import mysql from 'mysql2/promise'

// MySQL 連接設定
const dbConfig = {
  host: process.env.DB_HOST!,
  port: parseInt(process.env.DB_PORT!),
  database: process.env.DB_DATABASE!,
  user: process.env.DB_USERNAME!,
  password: process.env.DB_PASSWORD!,
  waitForConnections: true,
  connectionLimit: 10,
  queueLimit: 0
}

// 創建連接池
export const db = mysql.createPool(dbConfig)

// 測試連接函數
export async function testConnection() {
  try {
    const connection = await db.getConnection()
    console.log('MySQL 資料庫連接成功')
    connection.release()
    return true
  } catch (error) {
    console.error('MySQL 資料庫連接失敗:', error)
    return false
  }
}

// Database types
export interface User {
  id: string
  name: string
  email: string
  role: "executive" | "manager" | "hr"
  avatar_url?: string
  created_at: string
  updated_at: string
}

export interface KPI {
  id: string
  user_id: string
  title: string
  description?: string
  category: "financial" | "operational" | "team" | "innovation" | "strategy"
  weight: number
  target_value: number
  current_value: number
  unit?: string
  start_date: string
  end_date: string
  approved_by?: string
  status: "pending" | "approved" | "rejected" | "active" | "completed"
  created_at: string
  updated_at: string
}

export interface KPIProgress {
  id: string
  kpi_id: string
  progress: number
  comment?: string
  attachment_url?: string
  blockers?: string
  created_by: string
  created_at: string
}

export interface Review {
  id: string
  reviewer_id: string
  reviewee_id: string
  review_type: "quarterly" | "annual" | "one_on_one" | "goal_setting"
  scheduled_date: string
  completed_date?: string
  status: "scheduled" | "in_progress" | "completed" | "cancelled"
  summary?: string
  overall_rating?: number
  created_at: string
  updated_at: string
}

// CRUD API functions
export const kpiService = {
  // READ - 獲取用戶的 KPI
  async getKPIsByUser(userId: string): Promise<KPI[]> {
    try {
      const [rows] = await db.execute(
        'SELECT * FROM kpi WHERE user_id = ? AND status = ?',
        [userId, 'active']
      )
      return rows as KPI[]
    } catch (error) {
      console.error('獲取 KPI 失敗:', error)
      throw error
    }
  },

  // CREATE - 創建新 KPI
  async createKPI(kpi: Omit<KPI, "id" | "created_at" | "updated_at">): Promise<KPI> {
    try {
      const id = `kpi_${Date.now()}_${Math.random().toString(36).substr(2, 9)}`
      const now = new Date().toISOString()
      
      await db.execute(
        `INSERT INTO kpi (id, user_id, title, description, category, weight, target_value, 
         current_value, unit, start_date, end_date, approved_by, status, created_at, updated_at) 
         VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`,
        [
          id, kpi.user_id, kpi.title, kpi.description, kpi.category, kpi.weight,
          kpi.target_value, kpi.current_value, kpi.unit, kpi.start_date, kpi.end_date,
          kpi.approved_by, kpi.status, now, now
        ]
      )
      
      const [rows] = await db.execute('SELECT * FROM kpi WHERE id = ?', [id])
      return (rows as KPI[])[0]
    } catch (error) {
      console.error('創建 KPI 失敗:', error)
      throw error
    }
  },

  // UPDATE - 更新 KPI 進度
  async updateKPIProgress(kpiId: string, progress: number, comment?: string, blockers?: string, userId?: string): Promise<void> {
    try {
      const id = `progress_${Date.now()}_${Math.random().toString(36).substr(2, 9)}`
      const now = new Date().toISOString()
      
      await db.execute(
        `INSERT INTO kpi_progress (id, kpi_id, progress, comment, blockers, created_by, created_at) 
         VALUES (?, ?, ?, ?, ?, ?, ?)`,
        [id, kpiId, progress, comment, blockers, userId || 'system', now]
      )
      
      // 同時更新 KPI 的當前值
      await db.execute(
        'UPDATE kpi SET current_value = ?, updated_at = ? WHERE id = ?',
        [progress, now, kpiId]
      )
    } catch (error) {
      console.error('更新 KPI 進度失敗:', error)
      throw error
    }
  },

  // UPDATE - 更新 KPI
  async updateKPI(id: string, updates: Partial<KPI>): Promise<KPI> {
    try {
      const now = new Date().toISOString()
      const fields = Object.keys(updates).filter(key => key !== 'id').map(key => `${key} = ?`)
      const values = Object.values(updates).filter((_, index) => Object.keys(updates)[index] !== 'id')
      
      if (fields.length === 0) throw new Error('沒有要更新的欄位')
      
      await db.execute(
        `UPDATE kpi SET ${fields.join(', ')}, updated_at = ? WHERE id = ?`,
        [...values, now, id]
      )
      
      const [rows] = await db.execute('SELECT * FROM kpi WHERE id = ?', [id])
      return (rows as KPI[])[0]
    } catch (error) {
      console.error('更新 KPI 失敗:', error)
      throw error
    }
  },

