tridactyl/src/messaging.ts

import {l, activeTabId} from './lib/webext'

export type TabMessageType = 
    "excmd_content" |
    "keydown_content" |
    "commandline_content" |
    "commandline_frame" |
    "hinting_content"
export type NonTabMessageType = 
    "keydown_background" |
    "commandline_background"
export type MessageType = TabMessageType | NonTabMessageType

export interface Message {
    type: MessageType
    // and other unknown attributes...
    [key: string]: any
}

export type listener = (message: Message, sender?, sendResponse?) => void|Promise<any>

// Calls methods on obj that match .command and sends responses back
export function attributeCaller(obj) {
    function handler(message: Message, sender, sendResponse) {
        console.log(message)

        // Args may be undefined, but you can't spread undefined...
        if (message.args === undefined) message.args = []

        // Call command on obj
        try {
            let response = obj[message.command](...message.args)

            // Return response to sender
            if (response instanceof Promise) {
                return response
            } else {
                sendResponse(response)
            }
        } catch (e) {
            return new Promise((resolve, error)=>error(e))
        }
    }
    return handler
}


/** Send a message to non-content scripts */
export async function message(type: NonTabMessageType, command, args?) {
    // One day typescript will be smart enough to back propagate this cast.
    return l(browser.runtime.sendMessage({type, command, args} as Message))
}

/** Message the active tab of the currentWindow */
//#background_helper
export async function messageActiveTab(type: TabMessageType, command: string, args?: any[]) {
    return messageTab(await activeTabId(), type, command, args)
}

export async function messageTab(tabId, type: TabMessageType, command, args?) {
    let message: Message = {
        type,
        command,
        args,
    }
    return l(browser.tabs.sendMessage(tabId, message))
}

export async function messageAllTabs(type: TabMessageType, command: string, args?: any[]) {
    let responses = []
    for (let tab of await browser.tabs.query({})) {
        try { responses.push(await messageTab(tab.id, type, command, args)) }
        catch (e) { console.error(e) }
    }
    return responses
}


const listeners = new Map<string, Set<listener>>()

/** Register a listener to be called for each message with type */
export function addListener(type: MessageType, callback: listener) {
    if (!listeners.get(type)) {
        listeners.set(type, new Set())
    }
    listeners.get(type).add(callback)
    return () => { listeners.get(type).delete(callback) }
}

/** Recv a message from runtime.onMessage and send to all listeners */
function onMessage(message, sender, sendResponse) {
    if (listeners.get(message.type)) {
        for (let listener of listeners.get(message.type)) {
            listener(message, sender, sendResponse)
        }
    }
}


browser.runtime.onMessage.addListener(onMessage)