'use strict';

/**
 * 仓库库存动销分析 —— 业务库取数
 *
 * 一次查询覆盖全部仓库 × 全部动销等级：
 *   库存件数：rpt.jst_inventoryInfo 实时库存（按 wms_co_id + sku_id 汇总）
 *   销量：    rpt.jst_OrderItem × rpt.jst_Orders，按 send_date，排除 Delete/Cancelled
 *             （与「每日进销存」的发货口径一致）
 *   日销：    销量 / 统计窗口天数 → 分档得到动销等级
 *
 * 只统计「有库存或有销量」的 SKU：库存为 0 且窗口内无销量的 SKU 已下架，
 * 计入「销售=0」会虚增分母，故整体剔除。
 */

const { SALES_GRADE_RULES } = require('../config/stockSalesAnalysis');

/** mssql 不支持数组参数，按位展开成 @p0,@p1... */
function buildInClause(values, prefix) {
  const params = {};
  const clause = values
    .map((v, i) => {
      const key = `${prefix}${i}`;
      params[key] = v;
      return `@${key}`;
    })
    .join(',');
  return { clause, params };
}

/**
 * 日销分档表达式：从高档往低档依次命中。
 * 最后一档「销售=0」由 `salesQty <= 0` 兜底（销量为 NULL 视同 0）。
 */
function buildGradeCase(salesExpr = 'ISNULL(b.salesQty, 0)', daysParam = '@days') {
  const branches = SALES_GRADE_RULES
    .filter((rule) => rule.lower > 0)
    .map((rule) => {
      const daily = `(${salesExpr} / ${daysParam})`;
      const lower = `${daily} >= ${rule.lower}`;
      const upper = rule.upper == null ? null : `${daily} < ${rule.upper}`;
      const cond = upper ? `${lower} AND ${upper}` : lower;
      return `WHEN ${cond} THEN '${rule.key}'`;
    });

  return `
      CASE
        ${branches.join('\n        ')}
        WHEN ${salesExpr} > 0 THEN 'slow2'
        ELSE 'zero'
      END`;
}

/**
 * 每个仓库 × 每个动销等级的 SKU 数、库存件数、销量。
 * @returns {Promise<Array<{wmsCoId:string, gradeKey:string, skuCount:number, stockQty:number, salesQty:number, dailySales:number}>>}
 */
async function fetchGradeRows(cloudDb, wmsCoIds, { shipFrom, shipTo, days }) {
  if (!cloudDb || typeof cloudDb.query !== 'function') {
    throw new TypeError('fetchGradeRows 的第一个参数必须是业务库实例');
  }
  if (!Array.isArray(wmsCoIds) || wmsCoIds.length === 0) return [];
  if (!shipFrom || !shipTo || !days) return [];

  const invIn = buildInClause(wmsCoIds, 'w');
  const shipIn = buildInClause(wmsCoIds, 'v');
  const gradeCase = buildGradeCase();

  const sqlText = `
    WITH inv AS (
      SELECT i.wms_co_id AS wmsCoId,
             i.sku_id    AS skuId,
             SUM(CAST(ISNULL(i.qty, 0) AS DECIMAL(18, 2))) AS stockQty
        FROM rpt.jst_inventoryInfo i
       WHERE i.wms_co_id IN (${invIn.clause})
       GROUP BY i.wms_co_id, i.sku_id
    ),
    ship AS (
      SELECT o.wms_co_id AS wmsCoId,
             oi.sku_id   AS skuId,
             SUM(CAST(ISNULL(oi.qty, 0) AS DECIMAL(18, 2))) AS salesQty
        FROM rpt.jst_OrderItem oi
        JOIN rpt.jst_Orders o ON o.o_id = oi.o_id
       WHERE o.wms_co_id IN (${shipIn.clause})
         AND o.send_date >= @shipFrom
         AND o.send_date < @shipTo
         AND ISNULL(o.status, '') NOT IN ('Delete', 'Cancelled')
       GROUP BY o.wms_co_id, oi.sku_id
    ),
    base AS (
      SELECT u.wmsCoId,
             u.skuId,
             SUM(u.stockQty) AS stockQty,
             SUM(u.salesQty) AS salesQty
        FROM (
          SELECT wmsCoId, skuId, stockQty, CAST(0 AS DECIMAL(18, 2)) AS salesQty FROM inv
          UNION ALL
          SELECT wmsCoId, skuId, CAST(0 AS DECIMAL(18, 2)) AS stockQty, salesQty FROM ship
        ) u
       GROUP BY u.wmsCoId, u.skuId
    ),
    graded AS (
      SELECT b.wmsCoId,
             b.stockQty,
             b.salesQty,
             ${gradeCase} AS gradeKey
        FROM base b
       WHERE ABS(ISNULL(b.stockQty, 0)) > 0.0001
          OR ABS(ISNULL(b.salesQty, 0)) > 0.0001
    )
    SELECT g.wmsCoId,
           g.gradeKey,
           COUNT(*)                                     AS skuCount,
           CAST(SUM(ISNULL(g.stockQty, 0)) AS DECIMAL(18, 2))  AS stockQty,
           CAST(SUM(ISNULL(g.salesQty, 0)) AS DECIMAL(18, 2))  AS salesQty,
           CAST(SUM(ISNULL(g.salesQty, 0) / @days) AS DECIMAL(18, 4)) AS dailySales
      FROM graded g
     GROUP BY g.wmsCoId, g.gradeKey`;

  const rows = await cloudDb.query(sqlText, {
    ...invIn.params,
    ...shipIn.params,
    shipFrom,
    shipTo,
    days,
  }, { requestTimeout: 180000 });

  return rows.map((r) => ({
    wmsCoId: String(r.wmsCoId),
    gradeKey: String(r.gradeKey),
    skuCount: Number(r.skuCount) || 0,
    stockQty: Number(r.stockQty) || 0,
    salesQty: Number(r.salesQty) || 0,
    dailySales: Number(r.dailySales) || 0,
  }));
}

