'use strict';

const fs = require('fs');
const path = require('path');
const dayjs = require('dayjs');
const XLSX = require('xlsx');
const database = require('../config/database');

const INSERT_BATCH_SIZE = 500;

const TARGET_COLUMNS = [
  'stat_date',
  'as_id',
  'outer_as_id',
  'o_id',
  'so_id',
  'process_result',
  'question_type',
  'apply_time',
  'original_order_no',
  'original_courier_name',
  'original_waybill_no',
  'source_file',
];

function textOrEmpty(value) {
  if (value === null || value === undefined) {
    return '';
  }
  return String(value).trim();
}

function normalizeWaybill(value) {
  return textOrEmpty(value).replace(/^[@']+(?=[A-Za-z0-9])/u, '');
}

function normalizeDate(value) {
  const parsed = dayjs(value);
  if (!parsed.isValid()) {
    throw new Error(`Invalid date: ${value}`);
  }
  return parsed.format('YYYY-MM-DD');
}

function normalizeDateTime(value) {
  if (value === null || value === undefined || value === '') {
    return null;
  }

  if (value instanceof Date) {
    const parsed = dayjs(value);
    return parsed.isValid() ? parsed.format('YYYY-MM-DD HH:mm:ss') : null;
  }

  if (typeof value === 'number') {
    const decoded = XLSX.SSF.parse_date_code(value);
    if (!decoded) return null;
    return dayjs(new Date(
      decoded.y,
      decoded.m - 1,
      decoded.d,
      decoded.H,
      decoded.M,
      Math.floor(decoded.S)
    )).format('YYYY-MM-DD HH:mm:ss');
  }

  const text = textOrEmpty(value).replace(/\//g, '-');
  if (!text) return null;
  const parsed = dayjs(text);
  return parsed.isValid() ? parsed.format('YYYY-MM-DD HH:mm:ss') : null;
}

function normalizeSheetRow(row) {
  const normalized = {};
  for (const [key, value] of Object.entries(row || {})) {
    normalized[textOrEmpty(key)] = value;
  }
  return normalized;
}

function getRowValue(row, keys) {
  for (const key of keys) {
    if (Object.prototype.hasOwnProperty.call(row, key)) {
      return row[key];
    }
  }
  return '';
}

function parseWorkbook(filePath) {
  const extension = path.extname(filePath).toLowerCase();
  const workbook = extension === '.csv' || extension === '.tsv'
    ? XLSX.read(fs.readFileSync(filePath, 'utf8'), {
        type: 'string',
        raw: false,
      })
    : XLSX.readFile(filePath, {
        cellDates: true,
        raw: false,
      });
  const sheetName = workbook.SheetNames[0];
  if (!sheetName) {
    throw new Error(`Workbook has no sheets: ${filePath}`);
  }

  return XLSX.utils.sheet_to_json(workbook.Sheets[sheetName], {
    defval: '',
    raw: false,
  }).map(normalizeSheetRow);
}

function toImportRow(row, sourceFile) {
  const applyTime = normalizeDateTime(getRowValue(row, ['申请日期']));
  if (!applyTime) {
    return null;
  }

  const asId = textOrEmpty(getRowValue(row, ['售后单号']));
  const outerAsId = textOrEmpty(getRowValue(row, ['退款编码']));
  if (!asId && !outerAsId) {
    return null;
  }

  return {
    stat_date: normalizeDate(applyTime),
    as_id: asId,
    outer_as_id: outerAsId,
    o_id: textOrEmpty(getRowValue(row, ['内部订单号'])),
    so_id: textOrEmpty(getRowValue(row, ['线上订单号', '线上子订单编号'])),
    process_result: textOrEmpty(getRowValue(row, ['处理结果'])),
    question_type: textOrEmpty(getRowValue(row, ['问题类型'])),
    apply_time: applyTime,
    original_order_no: textOrEmpty(getRowValue(row, ['原始订单号'])),
    original_courier_name: textOrEmpty(getRowValue(row, ['原订单快递'])),
    original_waybill_no: normalizeWaybill(getRowValue(row, ['原订单快递单号'])),
    source_file: sourceFile,
  };
}

function toInsertRow(row) {
  return TARGET_COLUMNS.map((column) => {
    if (column === 'apply_time') {
      return row[column] || null;
    }
    return row[column] || '';
  });
}

async function upsertRows(rows) {
  if (rows.length === 0) {
    return;
  }

  const columnSql = TARGET_COLUMNS.map((column) => `\`${column}\``).join(', ');
  for (let index = 0; index < rows.length; index += INSERT_BATCH_SIZE) {
    const batch = rows.slice(index, index + INSERT_BATCH_SIZE).map(toInsertRow);
    await database.local.query(
      `INSERT INTO aftersales_refund_export_override (${columnSql})
       VALUES ?
       ON DUPLICATE KEY UPDATE
         o_id = VALUES(o_id),
         so_id = VALUES(so_id),
         process_result = VALUES(process_result),
         question_type = VALUES(question_type),
         apply_time = VALUES(apply_time),
         original_order_no = VALUES(original_order_no),
         original_courier_name = VALUES(original_courier_name),
         original_waybill_no = VALUES(original_waybill_no),
         source_file = VALUES(source_file),
         imported_at = NOW()`,
      [batch]
    );
  }
}

function buildDateFilter(startDate, endDate) {
  if (!startDate && !endDate) {
    return () => true;
  }

