/*
 This file is part of GNU Taler
 (C) 2019 GNUnet e.V.

 GNU Taler is free software; you can redistribute it and/or modify it under the
 terms of the GNU General Public License as published by the Free Software
 Foundation; either version 3, or (at your option) any later version.

 GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
 A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

 You should have received a copy of the GNU General Public License along with
 GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
 */

/**
 * Helpers to create headless wallets.
 */

/**
 * Imports.
 */
import { Wallet } from "../wallet";
import { MemoryBackend, BridgeIDBFactory, shimIndexedDB } from "idb-bridge";
import { openDatabase } from "../db";
import Axios, { AxiosPromise, AxiosResponse } from "axios";
import {
  HttpRequestLibrary,
  HttpRequestOptions,
  Headers,
} from "../util/http";
import * as amounts from "../util/amounts";
import { Bank } from "./bank";

import fs = require("fs");
import { Logger } from "../util/logging";
import { NodeThreadCryptoWorkerFactory } from "../crypto/workers/nodeThreadWorker";
import { SynchronousCryptoWorkerFactory } from "../crypto/workers/synchronousWorker";
import { RequestThrottler } from "../util/RequestThrottler";
import { WalletNotification, NotificationType } from "../types/notifications";

const logger = new Logger("helpers.ts");

export class NodeHttpLib implements HttpRequestLibrary {
  private throttle = new RequestThrottler();

  private async req(
    method: "post" | "get",
    url: string,
    body: any,
    opt?: HttpRequestOptions,
  ) {
    if (this.throttle.applyThrottle(url)) {
      throw Error("request throttled");
    }
    let resp: AxiosResponse;
    try {
      resp = await Axios({
        method,
        url: url,
        responseType: "text",
        headers: opt?.headers,
        validateStatus: () => true,
        transformResponse: (x) => x,
        data: body,
      });
    } catch (e) {
      throw e;
    }
    const respText = resp.data;
    if (typeof respText !== "string") {
      throw Error("unexpected response type");
    }
    const makeJson = async () => {
      let responseJson;
      try {
        responseJson = JSON.parse(respText);
      } catch (e) {
        throw Error("Invalid JSON from HTTP response");
      }
      if (responseJson === null || typeof responseJson !== "object") {
        throw Error("Invalid JSON from HTTP response");
      }
      return responseJson;
    };
    const headers = new Headers();
    for (const hn of Object.keys(resp.headers)) {
      headers.set(hn, resp.headers[hn]);
    }
    return {
      headers,
      status: resp.status,
      text: async () => resp.data,
      json: makeJson,
    };
  }

  async get(
    url: string,
    opt?: HttpRequestOptions,
  ): Promise<import("../util/http").HttpResponse> {
    return this.req("get", url, undefined, opt);
  }

  async postJson(
    url: string,
    body: any,
    opt?: HttpRequestOptions,
  ): Promise<import("../util/http").HttpResponse> {
    return this.req("post", url, body, opt);
  }
}

export interface DefaultNodeWalletArgs {
  /**
   * Location of the wallet database.
   *
   * If not specified, the wallet starts out with an empty database and
   * the wallet database is stored only in memory.
   */
  persistentStoragePath?: string;

  /**
   * Handler for asynchronous notifications from the wallet.
   */
  notifyHandler?: (n: WalletNotification) => void;

  /**
   * If specified, use this as HTTP request library instead
   * of the default one.
   */
  httpLib?: HttpRequestLibrary;
}

/**
 * Get a wallet instance with default settings for node.
 */
export async function getDefaultNodeWallet(
  args: DefaultNodeWalletArgs = {},
): Promise<Wallet> {
  BridgeIDBFactory.enableTracing = false;
  const myBackend = new MemoryBackend();
  myBackend.enableTracing = false;

  const storagePath = args.persistentStoragePath;
  if (storagePath) {
    try {
      const dbContentStr: string = fs.readFileSync(storagePath, {
        encoding: "utf-8",
      });
      const dbContent = JSON.parse(dbContentStr);
      myBackend.importDump(dbContent);
    } catch (e) {
      console.error("could not read wallet file");
    }

    myBackend.afterCommitCallback = async () => {
      // Allow caller to stop persisting the wallet.
      if (args.persistentStoragePath === undefined) {
        return;
      }
      const dbContent = myBackend.exportDump();
      fs.writeFileSync(storagePath, JSON.stringify(dbContent, undefined, 2), {
        encoding: "utf-8",
      });
    };
  }

  BridgeIDBFactory.enableTracing = false;

  const myBridgeIdbFactory = new BridgeIDBFactory(myBackend);
  const myIdbFactory: IDBFactory = (myBridgeIdbFactory as any) as IDBFactory;

  let myHttpLib;
  if (args.httpLib) {
    myHttpLib = args.httpLib;
  } else {
    myHttpLib = new NodeHttpLib();
  }

  const myVersionChange = () => {
    console.error("version change requested, should not happen");
    throw Error();
  };

  const myUnsupportedUpgrade = () => {
    console.error("unsupported database migration");
    throw Error();
  };

  shimIndexedDB(myBridgeIdbFactory);

  const myDb = await openDatabase(
    myIdbFactory,
    myVersionChange,
    myUnsupportedUpgrade,
  );

  //const worker = new SynchronousCryptoWorkerFactory();
  //const worker = new NodeCryptoWorkerFactory();

  const worker = new NodeThreadCryptoWorkerFactory();

  const w = new Wallet(myDb, myHttpLib, worker);
  if (args.notifyHandler) {
    w.addNotificationListener(args.notifyHandler);
  }
  return w;
}

export async function withdrawTestBalance(
  myWallet: Wallet,
  amount: string = "TESTKUDOS:10",
  bankBaseUrl: string = "https://bank.test.taler.net/",
  exchangeBaseUrl: string = "https://exchange.test.taler.net/",
) {
  const reserveResponse = await myWallet.createReserve({
    amount: amounts.parseOrThrow(amount),
    exchange: exchangeBaseUrl,
    exchangeWire: "payto://unknown",
  });

  const reservePub = reserveResponse.reservePub;

  const bank = new Bank(bankBaseUrl);

  const bankUser = await bank.registerRandomUser();

  logger.trace(`Registered bank user ${JSON.stringify(bankUser)}`);

  const exchangePaytoUri = await myWallet.getExchangePaytoUri(exchangeBaseUrl, [
    "x-taler-bank",
  ]);

  const donePromise = new Promise((resolve, reject) => {
    myWallet.addNotificationListener(n => {
      if (
        n.type === NotificationType.ReserveDepleted &&
        n.reservePub === reservePub
      ) {
        resolve();
      }
    });
  });

  await bank.createReserve(bankUser, amount, reservePub, exchangePaytoUri);

  await myWallet.confirmReserve({ reservePub: reserveResponse.reservePub });
  await donePromise;
}