  // DELETE - 刪除 KPI（軟刪除，將狀態改為 deleted）
  async deleteKPI(id: string): Promise<void> {
    try {
      const now = new Date().toISOString()
      await db.execute(
        'UPDATE kpi SET status = ?, updated_at = ? WHERE id = ?',
        ['deleted', now, id]
      )
    } catch (error) {
      console.error('刪除 KPI 失敗:', error)
      throw error
    }
  },
}

export const reviewService = {
  // READ - 獲取即將到來的評審
  async getUpcomingReviews(userId: string): Promise<Review[]> {
    try {
      const [rows] = await db.execute(
        `SELECT r.*, u.name as reviewee_name, u.email as reviewee_email
         FROM reviews r
         LEFT JOIN users u ON r.reviewee_id = u.id
         WHERE r.reviewer_id = ? AND r.status = ?
         ORDER BY r.scheduled_date ASC`,
        [userId, 'scheduled']
      )
      return rows as Review[]
    } catch (error) {
      console.error('獲取評審列表失敗:', error)
      throw error
    }
  },

  // CREATE - 創建新評審
  async createReview(review: Omit<Review, "id" | "created_at" | "updated_at">): Promise<Review> {
    try {
      const id = `review_${Date.now()}_${Math.random().toString(36).substr(2, 9)}`
      const now = new Date().toISOString()
      
      await db.execute(
        `INSERT INTO reviews (id, reviewer_id, reviewee_id, review_type, scheduled_date, 
         completed_date, status, summary, overall_rating, created_at, updated_at) 
         VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`,
        [
          id, review.reviewer_id, review.reviewee_id, review.review_type, review.scheduled_date,
          review.completed_date, review.status, review.summary, review.overall_rating, now, now
        ]
      )
      
      const [rows] = await db.execute('SELECT * FROM reviews WHERE id = ?', [id])
      return (rows as Review[])[0]
    } catch (error) {
      console.error('創建評審失敗:', error)
      throw error
    }
  },

  // READ - 獲取所有評審
  async getAllReviews(): Promise<Review[]> {
    try {
      const [rows] = await db.execute('SELECT * FROM reviews ORDER BY created_at DESC')
      return rows as Review[]
    } catch (error) {
      console.error('獲取所有評審失敗:', error)
      throw error
    }
  },

  // UPDATE - 更新評審
  async updateReview(id: string, updates: Partial<Review>): Promise<Review> {
    try {
      const now = new Date().toISOString()
      const fields = Object.keys(updates).filter(key => key !== 'id').map(key => `${key} = ?`)
      const values = Object.values(updates).filter((_, index) => Object.keys(updates)[index] !== 'id')
      
      if (fields.length === 0) throw new Error('沒有要更新的欄位')
      
      await db.execute(
        `UPDATE reviews SET ${fields.join(', ')}, updated_at = ? WHERE id = ?`,
        [...values, now, id]
      )
      
      const [rows] = await db.execute('SELECT * FROM reviews WHERE id = ?', [id])
      return (rows as Review[])[0]
    } catch (error) {
      console.error('更新評審失敗:', error)
      throw error
    }
  },

  // DELETE - 刪除評審
  async deleteReview(id: string): Promise<void> {
    try {
      await db.execute('DELETE FROM reviews WHERE id = ?', [id])
    } catch (error) {
      console.error('刪除評審失敗:', error)
      throw error
    }
  },
}

// 用戶管理服務
export const userService = {
  // CREATE - 創建用戶
  async createUser(user: Omit<User, "id" | "created_at" | "updated_at">): Promise<User> {
    try {
      const id = `user_${Date.now()}_${Math.random().toString(36).substr(2, 9)}`
      const now = new Date().toISOString()
      
      await db.execute(
        `INSERT INTO users (id, name, email, role, avatar_url, created_at, updated_at) 
         VALUES (?, ?, ?, ?, ?, ?, ?)`,
        [id, user.name, user.email, user.role, user.avatar_url, now, now]
      )
      
      const [rows] = await db.execute('SELECT * FROM users WHERE id = ?', [id])
      return (rows as User[])[0]
    } catch (error) {
      console.error('創建用戶失敗:', error)
      throw error
    }
  },

  // READ - 獲取所有用戶
  async getAllUsers(): Promise<User[]> {
    try {
      const [rows] = await db.execute('SELECT * FROM users ORDER BY created_at DESC')
      return rows as User[]
    } catch (error) {
      console.error('獲取用戶列表失敗:', error)
      throw error
    }
  },

  // READ - 根據 ID 獲取用戶
  async getUserById(id: string): Promise<User | null> {
    try {
      const [rows] = await db.execute('SELECT * FROM users WHERE id = ?', [id])
      const users = rows as User[]
      return users.length > 0 ? users[0] : null
    } catch (error) {
      console.error('獲取用戶失敗:', error)
      throw error
    }
  },

  // UPDATE - 更新用戶
  async updateUser(id: string, updates: Partial<User>): Promise<User> {
    try {
      const now = new Date().toISOString()
      const fields = Object.keys(updates).filter(key => key !== 'id').map(key => `${key} = ?`)
      const values = Object.values(updates).filter((_, index) => Object.keys(updates)[index] !== 'id')
      
      if (fields.length === 0) throw new Error('沒有要更新的欄位')
      
      await db.execute(
        `UPDATE users SET ${fields.join(', ')}, updated_at = ? WHERE id = ?`,
        [...values, now, id]
      )
      
      const [rows] = await db.execute('SELECT * FROM users WHERE id = ?', [id])
      return (rows as User[])[0]
    } catch (error) {
      console.error('更新用戶失敗:', error)
      throw error
    }
  },

  // DELETE - 刪除用戶
  async deleteUser(id: string): Promise<void> {
    try {
      await db.execute('DELETE FROM users WHERE id = ?', [id])
    } catch (error) {
      console.error('刪除用戶失敗:', error)
      throw error
    }
  },
}