/*
 This file is part of GNU Taler
 (C) 2019 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/>
 */

/**
 * Imports.
 */
import {
  PrepareTipResult,
  parseTipUri,
  codecForTipPickupGetResponse,
  Amounts,
  getTimestampNow,
  TalerErrorDetails,
  NotificationType,
  TipPlanchetDetail,
  TalerErrorCode,
  codecForTipResponse,
  Logger,
} from "@gnu-taler/taler-util";
import { DerivedTipPlanchet } from "../crypto/cryptoTypes.js";
import {
  Stores,
  DenominationRecord,
  CoinRecord,
  CoinSourceType,
  CoinStatus,
} from "../db.js";
import {
  URL,
  readSuccessResponseJsonOrThrow,
  encodeCrock,
  getRandomBytes,
  getHttpResponseErrorDetails,
} from "../index.js";
import { j2s } from "@gnu-taler/taler-util";
import { checkDbInvariant, checkLogicInvariant } from "../util/invariants.js";
import { initRetryInfo, updateRetryInfoTimeout } from "../util/retries.js";
import { guardOperationException, makeErrorDetails } from "./errors.js";
import { updateExchangeFromUrl } from "./exchanges.js";
import { InternalWalletState } from "./state";
import {
  getExchangeWithdrawalInfo,
  updateWithdrawalDenoms,
  getCandidateWithdrawalDenoms,
  selectWithdrawalDenominations,
  denomSelectionInfoToState,
} from "./withdraw.js";

const logger = new Logger("operations/tip.ts");

export async function prepareTip(
  ws: InternalWalletState,
  talerTipUri: string,
): Promise<PrepareTipResult> {
  const res = parseTipUri(talerTipUri);
  if (!res) {
    throw Error("invalid taler://tip URI");
  }

  let tipRecord = await ws.db.getIndexed(
    Stores.tips.byMerchantTipIdAndBaseUrl,
    [res.merchantTipId, res.merchantBaseUrl],
  );

  if (!tipRecord) {
    const tipStatusUrl = new URL(
      `tips/${res.merchantTipId}`,
      res.merchantBaseUrl,
    );
    logger.trace("checking tip status from", tipStatusUrl.href);
    const merchantResp = await ws.http.get(tipStatusUrl.href);
    const tipPickupStatus = await readSuccessResponseJsonOrThrow(
      merchantResp,
      codecForTipPickupGetResponse(),
    );
    logger.trace(`status ${j2s(tipPickupStatus)}`);

    const amount = Amounts.parseOrThrow(tipPickupStatus.tip_amount);

    logger.trace("new tip, creating tip record");
    await updateExchangeFromUrl(ws, tipPickupStatus.exchange_url);
    const withdrawDetails = await getExchangeWithdrawalInfo(
      ws,
      tipPickupStatus.exchange_url,
      amount,
    );

    const walletTipId = encodeCrock(getRandomBytes(32));
    await updateWithdrawalDenoms(ws, tipPickupStatus.exchange_url);
    const denoms = await getCandidateWithdrawalDenoms(
      ws,
      tipPickupStatus.exchange_url,
    );
    const selectedDenoms = selectWithdrawalDenominations(amount, denoms);

    const secretSeed = encodeCrock(getRandomBytes(64));
    const denomSelUid = encodeCrock(getRandomBytes(32));

    tipRecord = {
      walletTipId: walletTipId,
      acceptedTimestamp: undefined,
      tipAmountRaw: amount,
      tipExpiration: tipPickupStatus.expiration,
      exchangeBaseUrl: tipPickupStatus.exchange_url,
      merchantBaseUrl: res.merchantBaseUrl,
      createdTimestamp: getTimestampNow(),
      merchantTipId: res.merchantTipId,
      tipAmountEffective: Amounts.sub(
        amount,
        Amounts.add(withdrawDetails.overhead, withdrawDetails.withdrawFee)
          .amount,
      ).amount,
      retryInfo: initRetryInfo(),
      lastError: undefined,
      denomsSel: denomSelectionInfoToState(selectedDenoms),
      pickedUpTimestamp: undefined,
      secretSeed,
      denomSelUid,
    };
    await ws.db.put(Stores.tips, tipRecord);
  }

