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.Budget;
import com.kaidi.oa.domain.RdGrantDisbursement;
import com.kaidi.oa.domain.Voucher;
import com.kaidi.oa.repository.BudgetRepository;
import com.kaidi.oa.repository.RdGrantDisbursementRepository;
import com.kaidi.oa.repository.VoucherRepository;
import jakarta.servlet.http.HttpServletRequest;
import org.springframework.transaction.annotation.Transactional;
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.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

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

/**
 * 政府资金到账·财务入账与项目预算提取联动（创新研发中心·申报服务部，需求 §3 资金拨付跟踪）。
 *
 * 补 PARTIAL（med）：原到账仅生成机构服务费付款单，未联动「财务凭证入账」「项目支出预算提取」。
 * 本控制器以「已到账」的 {@link RdGrantDisbursement} 为源，提供两条到账后联动动作（加法式，不改原控制器）：
 * <ul>
 *   <li>/{grantId}/post-voucher：生成「借 银行存款 / 贷 营业外收入-政府补助」的政府资金到账记账凭证
 *       （source=rd_grant），通知财务入账；同源幂等（已生成则 409）；</li>
 *   <li>/{grantId}/extract-budget：按到账资金提取一条项目支出预算（element=政府补助资金，budgetAmount=到账额），
 *       供后续合作单位费用/项目支出从该预算列支；同源幂等。</li>
 * </ul>
 * 金额一律 {@link Money}（BigDecimal）；级联写带 {@link Transactional}。
 */
@RestController
@RequestMapping("/api/oa/decl-grant-ledger")
public class DeclGrantLedgerController {

    private static final String ST_RECEIVED = "已到账";
    private static final String ST_SETTLED = "已分配";
    private static final String SRC_GRANT_VOUCHER = "rd_grant_receipt";
    private static final String SRC_GRANT_BUDGET = "政府补助资金";

    private final RdGrantDisbursementRepository grantRepo;
    private final VoucherRepository voucherRepo;
    private final BudgetRepository budgetRepo;
    private final CurrentUserResolver currentUser;

    public DeclGrantLedgerController(RdGrantDisbursementRepository grantRepo,
                                     VoucherRepository voucherRepo,
                                     BudgetRepository budgetRepo,
                                     CurrentUserResolver currentUser) {
        this.grantRepo = grantRepo;
        this.voucherRepo = voucherRepo;
        this.budgetRepo = budgetRepo;
        this.currentUser = currentUser;
    }

    /** 某笔资金的入账与预算提取联动状态（前端判断按钮可用性）。 */
    public record LedgerStatus(Long grantId, String projectName, double receivedAmount,
                               boolean vouchered, Long voucherId, String voucherNo,
                               boolean budgetExtracted, Long budgetId) {
    }

    @GetMapping("/{grantId}/status")
    public ApiResp<LedgerStatus> status(@PathVariable Long grantId) {
        RdGrantDisbursement g = loadGrant(grantId);
        Voucher v = findVoucher(grantId);
        Budget b = findBudget(grantId);
        return ApiResp.ok(new LedgerStatus(g.getId(), g.getProjectName(),
                Money.nz(g.getReceivedAmount()).doubleValue(),
                v != null, v == null ? null : v.getId(), v == null ? null : v.getVoucherNo(),
                b != null, b == null ? null : b.getId()));
    }

