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.AdminStockMove;
import com.kaidi.oa.domain.AdminSupply;
import com.kaidi.oa.repository.AdminStockMoveRepository;
import com.kaidi.oa.repository.AdminSupplyRepository;
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.PatchMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
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.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

/**
 * 行政/办公室·非生产性物资管理。覆盖物资分类档案（含安全库存/结存）、入库登记、出库领用，
 * 入库/出库时级联自动维护物资结存量 onHand；低库存预警（结存低于安全库存）、批次有效期预警；
 * 费用分摊聚合（按领用部门/项目归集出库金额，月末分摊报表口径）。
 *
 * 写口含金额（入库金额）与库存调整，读侧含参考单价/库存金额，已登记进 FINANCE_PREFIXES +
 * SENSITIVE_READ_PREFIXES（/api/oa/admin-supplies），统一收口 ADMIN/APPROVER。
 */
@RestController
@RequestMapping("/api/oa/admin-supplies")
public class AdminSupplyController {

    private final AdminSupplyRepository supplyRepo;
    private final AdminStockMoveRepository moveRepo;

    public AdminSupplyController(AdminSupplyRepository supplyRepo, AdminStockMoveRepository moveRepo) {
        this.supplyRepo = supplyRepo;
        this.moveRepo = moveRepo;
    }

    // ---------- 物资档案 CRUD ----------

    @GetMapping
    public ApiResp<List<AdminSupply>> list(@RequestParam(required = false) String category,
                                           @RequestParam(required = false) String status) {
        if (category != null && !category.isBlank()) {
            return ApiResp.ok(supplyRepo.findByCategory(category));
        }
        if (status != null && !status.isBlank()) {
            return ApiResp.ok(supplyRepo.findByStatus(status));
        }
        return ApiResp.ok(supplyRepo.findAll());
    }

    @GetMapping("/{id}")
    public ApiResp<AdminSupply> get(@PathVariable Long id) {
        return ApiResp.ok(supplyRepo.findById(id)
                .orElseThrow(() -> new NotFoundException("supply not found: " + id)));
    }

    public record SupplyRequest(
            String code, String name, String category, String spec, String unit,
            Double refPrice, Double safetyStock, Double onHand, Boolean batchManaged,
            String defaultDept, String status) {
    }

    @PostMapping
    public ApiResp<AdminSupply> create(@RequestBody SupplyRequest req) {
        if (req.name() == null || req.name().isBlank()) {
            throw new ApiException(400, "物资名称(name) 不能为空");
        }
        AdminSupply s = new AdminSupply();
        s.setCode(req.code() == null || req.code().isBlank()
                ? "WZ-" + (supplyRepo.count() + 1) : req.code());
        s.setName(req.name());
        s.setCategory(req.category() == null || req.category().isBlank() ? "办公用品" : req.category());
        s.setSpec(req.spec());
        s.setUnit(req.unit() == null || req.unit().isBlank() ? "个" : req.unit());
        s.setRefPrice(Money.of(req.refPrice()));
        s.setSafetyStock(req.safetyStock() == null ? 0d : req.safetyStock());
        s.setOnHand(req.onHand() == null ? 0d : req.onHand());
        s.setBatchManaged(Boolean.TRUE.equals(req.batchManaged()));
        s.setDefaultDept(req.defaultDept());
        s.setStatus(req.status() == null || req.status().isBlank() ? "启用" : req.status());
        s.setCreatedAt(Instant.now());
        return ApiResp.ok(supplyRepo.save(s));
    }

    @PatchMapping("/{id}")
    public ApiResp<AdminSupply> update(@PathVariable Long id, @RequestBody SupplyRequest req) {
        AdminSupply s = supplyRepo.findById(id)
                .orElseThrow(() -> new NotFoundException("supply not found: " + id));
        if (req.name() != null && !req.name().isBlank()) s.setName(req.name());
        if (req.category() != null && !req.category().isBlank()) s.setCategory(req.category());
        if (req.spec() != null) s.setSpec(req.spec());
        if (req.unit() != null && !req.unit().isBlank()) s.setUnit(req.unit());
        if (req.refPrice() != null) s.setRefPrice(Money.of(req.refPrice()));
        if (req.safetyStock() != null) s.setSafetyStock(req.safetyStock());
        // onHand 不允许在档案编辑里直改，只能由入库/出库流水维护，避免库存被随手改飞。
        if (req.batchManaged() != null) s.setBatchManaged(req.batchManaged());
        if (req.defaultDept() != null) s.setDefaultDept(req.defaultDept());
        if (req.status() != null && !req.status().isBlank()) s.setStatus(req.status());
        return ApiResp.ok(supplyRepo.save(s));
    }

