/*
	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 crypto from "crypto";
import { ConnectedAccount } from "../entities";
import { ConnectedAccountSchema, ConnectionCallbackSchema } from "@spacebar/schemas";
import { Config, DiscordApiErrors } from "../util";

/**
 * A connection that can be used to connect to an external service.
 */
export abstract class Connection {
    id: string;
    settings: { enabled: boolean };
    states: Map<string, string> = new Map();

    abstract init(): void;

    /**
     * Generates an authorization url for the connection.
     * @param args
     */
    abstract getAuthorizationUrl(userId: string): string;

    /**
     * Returns the redirect_uri for a connection type
     * @returns redirect_uri for this connection
     */
    getRedirectUri() {
        return `${Config.get().general.frontPage}/connections/${this.id}/callback`;
    }

    /**
     * Processes the callback
     * @param args Callback arguments
     */
    abstract handleCallback(params: ConnectionCallbackSchema): Promise<ConnectedAccount | null>;

    /**
     * Gets a user id from state
     * @param state the state to get the user id from
     * @returns the user id associated with the state
     */
    getUserId(state: string): string {
        if (!this.states.has(state)) throw DiscordApiErrors.INVALID_OAUTH_STATE;
        return this.states.get(state) as string;
    }

    /**
     * Generates a state
     * @param user_id The user id to generate a state for.
     * @returns a new state
     */
    createState(userId: string): string {
        const state = crypto.randomBytes(16).toString("hex");
        this.states.set(state, userId);

        return state;
    }

    /**
     * Takes a state and checks if it is valid, and deletes it.
     * @param state The state to check.
     */
    validateState(state: string): void {
        if (!this.states.has(state)) throw DiscordApiErrors.INVALID_OAUTH_STATE;
        this.states.delete(state);
    }

    /**
     * Creates a Connected Account in the database.
     * @param data connected account data
     * @returns the new connected account
     */
    async createConnection(data: ConnectedAccountSchema): Promise<ConnectedAccount> {
        const ca = ConnectedAccount.create({ ...data });
        await ca.save();
        return ca;
    }

    /**
     * Checks if a user has an exist connected account for the given extenal id.
     * @param userId the user id
     * @param externalId the connection id to find
     * @returns
     */
    async hasConnection(userId: string, externalId: string): Promise<boolean> {
        const existing = await ConnectedAccount.findOne({
            where: {
                user_id: userId,
                external_id: externalId,
            },
        });

        return !!existing;
    }
}