/*
	Spacebar: A FOSS re-implementation and extension of the Discord.com backend.
	Copyright (C) 2023 Spacebar and Spacebar Contributors
	
	This program is free software: you can redistribute it and/or modify
	it under the terms of the GNU Affero 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 Affero General Public License for more details.
	
	You should have received a copy of the GNU Affero General Public License
	along with this program.  If not, see <https://www.gnu.org/licenses/>.
*/

import { Config } from "@spacebar/util";
import { Embed, EmbedImage, EmbedType } from "@spacebar/schemas";
import * as cheerio from "cheerio";
import crypto from "crypto";
import { yellow } from "picocolors";
import probe from "probe-image-size";

export const DEFAULT_FETCH_OPTIONS: RequestInit = {
    redirect: "follow",
    headers: {
        "user-agent": "Mozilla/5.0 (compatible; Spacebar/1.0; +https://github.com/spacebarchat/server)",
        "accept-language": "en-US,en;q=0.9",
    },
    // size: 1024 * 1024 * 5, 	// grabbed from config later
    method: "GET",
};

const makeEmbedImage = (url: string | undefined, width: number | undefined, height: number | undefined): Required<EmbedImage> | undefined => {
    if (!url || !width || !height) return undefined;
    return {
        url,
        width,
        height,
        proxy_url: getProxyUrl(new URL(url), width, height),
    };
};

let hasWarnedAboutImagor = false;

export const getProxyUrl = (url: URL, width: number, height: number): string => {
    const { resizeWidthMax, resizeHeightMax, imagorServerUrl } = Config.get().cdn;
    const secret = Config.get().security.requestSignature;
    width = Math.min(width || 500, resizeWidthMax || width);
    height = Math.min(height || 500, resizeHeightMax || width);

    // Imagor
    if (imagorServerUrl) {
        const path = `${width}x${height}/${url.host}${url.pathname}`;

        const hash = crypto.createHmac("sha1", secret).update(path).digest("base64").replace(/\+/g, "-").replace(/\//g, "_");

        return `${imagorServerUrl}/${hash}/${path}`;
    }

    if (!hasWarnedAboutImagor) {
        hasWarnedAboutImagor = true;
        console.log("[Embeds]", yellow("Imagor has not been set up correctly. https://docs.spacebar.chat/setup/server/configuration/imagor/"));
    }

    return url.toString();
};

const getMeta = ($: cheerio.CheerioAPI, name: string): string | undefined => {
    let elem = $(`meta[property="${name}"]`);
    if (!elem.length) elem = $(`meta[name="${name}"]`);
    const ret = elem.attr("content") || elem.text();
    return ret.trim().length == 0 ? undefined : ret;
};

const tryParseInt = (str: string | undefined) => {
    if (!str) return undefined;
    try {
        return parseInt(str);
    } catch (e) {
        return undefined;
    }
};

export const getMetaDescriptions = (text: string) => {
    const $ = cheerio.load(text);

    return {
        type: getMeta($, "og:type"),
        title: getMeta($, "og:title") || $("title").first().text(),
        provider_name: getMeta($, "og:site_name"),
        author: getMeta($, "article:author"),
        description: getMeta($, "og:description") || getMeta($, "description"),
        image: getMeta($, "og:image") || getMeta($, "twitter:image"),
        image_fallback: $(`image`).attr("src"),
        video_fallback: $(`video`).attr("src"),
        width: tryParseInt(getMeta($, "og:image:width")),
        height: tryParseInt(getMeta($, "og:image:height")),
        url: getMeta($, "og:url"),
        youtube_embed: getMeta($, "og:video:secure_url"),
        site_name: getMeta($, "og:site_name"),

        $,
    };
};

const doFetch = async (url: URL, opts?: RequestInit) => {
    try {
        const res = await fetch(url, {
            ...DEFAULT_FETCH_OPTIONS,
            ...opts,
        });
        if (res.headers.get("content-length")) {
            const contentLength = parseInt(res.headers.get("content-length")!);
            if (Config.get().limits.message.maxEmbedDownloadSize && contentLength > Config.get().limits.message.maxEmbedDownloadSize) {
                return null;
            }
        }
        return res;
    } catch (e) {
        return null;
    }
};

const genericImageHandler = async (url: URL): Promise<Embed | null> => {
    const type = await fetch(url, {
        ...DEFAULT_FETCH_OPTIONS,
        method: "HEAD",
    });

    let image;

    if (type.headers.get("content-type")?.indexOf("image") !== -1) {
        const result = await probe(url.href);
        image = makeEmbedImage(url.href, result.width, result.height);
    } else if (type.headers.get("content-type")?.indexOf("video") !== -1) {
        // TODO
        return null;
    } else {
        // have to download the page, unfortunately
        const response = await doFetch(url);
        if (!response) return null;
        const metas = getMetaDescriptions(await response.text());
        image = makeEmbedImage(metas.image || metas.image_fallback, metas.width, metas.height);
    }

    if (!image) return null;

    return {
        url: url.href,
        type: EmbedType.image,
        thumbnail: image,
    };
};

export const EmbedHandlers: {
    [key: string]: (url: URL) => Promise<Embed | Embed[] | null>;
} = {
    // the url does not have a special handler
    default: async (url: URL) => {
        const type = await fetch(url, {
            ...DEFAULT_FETCH_OPTIONS,
            method: "HEAD",
        });
        if (type.headers.get("content-type")?.indexOf("image") !== -1) return await genericImageHandler(url);

        const response = await doFetch(url);
        if (!response) return null;

        const text = await response.text();
        const metas = getMetaDescriptions(text);

