package com.kaidi.oa.web;

import com.kaidi.oa.common.ApiException;
import com.kaidi.oa.common.ApiResp;
import com.kaidi.oa.common.Money;
import com.kaidi.oa.common.NotFoundException;
import com.kaidi.oa.domain.FinAdvance;
import com.kaidi.oa.domain.Voucher;
import com.kaidi.oa.repository.FinAdvanceRepository;
import com.kaidi.oa.repository.VoucherRepository;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import java.math.BigDecimal;
import java.time.Instant;
import java.time.LocalDate;
import java.util.List;
import java.util.Map;
import java.util.LinkedHashMap;

/**
 * 财务部·预收款 / 预付款管理（应收应付扩展场景）。
 *
 * 审计缺口：预收款场景未实现。
 *
 * 本控制器提供：
 *  1. 预收/预付台账 CRUD（登记预收款/预付款单）。
 *  2. POST /{id}/settle —— 核销：将预收款与对应应收单核销，累加核销额，状态机推进。
 *  3. POST /{id}/voucher —— 自动生成收/付款凭证（借 银行存款 / 贷 预收账款，或相反）。
 *  4. GET /summary —— 预收/预付汇总（待核销/已核销金额统计）。
 *
 * 写口：AuthInterceptor FINANCE_PREFIXES(/api/oa/fin-advances) 限 ADMIN/APPROVER。
 */
@RestController
@RequestMapping("/api/oa/fin-advances")
public class FinAdvanceController {

    private final FinAdvanceRepository advRepo;
    private final VoucherRepository voucherRepo;

    public FinAdvanceController(FinAdvanceRepository advRepo, VoucherRepository voucherRepo) {
        this.advRepo = advRepo;
        this.voucherRepo = voucherRepo;
    }

    @GetMapping
    public ApiResp<List<FinAdvance>> list(
            @RequestParam(required = false) String advanceType,
            @RequestParam(required = false) String status) {
        if (advanceType != null && status != null) {
            return ApiResp.ok(advRepo.findByAdvanceTypeAndStatus(advanceType, status));
        }
        if (advanceType != null) return ApiResp.ok(advRepo.findByAdvanceType(advanceType));
        if (status != null) return ApiResp.ok(advRepo.findByStatus(status));
        return ApiResp.ok(advRepo.findAll());
    }

    @GetMapping("/{id}")
    public ApiResp<FinAdvance> get(@PathVariable Long id) {
        return ApiResp.ok(advRepo.findById(id)
                .orElseThrow(() -> new NotFoundException("预收/预付记录不存在: " + id)));
    }

    public record AdvanceRequest(
            String advanceType, String partyName, String contractRef,
            Double amount, String receiptDate, String remark, String operator) {
    }

    @PostMapping
    public ApiResp<FinAdvance> create(@RequestBody AdvanceRequest req) {
        if (req.advanceType() == null ||
                (!FinAdvance.T_RECEIVED.equals(req.advanceType()) && !FinAdvance.T_PAID.equals(req.advanceType()))) {
            throw new ApiException(400, "类型(advanceType)必须为「预收」或「预付」");
        }
        if (req.partyName() == null || req.partyName().isBlank()) {
            throw new ApiException(400, "往来单位(partyName)不能为空");
        }
        if (req.amount() == null || req.amount() <= 0) {
            throw new ApiException(400, "金额(amount)必须大于 0");
        }
        FinAdvance a = new FinAdvance();
        a.setCode((FinAdvance.T_RECEIVED.equals(req.advanceType()) ? "YS-" : "YF-") + (advRepo.count() + 1));
        a.setAdvanceType(req.advanceType());
        a.setPartyName(req.partyName());
        a.setContractRef(req.contractRef());
        a.setAmount(Money.of(req.amount()));
        a.setSettledAmount(BigDecimal.ZERO);
        a.setRemainAmount(Money.of(req.amount()));
        a.setReceiptDate(req.receiptDate() != null ? req.receiptDate() : LocalDate.now().toString());
        a.setStatus(FinAdvance.S_OPEN);
        a.setRemark(req.remark());
        a.setOperator(req.operator());
        a.setCreatedAt(Instant.now());
        return ApiResp.ok(advRepo.save(a));
    }

    @PutMapping("/{id}")
    public ApiResp<FinAdvance> update(@PathVariable Long id, @RequestBody AdvanceRequest req) {
        FinAdvance a = advRepo.findById(id)
                .orElseThrow(() -> new NotFoundException("预收/预付记录不存在: " + id));
        if (FinAdvance.S_SETTLED.equals(a.getStatus())) {
            throw new ApiException(409, "已核销完毕的记录不允许修改");
        }
        if (req.partyName() != null && !req.partyName().isBlank()) a.setPartyName(req.partyName());
        if (req.contractRef() != null) a.setContractRef(req.contractRef());
        if (req.receiptDate() != null) a.setReceiptDate(req.receiptDate());
        if (req.remark() != null) a.setRemark(req.remark());
        return ApiResp.ok(advRepo.save(a));
    }

    @DeleteMapping("/{id}")
    public ApiResp<Void> delete(@PathVariable Long id) {
        FinAdvance a = advRepo.findById(id)
                .orElseThrow(() -> new NotFoundException("预收/预付记录不存在: " + id));
        if (!FinAdvance.S_OPEN.equals(a.getStatus())) {
            throw new ApiException(409, "已发生核销的记录不允许删除");
        }
        advRepo.deleteById(id);
        return ApiResp.ok(null);
    }