  const tipStatus: PrepareTipResult = {
    accepted: !!tipRecord && !!tipRecord.acceptedTimestamp,
    tipAmountRaw: Amounts.stringify(tipRecord.tipAmountRaw),
    exchangeBaseUrl: tipRecord.exchangeBaseUrl,
    merchantBaseUrl: tipRecord.merchantBaseUrl,
    expirationTimestamp: tipRecord.tipExpiration,
    tipAmountEffective: Amounts.stringify(tipRecord.tipAmountEffective),
    walletTipId: tipRecord.walletTipId,
  };

  return tipStatus;
}

async function incrementTipRetry(
  ws: InternalWalletState,
  walletTipId: string,
  err: TalerErrorDetails | undefined,
): Promise<void> {
  await ws.db.runWithWriteTransaction([Stores.tips], async (tx) => {
    const t = await tx.get(Stores.tips, walletTipId);
    if (!t) {
      return;
    }
    if (!t.retryInfo) {
      return;
    }
    t.retryInfo.retryCounter++;
    updateRetryInfoTimeout(t.retryInfo);
    t.lastError = err;
    await tx.put(Stores.tips, t);
  });
  if (err) {
    ws.notify({ type: NotificationType.TipOperationError, error: err });
  }
}

export async function processTip(
  ws: InternalWalletState,
  tipId: string,
  forceNow = false,
): Promise<void> {
  const onOpErr = (e: TalerErrorDetails): Promise<void> =>
    incrementTipRetry(ws, tipId, e);
  await guardOperationException(
    () => processTipImpl(ws, tipId, forceNow),
    onOpErr,
  );
}

async function resetTipRetry(
  ws: InternalWalletState,
  tipId: string,
): Promise<void> {
  await ws.db.mutate(Stores.tips, tipId, (x) => {
    if (x.retryInfo.active) {
      x.retryInfo = initRetryInfo();
    }
    return x;
  });
}

async function processTipImpl(
  ws: InternalWalletState,
  walletTipId: string,
  forceNow: boolean,
): Promise<void> {
  if (forceNow) {
    await resetTipRetry(ws, walletTipId);
  }
  let tipRecord = await ws.db.get(Stores.tips, walletTipId);
  if (!tipRecord) {
    return;
  }

  if (tipRecord.pickedUpTimestamp) {
    logger.warn("tip already picked up");
    return;
  }

  const denomsForWithdraw = tipRecord.denomsSel;

  tipRecord = await ws.db.get(Stores.tips, walletTipId);
  checkDbInvariant(!!tipRecord, "tip record should be in database");

  const planchets: DerivedTipPlanchet[] = [];
  // Planchets in the form that the merchant expects
  const planchetsDetail: TipPlanchetDetail[] = [];
  const denomForPlanchet: { [index: number]: DenominationRecord } = [];

  for (const dh of denomsForWithdraw.selectedDenoms) {
    const denom = await ws.db.get(Stores.denominations, [
      tipRecord.exchangeBaseUrl,
      dh.denomPubHash,
    ]);
    checkDbInvariant(!!denom, "denomination should be in database");
    for (let i = 0; i < dh.count; i++) {
      const deriveReq = {
        denomPub: denom.denomPub,
        planchetIndex: planchets.length,
        secretSeed: tipRecord.secretSeed,
      };
      logger.trace(`deriving tip planchet: ${j2s(deriveReq)}`);
      const p = await ws.cryptoApi.createTipPlanchet(deriveReq);
      logger.trace(`derive result: ${j2s(p)}`);
      denomForPlanchet[planchets.length] = denom;
      planchets.push(p);
      planchetsDetail.push({
        coin_ev: p.coinEv,
        denom_pub_hash: denom.denomPubHash,
      });
    }
  }

  const tipStatusUrl = new URL(
    `tips/${tipRecord.merchantTipId}/pickup`,
    tipRecord.merchantBaseUrl,
  );

  const req = { planchets: planchetsDetail };
  logger.trace(`sending tip request: ${j2s(req)}`);
  const merchantResp = await ws.http.postJson(tipStatusUrl.href, req);

  logger.trace(`got tip response, status ${merchantResp.status}`);

