import React, { useEffect, useMemo, useState } from 'react';
import { useParams, useNavigate } from 'react-router-dom';
import {
  Alert,
  Button,
  Input,
  Popover,
  Segmented,
  Skeleton,
  Table,
  Tag,
  Tooltip,
} from 'antd';
import {
  InfoCircleOutlined,
  QuestionCircleOutlined,
  ReloadOutlined,
  SearchOutlined,
  WarningOutlined,
} from '@ant-design/icons';
import { SycmBusinessPanel, SycmPage } from '../../components/Common';
import {
  findWarehouseBySlug,
  FORMULA_DESCRIPTION,
  LARGE_STOCK_MONITOR_WAREHOUSES,
  LEVEL_COLOR,
  LEVEL_FILTER_OPTIONS,
  LEVEL_LABEL,
  OVERVIEW_COLUMNS,
} from '../../constants/largeStockMonitor';
import {
  getLargeStockMonitorOverview,
  getLargeStockMonitorSkuList,
} from '../../api/largeStockMonitor';
import './style.css';

function formatNumber(value) {
  if (value === null || value === undefined || Number.isNaN(Number(value))) return value;
  const n = Number(value);
  if (!Number.isFinite(n)) return value;
  return n.toLocaleString('zh-CN', { maximumFractionDigits: 2 });
}

function formatPercent(value) {
  if (value === null || value === undefined || Number.isNaN(Number(value))) return value;
  const n = Number(value);
  if (!Number.isFinite(n)) return value;
  return `${n.toLocaleString('zh-CN', { maximumFractionDigits: 1 })}%`;
}

function formatMonths(value) {
  if (value === null || value === undefined || Number.isNaN(Number(value))) return value;
  const n = Number(value);
  if (!Number.isFinite(n)) return value;
  return `${n.toLocaleString('zh-CN', { maximumFractionDigits: 1 })} 月`;
}

function formatStock(value) {
  if (value === null || value === undefined || Number.isNaN(Number(value))) return value;
  const n = Number(value);
  if (!Number.isFinite(n)) return value;
  return n.toLocaleString('zh-CN', { maximumFractionDigits: 0 });
}

const OVERVIEW_RENDERERS = {
  periodStart: formatStock,
  openingBalance: formatStock,
  purchaseReturn: formatStock,
  purchaseIn: formatStock,
  salesOut: formatStock,
  salesReturn: formatStock,
  closingQty: formatStock,
  turnoverDays: formatPercent,
  warnLevel: formatStock,
  slowLevel: formatStock,
  staleLevel: formatStock,
  zombieLevel: formatStock,
};

const FormulaHelp = () => (
  <div className="large-stock-monitor-formula">
    <div className="large-stock-monitor-formula__title">计算口径</div>
    <ul>
      {FORMULA_DESCRIPTION.map((line) => (
        <li key={line}>{line}</li>
      ))}
    </ul>
  </div>
);

const LargeStockMonitor = () => {
  const { warehouseSlug } = useParams();
  const navigate = useNavigate();

  const warehouse = useMemo(() => {
    if (!warehouseSlug) return null;
    return findWarehouseBySlug(warehouseSlug) || LARGE_STOCK_MONITOR_WAREHOUSES[0] || null;
  }, [warehouseSlug]);

  const [overview, setOverview] = useState(null);
  const [overviewLoading, setOverviewLoading] = useState(true);
  const [overviewError, setOverviewError] = useState(null);

  const [skuListState, setSkuListState] = useState({
    items: [],
    total: 0,
    page: 1,
    pageSize: 20,
    loading: false,
  });
  const [filterLevel, setFilterLevel] = useState('');
  const [keyword, setKeyword] = useState('');

  useEffect(() => {
    if (!warehouse) {
      setOverview(null);
      setOverviewLoading(false);
      return;
    }
    let cancelled = false;
    setOverviewLoading(true);
    setOverviewError(null);
    getLargeStockMonitorOverview(warehouse.warehouse)
      .then((res) => {
        if (cancelled) return;
        setOverview(res?.data || null);
      })
      .catch((error) => {
        if (cancelled) return;
        setOverviewError(error?.message || '获取概览失败');
        setOverview(null);
      })
      .finally(() => {
        if (cancelled) return;
        setOverviewLoading(false);
      });
    return () => {
      cancelled = true;
    };
  }, [warehouse]);

