import pool from '../config/database';
import { ResultSetHeader } from 'mysql2';

export type PerformanceStatus = 'draft' | 'submitted' | 'under_review' | 'completed' | 'rejected';
export type PerformanceLevel = 'excellent' | 'qualified' | 'need_motivation' | 'unqualified';

export interface PerformanceRow {
  perf_id: number;
  user_id: number;
  month: string;
  status: PerformanceStatus;
  self_score: number | null;
  ai_score: number | null;
  manager_score: number | null;
  total_score: number | null;
  level: PerformanceLevel | null;
  reward_punish: string | null;
  work_summary: string | null;
  submit_time: Date | null;
  review_time: Date | null;
  review_opinion: string | null;
  created_at: Date;
  updated_at: Date;
}

export interface PerfItemRow {
  item_id?: number;
  perf_id: number;
  item_name: string;
  item_category: 'business' | 'comprehensive';
  weight: number;
  user_content: string | null;
  self_score: number | null;
  ai_score: number | null;
  ai_explanation: string | null;
  manager_score: number | null;
  manager_explanation: string | null;
  evidence_url: string | null;
}

export interface AttendanceRow {
  attendance_id?: number;
  perf_id: number;
  leave_days: number;
  late_times: number;
  absent_days: number;
  lack_card_times: number;
  attendance_score: number | null;
  remark: string | null;
}

export interface UpsertPerformanceData {
  userId: number;
  month: string;
  status: PerformanceStatus;
  selfScore?: number;
  workSummary?: string;
  items?: Omit<PerfItemRow, 'perf_id' | 'item_id'>[];
  attendance?: Omit<AttendanceRow, 'perf_id' | 'attendance_id'>;
}

export interface PerformanceFilter {
  month?: string;
  department?: string;
  employeeName?: string;
  status?: PerformanceStatus;
}

export interface PageInfo {
  page: number;
  pageSize: number;
}

export interface ReviewData {
  managerScore: number;
  reviewOpinion: string;
  totalScore: number;
  level: PerformanceLevel;
  rewardPunish: string;
  itemScores: { itemName: string; managerScore: number; managerExplanation: string }[];
}

export interface PerformanceListResult {
  total: number;
  records: PerformanceRow[];
}

/**
 * Create or update a performance record along with its items and attendance.
 * Uses INSERT ... ON DUPLICATE KEY UPDATE to handle the unique constraint on (user_id, month).
 */
export async function upsert(data: UpsertPerformanceData): Promise<number> {
  const conn = await pool.getConnection();
  try {
    await conn.beginTransaction();

    // Upsert performance_month
    const submitTime = data.status === 'submitted' ? new Date() : null;
    const [result] = await conn.query<ResultSetHeader>(
      `INSERT INTO performance_month (user_id, month, status, self_score, work_summary, submit_time)
       VALUES (?, ?, ?, ?, ?, ?)
       ON DUPLICATE KEY UPDATE
         status = VALUES(status),
         self_score = VALUES(self_score),
         work_summary = VALUES(work_summary),
         submit_time = COALESCE(VALUES(submit_time), submit_time)`,
      [data.userId, data.month, data.status, data.selfScore ?? null, data.workSummary ?? null, submitTime]
    );

    // Resolve perf_id (insertId is 0 on UPDATE, so fetch it)
    let perfId: number = result.insertId;
    if (perfId === 0) {
      const [rows] = await conn.query<any[]>(
        'SELECT perf_id FROM performance_month WHERE user_id = ? AND month = ?',
        [data.userId, data.month]
      );
      perfId = rows[0].perf_id;
    }

    // Upsert perf_items
    if (data.items && data.items.length > 0) {
      // Delete existing items and re-insert for simplicity
      await conn.query('DELETE FROM perf_item WHERE perf_id = ?', [perfId]);
      for (const item of data.items) {
        await conn.query(
          `INSERT INTO perf_item (perf_id, item_name, item_category, weight, user_content, self_score, evidence_url)
           VALUES (?, ?, ?, ?, ?, ?, ?)`,
          [perfId, item.item_name, item.item_category, item.weight, item.user_content ?? null, item.self_score ?? null, item.evidence_url ?? null]
        );
      }
    }

    // Upsert attendance
    if (data.attendance) {
      const att = data.attendance;
      await conn.query(
        `INSERT INTO attendance (perf_id, leave_days, late_times, absent_days, lack_card_times, attendance_score, remark)
         VALUES (?, ?, ?, ?, ?, ?, ?)
         ON DUPLICATE KEY UPDATE
           leave_days = VALUES(leave_days),
           late_times = VALUES(late_times),
           absent_days = VALUES(absent_days),
           lack_card_times = VALUES(lack_card_times),
           attendance_score = VALUES(attendance_score),
           remark = VALUES(remark)`,
        [perfId, att.leave_days, att.late_times, att.absent_days, att.lack_card_times, att.attendance_score ?? null, att.remark ?? null]
      );
    }

    await conn.commit();
    return perfId;
  } catch (err) {
    await conn.rollback();
    throw err;
  } finally {
    conn.release();
  }
}

