'use strict';

const crypto = require('crypto');
const fs = require('fs');
const path = require('path');
const ExcelJS = require('exceljs');
const config = require('../config');
const db = require('../infra/db');
const { buildBackupPayload } = require('./backup');

const EXPORT_TYPES = new Set([
  'employees',
  'online-exams',
  'practical-exams',
  'team-analysis',
  'analysis-report',
  'question-details',
  'backup',
]);

function safeNumber(value) {
  const number = Number(value);
  return Number.isFinite(number) ? number : null;
}

function jsonCell(value) {
  if (value == null) return null;
  return typeof value === 'object' ? JSON.stringify(value) : value;
}

function normalizeRows(rows) {
  return rows.map((row) => Object.fromEntries(
    Object.entries(row).map(([key, value]) => [key, jsonCell(value)]),
  ));
}

function addSheet(workbook, name, rows) {
  const normalized = normalizeRows(rows);
  const data = normalized.length > 0 ? normalized : [{ message: '无数据' }];
  const keys = [...new Set(data.flatMap((row) => Object.keys(row)))];
  const sheet = workbook.addWorksheet(name.slice(0, 31));
  sheet.columns = keys.map((key) => ({ header: key, key, width: Math.min(40, Math.max(12, key.length + 4)) }));
  sheet.addRows(data);
  sheet.getRow(1).font = { bold: true };
  sheet.views = [{ state: 'frozen', ySplit: 1 }];
}

function periodWhere(alias, params, values) {
  const clauses = [];
  const year = safeNumber(params.year);
  const month = safeNumber(params.month);
  if (year != null) {
    clauses.push(`${alias}.exam_year = ?`);
    values.push(year);
  }
  if (month != null) {
    clauses.push(`${alias}.exam_month = ?`);
    values.push(month);
  }
  if (params.team) {
    clauses.push('e.team = ?');
    values.push(String(params.team));
  }
  if (params.employeeId) {
    clauses.push(`${alias}.employee_id = ?`);
    values.push(String(params.employeeId));
  }
  return clauses;
}

async function employeesWorkbook(params = {}) {
  const values = [];
  const where = params.employeeId ? 'AND employee_id = ?' : 'AND (employment_status = \'在职\' OR employment_status IS NULL)';
  if (params.employeeId) values.push(String(params.employeeId));
  const rows = await db.query(
    `SELECT employee_id, internal_employee_id, name, team, position, native_place,
            nationality, political_status, education, education_type, graduate_school,
            graduate_date, skill_level, hire_date, birth_date, status, employment_status, source, details, extras
       FROM employees
      WHERE deleted_at IS NULL
        ${where}
      ORDER BY team, employee_id`,
    values,
  );
  const workbook = new ExcelJS.Workbook();
  addSheet(workbook, '员工档案', rows);
  return workbook;
}

async function onlineWorkbook(params) {
  const values = [];
  const clauses = periodWhere('o', params, values);
  const where = clauses.length ? `WHERE ${clauses.join(' AND ')}` : '';
  const exams = await db.query(
    `SELECT o.employee_id, e.name AS employee_name, e.team, e.position,
            o.exam_year, o.exam_month, o.paper_class, o.score, o.result,
            o.faults, o.choice_faults, o.submit_time, o.elapsed_seconds, o.details
       FROM online_exams o
       LEFT JOIN employees e ON e.employee_id = o.employee_id AND e.deleted_at IS NULL
       ${where}
      ORDER BY o.exam_year, o.exam_month, e.team, o.employee_id`,
    values,
  );
  const missingValues = [];
  const missingClauses = [];
  if (safeNumber(params.year) != null && safeNumber(params.month) != null) {
    missingClauses.push('m.missing_month = ?');
    missingValues.push(`${safeNumber(params.year)}-${String(safeNumber(params.month)).padStart(2, '0')}`);
  } else if (safeNumber(params.year) != null) {
    missingClauses.push('m.missing_month LIKE ?');
    missingValues.push(`${safeNumber(params.year)}-%`);
  }
  if (params.team) {
    missingClauses.push('e.team = ?');
    missingValues.push(String(params.team));
  }
  const missingWhere = missingClauses.length ? `WHERE ${missingClauses.join(' AND ')}` : '';
  const missing = await db.query(
    `SELECT m.employee_id, e.name AS employee_name, e.team, e.position,
            m.missing_month, m.reason, m.import_time, m.details
       FROM missing_exams m
       LEFT JOIN employees e ON e.employee_id = m.employee_id AND e.deleted_at IS NULL
       ${missingWhere}
      ORDER BY m.missing_month, e.team, m.employee_id`,
    missingValues,
  );
  const workbook = new ExcelJS.Workbook();
  addSheet(workbook, '在线考试', exams);
  addSheet(workbook, '缺考', missing);
  return workbook;
}

async function practicalWorkbook(params) {
  const values = [];
  const clauses = periodWhere('p', params, values);
  const where = clauses.length ? `WHERE ${clauses.join(' AND ')}` : '';
  const rows = await db.query(
    `SELECT p.employee_id, e.name AS employee_name, e.team, e.position,
            p.exam_year, p.exam_month, p.paper_id, p.pc_class AS paper_class,
            p.score, p.result, p.faults, p.create_time, p.details
       FROM practical_exams p
       LEFT JOIN employees e ON e.employee_id = p.employee_id AND e.deleted_at IS NULL
       ${where}
      ORDER BY p.exam_year, p.exam_month, e.team, p.employee_id`,
    values,
  );
  const workbook = new ExcelJS.Workbook();
  addSheet(workbook, '实操考试', rows);
  return workbook;
}

