const express = require('express');
const cloudDb = require('../config/cloudDatabase');
const { DAILY_INVENTORY_BASELINE } = require('../config/dailyInventoryBaseline');
const {
  PICKING_BIN_GRADE_RULES,
  PICKING_BIN_WINDOW_OPTIONS,
  PICKING_BIN_DEFAULT_DAYS,
  PICKING_BIN_TOTAL_LABEL,
  PICKING_BIN_BIN_TYPES,
} = require('../config/pickingBinSalesAnalysis');
const { fetchPickingBinSkuRows } = require('../services/pickingBinSalesAnalysis');
const { sendWorkbookDownload } = require('../services/exportWorkbook');

const router = express.Router();

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

/** 结果缓存：一次要扫订单明细 + 仓位明细两张大表，避免连续刷新重复打库 */
const RESULT_CACHE_TTL_MS = 5 * 60 * 1000;
const cacheByKey = new Map();

const round2 = (v) => Math.round((Number(v) || 0) * 100) / 100;
const round4 = (v) => Math.round((Number(v) || 0) * 10000) / 10000;

/** 快照日 + 次日 01:00 作为统一的统计基准时刻 */
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}`;
}

/** 发货窗口：[asOf - N 天, asOf) */
function buildShipWindow(asOf, days) {
  const to = new Date(`${asOf.slice(0, 10)}T${AS_OF_TIME}:00Z`);
  const from = new Date(to.getTime() - days * 86400000);
  const fmt = (dt) => dt.toISOString().slice(0, 19).replace('T', ' ');
  return { shipFrom: fmt(from), shipTo: fmt(to) };
}

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;
}

async function fetchBinTakenAt() {
  const rows = await cloudDb.query(
    `SELECT MAX(updateTime) AS takenAt FROM rpt.jst_packInventoryInfo`
  );
  return rows[0]?.takenAt || null;
}

/** 解析并收敛统计窗口天数，只允许白名单内的取值 */
function resolveDays(raw) {
  const n = Number.parseInt(String(raw ?? ''), 10);
  return PICKING_BIN_WINDOW_OPTIONS.includes(n) ? n : PICKING_BIN_DEFAULT_DAYS;
}

/** 解析仓库过滤，只允许出现在仓库清单里的 wmsCoId，防止任意拼参 */
function resolveWarehouses(raw) {
  const known = DAILY_INVENTORY_BASELINE.filter((b) => b.wmsCoId != null);
  const requested = String(raw || '')
    .split(',')
    .map((v) => v.trim())
    .filter(Boolean);
  const picked = requested.length > 0
    ? known.filter((b) => requested.includes(String(b.wmsCoId)))
    : known;
  return picked;
}

const GRADE_MAP = new Map(PICKING_BIN_GRADE_RULES.map((g) => [g.key, g]));

/** 明细行按「仓库 × 商品编码」去重后的商品个数 */
function dedupeCount(list) {
  return new Set(list.map((it) => `${it.wmsCoId}::${it.skuId}`)).size;
}

/**
 * GET /api/picking-bin-sales-analysis
 * 拣选库位动销分析：仓库 × 仓位 × 商品编码 → 库存数量 / 商品销量 / 商品日销 / 动销等级
 * 动销等级按「商品日销」判定（商品整档销量 ÷ 天数），不做仓位分摊。
 */
router.get('/', async (req, res) => {
  try {
    const force = String(req.query?.refresh || '') === '1';
    const days = resolveDays(req.query?.days);
    const warehouses = resolveWarehouses(req.query?.wmsCoId);
    const wmsCoIds = warehouses.map((b) => String(b.wmsCoId));

    const cacheKey = `${days}::${wmsCoIds.join('|')}`;
    const latestBizDate = await fetchLatestBizDate().catch(() => null);
    const cached = cacheByKey.get(cacheKey);
    if (!force && cached && cached.latestBizDate === latestBizDate
      && Date.now() - cached.at < RESULT_CACHE_TTL_MS) {
      return res.json({ success: true, data: cached.payload, cached: true });
    }

    const asOf = nextDayAsOf(latestBizDate);
    if (!asOf) {
      return res.status(503).json({
        success: false,
        error: '业务库暂无库存监控数据，无法定位统计基准日',
      });
    }

    const { shipFrom, shipTo } = buildShipWindow(asOf, days);
    const [rows, takenAt] = await Promise.all([
      fetchPickingBinSkuRows(cloudDb, wmsCoIds, { shipFrom, shipTo, days }),
      fetchBinTakenAt().catch(() => null),
    ]);

    const whMap = new Map(warehouses.map((b) => [String(b.wmsCoId), b.warehouse]));
    const items = rows.map((r) => ({
      wmsCoId: r.wmsCoId,
      binName: r.binName,
      binType: r.binType,
      skuId: r.skuId,
      warehouse: whMap.get(r.wmsCoId) || r.wmsCoId,
      stockQty: r.stockQty,
      skuCount: r.skuCount,
      salesQty: round2(r.salesQty),
      dailySales: round4(r.dailySales),
      gradeKey: r.gradeKey,
      gradeLabel: GRADE_MAP.get(r.gradeKey)?.label || '',
    }));

    // 每个「仓库 × 商品」只计一次销量，避免同一商品跨多个仓位被重复累加
    const skuSalesMap = new Map();
    rows.forEach((r) => {
      const key = `${r.wmsCoId}::${r.skuId}`;
      if (!skuSalesMap.has(key)) skuSalesMap.set(key, r.salesQty);
    });
    const dedupeSales = (list) => {
      const seen = new Set();
      return list.reduce((acc, it) => {
        const key = `${it.wmsCoId}::${it.skuId}`;
        if (seen.has(key)) return acc;
        seen.add(key);
        return acc + (skuSalesMap.get(key) || 0);
      }, 0);
    };

