/*
 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/>
 */

import { useState } from "preact/hooks";
import { MAX_RESULT_SIZE, PAGE_SIZE } from "../utils.js";
import { useBackendState } from "./backend.js";

import { AccessToken, AmountJson, Amounts, OperationOk, TalerCoreBankResultByMethod, TalerCorebankApi, TalerError, TalerHttpError } from "@gnu-taler/taler-util";
import _useSWR, { SWRHook } from "swr";
import { useBankCoreApiContext } from "../context/config.js";
import { assertUnreachable } from "../pages/HomePage.js";

// FIX default import https://github.com/microsoft/TypeScript/issues/49189
const useSWR = _useSWR as unknown as SWRHook;

export type TransferCalculation = {
  debit: AmountJson;
  credit: AmountJson;
  beforeFee: AmountJson;
};
type EstimatorFunction = (
  amount: AmountJson,
  sellFee: AmountJson,
  sellRate: number,
) => Promise<TransferCalculation>;

type CashoutEstimators = {
  estimateByCredit: EstimatorFunction;
  estimateByDebit: EstimatorFunction;
};

export function useEstimator(): CashoutEstimators {
  const { state } = useBackendState();
  const { api } = useBankCoreApiContext();
  return {
    estimateByCredit: async (amount, fee, rate) => {
      const resp = await api.getCashoutRate({
        credit: amount
      });
      if (resp.type === "fail") {
        // can't happen
        // not-supported: it should not be able to call this function
        // wrong-calculation: we are using just one parameter
        throw TalerError.fromDetail(resp.detail.code, {}, resp.detail.hint)
      }
      const credit = amount;
      const _credit = { ...credit, currency: fee.currency };
      const beforeFee = Amounts.sub(_credit, fee).amount;

      const debit = Amounts.parseOrThrow(resp.body.amount_debit);
      return {
        debit,
        beforeFee,
        credit,
      };
    },
    estimateByDebit: async (amount, fee, rate) => {
      const zeroBalance = Amounts.zeroOfCurrency(fee.currency);
      const zeroFiat = Amounts.zeroOfCurrency(fee.currency);
      const zeroCalc = {
        debit: zeroBalance,
        credit: zeroFiat,
        beforeFee: zeroBalance,
      };
      const resp = await api.getCashoutRate({ debit: amount });
      if (resp.type === "fail") {
        // can't happen
        // not-supported: it should not be able to call this function
        // wrong-calculation: we are using just one parameter
        throw TalerError.fromDetail(resp.detail.code, {}, resp.detail.hint)
      }
      const credit = Amounts.parseOrThrow(resp.body.amount_credit);
      const _credit = { ...credit, currency: fee.currency };
      const debit = amount;
      const beforeFee = Amounts.sub(_credit, fee).amount;
      return {
        debit,
        beforeFee,
        credit,
      };
    },
  };
}

export function useRatiosAndFeeConfig() {
  const { api, config } = useBankCoreApiContext();

  function fetcher() {
    return api.getConversionRates()
  }

  const { data, error } = useSWR<TalerCoreBankResultByMethod<"getConversionRates">, TalerHttpError>(
    !config.have_cashout || !config.fiat_currency ? false : [, "getConversionRates"], fetcher, {
    refreshInterval: 60 * 1000,
    refreshWhenHidden: false,
    revalidateOnFocus: false,
    revalidateIfStale: false,
    revalidateOnReconnect: false,
    refreshWhenOffline: false,
    errorRetryCount: 0,
    errorRetryInterval: 1,
    shouldRetryOnError: false,
    keepPreviousData: true,
  });

  if (data) return data;
  if (error) return error;
  return undefined;
}

interface PaginationFilter {
  account?: string;
  page?: number;
}

export function useBusinessAccounts() {
  const { state: credentials } = useBackendState();
  const token = credentials.status !== "loggedIn" ? undefined : credentials.token
  const { api } = useBankCoreApiContext();