async function questionDetailsWorkbook(params) {
  const values = [];
  const clauses = periodWhere('o', params, values);
  const where = clauses.length ? `WHERE ${clauses.join(' AND ')}` : '';
  const rows = await db.query(
    `SELECT o.employee_id, e.name AS employee_name, e.team, o.exam_year, o.exam_month,
            o.paper_class, o.score, o.result,
            JSON_EXTRACT(o.details, '$.questionScores') AS question_scores,
            o.details
       FROM online_exams o
       LEFT JOIN employees e ON e.employee_id = o.employee_id AND e.deleted_at IS NULL
       ${where}
      ORDER BY o.exam_year, o.exam_month, e.team, o.employee_id`,
    values,
  );
  const workbook = new ExcelJS.Workbook();
  addSheet(workbook, '题目作答原始明细', rows);
  return workbook;
}

async function teamWorkbook(params) {
  const year = safeNumber(params.year);
  const month = safeNumber(params.month);
  const values = [];
  const clauses = [];
  if (year != null) {
    clauses.push('year = ?');
    values.push(year);
  }
  if (month != null) {
    clauses.push('month = ?');
    values.push(month);
  }
  if (params.team) {
    clauses.push('team = ?');
    values.push(String(params.team));
  }
  const where = clauses.length ? `WHERE ${clauses.join(' AND ')}` : '';
  const [online, practical, kilometers] = await Promise.all([
    db.query(`SELECT * FROM online_exam_stats_monthly ${where} ORDER BY year, month, team`, values),
    db.query(`SELECT * FROM practical_exam_stats_monthly ${where} ORDER BY year, month, team`, values),
    db.query(`SELECT * FROM kilometers_stats_team_monthly ${where} ORDER BY year, month, team`, values),
  ]);
  const workbook = new ExcelJS.Workbook();
  addSheet(workbook, '在线考试班组统计', online);
  addSheet(workbook, '实操考试班组统计', practical);
  addSheet(workbook, '班组公里数', kilometers);
  return workbook;
}

function escapeHtml(value) {
  return String(value ?? '').replace(/[&<>"']/g, (char) => ({
    '&': '&amp;', '<': '&lt;', '>': '&gt;', '"': '&quot;', "'": '&#39;',
  })[char]);
}

async function analysisHtml(params) {
  const summaryRows = await db.query("SELECT payload, computed_at FROM dashboard_summary WHERE scope_key = 'global' LIMIT 1");
  const summary = summaryRows[0]?.payload || {};
  const team = params.team ? ` · ${escapeHtml(params.team)}` : '';
  return `<!doctype html><html lang="zh-CN"><head><meta charset="utf-8"><title>综合分析报告</title>
  <style>body{font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;margin:40px;color:#1f2937}h1{color:#0f766e}.grid{display:grid;grid-template-columns:repeat(3,1fr);gap:16px}.card{border:1px solid #d1d5db;border-radius:10px;padding:18px}.value{font-size:28px;font-weight:700}</style>
  </head><body><h1>综合分析报告${team}</h1><p>统计时间：${escapeHtml(summaryRows[0]?.computed_at || new Date().toISOString())}</p>
  <div class="grid">
  <div class="card">员工总数<div class="value">${Number(summary.totalEmployees) || 0}</div></div>
  <div class="card">在线考试<div class="value">${Number(summary.totalOnlineExams) || 0}</div></div>
  <div class="card">实操考试<div class="value">${Number(summary.totalPracticalExams) || 0}</div></div>
  <div class="card">在线通过率<div class="value">${Number(summary.passRate) || 0}%</div></div>
  <div class="card">累计公里数<div class="value">${Number(summary.totalKilometers) || 0}</div></div>
  <div class="card">驾驶员人数<div class="value">${Number(summary.uniqueKilometerEmployees) || 0}</div></div>
  </div></body></html>`;
}

function backupReplacer(_key, value) {
  if (Buffer.isBuffer(value)) return { encoding: 'base64', data: value.toString('base64') };
  return value;
}

async function backupJson() {
  const data = await buildBackupPayload();
  return JSON.stringify(data, backupReplacer, 2);
}

async function generate(jobUuid, type, params = {}) {
  if (!EXPORT_TYPES.has(type)) throw new Error(`不支持的导出类型：${type}`);
  fs.mkdirSync(config.exportDir, { recursive: true, mode: 0o700 });
  const baseName = `${type}-${jobUuid}`;
  let fileName;
  let filePath;
  let mimeType;

  if (type === 'analysis-report') {
    fileName = `${baseName}.html`;
    filePath = path.join(config.exportDir, fileName);
    mimeType = 'text/html; charset=utf-8';
    fs.writeFileSync(filePath, await analysisHtml(params), { mode: 0o600 });
  } else if (type === 'backup') {
    fileName = `${baseName}.json`;
    filePath = path.join(config.exportDir, fileName);
    mimeType = 'application/json; charset=utf-8';
    fs.writeFileSync(filePath, await backupJson(), { mode: 0o600 });
  } else {
    const factories = {
      employees: employeesWorkbook,
      'online-exams': onlineWorkbook,
      'practical-exams': practicalWorkbook,
      'team-analysis': teamWorkbook,
      'question-details': questionDetailsWorkbook,
    };
    const workbook = await factories[type](params);
    fileName = `${baseName}.xlsx`;
    filePath = path.join(config.exportDir, fileName);
    mimeType = 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet';
    await workbook.xlsx.writeFile(filePath);
    fs.chmodSync(filePath, 0o600);
  }

  const bytes = fs.readFileSync(filePath);
  return {
    fileName,
    filePath,
    mimeType,
    fileSize: bytes.length,
    fileHash: crypto.createHash('sha256').update(bytes).digest('hex'),
  };
}

module.exports = { EXPORT_TYPES, generate };