package com.goldenchart.service;

import com.goldenchart.dto.PaperLedgerEntryDto;
import com.goldenchart.dto.PaperPageDto;
import com.goldenchart.entity.GcPaperAccount;
import com.goldenchart.entity.GcPaperCashLedger;
import com.goldenchart.entity.GcPaperTrade;
import com.goldenchart.repository.GcPaperCashLedgerRepository;
import lombok.RequiredArgsConstructor;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.math.BigDecimal;
import java.time.LocalDateTime;

@Service
@RequiredArgsConstructor
@Transactional
public class PaperLedgerService {

    public static final String INITIAL     = "INITIAL";
    public static final String BUY_SETTLE  = "BUY_SETTLE";
    public static final String SELL_SETTLE = "SELL_SETTLE";
    public static final String RESET       = "RESET";

    private final GcPaperCashLedgerRepository ledgerRepo;

    public void recordInitial(GcPaperAccount account, BigDecimal initialCash) {
        ledgerRepo.save(GcPaperCashLedger.builder()
                .accountId(account.getId())
                .entryType(INITIAL)
                .amount(initialCash)
                .cashBefore(BigDecimal.ZERO)
                .cashAfter(initialCash)
                .build());
    }

    public void recordBuySettle(GcPaperAccount account, GcPaperTrade trade, BigDecimal totalCost) {
        BigDecimal before = account.getCashBalance().add(totalCost);
        ledgerRepo.save(GcPaperCashLedger.builder()
                .accountId(account.getId())
                .entryType(BUY_SETTLE)
                .amount(totalCost.negate())
                .cashBefore(before)
                .cashAfter(account.getCashBalance())
                .refTradeId(trade.getId())
                .symbol(trade.getSymbol())
                .build());
    }

    public void recordSellSettle(GcPaperAccount account, GcPaperTrade trade, BigDecimal netProceeds) {
        BigDecimal before = account.getCashBalance().subtract(netProceeds);
        ledgerRepo.save(GcPaperCashLedger.builder()
                .accountId(account.getId())
                .entryType(SELL_SETTLE)
                .amount(netProceeds)
                .cashBefore(before)
                .cashAfter(account.getCashBalance())
                .refTradeId(trade.getId())
                .symbol(trade.getSymbol())
                .build());
    }

    public void recordReset(GcPaperAccount account, BigDecimal cashBefore, BigDecimal newCash) {
        ledgerRepo.save(GcPaperCashLedger.builder()
                .accountId(account.getId())
                .entryType(RESET)
                .amount(newCash.subtract(cashBefore))
                .cashBefore(cashBefore)
                .cashAfter(newCash)
                .build());
    }

    @Transactional(readOnly = true)
    public PaperPageDto<PaperLedgerEntryDto> list(Long accountId, LocalDateTime from, LocalDateTime to,
                                                   int page, int size) {
        PageRequest pr = PageRequest.of(Math.max(0, page), Math.min(100, Math.max(1, size)));
        Page<GcPaperCashLedger> result = (from != null || to != null)
                ? ledgerRepo.findByAccountIdAndCreatedAtBetweenOrderByCreatedAtDesc(
                accountId,
                from != null ? from : LocalDateTime.of(2000, 1, 1, 0, 0),
                to != null ? to : LocalDateTime.now().plusYears(10),
                pr)
                : ledgerRepo.findByAccountIdOrderByCreatedAtDesc(accountId, pr);
        return PaperPageDto.<PaperLedgerEntryDto>builder()
                .content(result.getContent().stream().map(this::toDto).toList())
                .page(result.getNumber())
                .size(result.getSize())
                .totalElements(result.getTotalElements())
                .totalPages(result.getTotalPages())
                .build();
    }

    private PaperLedgerEntryDto toDto(GcPaperCashLedger e) {
        return PaperLedgerEntryDto.builder()
                .id(e.getId())
                .entryType(e.getEntryType())
                .amount(e.getAmount().doubleValue())
                .cashBefore(e.getCashBefore().doubleValue())
                .cashAfter(e.getCashAfter().doubleValue())
                .refTradeId(e.getRefTradeId())
                .symbol(e.getSymbol())
                .createdAt(e.getCreatedAt() != null ? e.getCreatedAt().toString() : null)
                .build();
    }
}