/*
	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 { ConnectedAccount, ConnectedAccountCommonOAuthTokenResponse, Connection, ConnectionLoader, DiscordApiErrors } from "@spacebar/util";
import wretch from "wretch";
import { FacebookSettings } from "./FacebookSettings";
import { ConnectionCallbackSchema } from "@spacebar/schemas";

export interface FacebookErrorResponse {
    error: {
        message: string;
        type: string;
        code: number;
        fbtrace_id: string;
    };
}

interface UserResponse {
    name: string;
    id: string;
}

export default class FacebookConnection extends Connection {
    public readonly id = "facebook";
    public readonly authorizeUrl = "https://www.facebook.com/v14.0/dialog/oauth";
    public readonly tokenUrl = "https://graph.facebook.com/v14.0/oauth/access_token";
    public readonly userInfoUrl = "https://graph.facebook.com/v14.0/me";
    public readonly scopes = ["public_profile"];
    settings: FacebookSettings = new FacebookSettings();

    init(): void {
        this.settings = ConnectionLoader.getConnectionConfig<FacebookSettings>(this.id, this.settings);

        if (this.settings.enabled && (!this.settings.clientId || !this.settings.clientSecret)) throw new Error(`Invalid settings for connection ${this.id}`);
    }

    getAuthorizationUrl(userId: string): string {
        const state = this.createState(userId);
        const url = new URL(this.authorizeUrl);

        url.searchParams.append("client_id", this.settings.clientId as string);
        url.searchParams.append("redirect_uri", this.getRedirectUri());
        url.searchParams.append("state", state);
        url.searchParams.append("response_type", "code");
        url.searchParams.append("scope", this.scopes.join(" "));
        url.searchParams.append("display", "popup");
        return url.toString();
    }

    getTokenUrl(code: string): string {
        const url = new URL(this.tokenUrl);
        url.searchParams.append("client_id", this.settings.clientId as string);
        url.searchParams.append("client_secret", this.settings.clientSecret as string);
        url.searchParams.append("code", code);
        url.searchParams.append("redirect_uri", this.getRedirectUri());
        return url.toString();
    }

    async exchangeCode(state: string, code: string): Promise<ConnectedAccountCommonOAuthTokenResponse> {
        this.validateState(state);

        const url = this.getTokenUrl(code);

        return wretch(url.toString())
            .headers({
                Accept: "application/json",
            })
            .get()
            .json<ConnectedAccountCommonOAuthTokenResponse>()
            .catch((e) => {
                console.error(e);
                throw DiscordApiErrors.GENERAL_ERROR;
            });
    }

    async getUser(token: string): Promise<UserResponse> {
        const url = new URL(this.userInfoUrl);

        return wretch(url.toString())
            .headers({
                Authorization: `Bearer ${token}`,
            })
            .get()
            .json<UserResponse>()
            .catch((e) => {
                console.error(e);
                throw DiscordApiErrors.GENERAL_ERROR;
            });
    }

    async handleCallback(params: ConnectionCallbackSchema): Promise<ConnectedAccount | null> {
        const { state, code } = params;
        if (!code) throw new Error("No code provided");

        const userId = this.getUserId(state);
        const tokenData = await this.exchangeCode(state, code);
        const userInfo = await this.getUser(tokenData.access_token);

        const exists = await this.hasConnection(userId, userInfo.id);

        if (exists) return null;

        return await this.createConnection({
            user_id: userId,
            external_id: userInfo.id,
            friend_sync: params.friend_sync,
            name: userInfo.name,
            type: this.id,
        });
    }
}