  // Hide transient errors.
  if (
    tipRecord.retryInfo.retryCounter < 5 &&
    ((merchantResp.status >= 500 && merchantResp.status <= 599) ||
      merchantResp.status === 424)
  ) {
    logger.trace(`got transient tip error`);
    const err = makeErrorDetails(
      TalerErrorCode.WALLET_UNEXPECTED_REQUEST_ERROR,
      "tip pickup failed (transient)",
      getHttpResponseErrorDetails(merchantResp),
    );
    await incrementTipRetry(ws, tipRecord.walletTipId, err);
    // FIXME: Maybe we want to signal to the caller that the transient error happened?
    return;
  }

  const response = await readSuccessResponseJsonOrThrow(
    merchantResp,
    codecForTipResponse(),
  );

  if (response.blind_sigs.length !== planchets.length) {
    throw Error("number of tip responses does not match requested planchets");
  }

  const newCoinRecords: CoinRecord[] = [];

  for (let i = 0; i < response.blind_sigs.length; i++) {
    const blindedSig = response.blind_sigs[i].blind_sig;

    const denom = denomForPlanchet[i];
    checkLogicInvariant(!!denom);
    const planchet = planchets[i];
    checkLogicInvariant(!!planchet);

    const denomSig = await ws.cryptoApi.rsaUnblind(
      blindedSig,
      planchet.blindingKey,
      denom.denomPub,
    );

    const isValid = await ws.cryptoApi.rsaVerify(
      planchet.coinPub,
      denomSig,
      denom.denomPub,
    );

    if (!isValid) {
      await ws.db.runWithWriteTransaction([Stores.tips], async (tx) => {
        const tipRecord = await tx.get(Stores.tips, walletTipId);
        if (!tipRecord) {
          return;
        }
        tipRecord.lastError = makeErrorDetails(
          TalerErrorCode.WALLET_TIPPING_COIN_SIGNATURE_INVALID,
          "invalid signature from the exchange (via merchant tip) after unblinding",
          {},
        );
        await tx.put(Stores.tips, tipRecord);
      });
      return;
    }

    newCoinRecords.push({
      blindingKey: planchet.blindingKey,
      coinPriv: planchet.coinPriv,
      coinPub: planchet.coinPub,
      coinSource: {
        type: CoinSourceType.Tip,
        coinIndex: i,
        walletTipId: walletTipId,
      },
      currentAmount: denom.value,
      denomPub: denom.denomPub,
      denomPubHash: denom.denomPubHash,
      denomSig: denomSig,
      exchangeBaseUrl: tipRecord.exchangeBaseUrl,
      status: CoinStatus.Fresh,
      suspended: false,
      coinEvHash: planchet.coinEvHash,
    });
  }

  await ws.db.runWithWriteTransaction(
    [Stores.coins, Stores.tips, Stores.withdrawalGroups],
    async (tx) => {
      const tr = await tx.get(Stores.tips, walletTipId);
      if (!tr) {
        return;
      }
      if (tr.pickedUpTimestamp) {
        return;
      }
      tr.pickedUpTimestamp = getTimestampNow();
      tr.lastError = undefined;
      tr.retryInfo = initRetryInfo(false);
      await tx.put(Stores.tips, tr);
      for (const cr of newCoinRecords) {
        await tx.put(Stores.coins, cr);
      }
    },
  );
}

export async function acceptTip(
  ws: InternalWalletState,
  tipId: string,
): Promise<void> {
  const tipRecord = await ws.db.get(Stores.tips, tipId);
  if (!tipRecord) {
    logger.error("tip not found");
    return;
  }

  tipRecord.acceptedTimestamp = getTimestampNow();
  await ws.db.put(Stores.tips, tipRecord);

  await processTip(ws, tipId);
  return;
}