        // TODO: handle video

        if (!metas.image) metas.image = metas.image_fallback;

        if (metas.image && (!metas.width || !metas.height)) {
            metas.image = new URL(metas.image, url).toString();
            const result = await probe(metas.image);
            metas.width = result.width;
            metas.height = result.height;
        }

        if (!metas.image && (!metas.title || !metas.description)) {
            // we don't have any content to display
            return null;
        }

        let embedType = EmbedType.link;
        if (metas.type == "article") embedType = EmbedType.article;
        if (metas.type == "object") embedType = EmbedType.article; // github
        if (metas.type == "rich") embedType = EmbedType.rich;

        return {
            url: url.href,
            type: embedType,
            title: metas.title,
            thumbnail: makeEmbedImage(metas.image, metas.width, metas.height),
            description: metas.description,
            provider: metas.site_name
                ? {
                      name: metas.site_name,
                      url: url.origin,
                  }
                : undefined,
        };
    },

    "giphy.com": genericImageHandler,
    "media4.giphy.com": genericImageHandler,
    "tenor.com": genericImageHandler,
    "c.tenor.com": genericImageHandler,
    "media.tenor.com": genericImageHandler,

    "facebook.com": (url) => EmbedHandlers["www.facebook.com"](url),
    "www.facebook.com": async (url: URL) => {
        const response = await doFetch(url);
        if (!response) return null;
        const metas = getMetaDescriptions(await response.text());

        return {
            url: url.href,
            type: EmbedType.link,
            title: metas.title,
            description: metas.description,
            thumbnail: makeEmbedImage(metas.image, 640, 640),
            color: 16777215,
        };
    },

    "twitter.com": (url) => EmbedHandlers["www.twitter.com"](url),
    "www.twitter.com": async (url: URL) => {
        const token = Config.get().external.twitter;
        if (!token) return null;

        if (!url.href.includes("/status/")) return null; // TODO;
        const id = url.pathname.split("/")[3]; // super bad lol
        if (!parseInt(id)) return null;
        const endpointUrl =
            `https://api.twitter.com/2/tweets/${id}` +
            `?expansions=author_id,attachments.media_keys` +
            `&media.fields=url,width,height` +
            `&tweet.fields=created_at,public_metrics` +
            `&user.fields=profile_image_url`;

        const response = await fetch(endpointUrl, {
            ...DEFAULT_FETCH_OPTIONS,
            headers: {
                authorization: `Bearer ${token}`,
            },
        });
        const json = (await response.json()) as {
            errors?: never[];
            includes: {
                users: {
                    profile_image_url: string;
                    username: string;
                    name: string;
                }[];
                media: {
                    type: string;
                    width: number;
                    height: number;
                    url: string;
                }[];
            };
            data: {
                text: string;
                created_at: string;
                public_metrics: { like_count: number; retweet_count: number };
            };
        };
        if (json.errors) return null;
        const author = json.includes.users[0];
        const text = json.data.text;
        const created_at = new Date(json.data.created_at);
        const metrics = json.data.public_metrics;
        const media = json.includes.media?.filter((x: { type: string }) => x.type == "photo");

        const embed: Embed = {
            type: EmbedType.rich,
            url: `${url.origin}${url.pathname}`,
            description: text,
            author: {
                url: `https://twitter.com/${author.username}`,
                name: `${author.name} (@${author.username})`,
                proxy_icon_url: getProxyUrl(new URL(author.profile_image_url), 400, 400),
                icon_url: author.profile_image_url,
            },
            timestamp: created_at,
            fields: [
                {
                    inline: true,
                    name: "Likes",
                    value: metrics.like_count.toString(),
                },
                {
                    inline: true,
                    name: "Retweet",
                    value: metrics.retweet_count.toString(),
                },
            ],
            color: 1942002,
            footer: {
                text: "Twitter",
                proxy_icon_url: getProxyUrl(new URL("https://abs.twimg.com/icons/apple-touch-icon-192x192.png"), 192, 192),
                icon_url: "https://abs.twimg.com/icons/apple-touch-icon-192x192.png",
            },
            // Discord doesn't send this?
            // provider: {
            // 	name: "Twitter",
            // 	url: "https://twitter.com"
            // },
        };

        if (media && media.length > 0) {
            embed.image = {
                width: media[0].width,
                height: media[0].height,
                url: media[0].url,
                proxy_url: getProxyUrl(new URL(media[0].url), media[0].width, media[0].height),
            };
            media.shift();
        }

        return embed;

