package middleware

import (
	ctxpkg "github.com/noahlann/nnet/pkg/context"
	routerpkg "github.com/noahlann/nnet/pkg/router"
)

// Chain 中间件链
type Chain struct {
	middlewares []routerpkg.Handler
}

// NewChain 创建中间件链
func NewChain(middlewares ...routerpkg.Handler) *Chain {
	return &Chain{
		middlewares: middlewares,
	}
}

// Then 执行中间件链
func (c *Chain) Then(handler routerpkg.Handler) routerpkg.Handler {
	if len(c.middlewares) == 0 {
		return handler
	}

	// 从后往前包装
	h := handler
	for i := len(c.middlewares) - 1; i >= 0; i-- {
		middleware := c.middlewares[i]
		h = c.wrapHandler(middleware, h)
	}
	return h
}

// wrapHandler 包装处理器
func (c *Chain) wrapHandler(middleware, handler routerpkg.Handler) routerpkg.Handler {
	return func(ctx ctxpkg.Context) error {
		// 执行中间件
		if err := middleware(ctx); err != nil {
			return err
		}
		// 执行下一个处理器
		return handler(ctx)
	}
}

// Append 添加中间件
func (c *Chain) Append(middleware ...routerpkg.Handler) {
	c.middlewares = append(c.middlewares, middleware...)
}

// Prepend 前置添加中间件
func (c *Chain) Prepend(middleware ...routerpkg.Handler) {
	c.middlewares = append(middleware, c.middlewares...)
}