ThreadNet-Web/src/autocomplete/Autocompleter.js

// @flow

import type {Component} from 'react';
import CommandProvider from './CommandProvider';
import DuckDuckGoProvider from './DuckDuckGoProvider';
import RoomProvider from './RoomProvider';
import UserProvider from './UserProvider';
import EmojiProvider from './EmojiProvider';
import Q from 'q';

export type SelectionRange = {
    start: number,
    end: number
};

export type Completion = {
    completion: string,
    component: ?Component,
    range: SelectionRange,
    command: ?string,
};

const PROVIDERS = [
    UserProvider,
    RoomProvider,
    EmojiProvider,
    CommandProvider,
    DuckDuckGoProvider,
].map(completer => completer.getInstance());

// Providers will get rejected if they take longer than this.
const PROVIDER_COMPLETION_TIMEOUT = 3000;

export async function getCompletions(query: string, selection: SelectionRange, force: boolean = false): Array<Completion> {
    /* Note: That this waits for all providers to return is *intentional*
     otherwise, we run into a condition where new completions are displayed
     while the user is interacting with the list, which makes it difficult
     to predict whether an action will actually do what is intended

     It ends up containing a list of Q promise states, which are objects with
     state (== "fulfilled" || "rejected") and value. */
    const completionsList = await Q.allSettled(
        PROVIDERS.map(provider => {
            return Q(provider.getCompletions(query, selection, force))
                .timeout(PROVIDER_COMPLETION_TIMEOUT);
        })
    );

    return completionsList
        .filter(completion => completion.state === "fulfilled")
        .map((completionsState, i) => {
            return {
                completions: completionsState.value,
                provider: PROVIDERS[i],

                /* the currently matched "command" the completer tried to complete
                 * we pass this through so that Autocomplete can figure out when to
                 * re-show itself once hidden.
                 */
                command: PROVIDERS[i].getCurrentCommand(query, selection, force),
            };
        });
}