package middleware

import (
	"net/http"
)

// Middleware 中间件接口
type Middleware interface {
	ServeHTTP(http.ResponseWriter, *http.Request, http.HandlerFunc)
}

// Chain 中间件链
type Chain struct {
	middlewares []Middleware
}

// NewChain 创建新的中间件链
func NewChain(middlewares ...Middleware) *Chain {
	return &Chain{
		middlewares: middlewares,
	}
}

// Then 将中间件链应用到处理器
func (c *Chain) Then(h http.Handler) http.Handler {
	if h == nil {
		h = http.DefaultServeMux
	}

	for i := len(c.middlewares) - 1; i >= 0; i-- {
		h = c.wrap(h, c.middlewares[i])
	}

	return h
}

// wrap 包装处理器
func (c *Chain) wrap(h http.Handler, m Middleware) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		m.ServeHTTP(w, r, h.ServeHTTP)
	})
}

// Add 添加中间件
func (c *Chain) Add(middlewares ...Middleware) *Chain {
	c.middlewares = append(c.middlewares, middlewares...)
	return c
}

// Remove 移除中间件
func (c *Chain) Remove(index int) *Chain {
	if index < 0 || index >= len(c.middlewares) {
		return c
	}
	c.middlewares = append(c.middlewares[:index], c.middlewares[index+1:]...)
	return c
}

// Clear 清空中间件链
func (c *Chain) Clear() *Chain {
	c.middlewares = nil
	return c
}