package storage

import (
	"database/sql"
	"fmt"
	"log"
	"os"
	"time"

	_ "github.com/go-sql-driver/mysql"
)

// DBConfig 数据库配置
type DBConfig struct {
	Host     string
	Port     int
	User     string
	Password string
	Database string
}

var db *sql.DB

// InitDB 初始化数据库连接
func InitDB(config DBConfig) error {
	dsn := fmt.Sprintf("%s:%s@tcp(%s:%d)/%s?charset=utf8mb4&parseTime=True&loc=Local",
		config.User, config.Password, config.Host, config.Port, config.Database)

	var err error
	db, err = sql.Open("mysql", dsn)
	if err != nil {
		return fmt.Errorf("failed to open database: %v", err)
	}

	// 配置连接池
	db.SetMaxOpenConns(25)
	db.SetMaxIdleConns(5)
	db.SetConnMaxLifetime(5 * time.Minute)

	// 测试连接
	if err := db.Ping(); err != nil {
		return fmt.Errorf("failed to ping database: %v", err)
	}

	log.Println("✅ Database connection established")

	// 自动迁移表结构
	if err := autoMigrate(); err != nil {
		return fmt.Errorf("failed to auto migrate: %v", err)
	}

	return nil
}

// autoMigrate 自动创建或更新表结构
func autoMigrate() error {
	// 创建 customers 表
	createCustomersTable := `
	CREATE TABLE IF NOT EXISTS customers (
		id VARCHAR(64) PRIMARY KEY,
		created_at DATETIME NOT NULL,
		customer_name VARCHAR(255) NOT NULL,
		intended_product VARCHAR(255),
		version VARCHAR(100),
		description TEXT,
		solution TEXT,
		type VARCHAR(100),
		module VARCHAR(100),
		status_progress VARCHAR(100),
		reporter VARCHAR(255),
		screenshots TEXT,
		INDEX idx_customer_name (customer_name),
		INDEX idx_created_at (created_at)
	) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
	`

	if _, err := db.Exec(createCustomersTable); err != nil {
		return fmt.Errorf("failed to create customers table: %v", err)
	}

	// 创建 followups 表
	createFollowupsTable := `
	CREATE TABLE IF NOT EXISTS followups (
		id VARCHAR(64) PRIMARY KEY,
		created_at DATETIME NOT NULL,
		customer_name VARCHAR(255) NOT NULL,
		deal_status VARCHAR(50),
		customer_level VARCHAR(50),
		industry VARCHAR(100),
		follow_up_time DATETIME,
		notification_sent BOOLEAN DEFAULT FALSE,
		INDEX idx_customer_name (customer_name),
		INDEX idx_follow_up_time (follow_up_time)
	) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
	`

	if _, err := db.Exec(createFollowupsTable); err != nil {
		return fmt.Errorf("failed to create followups table: %v", err)
	}

	// 创建 trial_periods 表
	createTrialPeriodsTable := `
	CREATE TABLE IF NOT EXISTS trial_periods (
		id VARCHAR(64) PRIMARY KEY,
		customer_name VARCHAR(255) NOT NULL,
		source VARCHAR(100),
		intended_product VARCHAR(255),
		start_time DATETIME,
		end_time DATETIME,
		is_trial BOOLEAN DEFAULT TRUE,
		created_at DATETIME NOT NULL,
		INDEX idx_customer_name (customer_name),
		INDEX idx_end_time (end_time)
	) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
	`

	if _, err := db.Exec(createTrialPeriodsTable); err != nil {
		return fmt.Errorf("failed to create trial_periods table: %v", err)
	}

	// 检查并添加 screenshots 列（如果不存在）
	// MySQL 不支持 IF NOT EXISTS，所以我们需要先检查列是否存在
	var columnExists int
	err := db.QueryRow(`
		SELECT COUNT(*) 
		FROM INFORMATION_SCHEMA.COLUMNS 
		WHERE TABLE_SCHEMA = DATABASE() 
		AND TABLE_NAME = 'customers' 
		AND COLUMN_NAME = 'screenshots'
	`).Scan(&columnExists)

	if err != nil {
		return fmt.Errorf("failed to check screenshots column: %v", err)
	}

	if columnExists == 0 {
		_, err = db.Exec("ALTER TABLE customers ADD COLUMN screenshots TEXT")
		if err != nil {
			return fmt.Errorf("failed to add screenshots column: %v", err)
		}
		log.Println("✅ Added screenshots column to customers table")
	}

	log.Println("✅ Database tables migrated successfully")
	return nil
}

// GetDB 获取数据库连接
func GetDB() *sql.DB {
	return db
}

// CloseDB 关闭数据库连接
func CloseDB() error {
	if db != nil {
		return db.Close()
	}
	return nil
}

// GetDBConfigFromEnv 从环境变量获取数据库配置
func GetDBConfigFromEnv() DBConfig {
	config := DBConfig{
		Host:     "localhost",
		Port:     3306,
		User:     "root",
		Password: "",
		Database: "crm_db",
	}

	if host := os.Getenv("DB_HOST"); host != "" {
		config.Host = host
	}
	if user := os.Getenv("DB_USER"); user != "" {
		config.User = user
	}
	if pwd := os.Getenv("DB_PASSWORD"); pwd != "" {
		config.Password = pwd
	}
	if dbName := os.Getenv("DB_NAME"); dbName != "" {
		config.Database = dbName
	}
	if port := os.Getenv("DB_PORT"); port != "" {
		fmt.Sscanf(port, "%d", &config.Port)
	}

	return config
}