import AuthProof from "./AuthProof";
import MysqlConnectionManager from "../db/MysqlConnectionManager";
import User from "./models/User";
import {Connection} from "mysql";
import {Request} from "express";
import {PENDING_ACCOUNT_REVIEW_MAIL_TEMPLATE} from "../Mails";
import Mail from "../Mail";
import Controller from "../Controller";
import config from "config";

export default abstract class AuthGuard<P extends AuthProof<User>> {
    protected abstract async getProofForSession(session: Express.Session): Promise<P | null>;

    protected async getProofForRequest(req: Request): Promise<P | null> {
        return null;
    }

    public async getProof(req: Request): Promise<P | null> {
        let proof = await this.isAuthenticatedViaRequest(req);
        if (!proof && req.session) {
            proof = await this.isAuthenticated(req.session);
        }
        return proof;
    }

    public async isAuthenticated(session: Express.Session): Promise<P | null> {
        if (!session.is_authenticated) return null;

        const proof = await this.getProofForSession(session);

        if (!proof || !await proof.isValid() || !await proof.isAuthorized()) {
            await proof?.revoke();
            session.is_authenticated = false;
            return null;
        }

        return proof;
    }

    public async isAuthenticatedViaRequest(req: Request): Promise<P | null> {
        const proof = await this.getProofForRequest(req);

        if (!proof || !await proof.isValid() || !await proof.isAuthorized()) {
            await proof?.revoke();
            return null;
        }

        return proof;
    }

    public async authenticateOrRegister(
        session: Express.Session,
        proof: P,
        onLogin?: (user: User) => Promise<void>,
        onRegister?: (connection: Connection, user: User) => Promise<RegisterCallback[]>
    ): Promise<User> {
        if (!await proof.isValid()) throw new InvalidAuthProofError();
        if (!await proof.isAuthorized()) throw new UnauthorizedAuthProofError();

        let user = await proof.getResource();

        // Register if user doesn't exist
        if (!user) {
            const callbacks: RegisterCallback[] = [];

            await MysqlConnectionManager.wrapTransaction(async connection => {
                user = User.create({});
                await user.save(connection, c => callbacks.push(c));
                if (onRegister) {
                    (await onRegister(connection, user)).forEach(c => callbacks.push(c));
                }
            });

            for (const callback of callbacks) {
                await callback();
            }

            if (user) {
                if (!user!.isApproved()) {
                    await new Mail(PENDING_ACCOUNT_REVIEW_MAIL_TEMPLATE, {
                        username: user!.name,
                        link: config.get<string>('base_url') + Controller.route('accounts-approval'),
                    }).send(config.get<string>('app.contact_email'));
                }
            } else {
                throw new Error('Unable to register user.');
            }
        }

        // Don't login if user isn't approved
        if (!user.isApproved()) {
            throw new PendingApprovalAuthError();
        }

        // Login
        session.is_authenticated = true;
        if (onLogin) await onLogin(user);

        return user;
    }

}

export class AuthError extends Error {
    constructor(message: string) {
        super(message);
    }
}

export class AuthProofError extends AuthError {
}

export class InvalidAuthProofError extends AuthProofError {
    constructor() {
        super('Invalid auth proof.');
    }
}

export class UnauthorizedAuthProofError extends AuthProofError {
    constructor() {
        super('Unauthorized auth proof.');
    }
}

export class PendingApprovalAuthError extends AuthError {
    constructor() {
        super(`User is not approved.`);
    }
}

export type RegisterCallback = () => Promise<void>;