const express = require('express');
const cloudDb = require('../config/cloudDatabase');
const {
  DAILY_INVENTORY_BASELINE,
  BASELINE_DATE,
  FLOW_COLUMNS,
} = require('../config/dailyInventoryBaseline');

const router = express.Router();

/** 库存衡量基准时刻：快照日次日 01:00（报表库每日凌晨 1 点跑批，标注 T-1） */
const AS_OF_TIME = '01:00';

const toNumber = (v) => {
  if (v == null) return null;
  const n = Number(v);
  return Number.isFinite(n) ? n : null;
};

/** 快照日 + 次日 01:00 作为统一的库龄/分级基准 */
function nextDayAsOf(bizDate) {
  if (!bizDate || !/^\d{4}-\d{2}-\d{2}$/.test(bizDate)) return null;
  const d = new Date(`${bizDate}T00:00:00Z`);
  d.setUTCDate(d.getUTCDate() + 1);
  return `${d.toISOString().slice(0, 10)} ${AS_OF_TIME}`;
}

async function fetchLatestBizDate() {
  const rows = await cloudDb.query(
    `SELECT MAX(CONVERT(VARCHAR(10), date, 23)) AS d FROM rpt.pm_stockMonitor`
  );
  return rows[0]?.d || null;
}

/**
 * 派生列（SQL CASE WHEN 下沉计算）
 * - 库龄(天) = DATEDIFF(asOf, created)
 * - 库存周转天数 = 月度发货总件数 / 月度日均库存件数 × 100%
 *   月度发货总件数 = threeAvgSale × 30；月度日均库存件数 = jsStock
 * - 四级分级：库龄 + 周转率双维度
 */
function buildDerivedColumns(asOf) {
  const A = '@asOf';
  void A;
  const ageDays = `DATEDIFF(DAY, m.created, @asOf)`;
  const turnover = `(ISNULL(m.threeAvgSale, 0) * 30.0 * 100.0 / NULLIF(m.jsStock, 0))`;
  return {
    ageDays,
    turnoverDays: `CAST(${turnover} AS DECIMAL(18, 4))`,
    levelExpr: `
      CASE
        WHEN m.created IS NULL OR ISNULL(m.jsStock, 0) = 0 OR ${turnover} IS NULL THEN NULL
        WHEN ${ageDays} < 90 AND ${turnover} BETWEEN 30 AND 199 THEN 'warn'
        WHEN ${ageDays} < 90 AND ${turnover} >= 200 THEN 'slow'
        WHEN ${ageDays} >= 90 AND ${turnover} BETWEEN 30 AND 99 THEN 'slow'
        WHEN ${ageDays} BETWEEN 90 AND 365 AND ${turnover} >= 100 THEN 'stale'
        WHEN ${ageDays} > 365 AND ${turnover} BETWEEN 100 AND 199 THEN 'stale'
        WHEN ${ageDays} > 365 AND ${turnover} >= 200 THEN 'zombie'
        ELSE NULL
      END`,
  };
}

/** 该仓快照里的四级库存量与平均周转天数 */
async function fetchGradeMetrics(dbWarehouse, bizDate, asOf) {
  const D = buildDerivedColumns(asOf);
  const rows = await cloudDb.query(
    `SELECT COUNT(*) AS skuCount,
            SUM(CAST(ISNULL(m.jsStock, 0) AS DECIMAL(18, 2))) AS gradeStock,
            AVG(${D.turnoverDays}) AS avgTurnover,
            SUM(CASE WHEN ${D.levelExpr} = 'warn' THEN CAST(ISNULL(m.jsStock, 0) AS DECIMAL(18, 2)) ELSE 0 END) AS warnLevel,
            SUM(CASE WHEN ${D.levelExpr} = 'slow' THEN CAST(ISNULL(m.jsStock, 0) AS DECIMAL(18, 2)) ELSE 0 END) AS slowLevel,
            SUM(CASE WHEN ${D.levelExpr} = 'stale' THEN CAST(ISNULL(m.jsStock, 0) AS DECIMAL(18, 2)) ELSE 0 END) AS staleLevel,
            SUM(CASE WHEN ${D.levelExpr} = 'zombie' THEN CAST(ISNULL(m.jsStock, 0) AS DECIMAL(18, 2)) ELSE 0 END) AS zombieLevel
       FROM rpt.pm_stockMonitor m
      WHERE m.warehouse = @warehouse
        AND CONVERT(VARCHAR(10), m.date, 23) = @bizDate`,
    { warehouse: dbWarehouse, bizDate, asOf }
  );
  const r = rows[0] || {};
  if (!Number(r.skuCount || 0)) return null;
  return {
    skuCount: toNumber(r.skuCount),
    gradeStock: toNumber(r.gradeStock),
    turnoverDays: toNumber(r.avgTurnover),
    warnLevel: toNumber(r.warnLevel),
    slowLevel: toNumber(r.slowLevel),
    staleLevel: toNumber(r.staleLevel),
    zombieLevel: toNumber(r.zombieLevel),
  };
}

