROR_TRANSIENT );
		if ( is_string( $failed ) && '' !== $failed ) {
			return self::fail( 'smsportal_unavailable', $failed, 0 );
		}

		$info = self::fetch_info();
		if ( is_wp_error( $info ) ) {
			if ( 'smsportal_unavailable' === $info->get_error_code() ) {
				set_transient( self::INFO_ERROR_TRANSIENT, $info->get_error_message(), self::INFO_ERROR_TTL );
			}
			return $info;
		}
		set_transient( self::INFO_TRANSIENT, $info, self::INFO_TTL );
		return $info;
	}

	/**
	 * Connection state from the cache only, without asking smsportal.app (for the screen header).
	 *
	 * @return array<string,mixed>|null Null when nothing is cached.
	 */
	public static function cached_info(): ?array {
		$cached = get_transient( self::INFO_TRANSIENT );
		return is_array( $cached ) ? $cached : null;
	}

	/**
	 * Forget cached connection state (after connecting or disconnecting).
	 *
	 * @return void
	 */
	public static function forget_info(): void {
		delete_transient( self::INFO_TRANSIENT );
		delete_transient( self::INFO_ERROR_TRANSIENT );
	}

	/**
	 * Ask smsportal.app for the connection state.
	 *
	 * @return array<string,mixed>|WP_Error
	 */
	private static function fetch_info() {
		$body = self::request( 'GET', '/api/v1/integrations/connection', self::INFO_TIMEOUT );
		if ( is_wp_error( $body ) ) {
			return $body;
		}
		$info = isset( $body['data'] ) && is_array( $body['data'] ) ? $body['data'] : $body;
		if ( empty( $info['connection_id'] ) && empty( $info['device_id'] ) ) {
			return self::fail( 'smsportal_unavailable', __( 'smsportal.app sent an unexpected answer.', '85pl-android-sms-api' ), 0 );
		}
		return $info;
	}

	/**
	 * Call the API with the connection key.
	 *
	 * @param string                    $method  GET or POST.
	 * @param string                    $path    Path starting with /api.
	 * @param int                       $timeout Seconds.
	 * @param array<string,mixed>|null  $payload JSON body.
	 * @return array<string,mixed>|WP_Error Decoded JSON body of a 2xx answer.
	 */
	private static function request( string $method, string $path, int $timeout, ?array $payload = null ) {
		$api_key = Connection::api_key();
		if ( null === $api_key ) {
			return new WP_Error( 'smsportal_not_connected', __( 'This site is not connected to smsportal.app.', '85pl-android-sms-api' ) );
		}

		$args = array(
			'method'  => $method,
			'timeout'     => $timeout,
			'redirection' => 0,
			'headers'     => array(
				'x-api-key' => $api_key,
				'Accept'    => 'application/json',
			),
		);
		if ( null !== $payload ) {
			$args['headers']['Content-Type'] = 'application/json';
			$args['body']                    = wp_json_encode( $payload );
		}

		$response = wp_remote_request( Connection::server_url() . $path, $args );
		if ( is_wp_error( $response ) ) {
			return self::fail(
				'smsportal_unavailable',
				/* translators: %s: network error, e.g. "cURL error 28: Operation timed out". */
				sprintf( __( 'smsportal.app could not be reached (%s).', '85pl-android-sms-api' ), $response->get_error_message() ),
				0
			);
		}

		$status  = (int) wp_remote_retrieve_response_code( $response );
		$decoded = json_decode( (string) wp_remote_retrieve_body( $response ), true );
		$decoded = is_array( $decoded ) ? $decoded : array();

		if ( $status >= 200 && $status < 300 ) {
			return $decoded;
		}
		return self::error_for_status( $status, $decoded );
	}

	/**
	 * Map a non-2xx answer to a WP_Error.
	 *
	 * @param int                 $status  HTTP status.
	 * @param array<string,mixed> $decoded Decoded body.
	 * @return WP_Error
	 */
	private static function error_for_status( int $status, array $decoded ): WP_Error {
		if ( 401 === $status ) {
			Connection::disconnect( 'server' );
			self::forget_info();
			ConnectionLog::add( 'auth_error', __( 'smsportal.app rejected the access key; the connection was removed.', '85pl-android-sms-api' ) );
			return self::fail( 'smsportal_unauthorized', __( 'The connection to smsportal.app is no longer valid. Please connect again.', '85pl-android-sms-api' ), $status );
		}
		if ( 429 === $status && ! empty( $decoded['hasReachedLimit'] ) ) {
			/* translators: %s: explanation from smsportal.app, e.g. "Your account has used its 50 messages…". */
			$message = sprintf( __( 'The smsportal.app plan limit is reached: %s', '85pl-android-sms-api' ), self::reason( $decoded ) );
			return self::fail( 'smsportal_limit_reached', $message, $status );
		}
		if ( 429 === $status ) {
			return self::fail( 'smsportal_rate_limited', __( 'smsportal.app is receiving too many requests. Try again shortly.', '85pl-android-sms-api' ), $status );
		}
		if ( $status >= 400 && $status < 500 && ! in_array( $status, self::RETRYABLE_4XX, true ) ) {
			/* translators: 1: HTTP status code, 2: reason from smsportal.app. */
			$message = sprintf( __( 'smsportal.app rejected the request (HTTP %1$d): %2$s', '85pl-android-sms-api' ), $status, self::reason( $decoded ) );
			ConnectionLog::add( 'send_error', $message );
			return self::fail( 'smsportal_rejected', $message, $status );
		}
		/* translators: %d: HTTP status code. */
		return self::fail( 'smsportal_unavailable', sprintf( __( 'smsportal.app is temporarily unavailable (HTTP %d).', '85pl-android-sms-api' ), $status ), $status );
	}

	/**
	 * Reason given by smsportal.app ("error", else "message"), cleaned and shortened; "-" when none.
	 *
	 * @param array<string,mixed> $decoded Decoded body.
	 * @return string
	 */
	private static function reason( array $decoded ): string {
		$reason = isset( $decoded['error'] ) && is_string( $decoded['error'] ) ? $decoded['error'] : '';
		if ( '' === $reason && isset( $decoded['message'] ) && is_string( $decoded['message'] ) ) {
			$reason = $decoded['message'];
		}
		$reason = mb_substr( sanitize_text_field( $reason ), 0, self::MAX_REASON_LENGTH );
		return '' === $reason ? '-' : $reason;
	}

	/**
	 * Build an error with its secrets removed.
	 *
	 * @param string $code    Error code.
	 * @param string $message Message.
	 * @param int    $status  HTTP status (0 = none).
	 * @return WP_Error
	 */
	private static function fail( string $code, string $message, int $status ): WP_Error {
		return new WP_Error( $code, self::redact( $message ), array( 'status' => $status ) );
	}

	/**
	 * Remove the API key (and anything shaped like one) from a text.
	 *
	 * @param string $text Text.
	 * @return string
	 */
	private static function redact( string $text ): string {
		$secrets = array_filter( array( Connection::api_key(), Connection::webhook_secret() ) );
		if ( $secrets ) {
			$text = str_replace( $secrets, '[redacted]', $text );
		}
		return (string) preg_replace( '/txb_[A-Za-z0-9_\-]+/', '[redacted]', $text );
	}
}