/*
	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, ConnectionLoader, DiscordApiErrors, RefreshableConnection } from "@spacebar/util";
import wretch from "wretch";
import { SpotifySettings } from "./SpotifySettings";
import { ConnectionCallbackSchema } from "@spacebar/schemas";

export interface UserResponse {
    display_name: string;
    id: string;
}

export interface TokenErrorResponse {
    error: string;
    error_description: string;
}

export interface ErrorResponse {
    error: {
        status: number;
        message: string;
    };
}

export default class SpotifyConnection extends RefreshableConnection {
    public readonly id = "spotify";
    public readonly authorizeUrl = "https://accounts.spotify.com/authorize";
    public readonly tokenUrl = "https://accounts.spotify.com/api/token";
    public readonly userInfoUrl = "https://api.spotify.com/v1/me";
    public readonly scopes = ["user-read-private", "user-read-playback-state", "user-modify-playback-state", "user-read-currently-playing"];
    settings: SpotifySettings = new SpotifySettings();

    init(): void {
        /**
         * The way Discord shows the currently playing song is by using Spotifys partner API. This is obviously not possible for us.
         * So to prevent spamming the spotify api we disable the ability to refresh.
         */
        this.refreshEnabled = false;

        this.settings = ConnectionLoader.getConnectionConfig<SpotifySettings>(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("response_type", "code");
        url.searchParams.append("scope", this.scopes.join(" "));
        url.searchParams.append("state", state);
        return url.toString();
    }

    getTokenUrl(): string {
        return this.tokenUrl;
    }

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

        const url = this.getTokenUrl();

        return wretch(url.toString())
            .headers({
                Accept: "application/json",
                "Content-Type": "application/x-www-form-urlencoded",
                Authorization: `Basic ${Buffer.from(`${this.settings.clientId as string}:${this.settings.clientSecret as string}`).toString("base64")}`,
            })
            .body(
                new URLSearchParams({
                    grant_type: "authorization_code",
                    code: code,
                    redirect_uri: this.getRedirectUri(),
                }),
            )
            .post()
            .json<ConnectedAccountCommonOAuthTokenResponse>()
            .catch((e) => {
                console.error(e);
                throw DiscordApiErrors.GENERAL_ERROR;
            });
    }

    async refreshToken(connectedAccount: ConnectedAccount): Promise<ConnectedAccountCommonOAuthTokenResponse> {
        if (!connectedAccount.token_data?.refresh_token) throw new Error("No refresh token available.");
        const refresh_token = connectedAccount.token_data.refresh_token;
        const url = this.getTokenUrl();

        return wretch(url.toString())
            .headers({
                Accept: "application/json",
                "Content-Type": "application/x-www-form-urlencoded",
                Authorization: `Basic ${Buffer.from(`${this.settings.clientId as string}:${this.settings.clientSecret as string}`).toString("base64")}`,
            })
            .body(
                new URLSearchParams({
                    grant_type: "refresh_token",
                    refresh_token,
                }),
            )
            .post()
            .unauthorized(async () => {
                // assume the token was revoked
                await connectedAccount.revoke();
                return DiscordApiErrors.CONNECTION_REVOKED;
            })
            .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({
            token_data: { ...tokenData, fetched_at: Date.now() },
            user_id: userId,
            external_id: userInfo.id,
            friend_sync: params.friend_sync,
            name: userInfo.display_name,
            type: this.id,
        });
    }
}