import { type Session, type SessionData } from "express-session";
import type { Empty, ProcDecoratorGenerator } from "./base.js";

export type SessionCtx = {
    session: {
        clear: () => Promise<void>;
        removeItem: (key: string) => boolean;
        getItem: <T>(key: string) => T | undefined;
        setItem: (key: string, value: unknown) => void;
        raw: Session & Partial<SessionData> & Record<string, unknown>;
    }
}

export function StartSession<Q extends object = Empty>(): ProcDecoratorGenerator<SessionCtx, Q> {
    return (inCtx, req) => {
        if (!req.session) {
            throw 'Express-session required';
        }
        const sessionObj = {
            raw: req.session
        } as SessionCtx['session'];
        sessionObj.clear = () => {
            return new Promise((resolve) => {
                sessionObj.raw = req.session.regenerate(resolve) as SessionCtx['session']['raw'];
            })
        }
        sessionObj.removeItem = (key: string): boolean => {
            if (key in sessionObj.raw) {
                delete sessionObj.raw[key];
                return true;
            }
            return false;
        }
        sessionObj.getItem = <T>(key: string): T | undefined => {
            if (!(key in sessionObj.raw)) {
                return undefined;
            }
            return sessionObj.raw[key] as T;
        }
        sessionObj.setItem = <T>(key: string, value: T | undefined): void => {
            if (value === undefined) {
                sessionObj.removeItem(key);
                return;
            }
            sessionObj.raw[key] = value;
        }

        return [
            {
                result: true,
            },
            {
                session: sessionObj,
                ...inCtx,
            }
        ]
    }
}