  const start = startDate ? normalizeDate(startDate) : null;
  const end = endDate ? normalizeDate(endDate) : start;
  return (row) => {
    if (start && row.stat_date < start) return false;
    if (end && row.stat_date > end) return false;
    return true;
  };
}

async function importAftersalesRefundExportOverrideFile(filePath, options = {}) {
  const resolvedPath = path.resolve(filePath);
  if (!fs.existsSync(resolvedPath)) {
    throw new Error(`File not found: ${resolvedPath}`);
  }

  const sourceFile = path.basename(resolvedPath);
  const shouldKeep = buildDateFilter(options.startDate, options.endDate);
  const rows = parseWorkbook(resolvedPath)
    .map((row) => toImportRow(row, sourceFile))
    .filter(Boolean)
    .filter(shouldKeep);

  await upsertRows(rows);

  const dateSummary = rows.reduce((acc, row) => {
    acc[row.stat_date] = (acc[row.stat_date] || 0) + 1;
    return acc;
  }, {});

  return {
    filePath: resolvedPath,
    rowCount: rows.length,
    dates: Object.keys(dateSummary).sort(),
    dateSummary,
  };
}

function buildOverrideSetClause() {
  return `
    t.process_result = CASE
      WHEN NULLIF(o.process_result, '') IS NOT NULL THEN o.process_result
      ELSE t.process_result
    END,
    t.original_order_no = CASE
      WHEN NULLIF(o.original_order_no, '') IS NOT NULL THEN o.original_order_no
      ELSE t.original_order_no
    END,
    t.original_courier_name = CASE
      WHEN NULLIF(o.original_courier_name, '') IS NOT NULL THEN o.original_courier_name
      ELSE t.original_courier_name
    END,
    t.original_waybill_no = CASE
      WHEN NULLIF(o.original_waybill_no, '') IS NOT NULL THEN o.original_waybill_no
      ELSE t.original_waybill_no
    END
  `;
}

async function applyAftersalesRefundExportOverrides(statDate) {
  const setClause = buildOverrideSetClause();
  const updates = [
    `UPDATE aftersales_refund_detail_read t
     JOIN aftersales_refund_export_override o
       ON t.stat_date = o.stat_date
      AND t.as_id <> ''
      AND o.as_id <> ''
      AND t.as_id = o.as_id
     SET ${setClause}
     WHERE t.stat_date = ?`,
    `UPDATE aftersales_refund_detail_read t
     JOIN aftersales_refund_export_override o
       ON t.stat_date = o.stat_date
      AND t.outer_as_id <> ''
      AND o.outer_as_id <> ''
      AND t.outer_as_id = o.outer_as_id
     SET ${setClause}
     WHERE t.stat_date = ?
       AND (t.process_result = '' OR t.original_waybill_no = '' OR t.original_courier_name = '')`,
    `UPDATE aftersales_refund_detail_read t
     JOIN aftersales_refund_export_override o
       ON t.stat_date = o.stat_date
      AND t.o_id <> ''
      AND o.o_id <> ''
      AND t.so_id <> ''
      AND o.so_id <> ''
      AND t.o_id = o.o_id
      AND t.so_id = o.so_id
     SET ${setClause}
     WHERE t.stat_date = ?
       AND (t.process_result = '' OR t.original_waybill_no = '' OR t.original_courier_name = '')`,
  ];

  let affectedRows = 0;
  for (const sql of updates) {
    const result = await database.local.query(sql, [statDate]);
    affectedRows += Number(result.affectedRows || 0);
  }

  const insertMissingResult = await database.local.query(
    `INSERT INTO aftersales_refund_detail_read (
       stat_date,
       source_key,
       source_table,
       as_id,
       outer_as_id,
       o_id,
       so_id,
       type,
       node,
       order_labels,
       shop_name,
       freight,
       refund,
       payment,
       free_amount,
       total_refund_money,
       shop_status,
       question_type,
       process_result,
       status,
       created,
       modified,
       l_id,
       confirm_date,
       creator_name,
       original_order_no,
       original_courier_name,
       original_waybill_no
     )
     SELECT
       o.stat_date,
       'aftersales_refund_export_override' AS source_key,
       CONCAT('local.', o.source_file) AS source_table,
       o.as_id,
       o.outer_as_id,
       o.o_id,
       o.so_id,
       '' AS type,
       '' AS node,
       '' AS order_labels,
       '' AS shop_name,
       0 AS freight,
       0 AS refund,
       0 AS payment,
       0 AS free_amount,
       0 AS total_refund_money,
       '' AS shop_status,
       o.question_type,
       o.process_result,
       '' AS status,
       o.apply_time AS created,
       o.apply_time AS modified,
       '' AS l_id,
       NULL AS confirm_date,
       '' AS creator_name,
       o.original_order_no,
       o.original_courier_name,
       o.original_waybill_no
     FROM aftersales_refund_export_override o
     LEFT JOIN aftersales_refund_detail_read t
       ON t.stat_date = o.stat_date
      AND (
        (o.as_id <> '' AND t.as_id = o.as_id)
        OR (o.outer_as_id <> '' AND t.outer_as_id = o.outer_as_id)
        OR (o.o_id <> '' AND o.so_id <> '' AND t.o_id = o.o_id AND t.so_id = o.so_id)
      )
     WHERE o.stat_date = ?
       AND t.id IS NULL`,
    [statDate]
  );

  return {
    statDate,
    affectedRows,
    insertedRows: Number(insertMissingResult.affectedRows || 0),
  };
}

module.exports = {
  applyAftersalesRefundExportOverrides,
  importAftersalesRefundExportOverrideFile,
};