/** Query a performance record for a specific user and month, including items and attendance. */
export async function findByUserAndMonth(userId: number, month: string): Promise<PerformanceRow | null> {
  const [rows] = await pool.query<any[]>(
    'SELECT * FROM performance_month WHERE user_id = ? AND month = ? LIMIT 1',
    [userId, month]
  );
  return rows.length > 0 ? (rows[0] as PerformanceRow) : null;
}

/** Query subordinates' performance records with optional filters and pagination. */
export async function findByManagerId(
  managerId: number,
  filters: PerformanceFilter,
  page: PageInfo
): Promise<PerformanceListResult> {
  const conditions: string[] = ['u.manager_id = ?'];
  const params: any[] = [managerId];

  if (filters.month) {
    conditions.push('pm.month = ?');
    params.push(filters.month);
  }
  if (filters.department) {
    conditions.push('u.department = ?');
    params.push(filters.department);
  }
  if (filters.employeeName) {
    conditions.push('u.name LIKE ?');
    params.push(`%${filters.employeeName}%`);
  }
  if (filters.status) {
    conditions.push('pm.status = ?');
    params.push(filters.status);
  }

  const where = conditions.join(' AND ');
  const offset = (page.page - 1) * page.pageSize;

  const [countRows] = await pool.query<any[]>(
    `SELECT COUNT(*) AS total
     FROM performance_month pm
     JOIN user u ON pm.user_id = u.user_id
     WHERE ${where}`,
    params
  );
  const total: number = countRows[0].total;

  const [rows] = await pool.query<any[]>(
    `SELECT pm.*
     FROM performance_month pm
     JOIN user u ON pm.user_id = u.user_id
     WHERE ${where}
     ORDER BY pm.month DESC, pm.created_at DESC
     LIMIT ? OFFSET ?`,
    [...params, page.pageSize, offset]
  );

  return { total, records: rows as PerformanceRow[] };
}

/** Update only the status of a performance record. */
export async function updateStatus(perfId: number, status: PerformanceStatus): Promise<void> {
  await pool.query(
    'UPDATE performance_month SET status = ? WHERE perf_id = ?',
    [status, perfId]
  );
}

/** Query performance records for a specific employee with optional month filter and pagination. */
export async function findByUserId(
  userId: number,
  month: string | undefined,
  page: PageInfo
): Promise<PerformanceListResult> {
  const conditions: string[] = ['pm.user_id = ?'];
  const params: any[] = [userId];

  if (month) {
    conditions.push('pm.month = ?');
    params.push(month);
  }

  const where = conditions.join(' AND ');
  const offset = (page.page - 1) * page.pageSize;

  const [countRows] = await pool.query<any[]>(
    `SELECT COUNT(*) AS total FROM performance_month pm WHERE ${where}`,
    params
  );
  const total: number = countRows[0].total;

  const [rows] = await pool.query<any[]>(
    `SELECT pm.* FROM performance_month pm WHERE ${where}
     ORDER BY pm.month DESC, pm.created_at DESC
     LIMIT ? OFFSET ?`,
    [...params, page.pageSize, offset]
  );

  return { total, records: rows as PerformanceRow[] };
}

/** Query full detail of a performance record including items and attendance. */
export async function findDetailByPerfId(perfId: number): Promise<{
  performance: PerformanceRow;
  items: PerfItemRow[];
  attendance: AttendanceRow | null;
} | null> {
  const [perfRows] = await pool.query<any[]>(
    'SELECT * FROM performance_month WHERE perf_id = ? LIMIT 1',
    [perfId]
  );
  if (perfRows.length === 0) return null;

  const [itemRows] = await pool.query<any[]>(
    'SELECT * FROM perf_item WHERE perf_id = ?',
    [perfId]
  );

  const [attRows] = await pool.query<any[]>(
    'SELECT * FROM attendance WHERE perf_id = ? LIMIT 1',
    [perfId]
  );

  return {
    performance: perfRows[0] as PerformanceRow,
    items: itemRows as PerfItemRow[],
    attendance: attRows.length > 0 ? (attRows[0] as AttendanceRow) : null,
  };
}

/** Update manager review results and archive the performance record. */
export async function updateReview(perfId: number, reviewData: ReviewData): Promise<void> {
  const conn = await pool.getConnection();
  try {
    await conn.beginTransaction();

    await conn.query(
      `UPDATE performance_month
       SET manager_score = ?, review_opinion = ?, total_score = ?, level = ?,
           reward_punish = ?, status = 'completed', review_time = NOW()
       WHERE perf_id = ?`,
      [reviewData.managerScore, reviewData.reviewOpinion, reviewData.totalScore, reviewData.level, reviewData.rewardPunish, perfId]
    );

    for (const item of reviewData.itemScores) {
      await conn.query(
        `UPDATE perf_item SET manager_score = ?, manager_explanation = ?
         WHERE perf_id = ? AND item_name = ?`,
        [item.managerScore, item.managerExplanation, perfId, item.itemName]
      );
    }

    await conn.commit();
  } catch (err) {
    await conn.rollback();
    throw err;
  } finally {
    conn.release();
  }
}