  const reloadSkuList = (nextPage, nextPageSize, nextLevel, nextKeyword) => {
    if (!warehouse) return;
    setSkuListState((prev) => ({ ...prev, loading: true }));
    getLargeStockMonitorSkuList({
      warehouse: warehouse.warehouse,
      page: nextPage,
      pageSize: nextPageSize,
      level: nextLevel,
      keyword: nextKeyword,
    })
      .then((res) => {
        setSkuListState({
          items: res?.data?.items || [],
          total: res?.data?.total || 0,
          page: nextPage,
          pageSize: nextPageSize,
          loading: false,
        });
      })
      .catch(() => {
        setSkuListState((prev) => ({ ...prev, loading: false }));
      });
  };

  useEffect(() => {
    if (!warehouse) return;
    reloadSkuList(1, skuListState.pageSize, filterLevel, keyword.trim());
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [warehouse, filterLevel]);

  const handleTableChange = (pagination) => {
    const nextPage = pagination.current || 1;
    const nextPageSize = pagination.pageSize || 20;
    reloadSkuList(nextPage, nextPageSize, filterLevel, keyword.trim());
  };

  const handleSearch = () => {
    reloadSkuList(1, skuListState.pageSize, filterLevel, keyword.trim());
  };

  const overviewCells = useMemo(() => {
    const map = overview?.overview || null;
    return OVERVIEW_COLUMNS.map((column) => {
      const value = map ? map[column.key] : '—';
      const rendered = column.available && value !== '—' && OVERVIEW_RENDERERS[column.key]
        ? OVERVIEW_RENDERERS[column.key](value)
        : value;
      return { ...column, value, rendered };
    });
  }, [overview]);

  const skuColumns = useMemo(() => ([
    {
      title: 'SKU',
      dataIndex: 'sku',
      key: 'sku',
      width: 130,
      fixed: 'left',
      render: (value, record) => (
        <div className="large-stock-monitor-sku-cell">
          <strong>{value || '-'}</strong>
          {record.spu ? <span className="large-stock-monitor-sku-cell__meta">SPU {record.spu}</span> : null}
        </div>
      ),
    },
    {
      title: '商品名称',
      dataIndex: 'skuName',
      key: 'skuName',
      width: 260,
      render: (value) => <span title={value}>{value || '-'}</span>,
    },
    {
      title: '分类',
      dataIndex: 'category',
      key: 'category',
      width: 120,
      render: (value) => value || '-',
    },
    {
      title: '供应商',
      dataIndex: 'supplier',
      key: 'supplier',
      width: 140,
      render: (value) => value || '-',
    },
    {
      title: '当前库存',
      dataIndex: 'jsStock',
      key: 'jsStock',
      width: 100,
      align: 'right',
      render: formatStock,
    },
    {
      title: () => (
        <span>
          库龄
          <Tooltip title="(今天 - 入库时间) / 30，单位：月">
            <QuestionCircleOutlined style={{ marginLeft: 4, color: '#999' }} />
          </Tooltip>
        </span>
      ),
      dataIndex: 'ageMonths',
      key: 'ageMonths',
      width: 100,
      align: 'right',
      render: formatMonths,
    },
    {
      title: () => (
        <span>
          月度发货
          <Tooltip title="≈ threeAvgSale × 30（业务库仅有 3 天日均销量）">
            <QuestionCircleOutlined style={{ marginLeft: 4, color: '#999' }} />
          </Tooltip>
        </span>
      ),
      dataIndex: 'monthlyShipment',
      key: 'monthlyShipment',
      width: 110,
      align: 'right',
      render: formatNumber,
    },
    {
      title: () => (
        <span>
          日均库存
          <Tooltip title="≈ jsStock（业务库仅保留最近一天快照，作为日均近似）">
            <QuestionCircleOutlined style={{ marginLeft: 4, color: '#999' }} />
          </Tooltip>
        </span>
      ),
      dataIndex: 'avgDailyStock',
      key: 'avgDailyStock',
      width: 110,
      align: 'right',
      render: formatStock,
    },
    {
      title: () => (
        <span>
          库存周转天数
          <Tooltip title="= 月度发货 / 日均库存 × 100%（实际为周转率 %，沿用 Excel 列名）">
            <QuestionCircleOutlined style={{ marginLeft: 4, color: '#999' }} />
          </Tooltip>
        </span>
      ),
      dataIndex: 'turnoverDays',
      key: 'turnoverDays',
      width: 130,
      align: 'right',
      render: formatPercent,
    },
    {
      title: '级别',
      dataIndex: 'level',
      key: 'level',
      width: 130,
      fixed: 'right',
      render: (value) => {
        if (!value) return <span style={{ color: '#999' }}>—</span>;
        return <Tag color={LEVEL_COLOR[value]}>{LEVEL_LABEL[value] || value}</Tag>;
      },
    },
  ]), []);