/**
 * 「销售=0」档的 SKU 级明细（导出用）。
 * 口径与 fetchGradeRows 完全一致：同一分档表达式命中 gradeKey='zero'，
 * 即统计窗口内销量 <= 0 且「有库存或有销量」的 SKU。
 * 系统仓位取自 rpt.jst_packInventoryInfo.bin（一个 SKU 可能占多个仓位，按名称排序后用「、」连接；
 * 库存为 0 的仓位记录已排除）。该表只覆盖部分仓库，未覆盖到的 SKU 返回空串。
 * @returns {Promise<Array<{wmsCoId:string, skuId:string, skuName:string, binName:string, stockQty:number, salesQty:number}>>}
 */
async function fetchZeroSaleSkuRows(cloudDb, wmsCoIds, { shipFrom, shipTo, days }) {
  if (!cloudDb || typeof cloudDb.query !== 'function') {
    throw new TypeError('fetchZeroSaleSkuRows 的第一个参数必须是业务库实例');
  }
  if (!Array.isArray(wmsCoIds) || wmsCoIds.length === 0) return [];
  if (!shipFrom || !shipTo || !days) return [];

  const invIn = buildInClause(wmsCoIds, 'w');
  const shipIn = buildInClause(wmsCoIds, 'v');
  const gradeCase = buildGradeCase();

  const sqlText = `
    WITH bin AS (
      SELECT d.wmsCoId,
             d.skuId,
             STRING_AGG(CAST(d.b AS NVARCHAR(MAX)), '、') WITHIN GROUP (ORDER BY d.b) AS binName
        FROM (
          SELECT DISTINCT p.wms_co_id AS wmsCoId,
                          p.sku_id    AS skuId,
                          LTRIM(RTRIM(p.bin)) AS b
            FROM rpt.jst_packInventoryInfo p
           WHERE ISNULL(p.bin, '') <> ''
             AND ISNULL(p.qty, 0) <> 0
        ) d
       GROUP BY d.wmsCoId, d.skuId
    ),
    inv AS (
      SELECT i.wms_co_id AS wmsCoId,
             i.sku_id    AS skuId,
             SUM(CAST(ISNULL(i.qty, 0) AS DECIMAL(18, 2))) AS stockQty
        FROM rpt.jst_inventoryInfo i
       WHERE i.wms_co_id IN (${invIn.clause})
       GROUP BY i.wms_co_id, i.sku_id
    ),
    ship AS (
      SELECT o.wms_co_id AS wmsCoId,
             oi.sku_id   AS skuId,
             SUM(CAST(ISNULL(oi.qty, 0) AS DECIMAL(18, 2))) AS salesQty
        FROM rpt.jst_OrderItem oi
        JOIN rpt.jst_Orders o ON o.o_id = oi.o_id
       WHERE o.wms_co_id IN (${shipIn.clause})
         AND o.send_date >= @shipFrom
         AND o.send_date < @shipTo
         AND ISNULL(o.status, '') NOT IN ('Delete', 'Cancelled')
       GROUP BY o.wms_co_id, oi.sku_id
    ),
    base AS (
      SELECT u.wmsCoId,
             u.skuId,
             SUM(u.stockQty) AS stockQty,
             SUM(u.salesQty) AS salesQty
        FROM (
          SELECT wmsCoId, skuId, stockQty, CAST(0 AS DECIMAL(18, 2)) AS salesQty FROM inv
          UNION ALL
          SELECT wmsCoId, skuId, CAST(0 AS DECIMAL(18, 2)) AS stockQty, salesQty FROM ship
        ) u
       GROUP BY u.wmsCoId, u.skuId
    ),
    graded AS (
      SELECT b.wmsCoId,
             b.skuId,
             b.stockQty,
             b.salesQty,
             ${gradeCase} AS gradeKey
        FROM base b
       WHERE ABS(ISNULL(b.stockQty, 0)) > 0.0001
          OR ABS(ISNULL(b.salesQty, 0)) > 0.0001
    )
    SELECT g.wmsCoId,
           g.skuId,
           ISNULL(s.name, '') AS skuName,
           ISNULL(bn.binName, '') AS binName,
           CAST(g.stockQty AS DECIMAL(18, 2)) AS stockQty,
           CAST(g.salesQty AS DECIMAL(18, 2)) AS salesQty
      FROM graded g
      LEFT JOIN rpt.jst_sku s ON s.sku_id = g.skuId
      LEFT JOIN bin bn ON bn.wmsCoId = g.wmsCoId AND bn.skuId = g.skuId
     WHERE g.gradeKey = 'zero'
     ORDER BY g.wmsCoId, g.stockQty DESC, g.skuId`;

  const rows = await cloudDb.query(sqlText, {
    ...invIn.params,
    ...shipIn.params,
    shipFrom,
    shipTo,
    days,
  }, { requestTimeout: 180000 });

  return rows.map((r) => ({
    wmsCoId: String(r.wmsCoId),
    skuId: String(r.skuId ?? ''),
    skuName: r.skuName == null ? '' : String(r.skuName),
    binName: r.binName == null ? '' : String(r.binName),
    stockQty: Number(r.stockQty) || 0,
    salesQty: Number(r.salesQty) || 0,
  }));
}

module.exports = {
  buildInClause,
  buildGradeCase,
  fetchGradeRows,
  fetchZeroSaleSkuRows,
};