fx_cast/ext/src/background/ShimManager.ts

"use strict";

import bridge from "../lib/bridge";
import loadSender from "../lib/loadSender";
import options from "../lib/options";

import { Message } from "../types";

import { getMediaTypesForPageUrl } from "../lib/utils";
import { ReceiverSelectorMediaType } from "./receiverSelector";

import ReceiverSelectorManager
    from "./receiverSelector/ReceiverSelectorManager";

import StatusManager from "./StatusManager";


type Port = browser.runtime.Port | MessagePort;

export interface Shim {
    bridgePort: browser.runtime.Port;
    contentPort: Port;
    contentTabId?: number;
    contentFrameId?: number;
}


// tslint:disable-next-line:new-parens
export default new class ShimManager {
    private activeShims = new Set<Shim>();

    public async init () {
        await this.initStatusListeners();
    }

    public async createShim (port: Port) {
        const shim = await (port instanceof MessagePort
            ? this.createShimFromBackground(port)
            : this.createShimFromContent(port));

        shim.contentPort.postMessage({
            subject: "shim:/initialized"
          , data: await bridge.getInfo()
        });

        this.activeShims.add(shim);
    }

    private async createShimFromBackground (
            contentPort: MessagePort): Promise<Shim> {

        const shim: Shim = {
            bridgePort: await bridge.connect()
          , contentPort
        };

        shim.bridgePort.onDisconnect.addListener(() => {
            contentPort.close();
            this.activeShims.delete(shim);
        });

        shim.bridgePort.onMessage.addListener((message: Message) => {
            contentPort.postMessage(message);
        });

        contentPort.onmessage = ev => {
            const message = ev.data as Message;
            this.handleContentMessage(shim, message);
        };

        return shim;
    }

    private async createShimFromContent (
            contentPort: browser.runtime.Port): Promise<Shim> {

        /**
         * If there's already an active shim for the sender
         * tab/frame ID, disconnect it.
         */
        for (const activeShim of this.activeShims) {
            if (activeShim.contentTabId === contentPort.sender.tab.id
             && activeShim.contentFrameId === contentPort.sender.frameId) {
                activeShim.bridgePort.disconnect();
            }
        }

        const shim: Shim = {
            bridgePort: await bridge.connect()
          , contentPort
          , contentTabId: contentPort.sender.tab.id
          , contentFrameId: contentPort.sender.frameId
        };


        const onContentPortMessage = (message: Message) => {
            this.handleContentMessage(shim, message);
        };

        const onBridgePortMessage = (message: Message) => {
            contentPort.postMessage(message);
        };

        const onDisconnect = () => {
            shim.bridgePort.onMessage.removeListener(onBridgePortMessage);
            contentPort.onMessage.removeListener(onContentPortMessage);

            shim.bridgePort.disconnect();
            contentPort.disconnect();

            this.activeShims.delete(shim);
        };


        shim.bridgePort.onDisconnect.addListener(onDisconnect);
        shim.bridgePort.onMessage.addListener(onBridgePortMessage);

        contentPort.onDisconnect.addListener(onDisconnect);
        contentPort.onMessage.addListener(onContentPortMessage);

        return shim;
    }

    private async handleContentMessage (shim: Shim, message: Message) {
        const [ destination ] = message.subject.split(":/");
        if (destination === "bridge") {
            shim.bridgePort.postMessage(message);
        }

        switch (message.subject) {
            case "main:/shimInitialized": {
                for (const receiver of StatusManager.getReceivers()) {
                    shim.contentPort.postMessage({
                        subject: "shim:/serviceUp"
                      , data: { id: receiver.id }
                    });
                }

                break;
            }

            case "main:/selectReceiverBegin": {
                const contentTab = await browser.tabs.get(shim.contentTabId);
                const availableMediaTypes = getMediaTypesForPageUrl(
                        contentTab.url);

                try {
                    const selection = await ReceiverSelectorManager
                            .getSelection(
                                    ReceiverSelectorMediaType.App
                                  , availableMediaTypes);

                    // Handle cancellation
                    if (!selection) {
                        shim.contentPort.postMessage({
                            subject: "shim:/selectReceiverCancelled"
                        });

                        break;
                    }

                    /**
                     * If the media type returned from the selector has been
                     * changed, we need to cancel the current sender and switch
                     * it out for the right one.
                     */
                    if (selection.mediaType !== ReceiverSelectorMediaType.App) {
                        shim.contentPort.postMessage({
                            subject: "shim:/selectReceiverCancelled"
                        });

                        loadSender({
                            tabId: shim.contentTabId
                          , frameId: shim.contentFrameId
                          , selection
                        });

                        break;
                    }

                    // Pass selection back to shim
                    shim.contentPort.postMessage({
                        subject: "shim:/selectReceiverEnd"
                      , data: selection
                    });

                } catch (err) {
                    // TODO: Report errors properly
                    shim.contentPort.postMessage({
                        subject: "shim:/selectReceiverCancelled"
                    });
                }

                break;
            }

            /**
             * TODO: If we're closing a selector, make sure it's the
             * same one that caused the session creation.
             */
            case "main:/sessionCreated": {
                const selector = await ReceiverSelectorManager.getSelector();
                const shouldClose = await options.get(
                        "receiverSelectorWaitForConnection");

                if (selector.isOpen && shouldClose) {
                    selector.close();
                }

                break;
            }
        }
    }

    private async initStatusListeners () {
        StatusManager.addEventListener("serviceUp", ev => {
            for (const shim of this.activeShims) {
                shim.contentPort.postMessage({
                    subject: "shim:/serviceUp"
                  , data: { id: ev.detail.id }
                });
            }
        });

        StatusManager.addEventListener("serviceDown", ev => {
            for (const shim of this.activeShims) {
                shim.contentPort.postMessage({
                    subject: "shim:/serviceDown"
                  , data: { id: ev.detail.id }
                });
            }
        });
    }
};