/*
 * Vencord, a modification for Discord's desktop app
 * Copyright (c) 2022 Vendicated and contributors
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
*/

import { Settings } from "@api/settings";
import { VENCORD_USER_AGENT } from "@utils/constants";
import { debounce } from "@utils/debounce";
import { useAwaiter } from "@utils/misc";

import { PronounsFormat } from ".";
import { PronounCode, PronounMapping, PronounsResponse } from "./types";

// A map of cached pronouns so the same request isn't sent twice
const cache: Record<string, PronounCode> = {};
// A map of ids and callbacks that should be triggered on fetch
const requestQueue: Record<string, ((pronouns: PronounCode) => void)[]> = {};

// Executes all queued requests and calls their callbacks
const bulkFetch = debounce(async () => {
    const ids = Object.keys(requestQueue);
    const pronouns = await bulkFetchPronouns(ids);
    for (const id of ids) {
        // Call all callbacks for the id
        requestQueue[id]?.forEach(c => c(pronouns[id]));
        delete requestQueue[id];
    }
});

export function awaitAndFormatPronouns(id: string): string | null {
    const [result, , isPending] = useAwaiter(() => fetchPronouns(id), {
        fallbackValue: getCachedPronouns(id),
        onError: e => console.error("Fetching pronouns failed: ", e)
    });

    // If the result is present and not "unspecified", and there is a mapping for the code, then return the mappings
    if (result && result !== "unspecified" && PronounMapping[result])
        return formatPronouns(result);

    return null;
}

// Gets the cached pronouns, if you're too impatient for a promise!
export function getCachedPronouns(id: string): PronounCode | null {
    return cache[id] ?? null;
}

// Fetches the pronouns for one id, returning a promise that resolves if it was cached, or once the request is completed
export function fetchPronouns(id: string): Promise<PronounCode> {
    return new Promise(res => {
        // If cached, return the cached pronouns
        if (id in cache) res(getCachedPronouns(id)!);
        // If there is already a request added, then just add this callback to it
        else if (id in requestQueue) requestQueue[id].push(res);
        // If not already added, then add it and call the debounced function to make sure the request gets executed
        else {
            requestQueue[id] = [res];
            bulkFetch();
        }
    });
}

async function bulkFetchPronouns(ids: string[]): Promise<PronounsResponse> {
    const params = new URLSearchParams();
    params.append("platform", "discord");
    params.append("ids", ids.join(","));

    try {
        const req = await fetch("https://pronoundb.org/api/v1/lookup-bulk?" + params.toString(), {
            method: "GET",
            headers: {
                "Accept": "application/json",
                "X-PronounDB-Source": VENCORD_USER_AGENT
            }
        });
        return await req.json()
            .then((res: PronounsResponse) => {
                Object.assign(cache, res);
                return res;
            });
    } catch (e) {
        // If the request errors, treat it as if no pronouns were found for all ids, and log it
        console.error("PronounDB fetching failed: ", e);
        const dummyPronouns = Object.fromEntries(ids.map(id => [id, "unspecified"] as const));
        Object.assign(cache, dummyPronouns);
        return dummyPronouns;
    }
}

export function formatPronouns(pronouns: PronounCode): string {
    const { pronounsFormat } = Settings.plugins.PronounDB as { pronounsFormat: PronounsFormat, enabled: boolean; };
    // For capitalized pronouns, just return the mapping (it is by default capitalized)
    if (pronounsFormat === PronounsFormat.Capitalized) return PronounMapping[pronouns];
    // If it is set to lowercase and a special code (any, ask, avoid), then just return the capitalized text
    else if (
        pronounsFormat === PronounsFormat.Lowercase
        && ["any", "ask", "avoid", "other"].includes(pronouns)
    ) return PronounMapping[pronouns];
    // Otherwise (lowercase and not a special code), then convert the mapping to lowercase
    else return PronounMapping[pronouns].toLowerCase();
}