// /models/analysisModel.js
const { getDb } = require('../dbPool');

/**
 * 지정된 기간 동안의 작업 보고서 데이터를 집계하여 분석합니다.
 * 이 함수는 여러 개의 SQL 쿼리를 병렬로 실행하여 효율성을 높입니다.
 * @param {string} startDate - 시작일 (YYYY-MM-DD)
 * @param {string} endDate - 종료일 (YYYY-MM-DD)
 * @returns {Promise<object>} - 요약, 프로젝트별, 작업자별, 작업별 집계 데이터 및 상세 내역
 */
const getAnalysis = async (startDate, endDate) => {
  try {
    const db = await getDb();

    // SQL 쿼리에서 반복적으로 사용될 WHERE 조건과 실제 투입 시간 계산 로직
    const whereClause = `WHERE dwr.report_date BETWEEN ? AND ?`;
    const workHoursCalc = `
      CASE dwr.work_details
        WHEN '연차' THEN 0 WHEN '반차' THEN 4 WHEN '반반차' THEN 6
        WHEN '조퇴' THEN 2 WHEN '휴무' THEN 0 WHEN '유급' THEN 0
        ELSE 8
      END + (COALESCE(dwr.overtime_hours, 0) * 1.5)
    `;

    // 1. 요약 정보 쿼리
    const summarySql = `
      SELECT
        COUNT(DISTINCT dwr.project_id) as totalProjects,
        COUNT(DISTINCT dwr.worker_id) as totalworkers,
        COUNT(DISTINCT dwr.task_id) as totalTasks,
        SUM(${workHoursCalc}) as totalHours
      FROM DailyWorkReports dwr
      ${whereClause} AND (${workHoursCalc}) > 0
    `;
    
    // 2. 프로젝트별 집계 쿼리
    const byProjectSql = `
      SELECT p.project_name as name, SUM(${workHoursCalc}) as hours, COUNT(DISTINCT dwr.worker_id) as participants
      FROM DailyWorkReports dwr
      JOIN Projects p ON dwr.project_id = p.project_id
      ${whereClause}
      GROUP BY p.project_name
      HAVING hours > 0
      ORDER BY hours DESC;
    `;

    // 3. 작업자별 집계 쿼리
    const byWorkerSql = `
      SELECT w.worker_name as name, SUM(${workHoursCalc}) as hours, COUNT(DISTINCT dwr.project_id) as participants
      FROM DailyWorkReports dwr
      JOIN workers w ON dwr.worker_id = w.worker_id
      ${whereClause}
      GROUP BY w.worker_name
      HAVING hours > 0
      ORDER BY hours DESC;
    `;
    
    // 4. 작업별 집계 쿼리
    const byTaskSql = `
      SELECT t.category as name, SUM(${workHoursCalc}) as hours, COUNT(DISTINCT dwr.worker_id) as participants
      FROM DailyWorkReports dwr
      JOIN Tasks t ON dwr.task_id = t.task_id
      ${whereClause}
      GROUP BY t.category
      HAVING hours > 0
      ORDER BY hours DESC;
    `;

    // 5. 상세 내역 쿼리
    const detailsSql = `
      SELECT 
        dwr.report_date as date, p.project_name, w.worker_name,
        t.category as task_category, dwr.work_details,
        (${workHoursCalc}) as work_hours, dwr.memo
      FROM DailyWorkReports dwr
      JOIN Projects p ON dwr.project_id = p.project_id
      JOIN workers w ON dwr.worker_id = w.worker_id
      JOIN Tasks t ON dwr.task_id = t.task_id
      ${whereClause}
      HAVING work_hours > 0
      ORDER BY dwr.report_date DESC;
    `;

    // 모든 쿼리를 병렬로 실행
    const [
      [summaryResult], 
      [byProject], 
      [byWorker], 
      [byTask], 
      [details]
    ] = await Promise.all([
      db.query(summarySql, [startDate, endDate]),
      db.query(byProjectSql, [startDate, endDate]),
      db.query(byWorkerSql, [startDate, endDate]),
      db.query(byTaskSql, [startDate, endDate]),
      db.query(detailsSql, [startDate, endDate])
    ]);

    return {
      summary: summaryResult[0],
      byProject,
      byWorker,
      byTask,
      details
    };

  } catch (err) {
    console.error('[Model] 분석 데이터 조회 오류:', err);
    throw new Error('데이터베이스에서 분석 데이터를 조회하는 중 오류가 발생했습니다.');
  }
};

module.exports = {
  getAnalysis
};