/** 实时期末库存（单仓 wms_co_id），并带回最近更新时间便于核对时效 */
async function fetchClosingQty(wmsCoId) {
  if (wmsCoId == null) return null;
  const rows = await cloudDb.query(
    `SELECT ISNULL(SUM(CAST(qty AS DECIMAL(18, 2))), 0) AS qty,
            COUNT(CASE WHEN ISNULL(qty, 0) <> 0 THEN 1 END) AS skuCount,
            MAX(modified) AS takenAt
       FROM rpt.jst_inventoryInfo
      WHERE wms_co_id = @wmsCoId`,
    { wmsCoId }
  );
  const r = rows[0] || {};
  return {
    closingQty: toNumber(r.qty),
    closingSkuCount: toNumber(r.skuCount) || 0,
    closingTakenAt: r.takenAt || null,
  };
}

/**
 * GET /api/daily-inventory
 * 每日进销存：25 个仓库 × 进销存流水 + 期末 + 分级库存量
 *
 * 数据源分工：
 *   - 期初数量 与 12 个流水列：22 号基准（dailyInventoryBaseline.js）
 *   - 期末数量：jst_inventoryInfo 实时库存
 *   - 库存周转天数 / 四级库存量：pm_stockMonitor 快照
 */
router.get('/', async (req, res) => {
  try {
    const latestBizDate = await fetchLatestBizDate().catch(() => null);
    const asOf = nextDayAsOf(latestBizDate);

    const items = [];
    for (const base of DAILY_INVENTORY_BASELINE) {
      const flows = {};
      for (const col of FLOW_COLUMNS) flows[col.field] = base[col.field] ?? 0;

      const closing = await fetchClosingQty(base.wmsCoId).catch(() => null);
      const grade = base.dbWarehouse && latestBizDate
        ? await fetchGradeMetrics(base.dbWarehouse, latestBizDate, asOf).catch(() => null)
        : null;

      items.push({
        warehouse: base.warehouse,
        dbWarehouse: base.dbWarehouse,
        openingQty: base.openingQty,
        openingQtyExtra: base.openingQtyExtra,
        ...flows,
        closingQty: closing?.closingQty ?? null,
        closingSkuCount: closing?.closingSkuCount ?? null,
        closingTakenAt: closing?.closingTakenAt ?? null,
        turnoverDays: grade?.turnoverDays ?? null,
        gradeStock: grade?.gradeStock ?? null,
        warnLevel: grade?.warnLevel ?? null,
        slowLevel: grade?.slowLevel ?? null,
        staleLevel: grade?.staleLevel ?? null,
        zombieLevel: grade?.zombieLevel ?? null,
        hasGrade: Boolean(grade),
      });
    }

    // 合计行：便于与表格总额核对
    const sum = (k) => items.reduce((acc, it) => acc + (Number(it[k]) || 0), 0);
    const totals = { warehouse: '合计', dbWarehouse: '', isTotal: true };
    for (const k of ['openingQty', 'openingQtyExtra', ...FLOW_COLUMNS.map((c) => c.field), 'closingQty', 'warnLevel', 'slowLevel', 'staleLevel', 'zombieLevel']) {
      totals[k] = Number(sum(k).toFixed(2));
    }

    res.json({
      success: true,
      data: {
        baselineDate: BASELINE_DATE,
        latestBizDate,
        asOf,
        flowColumns: FLOW_COLUMNS,
        items,
        totals,
      },
    });
  } catch (error) {
    console.error('[daily-inventory] 查询失败:', error.message);
    res.status(500).json({ success: false, error: '每日进销存数据查询失败', detail: error.message });
  }
});

module.exports = router;