nullcart/backend/src/modules/exchangeRate/services/ExchangeRateService.spec.ts

import { Logger } from '@nestjs/common';
import type { ConfigService } from '@nestjs/config';
import axios from 'axios';
import { PaymentMethod } from '../../payment/types/PaymentMethod';
import { ExchangeRateService } from './ExchangeRateService';

jest.mock('axios');

const mockedAxios = axios as jest.Mocked<typeof axios>;

const buildCoinPaprikaTicker = (price: number, fiat = 'USD') => ({
    quotes: { [fiat]: { price } }
});

const buildCoinPaprikaAxiosMock =
    (xmrPrice: number, btcPrice: number, fiat = 'USD') =>
    (url: string) => {
        if (url === `https://coinpaprika.test/v1/tickers/xmr-monero?quotes=${fiat}`) {
            return Promise.resolve({ data: buildCoinPaprikaTicker(xmrPrice, fiat) });
        }

        if (url === `https://coinpaprika.test/v1/tickers/btc-bitcoin?quotes=${fiat}`) {
            return Promise.resolve({ data: buildCoinPaprikaTicker(btcPrice, fiat) });
        }

        return Promise.reject(new Error(`unexpected url: ${url}`));
    };

describe('ExchangeRateService', () => {
    let service: ExchangeRateService;
    let configService: {
        get: jest.Mock;
    };
    let warnLogSpy: jest.SpiedFunction<typeof Logger.prototype.warn>;
    let errorLogSpy: jest.SpiedFunction<typeof Logger.prototype.error>;
    let logSpy: jest.SpiedFunction<typeof Logger.prototype.log>;

    beforeEach(() => {
        warnLogSpy = jest.spyOn(Logger.prototype, 'warn').mockImplementation(() => undefined);
        errorLogSpy = jest.spyOn(Logger.prototype, 'error').mockImplementation(() => undefined);
        logSpy = jest.spyOn(Logger.prototype, 'log').mockImplementation(() => undefined);

        configService = {
            get: jest.fn((key: string) => {
                if (key === 'shopSettings') {
                    return { shopFiatCurrency: 'USD' };
                }

                if (key === 'coingecko') {
                    return { apiBaseUrl: 'https://coingecko.test', rateFetchTimeoutMs: 5000 };
                }

                if (key === 'coinPaprika') {
                    return { apiBaseUrl: 'https://coinpaprika.test/v1', rateFetchTimeoutMs: 5000 };
                }

                return undefined;
            })
        };

        service = new ExchangeRateService(configService as unknown as ConfigService);
        mockedAxios.get.mockReset();
    });

    afterEach(() => {
        warnLogSpy.mockRestore();
        errorLogSpy.mockRestore();
        logSpy.mockRestore();
    });

    it('stores batched CoinGecko rates when the fetch succeeds', async () => {
        mockedAxios.get.mockResolvedValueOnce({
            data: {
                monero: { usd: 152.3456 },
                bitcoin: { usd: 95_432.1987 }
            }
        });

        await service.fetchLiveRates();

        expect(mockedAxios.get).toHaveBeenCalledWith(
            'https://coingecko.test/simple/price?ids=monero,bitcoin&vs_currencies=usd',
            { timeout: 5000 }
        );
        expect(service.getLiveFiatPerCrypto(PaymentMethod.Xmr)).toBe(152.35);
        expect(service.getLiveFiatPerCrypto(PaymentMethod.Btc)).toBe(95_432.2);
    });

    it('falls back to CoinPaprika when CoinGecko fails', async () => {
        mockedAxios.get
            .mockRejectedValueOnce(new Error('coingecko down'))
            .mockImplementation(buildCoinPaprikaAxiosMock(149.876, 94_999.5));

        await service.fetchLiveRates();

        expect(warnLogSpy).toHaveBeenCalled();
        expect(mockedAxios.get).toHaveBeenCalledWith(
            'https://coinpaprika.test/v1/tickers/xmr-monero?quotes=USD',
            { timeout: 5000 }
        );
        expect(mockedAxios.get).toHaveBeenCalledWith(
            'https://coinpaprika.test/v1/tickers/btc-bitcoin?quotes=USD',
            { timeout: 5000 }
        );
        expect(service.getLiveFiatPerCrypto(PaymentMethod.Xmr)).toBe(149.88);
        expect(service.getLiveFiatPerCrypto(PaymentMethod.Btc)).toBe(94_999.5);
    });

    it('leaves cached rates null when both providers fail on the first fetch', async () => {
        mockedAxios.get
            .mockRejectedValueOnce(new Error('coingecko down'))
            .mockRejectedValue(new Error('coinpaprika down'));

        await service.fetchLiveRates();

        expect(errorLogSpy).toHaveBeenCalled();
        expect(service.getLiveFiatPerCrypto(PaymentMethod.Xmr)).toBeNull();
        expect(service.getLiveFiatPerCrypto(PaymentMethod.Btc)).toBeNull();
    });

    it('falls back to CoinPaprika when CoinGecko returns an invalid payload', async () => {
        mockedAxios.get
            .mockResolvedValueOnce({ data: { monero: { usd: -1 }, bitcoin: { usd: 95_000 } } })
            .mockImplementation(buildCoinPaprikaAxiosMock(151.11, 95_111.11));

