stocks-be/src/main/java/com/danielbohry/stocks/service/PortfolioService.java

package com.danielbohry.stocks.service;

import com.danielbohry.stocks.context.UserContextHolder;
import com.danielbohry.stocks.domain.Portfolio;
import com.danielbohry.stocks.domain.Quote;
import com.danielbohry.stocks.domain.Stock;
import com.danielbohry.stocks.exception.BadRequestException;
import com.danielbohry.stocks.exception.NotFoundException;
import com.danielbohry.stocks.repository.PortfolioRepository;
import com.danielbohry.stocks.service.ExchangeService.ExchangeRateResponse;
import lombok.AllArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;

import java.math.BigDecimal;
import java.math.RoundingMode;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.UUID;

import static java.time.LocalDateTime.now;
import static java.util.Collections.emptyList;

@Slf4j
@Service
@AllArgsConstructor
public class PortfolioService {

    private final PortfolioRepository repository;
    private final StockService stockService;
    private final ExchangeService exchangeService;

    public List<Portfolio> getAll() {
        return repository.findAll();
    }

    public List<String> getAllIds() {
        return repository.findAllPortfolioIds();
    }

    @Cacheable(value = "portfolio", key = "#username + '_' + #currency")
    public List<Portfolio> getByUser(String username, String currency) {
        List<Portfolio> portfolios = repository.findAllByUsername(username);

        return portfolios.stream()
            .map(portfolio -> get(portfolio.getId(), currency))
            .toList();
    }

    public Portfolio get(String id, String currency) {
        Portfolio portfolio = repository.findById(id)
            .orElseThrow(() -> new NotFoundException("No portfolio found with id: " + id));

        ExchangeRateResponse exchangeRate = exchangeService.getCurrentRate(currency);
        Map<String, BigDecimal> rates = exchangeRate.getConversionRates();
        BigDecimal targetRate = rates.getOrDefault(currency, BigDecimal.ONE);

        log.info("Getting portfolio [{}] and converting to [{}]", id, currency);
        List<Stock> updatedStocks = portfolio.getStocks().stream()
            .peek(stock -> {
                Quote quote = stockService.getStockQuote(stock.getCode());
                stock.setName(quote.getName());

                BigDecimal quoteRate = rates.getOrDefault(quote.getCurrency(), BigDecimal.ONE);

                BigDecimal convertedPrice = quote.getPrice()
                    .divide(quoteRate, 2, RoundingMode.HALF_UP)
                    .multiply(targetRate);

                stock.setPrice(convertedPrice);
                stock.setTotal(convertedPrice.multiply(new BigDecimal(stock.getQuantity())));
            }).toList();

        portfolio.setStocks(updatedStocks);

        return portfolio;
    }

    public Portfolio create() {
        String id = UUID.randomUUID().toString();

        Portfolio toSave = Portfolio.builder()
            .id(id)
            .stocks(emptyList())
            .username(UserContextHolder.get().getUsername())
            .createdAt(now())
            .updatedAt(now())
            .build();

        return repository.save(toSave);
    }

    public Portfolio update(String id, List<Stock> stocks) {
        log.info("Updating portfolio [{}]", id);
        Optional<Portfolio> portfolio = repository.findById(id);

        if (portfolio.isEmpty()) {
            throw new NotFoundException("Failed to update portfolio with id: " + id);
        }

        validate(stocks);

        Portfolio toUpdate = portfolio.get();
        toUpdate.setUpdatedAt(now());
        toUpdate.setStocks(stocks);
        return repository.save(toUpdate);
    }

    public void delete(String id) {
        log.info("Deleting portfolio [{}]", id);
        repository.deleteById(id);
    }

    public void cleanup() {
        repository.findAllByEmptyStocks().forEach(portfolio -> {
            if (portfolio.getStocks().isEmpty()) {
                log.info("Removing empty portfolio [{}]", portfolio.getId());
                repository.deleteById(portfolio.getId());
            }
        });
    }

    private void validate(List<Stock> stocks) {
        boolean anyInvalid = stocks.stream()
            .anyMatch(stock -> !stockService.isValid(stock.getCode()));

        if (anyInvalid) {
            throw new BadRequestException("Invalid stock found");
        }
    }

}