import octopus_url from "../../static/generated/emoji/images-google-64/1f419.png";
import google_blob_sheet from "../generated/emoji/google-blob.webp";
import google_sheet from "../generated/emoji/google.webp";
import twitter_sheet from "../generated/emoji/twitter.webp";

import * as blueslip from "./blueslip";
import {user_settings} from "./user_settings";

import google_blob_css from "!style-loader?injectType=lazyStyleTag!css-loader!../generated/emoji-styles/google-blob-sprite.css";
import google_css from "!style-loader?injectType=lazyStyleTag!css-loader!../generated/emoji-styles/google-sprite.css";
import twitter_css from "!style-loader?injectType=lazyStyleTag!css-loader!../generated/emoji-styles/twitter-sprite.css";

type EmojiSet = {
    css: {use: () => void; unuse: () => void};
    sheet: string;
};

const emojisets = new Map<string, EmojiSet>([
    ["google", {css: google_css, sheet: google_sheet}],
    ["google-blob", {css: google_blob_css, sheet: google_blob_sheet}],
    ["twitter", {css: twitter_css, sheet: twitter_sheet}],
]);

// For `text` emoji set we fallback to `google` emoji set
// for displaying emojis in emoji picker and typeahead.
emojisets.set("text", emojisets.get("google")!);

let current_emojiset: EmojiSet | undefined;

async function fetch_emojiset(name: string, url: string): Promise<void> {
    const MAX_RETRIES = 3;
    const RETRY_DELAY = 10000; // 10 seconds

    for (let attempt = 1; attempt <= MAX_RETRIES; attempt += 1) {
        try {
            const response = await fetch(url);

            if (!response.ok) {
                throw new Error(`HTTP error! status: ${response.status}`);
            }

            // If the fetch is successful, resolve the promise and return
            return;
        } catch (error) {
            if (!navigator.onLine) {
                // If the user is offline, retry once they are online.
                await new Promise<void>((resolve) => {
                    // We don't want to throw an error here since this is clearly something wrong with user's network.
                    blueslip.warn(
                        `Failed to load emojiset ${name} from ${url}. Retrying when online.`,
                    );
                    window.addEventListener(
                        "online",
                        () => {
                            resolve();
                        },
                        {once: true},
                    );
                });
            } else {
                blueslip.warn(
                    `Failed to load emojiset ${name} from ${url}. Attempt ${attempt} of ${MAX_RETRIES}.`,
                );

                // If this was the last attempt, rethrow the error
                if (attempt === MAX_RETRIES) {
                    blueslip.error(
                        `Failed to load emojiset ${name} from ${url} after ${MAX_RETRIES} attempts.`,
                    );
                    throw error;
                }

                // Wait before the next attempt
                await new Promise((resolve) => setTimeout(resolve, RETRY_DELAY));
            }
        }
    }
}

export async function select(name: string): Promise<void> {
    const new_emojiset = emojisets.get(name);
    if (new_emojiset === current_emojiset) {
        return;
    }

    if (!new_emojiset) {
        throw new Error("Unknown emojiset " + name);
    }

    await fetch_emojiset(name, new_emojiset.sheet);

    if (current_emojiset) {
        current_emojiset.css.unuse();
    }
    new_emojiset.css.use();
    current_emojiset = new_emojiset;
}

export function initialize(): void {
    void select(user_settings.emojiset);

    // Load the octopus image in the background, so that the browser
    // will cache it for later use.  Note that we hardcode the octopus
    // emoji to the old Google one because it's better.
    //
    // TODO: We should probably just make this work just like the Zulip emoji.
    const octopus_image = new Image();
    octopus_image.src = octopus_url;
}