import { NextFunction, Request, Response } from "express";
import { JwtPayload, sign, verify } from "jsonwebtoken";
import { query } from "./database";
import { errors } from "./errors";

const jwtSecret = process.env.JWT_SECRET || "[generic token]";

const tokenTypes = {
    BEARER: 1
}

if (jwtSecret === "[generic token]") {
    console.error("ERROR: No JWT_SECRET environment variable was specified.");
    console.error("ERROR: exiting...");
    process.exit(1);
}

export function getPublicUserObject(user: User) {
    const newUser = { ...user };
    newUser.password = undefined;
    delete newUser.password;

    return newUser;
}

export function signToken(userId: number) {
    return new Promise((resolve, reject) => {
        const payload = {
            id: userId,
            type: tokenTypes.BEARER
        };

        sign(
            payload,
            jwtSecret,
            {
                expiresIn: "2d"
            },
            (error, encoded) => {
                if (error) {
                    reject(error);
                    return;
                }
                if (!encoded) {
                    reject("got undefined encoded value");
                    return;
                }

                resolve(encoded);
            }
        );
    });
}

export function decodeToken(encoded: string): Promise<User> {
    return new Promise((resolve, reject) => {
        verify(
            encoded,
            jwtSecret,
            async (error, decoded) => {
                if (error) {
                    reject(error);
                    return;
                }
                if (!decoded) {
                    reject("got undefined decoded value");
                    return;
                }
                if (typeof decoded === "string") {
                    reject("decoded value is a string, expected JwtPayload");
                    return;
                }
                if (!decoded.id || !decoded.type) {
                    reject("token does not match format");
                    return;
                }

                const user = await query("SELECT * FROM users WHERE id = $1", [decoded.id]);
                if (user.rowCount < 1) {
                    reject("user does not exist (could not find in database by id)");
                    return;
                }
                resolve(user.rows[0]);
            }
        )
    });
}

export async function decodeTokenOrNull(encoded: string): Promise<User | undefined> {
    try {
        const decoded = await decodeToken(encoded);
        return decoded;
    } catch (o_o) {
        return undefined;
    }
}

export function authenticateRoute() {
    return async (req: Request, res: Response, next: NextFunction) => {
        const pass = (user: User | null = null) => {
            if (!user) {
                res.status(403).send({
                    ...errors.BAD_AUTH
                });
                return;
            }

            req.user = user;
            req.publicUser = getPublicUserObject(user);
            next();
        };

        const authHeader = req.get("Authorization");
        if (!authHeader) return pass();

        const authParts = authHeader.split(" ");
        if (authParts.length !== 2) return pass();

        const [ authType, authToken ] = authParts;
        if (authType !== "Bearer") return pass();
        if (typeof authToken !== "string") return pass();

        decodeTokenOrNull(authToken).then((decoded) => {
            pass(decoded);
        }).catch(() => {
            pass(null);
        });
    };
}