// Type definitions for koa-session 5.7
// Project: https://github.com/koajs/session
// Definitions by: Yu Hsin Lu <https://github.com/kerol2r20>
//                 Tomek Łaziuk <https://github.com/tlaziuk>
// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
// TypeScript Version: 2.3

/* =================== USAGE ===================

    import session = require("koa-session");
    import Koa = require("koa");

    var app = new Koa();
    app.use(session(app));

 =============================================== */

import * as Koa from "koa";

declare namespace session {
    /**
     * Session model.
     */
    interface Session {
        /**
         * JSON representation of the session.
         */
        toJSON(): object;

        /**
         * alias to `toJSON`
         */
        inspect(): object;

        /**
         * Return how many values there are in the session object.
         * Used to see if it"s "populated".
         */
        readonly length: number;

        /**
         * populated flag, which is just a boolean alias of .length.
         */
        readonly populated: boolean;

        /**
         * get/set session maxAge
         */
        maxAge: opts["maxAge"];

        /**
         * save this session no matter whether it is populated
         */
        save(): void;

        /**
         * allow to put any value on session object
         */
        [_: string]: any;
    }

    interface ContextSession {
        ctx: Koa.Context;

        app: Koa.Context["app"];

        opts: opts;

        store: stores;

        session: Session | false;

        /**
         * internal logic of `ctx.session`
         */
        get(): Session;

        /**
         * internal logic of `ctx.session=`
         */
        set(val: any): void;

        prevHash: string;

        /**
         * init session from external store
         * will be called in the front of session middleware
         */
        initFromExternal(): Promise<void>;

        /**
         * Commit the session changes or removal.
         */
        commit(): Promise<void>;
    }

    interface util {
        /**
         * Decode the base64 cookie value to an object.
         */
        decode(str: string): object;

        /**
         * Encode an object into a base64-encoded JSON string.
         */
        encode(obj: object): string;

        hash(sess: any): string;
    }

    interface opts {
        /**
         * cookie key (default is koa:sess)
         */
        key: string;

        /**
         * maxAge in ms (default is 1 days)
         * "session" will result in a cookie that expires when session/browser is closed
         * Warning: If a session cookie is stolen, this cookie will never expire
         */
        maxAge?: number | "session";

        /**
         * can overwrite or not (default true)
         */
        overwrite: boolean;

        /**
         * httpOnly or not (default true)
         */
        httpOnly: boolean;

        /**
         * signed or not (default true)
         */
        signed: boolean;

        /**
         * custom encode method
         */
        encode: util["encode"];

        /**
         * custom decode method
         */
        decode: util["decode"];

        /**
         * The way of generating external session id is controlled by the options.genid, which defaults to Date.now() + "-" + uid.sync(24).
         */
        genid: () => string;

        /**
         * Force a session identifier cookie to be set on every response. The expiration is reset to the original maxAge, resetting the expiration countdown. default is false
         */
        rolling?: boolean;

        /**
         * You can store the session content in external stores(redis, mongodb or other DBs)
         */
        store?: stores;

        /**
         * If your session store requires data or utilities from context, opts.ContextStore is alse supported.
         * ContextStore must be a class which claims three instance methods demonstrated above.
         * new ContextStore(ctx) will be executed on every request.
         */
        ContextStore?: { new(): stores };

        /**
         * If you want to add prefix for all external session id, you can use options.prefix, it will not work if options.genid present.
         */
        prefix?: string;

        /**
         * Hook: valid session value before use it
         */
        valid?(ctx: Koa.Context, session: Partial<Session>): void;

        /**
         * Hook: before save session
         */
        beforeSave?(ctx: Koa.Context, session: Session): void;
    }

    interface stores {
        /**
         * get session object by key
         */
        get(key: string, maxAge: opts["maxAge"], data: { rolling: opts["rolling"] }): any;

        /**
         * set session object for key, with a maxAge (in ms)
         */
        set(key: string, sess: Partial<Session> & { _expire?: number, _maxAge?: number }, maxAge: opts["maxAge"], data: { changed: boolean; rolling: opts["rolling"] }): any;

        /**
         * destroy session for key
         */
        destroy(key: string): any;
    }
}

declare function session(CONFIG: Partial<session.opts>, app: Koa): Koa.Middleware;

declare function session(app: Koa): Koa.Middleware;

declare module "koa" {
    interface Context {
        session: session.Session | undefined;
        readonly sessionOptions: session.opts | undefined;
    }

    interface Application {
        on(name: "session:missed" | "session:expired" | "session:invalid", data: { key?: string, value?: Partial<session.Session>, ctx: Context }): void;
        once(name: "session:missed" | "session:expired" | "session:invalid", data: { key?: string, value?: Partial<session.Session>, ctx: Context }): void;
    }
}

export = session;