/*
 This file is part of GNU Taler
 (C) 2022 Taler Systems S.A.

 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/>
 */

/**
 * Client for the Taler (demo-)bank.
 */

/**
 * Imports.
 */
import {
  AmountString,
  base64FromArrayBuffer,
  buildCodecForObject,
  Codec,
  codecForAny,
  codecForString,
  encodeCrock,
  generateIban,
  getRandomBytes,
  j2s,
  Logger,
  stringToBytes,
  TalerError,
  TalerErrorCode,
} from "@gnu-taler/taler-util";
import {
  checkSuccessResponseOrThrow,
  createPlatformHttpLib,
  HttpRequestLibrary,
  readSuccessResponseJsonOrThrow,
} from "@gnu-taler/taler-util/http";

const logger = new Logger("bank-api-client.ts");

export enum CreditDebitIndicator {
  Credit = "credit",
  Debit = "debit",
}

export interface BankAccountBalanceResponse {
  balance: {
    amount: AmountString;
    credit_debit_indicator: CreditDebitIndicator;
  };
}

export interface BankUser {
  username: string;
  password: string;
  accountPaytoUri: string;
}

export interface WithdrawalOperationInfo {
  withdrawal_id: string;
  taler_withdraw_uri: string;
}

/**
 * Helper function to generate the "Authorization" HTTP header.
 */
function makeBasicAuthHeader(username: string, password: string): string {
  const auth = `${username}:${password}`;
  const authEncoded: string = base64FromArrayBuffer(stringToBytes(auth));
  return `Basic ${authEncoded}`;
}

const codecForWithdrawalOperationInfo = (): Codec<WithdrawalOperationInfo> =>
  buildCodecForObject<WithdrawalOperationInfo>()
    .property("withdrawal_id", codecForString())
    .property("taler_withdraw_uri", codecForString())
    .build("WithdrawalOperationInfo");

export interface BankAccessApiClientArgs {
  auth?: { username: string; password: string };
  httpClient?: HttpRequestLibrary;
}

export interface BankAccessApiCreateTransactionRequest {
  amount: AmountString;
  paytoUri: string;
}

export class WireGatewayApiClientArgs {
  auth?: {
    username: string;
    password: string;
  };
  httpClient?: HttpRequestLibrary;
}

/**
 * This API look like it belongs to harness
 * but it will be nice to have in utils to be used by others
 */
export class WireGatewayApiClient {
  httpLib;

  constructor(
    private baseUrl: string,
    private args: WireGatewayApiClientArgs = {},
  ) {
    this.httpLib = args.httpClient ?? createPlatformHttpLib();
  }

  private makeAuthHeader(): Record<string, string> {
    const auth = this.args.auth;
    if (auth) {
      return {
        Authorization: makeBasicAuthHeader(auth.username, auth.password),
      };
    }
    return {};
  }

  async adminAddIncoming(params: {
    amount: string;
    reservePub: string;
    debitAccountPayto: string;
  }): Promise<void> {
    let url = new URL(`admin/add-incoming`, this.baseUrl);
    const resp = await this.httpLib.fetch(url.href, {
      method: "POST",
      body: {
        amount: params.amount,
        reserve_pub: params.reservePub,
        debit_account: params.debitAccountPayto,
      },
      headers: this.makeAuthHeader(),
    });
    logger.info(`add-incoming response status: ${resp.status}`);
    await checkSuccessResponseOrThrow(resp);
  }
}

/**
 * This API look like it belongs to harness
 * but it will be nice to have in utils to be used by others
 */
export class BankAccessApiClient {
  httpLib: HttpRequestLibrary;

  constructor(
    private baseUrl: string,
    private args: BankAccessApiClientArgs = {},
  ) {
    this.httpLib = args.httpClient ?? createPlatformHttpLib();
  }

  setAuth(auth: { username: string; password: string }) {
    this.args.auth = auth;
  }

  private makeAuthHeader(): Record<string, string> {
    if (!this.args.auth) {
      return {};
    }
    const authHeaderValue = makeBasicAuthHeader(
      this.args.auth.username,
      this.args.auth.password,
    );
    return {
      Authorization: authHeaderValue,
    };
  }

