import nest from "@modules/nestjs";
import core from "@nestia/core";
import { NestFactory } from "@nestjs/core";
import express from "express";
import FakeIamport from "fake-iamport-server";
import FakeToss from "fake-toss-payments-server";

import { PaymentConfiguration } from "./PaymentConfiguration";
import { PaymentGlobal } from "./PaymentGlobal";
import PaymentAPI from "./api";

/**
 * 통합 결제 백엔드 서버.
 *
 * @author Samchon
 */
export class PaymentBackend {
    private application_?: nest.INestApplication;
    private is_closing_: boolean = false;

    private fake_servers_: IFakeServer[] = [];

    /**
     * 서버 개설하기.
     *
     * 통합 결제 백엔드 서버를 개설한다. 이 때 개설되는 서버의 종류는
     * {@link PaymentGlobal.mode} 를 따르며, 만일 개설되는 서버가 테스트 자동화 프로그램에
     * 의하여 시작된 것이라면 ({@link PaymentGlobal.testing} 값이 true), 이와 연동하게 될
     * 가짜 PG 결제사 서버들도 함께 개설한다.
     */
    public async open(): Promise<void> {
        //----
        // OPEN THE BACKEND SERVER
        //----
        // MOUNT CONTROLLERS
        this.application_ = await NestFactory.create(
            await core.EncryptedModule.dynamic(
                __dirname + "/controllers",
                PaymentConfiguration.ENCRYPTION_PASSWORD(),
            ),
            { logger: false },
        );

        // CONFIGURATIONS
        this.is_closing_ = false;
        this.application_.enableCors();
        this.application_.use(this.middleware.bind(this));

        // DO OPEN
        await this.application_.listen(PaymentConfiguration.API_PORT());

        // CONFIGURE FAKE SERVERS IF TESTING
        if (PaymentGlobal.testing === true) {
            // OPEN FAKE SERVERS
            this.fake_servers_ = [
                new FakeIamport.FakeIamportBackend(),
                new FakeToss.FakeTossBackend(),
            ];
            for (const server of this.fake_servers_) {
                await server.open();
            }

            // CONFIGURE WEBHOOK URLS
            const host: string = `http://127.0.0.1:${PaymentConfiguration.API_PORT()}`;
            FakeIamport.FakeIamportConfiguration.WEBHOOK_URL = `${host}${PaymentAPI.functional.payments.webhooks.iamport.METADATA.path}`;
            FakeToss.TossFakeConfiguration.WEBHOOK_URL = `${host}${PaymentAPI.functional.payments.webhooks.toss.METADATA.path}`;
        }

        //----
        // POST-PROCESSES
        //----
        // INFORM TO THE PM2
        if (process.send) process.send("ready");

        // WHEN KILL COMMAND COMES
        process.on("SIGINT", async () => {
            this.is_closing_ = true;
            await this.close();
            process.exit(0);
        });
    }

    /**
     * 개설한 서버 닫기.
     */
    public async close(): Promise<void> {
        if (this.application_ === undefined) return;

        // DO CLOSE
        await this.application_.close();
        delete this.application_;

        // EXIT FROM THE CRITICAL-SERVER
        if ((await PaymentGlobal.critical.is_loaded()) === true) {
            const critical = await PaymentGlobal.critical.get();
            await critical.close();
        }

        // CLOSE FAKE SERVERS
        for (const server of this.fake_servers_) {
            await server.close();
        }
        this.fake_servers_ = [];
    }

    private middleware(
        _request: express.Request,
        response: express.Response,
        next: FunctionLike,
    ): void {
        if (this.is_closing_ === true) response.set("Connection", "close");
        next();
    }
}

interface IFakeServer {
    open(): Promise<void>;
    close(): Promise<void>;
}
type FunctionLike = (...args: any) => any;