        await service.fetchLiveRates();

        expect(warnLogSpy).toHaveBeenCalled();
        expect(logSpy).toHaveBeenCalledWith('Successfully fetched live rates from CoinPaprika for USD');
        expect(mockedAxios.get).toHaveBeenCalledTimes(3);
        expect(service.getLiveFiatPerCrypto(PaymentMethod.Xmr)).toBe(151.11);
        expect(service.getLiveFiatPerCrypto(PaymentMethod.Btc)).toBe(95_111.11);
    });

    it('falls back to CoinPaprika when CoinGecko omits a coin', async () => {
        mockedAxios.get
            .mockResolvedValueOnce({ data: { monero: { usd: 150 } } })
            .mockImplementation(buildCoinPaprikaAxiosMock(149.5, 94_000));

        await service.fetchLiveRates();

        expect(warnLogSpy).toHaveBeenCalled();
        expect(service.getLiveFiatPerCrypto(PaymentMethod.Xmr)).toBe(149.5);
        expect(service.getLiveFiatPerCrypto(PaymentMethod.Btc)).toBe(94_000);
    });

    it('leaves cached rates null when CoinPaprika returns an invalid payload for one coin', async () => {
        mockedAxios.get.mockRejectedValueOnce(new Error('coingecko down')).mockImplementation((url: string) => {
            if (url === 'https://coinpaprika.test/v1/tickers/xmr-monero?quotes=USD') {
                return Promise.resolve({ data: buildCoinPaprikaTicker(151.11) });
            }

            if (url === 'https://coinpaprika.test/v1/tickers/btc-bitcoin?quotes=USD') {
                return Promise.resolve({ data: { quotes: { USD: { price: -1 } } } });
            }

            return Promise.reject(new Error(`unexpected url: ${url}`));
        });

        await service.fetchLiveRates();

        expect(errorLogSpy).toHaveBeenCalled();
        expect(service.getLiveFiatPerCrypto(PaymentMethod.Xmr)).toBeNull();
        expect(service.getLiveFiatPerCrypto(PaymentMethod.Btc)).toBeNull();
    });

    it('keeps the previous live rates when a refresh fails after a successful fetch', async () => {
        mockedAxios.get.mockResolvedValueOnce({
            data: {
                monero: { usd: 140 },
                bitcoin: { usd: 90_000 }
            }
        });
        await service.fetchLiveRates();

        mockedAxios.get
            .mockRejectedValueOnce(new Error('coingecko down'))
            .mockRejectedValue(new Error('coinpaprika down'));
        await service.fetchLiveRates();

        expect(service.getLiveFiatPerCrypto(PaymentMethod.Xmr)).toBe(140);
        expect(service.getLiveFiatPerCrypto(PaymentMethod.Btc)).toBe(90_000);
    });

    it('keeps the previous live rates when CoinPaprika returns an invalid payload for one coin on refresh', async () => {
        mockedAxios.get.mockResolvedValueOnce({
            data: {
                monero: { usd: 140 },
                bitcoin: { usd: 90_000 }
            }
        });
        await service.fetchLiveRates();

        mockedAxios.get.mockRejectedValueOnce(new Error('coingecko down')).mockImplementation((url: string) => {
            if (url === 'https://coinpaprika.test/v1/tickers/xmr-monero?quotes=USD') {
                return Promise.resolve({ data: buildCoinPaprikaTicker(151.11) });
            }

            if (url === 'https://coinpaprika.test/v1/tickers/btc-bitcoin?quotes=USD') {
                return Promise.resolve({ data: { quotes: { USD: { price: -1 } } } });
            }

            return Promise.reject(new Error(`unexpected url: ${url}`));
        });
        await service.fetchLiveRates();

        expect(errorLogSpy).toHaveBeenCalled();
        expect(service.getLiveFiatPerCrypto(PaymentMethod.Xmr)).toBe(140);
        expect(service.getLiveFiatPerCrypto(PaymentMethod.Btc)).toBe(90_000);
    });

    it('uses the shop fiat currency when building provider URLs', async () => {
        configService.get.mockImplementation((key: string) => {
            if (key === 'shopSettings') {
                return { shopFiatCurrency: 'EUR' };
            }

            if (key === 'coingecko') {
                return { apiBaseUrl: 'https://coingecko.test', rateFetchTimeoutMs: 5000 };
            }

            if (key === 'coinPaprika') {
                return { apiBaseUrl: 'https://coinpaprika.test/v1', rateFetchTimeoutMs: 5000 };
            }

            return undefined;
        });

        mockedAxios.get.mockResolvedValueOnce({
            data: {
                monero: { eur: 130.5 },
                bitcoin: { eur: 88_000.4 }
            }
        });

        await service.fetchLiveRates();

        expect(mockedAxios.get).toHaveBeenCalledWith(
            'https://coingecko.test/simple/price?ids=monero,bitcoin&vs_currencies=eur',
            { timeout: 5000 }
        );
        expect(service.getLiveFiatPerCrypto(PaymentMethod.Xmr)).toBe(130.5);
        expect(service.getLiveFiatPerCrypto(PaymentMethod.Btc)).toBe(88_000.4);
    });
});