fx_cast/ext/src/lib/bridge.ts

import semver from "semver";

import logger from "./logger";
import type { Port } from "../messaging";
import * as nativeMessaging from "./nativeMessaging";
import options from "./options";

export const BRIDGE_TIMEOUT = 5000;

/**
 * Creates a bridge instance and returns a message port.
 */
async function connect(): Promise<Port> {
    const applicationName = await options.get("bridgeApplicationName");
    const bridgePort = nativeMessaging.connectNative(
        applicationName
    ) as unknown as Port;

    bridgePort.onDisconnect.addListener(() => {
        if (bridgePort.error) {
            console.error(
                `${applicationName} disconnected:`,
                bridgePort.error.message
            );
        } else {
            console.info(`${applicationName} disconnected`);
        }
    });

    return bridgePort;
}

export interface BridgeInfo {
    name: string;
    version: string;
    expectedVersion: string;
    isVersionExact: boolean;
    isVersionCompatible: boolean;
    isVersionOlder: boolean;
    isVersionNewer: boolean;
}

export class BridgeConnectionError extends Error {}
export class BridgeTimedOutError extends Error {}
export class BridgeAuthenticationError extends Error {}

/**
 * Creates a temporary bridge to query the version info,
 * compares the version to the extension version using semver
 * rules to determine compatiblity, then returns a
 * BridgeInfo object.
 */
const getInfo = () =>
    new Promise<BridgeInfo>(async (resolve, reject) => {
        const applicationName = await options.get("bridgeApplicationName");
        if (!applicationName) {
            reject(logger.error("Bridge application name not found."));
            return;
        }

        const bridgeTimeoutId = setTimeout(() => {
            logger.error("Bridge timed out.");
            reject(new BridgeTimedOutError());
        }, BRIDGE_TIMEOUT);

        let applicationVersion: string;
        try {
            const { version } = browser.runtime.getManifest();

            applicationVersion = await nativeMessaging.sendNativeMessage(
                applicationName,
                { subject: "bridge:/getInfo", data: version }
            );
        } catch (err) {
            if (err === 401) {
                reject(new BridgeAuthenticationError());
            } else {
                logger.error("Bridge connection failed.");
                reject(new BridgeConnectionError());
            }

            clearTimeout(bridgeTimeoutId);
            return;
        }

        clearTimeout(bridgeTimeoutId);

        const extensionVersion = browser.runtime.getManifest().version;
        const extensionVersionMajor = semver.major(extensionVersion);

        const versionDiff = semver.diff(applicationVersion, extensionVersion);

        /**
         * If the target version is above 0.x.x range, API is stable
         * and versions with minor or patch level changes should be
         * compatible.
         */
        const isVersionCompatible =
            semver.eq(applicationVersion, extensionVersion) ||
            (versionDiff !== "major" && extensionVersionMajor !== 0) ||
            (versionDiff === "patch" && extensionVersionMajor === 0);

        const isVersionExact = semver.eq(applicationVersion, extensionVersion);
        const isVersionOlder = semver.lt(applicationVersion, extensionVersion);
        const isVersionNewer = semver.gt(applicationVersion, extensionVersion);

        // Print compatibility info to console
        if (!isVersionCompatible) {
            logger.error(
                `Expecting ${applicationName} v${BRIDGE_VERSION}, found v${applicationVersion}. ${
                    isVersionOlder
                        ? "Try updating the native app to the latest version."
                        : "Try updating the extension to the latest version"
                }`
            );
        }

        resolve({
            name: applicationName,
            version: applicationVersion,
            expectedVersion: BRIDGE_VERSION,

            // Version info
            isVersionExact,
            isVersionCompatible,
            isVersionOlder,
            isVersionNewer
        });
    });

export default {
    connect,
    getInfo
};