  async getAccountBalance(
    username: string,
  ): Promise<BankAccountBalanceResponse> {
    const url = new URL(`accounts/${username}`, this.baseUrl);
    const resp = await this.httpLib.fetch(url.href, {
      headers: this.makeAuthHeader(),
    });
    return await resp.json();
  }

  async getTransactions(username: string): Promise<void> {
    const reqUrl = new URL(`accounts/${username}/transactions`, this.baseUrl);
    const resp = await this.httpLib.fetch(reqUrl.href, {
      method: "GET",
      headers: {
        ...this.makeAuthHeader(),
      },
    });

    const res = await readSuccessResponseJsonOrThrow(resp, codecForAny());
    logger.info(`result: ${j2s(res)}`);
  }

  async createTransaction(
    username: string,
    req: BankAccessApiCreateTransactionRequest,
  ): Promise<any> {
    const reqUrl = new URL(`accounts/${username}/transactions`, this.baseUrl);

    const resp = await this.httpLib.fetch(reqUrl.href, {
      method: "POST",
      body: req,
      headers: this.makeAuthHeader(),
    });

    return await readSuccessResponseJsonOrThrow(resp, codecForAny());
  }

  async registerAccount(
    username: string,
    password: string,
    options: {
      iban?: string;
    } = {},
  ): Promise<BankUser> {
    const url = new URL("testing/register", this.baseUrl);
    const resp = await this.httpLib.fetch(url.href, {
      method: "POST",
      body: {
        username,
        password,
        iban: options?.iban,
      },
    });
    let paytoUri = `payto://x-taler-bank/localhost/${username}`;
    if (resp.status !== 200 && resp.status !== 202 && resp.status !== 204) {
      logger.error(`${j2s(await resp.json())}`);
      throw TalerError.fromDetail(
        TalerErrorCode.GENERIC_UNEXPECTED_REQUEST_ERROR,
        {
          httpStatusCode: resp.status,
        },
      );
    }
    try {
      // Pybank has no body, thus this might throw.
      const respJson = await resp.json();
      // LibEuFin demobank returns payto URI in response
      if (respJson.paytoUri) {
        paytoUri = respJson.paytoUri;
      }
    } catch (e) {
      // Do nothing
    }
    return {
      password,
      username,
      accountPaytoUri: paytoUri,
    };
  }

  async createRandomBankUser(): Promise<BankUser> {
    const username = "user-" + encodeCrock(getRandomBytes(10)).toLowerCase();
    const password = "pw-" + encodeCrock(getRandomBytes(10)).toLowerCase();
    // FIXME: This is just a temporary workaround, because demobank is running out of short IBANs
    const iban = generateIban("DE", 15);
    return await this.registerAccount(username, password, {
      iban,
    });
  }

  async createWithdrawalOperation(
    user: string,
    amount: string,
  ): Promise<WithdrawalOperationInfo> {
    const url = new URL(`accounts/${user}/withdrawals`, this.baseUrl);
    const resp = await this.httpLib.fetch(url.href, {
      method: "POST",
      body: {
        amount,
      },
      headers: this.makeAuthHeader(),
    });
    return readSuccessResponseJsonOrThrow(
      resp,
      codecForWithdrawalOperationInfo(),
    );
  }

  async confirmWithdrawalOperation(
    username: string,
    wopi: WithdrawalOperationInfo,
  ): Promise<void> {
    const url = new URL(
      `accounts/${username}/withdrawals/${wopi.withdrawal_id}/confirm`,
      this.baseUrl,
    );
    logger.info(`confirming withdrawal operation via ${url.href}`);
    const resp = await this.httpLib.fetch(url.href, {
      method: "POST",
      body: {},
      headers: this.makeAuthHeader(),
    });

    logger.info(`response status ${resp.status}`);
    const respJson = await readSuccessResponseJsonOrThrow(resp, codecForAny());

    // FIXME: We don't check the status here!
  }

  async abortWithdrawalOperation(
    accountName: string,
    wopi: WithdrawalOperationInfo,
  ): Promise<void> {
    const url = new URL(
      `accounts/${accountName}/withdrawals/${wopi.withdrawal_id}/abort`,
      this.baseUrl,
    );
    const resp = await this.httpLib.fetch(url.href, {
      method: "POST",
      body: {},
      headers: this.makeAuthHeader(),
    });
    await readSuccessResponseJsonOrThrow(resp, codecForAny());
  }
}