        // TODO: Client won't merge these into a single embed, for some reason.
        // return [embed, ...media.map((x: any) => ({
        // 	// generate new embeds for each additional attachment
        // 	type: EmbedType.rich,
        // 	url: url.href,
        // 	image: {
        // 		width: x.width,
        // 		height: x.height,
        // 		url: x.url,
        // 		proxy_url: getProxyUrl(new URL(x.url), x.width, x.height)
        // 	}
        // }))];
    },

    "open.spotify.com": async (url: URL) => {
        const response = await doFetch(url);
        if (!response) return null;
        const metas = getMetaDescriptions(await response.text());

        return {
            url: url.href,
            type: EmbedType.link,
            title: metas.title,
            description: metas.description,
            thumbnail: makeEmbedImage(metas.image, 640, 640),
            provider: {
                url: "https://spotify.com",
                name: "Spotify",
            },
        };
    },

    // TODO: docs: Pixiv won't work without Imagor
    "pixiv.net": (url) => EmbedHandlers["www.pixiv.net"](url),
    "www.pixiv.net": async (url: URL) => {
        const response = await doFetch(url);
        if (!response) return null;
        const metas = getMetaDescriptions(await response.text());

        if (!metas.image) return null;

        return {
            url: url.href,
            type: EmbedType.image,
            title: metas.title,
            description: metas.description,
            image: makeEmbedImage(metas.image || metas.image_fallback, metas.width, metas.height),
            provider: {
                url: "https://pixiv.net",
                name: "Pixiv",
            },
        };
    },

    "store.steampowered.com": async (url: URL) => {
        const response = await doFetch(url);
        if (!response) return null;
        const metas = getMetaDescriptions(await response.text());
        const numReviews = metas.$("#review_summary_num_reviews").val() as string | undefined;
        const price = metas.$(".game_purchase_price.price").data("price-final") as number | undefined;
        const releaseDate = metas.$(".release_date").find("div.date").text().trim();
        const isReleased = new Date(releaseDate) < new Date();

        const fields: Embed["fields"] = [];

        if (numReviews)
            fields.push({
                name: "Reviews",
                value: numReviews,
                inline: true,
            });

        if (price)
            fields.push({
                name: "Price",
                value: `$${price / 100}`,
                inline: true,
            });

        // if the release date is in the past, it's already out
        if (releaseDate && !isReleased)
            fields.push({
                name: "Release Date",
                value: releaseDate,
                inline: true,
            });

        return {
            url: url.href,
            type: EmbedType.rich,
            title: metas.title,
            description: metas.description,
            image: {
                // TODO: meant to be thumbnail.
                // isn't this standard across all of steam?
                width: 460,
                height: 215,
                url: metas.image,
                proxy_url: metas.image ? getProxyUrl(new URL(metas.image), 460, 215) : undefined,
            },
            provider: {
                url: "https://store.steampowered.com",
                name: "Steam",
            },
            fields,
            // TODO: Video
        };
    },

    "reddit.com": (url) => EmbedHandlers["www.reddit.com"](url),
    "www.reddit.com": async (url: URL) => {
        const res = await EmbedHandlers["default"](url);
        return {
            ...res,
            color: 16777215,
            provider: {
                name: "reddit",
            },
        };
    },

    "youtu.be": (url) => EmbedHandlers["www.youtube.com"](url),
    "youtube.com": (url) => EmbedHandlers["www.youtube.com"](url),
    "www.youtube.com": async (url: URL): Promise<Embed | null> => {
        const response = await doFetch(url, { headers: { cookie: "CONSENT=PENDING+999; hl=en" } });
        if (!response) return null;
        const metas = getMetaDescriptions(await response.text());

        return {
            video: makeEmbedImage(metas.youtube_embed, metas.width, metas.height),
            url: url.href,
            type: metas.youtube_embed ? EmbedType.video : EmbedType.link,
            title: metas.title,
            thumbnail: makeEmbedImage(metas.image || metas.image_fallback, metas.width, metas.height),
            provider: {
                url: "https://www.youtube.com",
                name: "YouTube",
            },
            description: metas.description,
            color: 16711680,
            author: metas.author
                ? {
                      name: metas.author,
                      // TODO: author channel url
                  }
                : undefined,
        };
    },

    "www.xkcd.com": (url) => EmbedHandlers["xkcd.com"](url),
    "xkcd.com": async (url) => {
        const response = await doFetch(url);
        if (!response) return null;

        const metas = getMetaDescriptions(await response.text());
        const hoverText = metas.$("#comic img").attr("title");

        if (!metas.image) return null;

        const { width, height } = await probe(metas.image);

        return {
            url: url.href,
            type: EmbedType.rich,
            title: `xkcd: ${metas.title}`,
            image: makeEmbedImage(metas.image, width, height),
            footer: hoverText
                ? {
                      text: hoverText,
                  }
                : undefined,
        };
    },

    // the url is an image from this instance
    self: async (url: URL): Promise<Embed | null> => {
        const result = await probe(url.href);

        return {
            url: url.href,
            type: EmbedType.image,
            thumbnail: {
                width: result.width,
                height: result.height,
                url: url.href,
                proxy_url: url.href,
            },
        };
    },
};