    // ---------- 核销 ----------

    public record SettleRequest(Double settleAmount, Long arApItemId, String operator) {
    }

    /**
     * 核销：将预收/预付款向应收/应付单核销，累加已核销额，状态机：待核销→部分核销→已核销。
     */
    @PostMapping("/{id}/settle")
    @Transactional
    public ApiResp<FinAdvance> settle(@PathVariable Long id, @RequestBody SettleRequest req) {
        FinAdvance a = advRepo.findById(id)
                .orElseThrow(() -> new NotFoundException("预收/预付记录不存在: " + id));
        if (FinAdvance.S_SETTLED.equals(a.getStatus())) {
            throw new ApiException(409, "已全额核销，无需再次核销");
        }
        if (req.settleAmount() == null || req.settleAmount() <= 0) {
            throw new ApiException(400, "核销金额必须大于 0");
        }
        BigDecimal add = Money.of(req.settleAmount());
        BigDecimal remain = Money.nz(a.getRemainAmount());
        if (Money.gt(add, remain)) {
            throw new ApiException(409, "核销金额超过未核销余额（剩余 " + remain + "）");
        }
        BigDecimal newSettled = Money.add(a.getSettledAmount(), add);
        a.setSettledAmount(newSettled);
        a.setRemainAmount(Money.sub(a.getAmount(), newSettled));
        a.setStatus(newSettled.compareTo(a.getAmount()) >= 0 ? FinAdvance.S_SETTLED : FinAdvance.S_PARTIAL);
        if (req.arApItemId() != null) a.setArApItemId(req.arApItemId());
        return ApiResp.ok(advRepo.save(a));
    }

    // ---------- 自动生成凭证 ----------

    public record VoucherRequest(String preparer) {
    }

    /**
     * 自动生成凭证：
     * 预收 → 借 1002/银行存款 / 贷 2203/预收账款
     * 预付 → 借 1123/预付账款 / 贷 1002/银行存款
     */
    @PostMapping("/{id}/voucher")
    @Transactional
    public ApiResp<FinAdvance> generateVoucher(@PathVariable Long id,
                                                @RequestBody(required = false) VoucherRequest req) {
        FinAdvance a = advRepo.findById(id)
                .orElseThrow(() -> new NotFoundException("预收/预付记录不存在: " + id));
        if (a.getVoucherId() != null) {
            throw new ApiException(409, "已生成凭证，不可重复生成");
        }
        String preparer = req != null && req.preparer() != null ? req.preparer() : "系统自动";
        Voucher v = new Voucher();
        boolean isReceived = FinAdvance.T_RECEIVED.equals(a.getAdvanceType());
        v.setVoucherNo((isReceived ? "YS-" : "YF-") + (voucherRepo.count() + 1));
        v.setVoucherDate(a.getReceiptDate() != null ? a.getReceiptDate() : LocalDate.now().toString());
        v.setSummary((isReceived ? "收到预收款" : "支付预付款") + "—" + a.getPartyName() + " " + a.getCode());
        v.setDebitAccount(isReceived ? "1002" : "1123");
        v.setCreditAccount(isReceived ? "2203" : "1002");
        v.setAmount(Money.nz(a.getAmount()));
        v.setStatus(Voucher.S_DRAFT);
        v.setPreparer(preparer);
        v.setReversed(Boolean.FALSE);
        v.setIsReversal(Boolean.FALSE);
        v.setSourceType(isReceived ? "fin-advance-received" : "fin-advance-paid");
        v.setSourceId(a.getId());
        v.setCreatedAt(Instant.now());
        voucherRepo.save(v);
        a.setVoucherId(v.getId());
        return ApiResp.ok(advRepo.save(a));
    }

    // ---------- 汇总 ----------

    @GetMapping("/summary")
    public ApiResp<Map<String, Object>> summary() {
        List<FinAdvance> all = advRepo.findAll();
        BigDecimal recTotal = BigDecimal.ZERO, recSettled = BigDecimal.ZERO, recRemain = BigDecimal.ZERO;
        BigDecimal paidTotal = BigDecimal.ZERO, paidSettled = BigDecimal.ZERO, paidRemain = BigDecimal.ZERO;
        for (FinAdvance a : all) {
            if (FinAdvance.T_RECEIVED.equals(a.getAdvanceType())) {
                recTotal = Money.add(recTotal, a.getAmount());
                recSettled = Money.add(recSettled, a.getSettledAmount());
                recRemain = Money.add(recRemain, a.getRemainAmount());
            } else {
                paidTotal = Money.add(paidTotal, a.getAmount());
                paidSettled = Money.add(paidSettled, a.getSettledAmount());
                paidRemain = Money.add(paidRemain, a.getRemainAmount());
            }
        }
        Map<String, Object> result = new LinkedHashMap<>();
        result.put("receivedTotal", recTotal);
        result.put("receivedSettled", recSettled);
        result.put("receivedRemain", recRemain);
        result.put("paidTotal", paidTotal);
        result.put("paidSettled", paidSettled);
        result.put("paidRemain", paidRemain);
        return ApiResp.ok(result);
    }
}