learn/golang-learn/base/44-interface1/main.go

package main

import "fmt"

// ========== 接口定义 ==========
// 支付接口 - 定义支付行为契约
type Payment interface {
	Pay(amount float64) bool
	Refund(amount float64) bool
	GetBalance() float64
	GetProviderName() string
}

// ========== 结构体定义 ==========
// 支付宝支付
type Alipay struct {
	Account string
	Balance float64
}

// 微信支付
type WechatPay struct {
	OpenID  string
	Balance float64
	Frozen  float64 // 冻结金额
}

// 银行卡支付
type BankCard struct {
	CardNumber string
	Balance    float64
	BankName   string
}

// ========== 方法实现 - Alipay ==========
func (a *Alipay) Pay(amount float64) bool {
	if amount <= 0 || amount > a.Balance {
		fmt.Printf("支付宝支付失败！金额: %.2f, 余额: %.2f\n", amount, a.Balance)
		return false
	}
	a.Balance -= amount
	fmt.Printf("支付宝支付成功！扣款: %.2f, 剩余余额: %.2f\n", amount, a.Balance)
	return true
}

func (a *Alipay) Refund(amount float64) bool {
	if amount <= 0 {
		return false
	}
	a.Balance += amount
	fmt.Printf("支付宝退款成功！退款: %.2f, 当前余额: %.2f\n", amount, a.Balance)
	return true
}

func (a Alipay) GetBalance() float64 {
	return a.Balance
}

func (a Alipay) GetProviderName() string {
	return "支付宝"
}

// ========== 方法实现 - WechatPay ==========
func (w *WechatPay) Pay(amount float64) bool {
	available := w.Balance - w.Frozen
	if amount <= 0 || amount > available {
		fmt.Printf("微信支付失败！金额: %.2f, 可用余额: %.2f\n", amount, available)
		return false
	}
	w.Balance -= amount
	fmt.Printf("微信支付成功！扣款: %.2f, 剩余余额: %.2f\n", amount, w.Balance)
	return true
}

func (w *WechatPay) Refund(amount float64) bool {
	if amount <= 0 {
		return false
	}
	w.Balance += amount
	fmt.Printf("微信退款成功！退款: %.2f, 当前余额: %.2f\n", amount, w.Balance)
	return true
}

func (w WechatPay) GetBalance() float64 {
	return w.Balance
}

func (w WechatPay) GetProviderName() string {
	return "微信支付"
}

// 微信特有方法（不在接口中）
func (w *WechatPay) FreezeAmount(amount float64) {
	w.Frozen += amount
	fmt.Printf("冻结金额: %.2f, 总冻结: %.2f\n", amount, w.Frozen)
}

func (w *WechatPay) UnfreezeAmount(amount float64) {
	if amount <= w.Frozen {
		w.Frozen -= amount
		fmt.Printf("解冻金额: %.2f, 剩余冻结: %.2f\n", amount, w.Frozen)
	}
}

// ========== 方法实现 - BankCard ==========
func (b *BankCard) Pay(amount float64) bool {
	if amount <= 0 || amount > b.Balance {
		fmt.Printf("银行卡支付失败！金额: %.2f, 余额: %.2f\n", amount, b.Balance)
		return false
	}
	b.Balance -= amount
	fmt.Printf("银行卡支付成功！扣款: %.2f, 剩余余额: %.2f\n", amount, b.Balance)
	return true
}

func (b *BankCard) Refund(amount float64) bool {
	if amount <= 0 {
		return false
	}
	b.Balance += amount
	fmt.Printf("银行卡退款成功！退款: %.2f, 当前余额: %.2f\n", amount, b.Balance)
	return true
}

func (b BankCard) GetBalance() float64 {
	return b.Balance
}

func (b BankCard) GetProviderName() string {
	return b.BankName + "银行卡"
}

// ========== 工具函数（使用接口） ==========
// 处理支付 - 接受任何实现 Payment 接口的类型
func ProcessPayment(p Payment, amount float64) bool {
	fmt.Printf("\n开始处理支付...\n")
	fmt.Printf("支付方式: %s\n", p.GetProviderName())
	fmt.Printf("当前余额: %.2f\n", p.GetBalance())

	success := p.Pay(amount)

	if success {
		fmt.Printf("✅ 支付处理完成\n")
	} else {
		fmt.Printf("❌ 支付处理失败\n")
	}

	return success
}

// 批量支付处理
func ProcessBatchPayments(payments []Payment, amount float64) {
	fmt.Printf("\n=== 批量支付处理 ===\n")
	successCount := 0

	for i, payment := range payments {
		fmt.Printf("\n第 %d 笔支付:\n", i+1)
		if ProcessPayment(payment, amount) {
			successCount++
		}
	}

	fmt.Printf("\n批量支付结果: 成功 %d/%d\n", successCount, len(payments))
}

// 检查支付方式状态
func CheckPaymentStatus(payments []Payment) {
	fmt.Printf("\n=== 支付方式状态检查 ===\n")
	for i, payment := range payments {
		fmt.Printf("%d. %s - 余额: %.2f\n",
			i+1, payment.GetProviderName(), payment.GetBalance())
	}
}

func main() {
	fmt.Println("=== 支付系统演示 ===\n")

	// 创建不同的支付实例
	alipay := &Alipay{Account: "zhangsan@alipay.com", Balance: 1000.0}
	wechat := &WechatPay{OpenID: "wx123456", Balance: 800.0}
	bankcard := &BankCard{CardNumber: "622588******1234", Balance: 5000.0, BankName: "招商银行"}

	// 演示微信特有方法
	wechat.FreezeAmount(200.0)

	// 将不同支付方式放入接口切片（多态）
	payments := []Payment{alipay, wechat, bankcard}

	// 1. 检查状态
	CheckPaymentStatus(payments)

	// 2. 单笔支付处理
	fmt.Println("\n=== 单笔支付演示 ===")
	ProcessPayment(alipay, 150.0)
	ProcessPayment(wechat, 100.0) // 注意：微信有冻结金额

	// 3. 批量支付处理
	ProcessBatchPayments(payments, 50.0)

	// 4. 退款演示
	fmt.Println("\n=== 退款演示 ===")
	alipay.Refund(50.0)
	wechat.Refund(30.0)

	// 5. 最终状态检查
	CheckPaymentStatus(payments)

	// 6. 类型断言演示：访问具体类型的特有方法
	fmt.Println("\n=== 类型断言访问特有方法 ===")
	for _, payment := range payments {
		// 检查是否是 WechatPay 类型
		if wechatPay, ok := payment.(*WechatPay); ok {
			fmt.Printf("发现微信支付，冻结金额: %.2f\n", wechatPay.Frozen)
			wechatPay.UnfreezeAmount(100.0) // 解冻部分金额
		}
	}

	// 7. 类型切换演示
	fmt.Println("\n=== 类型切换演示 ===")
	for i, payment := range payments {
		switch p := payment.(type) {
		case *Alipay:
			fmt.Printf("%d. 支付宝账户: %s\n", i+1, p.Account)
		case *WechatPay:
			fmt.Printf("%d. 微信OpenID: %s, 冻结金额: %.2f\n", i+1, p.OpenID, p.Frozen)
		case *BankCard:
			fmt.Printf("%d. 银行卡号: %s\n", i+1, p.CardNumber)
		default:
			fmt.Printf("%d. 未知支付类型\n", i+1)
		}
	}
}