revite/src/mobx/stores/Draft.ts

import { action, computed, makeAutoObservable, ObservableMap } from "mobx";

import Persistent from "../Persistent";

interface Data {
    drafts: Record<string, string>;
}

/**
 * Handles storing draft (currently being written) messages.
 */
export default class Draft implements Persistent<Data> {
    private drafts: ObservableMap<string, string>;

    /**
     * Construct new Draft store.
     */
    constructor() {
        this.drafts = new ObservableMap();
        makeAutoObservable(this);
    }

    toJSON() {
        return {
            drafts: this.drafts,
        };
    }

    @action hydrate(data: Data) {
        Object.keys(data.drafts).forEach((key) =>
            this.drafts.set(key, data.drafts[key]),
        );
    }

    /**
     * Get draft for a channel.
     * @param channel Channel ID
     */
    @computed get(channel: string) {
        return this.drafts.get(channel);
    }

    /**
     * Check whether a channel has a draft.
     * @param channel Channel ID
     */
    @computed has(channel: string) {
        return this.drafts.has(channel) && this.drafts.get(channel)!.length > 0;
    }

    /**
     * Set draft for a channel.
     * @param channel Channel ID
     * @param content Draft content
     */
    @action set(channel: string, content?: string) {
        if (typeof content === "undefined") {
            return this.clear(channel);
        }

        this.drafts.set(channel, content);
    }

    /**
     * Clear draft from a channel.
     * @param channel Channel ID
     */
    @action clear(channel: string) {
        this.drafts.delete(channel);
    }

    /**
     * Reset and clear all drafts.
     */
    @action reset() {
        this.drafts.clear();
    }
}