    /** 生成政府资金到账记账凭证：借 银行存款 / 贷 营业外收入-政府补助。要求资金已到账、同源未入账。 */
    @PostMapping("/{grantId}/post-voucher")
    @Transactional
    public ApiResp<Voucher> postVoucher(@PathVariable Long grantId, HttpServletRequest request) {
        RdGrantDisbursement g = loadGrant(grantId);
        requireReceived(g);
        if (findVoucher(grantId) != null) {
            throw new ApiException(409, "该笔资金已生成到账入账凭证，请勿重复");
        }
        BigDecimal amount = Money.nz(g.getReceivedAmount());
        if (Money.lte0(amount)) {
            throw new ApiException(400, "到账金额为 0，无法入账");
        }
        Voucher v = new Voucher();
        v.setVoucherNo("PZ-ZJ" + g.getId());
        v.setVoucherDate(LocalDate.now().toString());
        v.setSummary("收到政府资助资金到账：" + g.getProjectName()
                + (g.getAuthority() == null ? "" : "（" + g.getAuthority() + "）"));
        v.setDebitAccount("银行存款");
        v.setCreditAccount("营业外收入-政府补助");
        v.setAmount(amount);
        v.setStatus("待审核");
        v.setPreparer(currentUser.resolveLabel(request));
        v.setSourceType(SRC_GRANT_VOUCHER);
        v.setSourceId(g.getId());
        v.setCreatedAt(Instant.now());
        return ApiResp.ok(voucherRepo.save(v));
    }

    /** 按到账资金提取项目支出预算（element=政府补助资金）。要求资金已到账、同源未提取。 */
    @PostMapping("/{grantId}/extract-budget")
    @Transactional
    public ApiResp<Budget> extractBudget(@PathVariable Long grantId, HttpServletRequest request) {
        RdGrantDisbursement g = loadGrant(grantId);
        requireReceived(g);
        if (findBudget(grantId) != null) {
            throw new ApiException(409, "该笔资金已提取项目支出预算，请勿重复");
        }
        BigDecimal amount = Money.nz(g.getReceivedAmount());
        if (Money.lte0(amount)) {
            throw new ApiException(400, "到账金额为 0，无法提取预算");
        }
        Budget b = new Budget();
        b.setName("政府补助专项预算·" + g.getProjectName());
        b.setProjectId(g.getPolicyApplicationId());
        b.setCompanySubject(g.getCompanySubject());
        b.setElement(SRC_GRANT_BUDGET);
        b.setYear(String.valueOf(LocalDate.now().getYear()));
        b.setPeriod("年度");
        b.setBudgetAmount(amount);
        b.setActualAmount(Money.ZERO);
        b.setOwner(g.getOwner() == null || g.getOwner().isBlank()
                ? currentUser.resolveLabel(request) : g.getOwner());
        b.setStatus("执行中");
        b.setCreatedAt(Instant.now());
        // 复用 name 末尾标注来源 grant id，便于同源幂等检测（避免改动共享 Budget 实体加新列）。
        b.setName(b.getName() + " #G" + g.getId());
        return ApiResp.ok(budgetRepo.save(b));
    }

    // ---------- helpers ----------

    private RdGrantDisbursement loadGrant(Long id) {
        return grantRepo.findById(id)
                .orElseThrow(() -> new NotFoundException("grant disbursement not found: " + id));
    }

    private void requireReceived(RdGrantDisbursement g) {
        if (!ST_RECEIVED.equals(g.getStatus()) && !ST_SETTLED.equals(g.getStatus())) {
            throw new ApiException(400, "资金尚未全额到账，不能入账/提取预算（当前：" + g.getStatus() + "）");
        }
    }

    /** 同源凭证检测：source=rd_grant_receipt 且 sourceId=grantId。 */
    private Voucher findVoucher(Long grantId) {
        for (Voucher v : voucherRepo.findAll()) {
            if (SRC_GRANT_VOUCHER.equals(v.getSourceType()) && grantId.equals(v.getSourceId())) {
                return v;
            }
        }
        return null;
    }

    /** 同源预算检测：element=政府补助资金 且 name 末尾标注 #G<grantId>。 */
    private Budget findBudget(Long grantId) {
        String tag = "#G" + grantId;
        for (Budget b : budgetRepo.findByElement(SRC_GRANT_BUDGET)) {
            if (b.getName() != null && b.getName().endsWith(tag)) {
                return b;
            }
        }
        return null;
    }
}