    // 各动销等级汇总：商品数按「仓库 × 商品」去重，库存按明细行求和（无重复）
    const summary = PICKING_BIN_GRADE_RULES.map((grade) => {
      const hit = items.filter((it) => it.gradeKey === grade.key);
      const salesQty = round2(dedupeSales(hit));
      return {
        key: grade.key,
        label: grade.label,
        tip: grade.tip,
        rowCount: hit.length,
        skuCount: dedupeCount(hit),
        stockQty: round2(hit.reduce((acc, it) => acc + it.stockQty, 0)),
        salesQty,
        dailySales: round4(salesQty / days),
      };
    });

    const dedupeAll = new Set(items.map((it) => `${it.wmsCoId}::${it.skuId}`));
    const totalSales = round2(dedupeSales(items));
    const total = {
      key: '__total__',
      label: PICKING_BIN_TOTAL_LABEL,
      rowCount: items.length,
      skuCount: dedupeAll.size,
      stockQty: round2(summary.reduce((acc, s) => acc + s.stockQty, 0)),
      salesQty: totalSales,
      dailySales: round4(totalSales / days),
    };

    const payload = {
      days,
      windowOptions: PICKING_BIN_WINDOW_OPTIONS,
      binTypes: [...PICKING_BIN_BIN_TYPES],
      binTypeOptions: [...PICKING_BIN_BIN_TYPES],
      latestBizDate,
      asOf,
      shipWindow: { shipFrom, shipTo, days },
      takenAt,
      grades: PICKING_BIN_GRADE_RULES.map((g) => ({ key: g.key, label: g.label, tip: g.tip })),
      totalLabel: PICKING_BIN_TOTAL_LABEL,
      warehouses: warehouses.map((b) => ({ wmsCoId: String(b.wmsCoId), warehouse: b.warehouse })),
      items,
      summary,
      total,
    };

    cacheByKey.set(cacheKey, { latestBizDate, at: Date.now(), payload });
    return res.json({ success: true, data: payload });
  } catch (error) {
    console.error('[picking-bin-sales-analysis] 查询失败:', error.message);
    return res.status(500).json({
      success: false,
      error: '拣选库位动销分析数据查询失败',
      detail: error.message,
    });
  }
});

/**
 * GET /api/picking-bin-sales-analysis/export
 * 导出库位明细（只含拣选位）。query: days、wmsCoId（逗号分隔）、grade（逗号分隔）、format（xlsx|csv）
 */
router.get('/export', async (req, res) => {
  try {
    const days = resolveDays(req.query?.days);
    const warehouses = resolveWarehouses(req.query?.wmsCoId);
    const wmsCoIds = warehouses.map((b) => String(b.wmsCoId));
    const format = String(req.query?.format || 'xlsx').toLowerCase() === 'csv' ? 'csv' : 'xlsx';

    const grades = String(req.query?.grade || '')
      .split(',')
      .map((v) => v.trim())
      .filter((v) => GRADE_MAP.has(v));

    const latestBizDate = await fetchLatestBizDate().catch(() => null);
    const asOf = nextDayAsOf(latestBizDate);
    if (!asOf) {
      return res.status(503).json({
        success: false,
        error: '业务库暂无库存监控数据，无法定位统计基准日',
      });
    }

    const { shipFrom, shipTo } = buildShipWindow(asOf, days);
    // 导出按「仓位 × 商品编码」拆行：一个仓位有 N 个商品就输出 N 行
    const rows = await fetchPickingBinSkuRows(cloudDb, wmsCoIds, { shipFrom, shipTo, days });

    const whMap = new Map(warehouses.map((b) => [String(b.wmsCoId), b.warehouse]));
    const filtered = grades.length > 0
      ? rows.filter((r) => grades.includes(r.gradeKey))
      : rows;

    const sheetRows = filtered.map((r) => [
      whMap.get(r.wmsCoId) || r.wmsCoId,
      r.binName,
      r.binType,
      r.skuId,
      r.stockQty,
      r.skuCount,
      round2(r.salesQty),
      round4(r.allocatedSalesQty),
      round4(r.dailySales),
      GRADE_MAP.get(r.gradeKey)?.label || r.gradeKey,
      days,
      latestBizDate || '',
    ]);

    const fileName = `拣选库位动销分析-${(latestBizDate || '').replace(/-/g, '') || '未知日期'}`;
    const { totalRows } = sendWorkbookDownload(res, {
      fileName,
      format,
      sheets: [{
        name: '库位动销明细',
        header: [
          '仓库', '仓位', '类型', '商品编码', '库存数量', '仓位SKU数',
          `商品销量(近${days}天)`, `分摊销量(近${days}天)`, '商品日销',
          '动销等级', '统计天数', '统计基准日',
        ],
        rows: sheetRows,
      }],
    });
    console.log(`[picking-bin-sales-analysis] 导出: ${totalRows} 行, 仓库 ${wmsCoIds.length} 个, 仅拣选位, 窗口 ${days} 天`);
    return null;
  } catch (error) {
    console.error('[picking-bin-sales-analysis] 导出失败:', error.message);
    if (!res.headersSent) {
      return res.status(500).json({
        success: false,
        error: '拣选库位动销分析导出失败',
        detail: error.message,
      });
    }
    return null;
  }
});

module.exports = router;