/**
 * 每日进销存 —— 聚水潭官方进销存导出解析 / 导入
 *
 * 输入为聚水潭进销存报表按仓导出（xlsx），列包含：
 *   仓库、期初数量、[12 个流水列]、期末数量
 * 流水列符号沿用导出原值（出仓为负、入仓为正），前端不做二次转换。
 */
const XLSX = require('xlsx');
const {
  FLOW_COLUMNS,
  DAILY_INVENTORY_BASELINE,
} = require('../config/dailyInventoryBaseline');
const officialDb = require('../config/dailyInventoryOfficialDb');

const FLOW_FIELDS = FLOW_COLUMNS.map((c) => c.field);

/** 流水列中文表头 → field */
const LABEL_TO_FIELD = new Map(FLOW_COLUMNS.map((c) => [c.label, c.field]));

/** 仓库名 → wms_co_id（来自项目仓库清单） */
const WAREHOUSE_TO_ID = new Map(
  DAILY_INVENTORY_BASELINE.map((b) => [b.warehouse, b.wmsCoId])
);

const num = (v) => {
  if (v == null || v === '' || v === '-') return null;
  const n = Number(String(v).replace(/,/g, '').trim());
  return Number.isFinite(n) ? n : null;
};

/**
 * 把「表头 → 值」的记录数组归一化为官方行
 * @param {Array<Object>} records
 * @returns {{rows: Array, warnings: string[]}}
 */
function normalizeRecords(records) {
  const rows = [];
  const warnings = [];
  if (!Array.isArray(records)) return { rows, warnings: ['导入内容不是数组'] };

  records.forEach((rec, idx) => {
    const keys = Object.keys(rec);
    const warehouseKey = keys.find((k) => String(k).trim() === '仓库');
    if (!warehouseKey) return;
    const warehouse = String(rec[warehouseKey] ?? '').trim();
    if (!warehouse) return;

    const openingKey = keys.find((k) => String(k).trim() === '期初数量');
    const closingKey = keys.find((k) => String(k).trim() === '期末数量');
    if (!openingKey && !closingKey) {
      warnings.push(`第 ${idx + 2} 行缺少「期初数量 / 期末数量」列，已跳过`);
      return;
    }

    // 12 个流水列先置 null，导出行里没出现的列保持 null（区别于显式为 0）
    const flows = {};
    for (const field of FLOW_FIELDS) flows[field] = null;
    for (const k of keys) {
      const label = String(k).trim();
      const field = LABEL_TO_FIELD.get(label);
      if (!field) continue;
      flows[field] = num(rec[k]);
    }

    rows.push({
      warehouse,
      wmsCoId: WAREHOUSE_TO_ID.get(warehouse) ?? null,
      openingQty: openingKey ? num(rec[openingKey]) : null,
      closingQty: closingKey ? num(rec[closingKey]) : null,
      flows,
    });
  });

  if (!rows.length) warnings.push('未解析到任何仓库行，请确认包含「仓库」列');
  return { rows, warnings };
}

/**
 * 解析 xlsx 缓冲区（自动定位含「仓库」表头的工作表与表头行）
 * @param {Buffer} buffer
 */
function parseWorkbook(buffer) {
  const wb = XLSX.read(buffer, { type: 'buffer', cellDates: true });
  const warnings = [];
  for (const sheetName of wb.SheetNames) {
    const ws = wb.Sheets[sheetName];
    const grid = XLSX.utils.sheet_to_json(ws, { header: 1, defval: '', blankrows: false });
    const headerIdx = grid.findIndex((r) => r.some((c) => String(c).trim() === '仓库'));
    if (headerIdx < 0) continue;
    const header = grid[headerIdx].map((c) => String(c).trim());
    const body = grid.slice(headerIdx + 1)
      .filter((r) => r.some((c) => String(c).trim() !== ''))
      .map((r) => Object.fromEntries(header.map((h, i) => [h, r[i]])));
    const { rows, warnings: w } = normalizeRecords(body);
    if (rows.length) return { sheetName, rows, warnings: warnings.concat(w) };
    warnings.push(...w);
  }
  return { sheetName: null, rows: [], warnings: warnings.length ? warnings : ['未找到含「仓库」列的工作表'] };
}

/** 恒等式校验：期初 + Σ流水 = 期末 */
function checkBalance(rows, tolerance = 1) {
  return rows
    .map((r) => {
      const flowSum = FLOW_FIELDS.reduce((acc, f) => acc + (Number(r.flows?.[f]) || 0), 0);
      const opening = Number(r.openingQty) || 0;
      const closing = Number(r.closingQty) || 0;
      const diff = opening + flowSum - closing;
      return { warehouse: r.warehouse, opening, flowSum, closing, diff: Number(diff.toFixed(2)) };
    })
    .filter((r) => Math.abs(r.diff) > tolerance);
}

/**
 * 导入某业务日的官方进销存（先清后写）
 * @returns {Promise<{bizDate:string, imported:number, warnings:string[], mismatches:Array, unknownWarehouses:string[], missingWarehouses:string[]}>}
 */
async function importOfficial(bizDate, rows, { source = 'jst-export' } = {}) {
  await officialDb.deleteOfficial(bizDate);
  const imported = await officialDb.upsertOfficial(bizDate, rows, source);
  const mismatches = checkBalance(rows);
  const unknownWarehouses = rows.filter((r) => r.wmsCoId == null).map((r) => r.warehouse);
  const importedNames = new Set(rows.map((r) => r.warehouse));
  const missingWarehouses = DAILY_INVENTORY_BASELINE
    .filter((b) => !importedNames.has(b.warehouse))
    .map((b) => b.warehouse);
  return { bizDate, imported, warnings: [], mismatches, unknownWarehouses, missingWarehouses };
}

module.exports = {
  FLOW_FIELDS,
  LABEL_TO_FIELD,
  normalizeRecords,
  parseWorkbook,
  checkBalance,
  importOfficial,
};