    @DeleteMapping("/{id}")
    public ApiResp<Void> delete(@PathVariable Long id) {
        if (!supplyRepo.existsById(id)) {
            throw new NotFoundException("supply not found: " + id);
        }
        supplyRepo.deleteById(id);
        return ApiResp.ok(null);
    }

    // ---------- 库存流水（入库 / 出库） ----------

    @GetMapping("/{id}/moves")
    public ApiResp<List<AdminStockMove>> moves(@PathVariable Long id) {
        return ApiResp.ok(moveRepo.findBySupplyIdOrderByIdDesc(id));
    }

    @GetMapping("/moves")
    public ApiResp<List<AdminStockMove>> allMoves(@RequestParam(required = false) String direction) {
        if (direction != null && !direction.isBlank()) {
            return ApiResp.ok(moveRepo.findByDirection(direction));
        }
        return ApiResp.ok(moveRepo.findAll());
    }

    public record StockMoveRequest(
            Double qty, Double amount, String supplier, String dept, String project,
            String handler, String batchNo, String expireDate, String moveDate, String remark) {
    }

    /**
     * 入库登记：数量+金额+供应商，级联结存量 onHand += qty。
     */
    @PostMapping("/{id}/inbound")
    @Transactional
    public ApiResp<AdminStockMove> inbound(@PathVariable Long id, @RequestBody StockMoveRequest req) {
        AdminSupply s = supplyRepo.findById(id)
                .orElseThrow(() -> new NotFoundException("supply not found: " + id));
        double qty = req.qty() == null ? 0 : req.qty();
        if (qty <= 0) {
            throw new ApiException(400, "入库数量必须大于 0");
        }
        AdminStockMove m = baseMove(s, "入库", qty, req);
        m.setAmount(Money.of(req.amount()));
        m.setSupplier(req.supplier());
        AdminStockMove saved = moveRepo.save(m);

        s.setOnHand(nz(s.getOnHand()) + qty);
        supplyRepo.save(s);
        return ApiResp.ok(saved);
    }

    /**
     * 出库领用：级联结存量 onHand -= qty；库存不足时拒绝（不允许出成负库存）。
     * 出库归集领用部门/项目，供月末费用分摊聚合。
     */
    @PostMapping("/{id}/outbound")
    @Transactional
    public ApiResp<AdminStockMove> outbound(@PathVariable Long id, @RequestBody StockMoveRequest req) {
        AdminSupply s = supplyRepo.findById(id)
                .orElseThrow(() -> new NotFoundException("supply not found: " + id));
        double qty = req.qty() == null ? 0 : req.qty();
        if (qty <= 0) {
            throw new ApiException(400, "出库数量必须大于 0");
        }
        if (nz(s.getOnHand()) < qty) {
            throw new ApiException(409, "库存不足：当前结存 " + nz(s.getOnHand()) + "，申请出库 " + qty);
        }
        AdminStockMove m = baseMove(s, "出库", qty, req);
        // 出库金额 = 数量 × 参考单价（成本归集口径）。
        m.setAmount(Money.of(BigDecimal.valueOf(qty).multiply(Money.nz(s.getRefPrice()))));
        m.setDept(req.dept() == null || req.dept().isBlank() ? s.getDefaultDept() : req.dept());
        m.setProject(req.project());
        AdminStockMove saved = moveRepo.save(m);

        s.setOnHand(nz(s.getOnHand()) - qty);
        supplyRepo.save(s);
        return ApiResp.ok(saved);
    }

    private AdminStockMove baseMove(AdminSupply s, String direction, double qty, StockMoveRequest req) {
        AdminStockMove m = new AdminStockMove();
        m.setSupplyId(s.getId());
        m.setSupplyCode(s.getCode());
        m.setSupplyName(s.getName());
        m.setDirection(direction);
        m.setQty(qty);
        m.setHandler(req.handler());
        m.setBatchNo(req.batchNo());
        m.setExpireDate(req.expireDate());
        m.setMoveDate(req.moveDate() == null || req.moveDate().isBlank()
                ? LocalDate.now().toString() : req.moveDate());
        m.setRemark(req.remark());
        m.setCreatedAt(Instant.now());
        return m;
    }

    // ---------- 低库存 / 批次有效期 预警 ----------

    public record LowStockAlert(Long supplyId, String code, String name, String category,
                                String unit, double onHand, double safetyStock, double shortage) {
    }