  const siblingOptions = useMemo(() => LARGE_STOCK_MONITOR_WAREHOUSES.map((entry) => ({
    label: `${entry.group} · ${entry.warehouse.replace(/^简尚-/, '')}`,
    value: entry.slug,
    idx: entry.idx,
    group: entry.group,
  })), []);

  const fallbackNotice = warehouse && overview && !overview.hasData;

  return (
    <SycmPage className="large-stock-monitor-page">
      <SycmBusinessPanel className="large-stock-monitor-header" aria-label="大货库存监控概览">
        <div className="large-stock-monitor-header__top">
          <div>
            <h2>
              大货库存监控 · {warehouse ? warehouse.warehouse : '请选择仓库'}
              <Popover
                content={<FormulaHelp />}
                title="计算口径"
                trigger="hover"
                placement="rightTop"
              >
                <InfoCircleOutlined
                  style={{ marginLeft: 8, fontSize: 16, color: '#1677ff', cursor: 'help' }}
                />
              </Popover>
            </h2>
            <p className="large-stock-monitor-header__meta">
              <span>二级分类：{warehouse ? warehouse.group : '-'}</span>
              <span>分布时间：{overview?.asOf || overview?.latestBizDate || '—'}</span>
              {overview?.latestBizDate ? <span>库存快照日：{overview.latestBizDate}</span> : null}
              {overview?.closingTakenAt ? (
                <span>库存取数时间：{new Date(overview.closingTakenAt).toLocaleString('zh-CN', { hour12: false })}（实时）</span>
              ) : null}
              {overview?.period ? (
                <span>
                  流水区间：{overview.period.start} ~ {overview.period.end}（左闭右开）
                </span>
              ) : null}
              <span>SKU 数：{overview?.skuCount ?? '—'}</span>
              <span>平均周转率：{overview?.turnoverDaysAvg != null ? formatPercent(overview.turnoverDaysAvg) : '—'}</span>
              <span>最大周转率：{overview?.turnoverDaysMax != null ? formatPercent(overview.turnoverDaysMax) : '—'}</span>
            </p>
          </div>
          <div className="large-stock-monitor-header__actions">
            <Segmented
              value={warehouse?.slug}
              onChange={(value) => {
                if (value) {
                  navigate(`/planning/large-stock-monitor/${value}`);
                }
              }}
              options={siblingOptions.slice(0, 6)}
              className="large-stock-monitor-quick-switch"
            />
            <Button
              icon={<ReloadOutlined />}
              onClick={() => {
                if (warehouse) navigate(`/planning/large-stock-monitor/${warehouse.slug}`);
              }}
            >
              刷新
            </Button>
          </div>
        </div>

        {overviewError ? (
          <Alert
            type="error"
            showIcon
            message={`获取概览失败：${overviewError}`}
            style={{ marginBottom: 12 }}
          />
        ) : null}

        {fallbackNotice ? (
          <Alert
            type="warning"
            showIcon
            icon={<WarningOutlined />}
            message="业务库暂未同步该仓库的库存快照，周转率与四级库存量无数据源，显示「—」"
            style={{ marginBottom: 12 }}
          />
        ) : null}