  const [offset, setOffset] = useState<string | undefined>();

  function fetcher([token, offset]: [AccessToken, string]) {
    return api.getAccounts(token, {
      limit: MAX_RESULT_SIZE,
      offset,
      order: "asc"
    })
  }

  const { data, error } = useSWR<TalerCoreBankResultByMethod<"getAccounts">, TalerHttpError>(
    [token, offset, "getAccounts"], fetcher, {
    refreshInterval: 0,
    refreshWhenHidden: false,
    revalidateOnFocus: false,
    revalidateOnReconnect: false,
    refreshWhenOffline: false,
    errorRetryCount: 0,
    errorRetryInterval: 1,
    shouldRetryOnError: false,
    keepPreviousData: true,
  },
  );

  const isLastPage =
    data && data.type === "ok" && data.body.accounts.length < PAGE_SIZE;
  const isFirstPage = false;

  const pagination = {
    isLastPage,
    isFirstPage,
    loadMore: () => {
      if (isLastPage || data?.type !== "ok") return;
      const list = data.body.accounts
      if (list.length < MAX_RESULT_SIZE) {
        //FIXME: define pagination

        // setOffset(list[list.length - 1].row_id);
      }
    },
    loadMorePrev: () => {
      null;
    },
  };

  if (data) return { ok: true, data, ...pagination };
  if (error) return error;
  return undefined;
}

type CashoutWithId = TalerCorebankApi.CashoutStatusResponse & { id: string }
function notUndefined(c: CashoutWithId | undefined): c is CashoutWithId {
  return c !== undefined
}
export function useCashouts(account: string) {
  const { state: credentials } = useBackendState();
  const { api } = useBankCoreApiContext();
  const token = credentials.status !== "loggedIn" ? undefined : credentials.token

  async function fetcher([username, token]: [string, AccessToken]) {
    const list = await api.getAccountCashouts({ username, token })
    if (list.type !== "ok") {
      assertUnreachable(list.type)
    }
    const all: Array<CashoutWithId | undefined> = await Promise.all(list.body.cashouts.map(c => {
      return api.getCashoutById({ username, token }, c.cashout_id).then(r => {
        if (r.type === "fail") return undefined
        return { ...r.body, id: c.cashout_id }
      })
    }))

    const cashouts = all.filter(notUndefined)
    return { type: "ok" as const, body: { cashouts } }
  }

  const { data, error } = useSWR<OperationOk<{ cashouts: CashoutWithId[] }>, TalerHttpError>(
    [account, token, "getAccountCashouts"], fetcher, {
    refreshInterval: 0,
    refreshWhenHidden: false,
    revalidateOnFocus: false,
    revalidateOnReconnect: false,
    refreshWhenOffline: false,
    errorRetryCount: 0,
    errorRetryInterval: 1,
    shouldRetryOnError: false,
    keepPreviousData: true,
  });

  if (data) return data;
  if (error) return error;
  return undefined;
}

export function useCashoutDetails(cashoutId: string) {
  const { state: credentials } = useBackendState();
  const creds = credentials.status !== "loggedIn" ? undefined : credentials
  const { api } = useBankCoreApiContext();

  async function fetcher([username, token, id]: [string, AccessToken, string]) {
    return api.getCashoutById({ username, token }, id)
  }

  const { data, error } = useSWR<TalerCoreBankResultByMethod<"getCashoutById">, TalerHttpError>(
    [creds?.username, creds?.token, cashoutId, "getCashoutById"], fetcher, {
    refreshInterval: 0,
    refreshWhenHidden: false,
    revalidateOnFocus: false,
    revalidateOnReconnect: false,
    refreshWhenOffline: false,
    errorRetryCount: 0,
    errorRetryInterval: 1,
    shouldRetryOnError: false,
    keepPreviousData: true,
  });

  if (data) return data;
  if (error) return error;
  return undefined;
}