    /** 低库存预警：结存量低于安全库存（且安全库存>0）的物资，按缺口降序。 */
    @GetMapping("/alerts/low-stock")
    public ApiResp<List<LowStockAlert>> lowStockAlerts() {
        List<LowStockAlert> out = new ArrayList<>();
        for (AdminSupply s : supplyRepo.findAll()) {
            double onHand = nz(s.getOnHand());
            double safety = nz(s.getSafetyStock());
            if (safety > 0 && onHand < safety) {
                out.add(new LowStockAlert(s.getId(), s.getCode(), s.getName(), s.getCategory(),
                        s.getUnit(), onHand, safety, safety - onHand));
            }
        }
        out.sort((a, b) -> Double.compare(b.shortage(), a.shortage()));
        return ApiResp.ok(out);
    }

    public record ExpiryAlert(Long moveId, Long supplyId, String supplyName, String batchNo,
                              String expireDate, long daysToExpire, String level) {
    }

    /** 批次有效期预警：入库流水里 expireDate 落在 [今天-逾期, 今天+days] 的批次。 */
    @GetMapping("/alerts/expiry")
    public ApiResp<List<ExpiryAlert>> expiryAlerts(@RequestParam(required = false, defaultValue = "30") int days) {
        LocalDate today = LocalDate.now();
        List<ExpiryAlert> out = new ArrayList<>();
        for (AdminStockMove m : moveRepo.findByDirection("入库")) {
            LocalDate exp = parseDateOrNull(m.getExpireDate());
            if (exp == null) {
                continue;
            }
            long daysTo = java.time.temporal.ChronoUnit.DAYS.between(today, exp);
            if (daysTo > days) {
                continue;
            }
            String level = daysTo < 0 ? "已过期" : daysTo <= 7 ? "紧急" : daysTo <= 15 ? "临近" : "关注";
            out.add(new ExpiryAlert(m.getId(), m.getSupplyId(), m.getSupplyName(), m.getBatchNo(),
                    m.getExpireDate(), daysTo, level));
        }
        out.sort((a, b) -> Long.compare(a.daysToExpire(), b.daysToExpire()));
        return ApiResp.ok(out);
    }

    // ---------- 费用分摊（按部门/项目归集出库金额） ----------

    public record AllocRow(String dept, long moveCount, double totalQty, double totalAmount) {
    }

    public record AllocSummary(List<AllocRow> byDept, double grandTotal, String month) {
    }

    /**
     * 物资费用分摊报表：把出库领用按领用部门归集金额（数量×参考单价），可按月份 month=YYYY-MM 过滤。
     * 月末由行政推送财务，作为部门物资成本分摊依据。
     */
    @GetMapping("/cost/allocation")
    public ApiResp<AllocSummary> costAllocation(@RequestParam(required = false) String month) {
        Map<String, double[]> byDept = new LinkedHashMap<>(); // [count, qty]
        Map<String, BigDecimal> amtByDept = new LinkedHashMap<>();
        BigDecimal grand = BigDecimal.ZERO;
        for (AdminStockMove m : moveRepo.findByDirection("出库")) {
            if (month != null && !month.isBlank()) {
                String md = m.getMoveDate() == null ? "" : m.getMoveDate();
                if (!md.startsWith(month)) {
                    continue;
                }
            }
            String dept = m.getDept() == null || m.getDept().isBlank() ? "未归集" : m.getDept();
            double[] agg = byDept.computeIfAbsent(dept, k -> new double[2]);
            agg[0] += 1;
            agg[1] += nz(m.getQty());
            amtByDept.merge(dept, Money.nz(m.getAmount()), Money::add);
            grand = Money.add(grand, m.getAmount());
        }
        List<AllocRow> rows = new ArrayList<>();
        for (Map.Entry<String, double[]> e : byDept.entrySet()) {
            double[] agg = e.getValue();
            rows.add(new AllocRow(e.getKey(), (long) agg[0], agg[1],
                    amtByDept.getOrDefault(e.getKey(), BigDecimal.ZERO).doubleValue()));
        }
        rows.sort((a, b) -> Double.compare(b.totalAmount(), a.totalAmount()));
        return ApiResp.ok(new AllocSummary(rows, grand.doubleValue(), month == null ? "全部" : month));
    }

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

    private static double nz(Double v) {
        return v == null ? 0d : v;
    }

    private static LocalDate parseDateOrNull(String s) {
        if (s == null || s.isBlank()) {
            return null;
        }
        try {
            return LocalDate.parse(s.trim().substring(0, Math.min(10, s.trim().length())));
        } catch (RuntimeException e) {
            return null;
        }
    }
}