        {overview && overview.hasGrade === false ? (
          <Alert
            type="info"
            showIcon
            message="该仓库没有库存快照（pm_stockMonitor），库龄、周转天数与四级库存量无数据源，显示「—」；期末数量已按聚水潭实际库存取数"
            style={{ marginBottom: 12 }}
          />
        ) : null}

        {overview?.hasGrade && overview?.gradeBasisStock ? (
          <Alert
            type="warning"
            showIcon
            icon={<WarningOutlined />}
            message={`期末数量按聚水潭实际库存统计；四级库存量由库存快照分级得出，快照为「归属仓」口径（含已调拨到外仓的货，合计 ${formatStock(overview.gradeBasisStock)}），两者口径不同，不能直接相加核对`}
            style={{ marginBottom: 12 }}
          />
        ) : null}

        {overview?.requestedDate && overview?.fallbackDate ? (
          <Alert
            type="info"
            showIcon
            message={`未找到 ${overview.requestedDate} 的库存快照，已自动回退并展示 ${overview.fallbackDate} 的数据`}
            style={{ marginBottom: 12 }}
          />
        ) : null}

        {overview?.requestedDate && !overview?.fallbackDate && !overview?.hasData ? (
          <Alert
            type="warning"
            showIcon
            message={`未找到 ${overview.requestedDate} 及之前的库存快照，当前汇总字段全部为占位符「—」`}
            style={{ marginBottom: 12 }}
          />
        ) : null}

        <div className="large-stock-monitor-overview">
          {overviewLoading ? (
            <Skeleton active paragraph={{ rows: 2 }} />
          ) : (
            <div className="large-stock-monitor-grid">
              {overviewCells.map((cell) => (
                <div
                  key={cell.key}
                  className={`large-stock-monitor-grid__cell${cell.available ? ' is-available' : ' is-placeholder'}`}
                >
                  <span className="large-stock-monitor-grid__label">
                    {cell.label}
                    {cell.estimated ? <em className="large-stock-monitor-grid__est">估</em> : null}
                    {cell.tip ? (
                      <Tooltip title={cell.tip}>
                        <QuestionCircleOutlined className="large-stock-monitor-grid__help" />
                      </Tooltip>
                    ) : null}
                  </span>
                  <strong className="large-stock-monitor-grid__value">{cell.rendered}</strong>
                </div>
              ))}
            </div>
          )}
        </div>
      </SycmBusinessPanel>

      <SycmBusinessPanel className="large-stock-monitor-table" aria-label="SKU 库存明细">
        <div className="large-stock-monitor-toolbar">
          <span className="large-stock-monitor-toolbar__note">
            明细按库存快照（归属仓口径）分级，用于识别滞销/慢流/呆滞/僵尸 SKU
          </span>
          <Segmented
            value={filterLevel}
            onChange={setFilterLevel}
            options={LEVEL_FILTER_OPTIONS}
          />
          <Input.Search
            allowClear
            placeholder="搜索 SKU 编码或商品名称"
            value={keyword}
            onChange={(event) => setKeyword(event.target.value)}
            onSearch={handleSearch}
            enterButton={<><SearchOutlined /> 查询</>}
            style={{ maxWidth: 320 }}
          />
        </div>

        <Table
          className="large-stock-monitor-data-table"
          rowKey={(record) => `${record.sku}-${record.warehouse}`}
          columns={skuColumns}
          dataSource={skuListState.items}
          loading={skuListState.loading}
          scroll={{ x: 1280 }}
          pagination={{
            current: skuListState.page,
            pageSize: skuListState.pageSize,
            total: skuListState.total,
            showSizeChanger: true,
            showTotal: (total) => `共 ${total} 条`,
            pageSizeOptions: ['20', '50', '100'],
          }}
          onChange={handleTableChange}
          locale={{ emptyText: '该仓库暂无 SKU 库存快照' }}
        />
      </SycmBusinessPanel>
    </SycmPage>
  );
};

export default LargeStockMonitor;