package middleware

import (

"net/http"

)

// Middleware - A function type for defining middleware

type Middleware func(http.HandlerFunc) http.HandlerFunc

// Decorator - Interface for defining a middleware wrapping mechanism. This

// interface exists for the purpose of testing, but, of course, can be used

// at your discretion.

type Decorator interface {

// Append - Add Middleware to the beginning of the decorator chain. This

// Middleware will wrap all existing middleware.

Append(Middleware) Decorator

// Prepend - Add Middleware to the end of the decorator chain. This Middleware

// will be wrapped by all existing Middleware.

Prepend(Middleware) Decorator

// WrapHandler - Wraps the http.HandlerFunc with the Middleware added via the

// Append and Prepend methods

WrapHandler(http.HandlerFunc) http.HandlerFunc

}

// Wrapper - Concrete implementation of the Decorator interface

type Wrapper struct {

middlewares []Middleware

}

// Append - Concrete implementation of the Decorator.Append method

func (w *Wrapper) Append(mw Middleware) Decorator {

w.middlewares = append([]Middleware{mw}, w.middlewares...)

return w

}

// Prepend - Concrete implementation of the Decorator.Prepend method

func (w *Wrapper) Prepend(m Middleware) Decorator {

w.middlewares = append(w.middlewares, m)

return w

}

// WrapHandler - Concrete implementation of the Decorator.WrapHandler method

func (w *Wrapper) WrapHandler(h http.HandlerFunc) http.HandlerFunc {

var mw Middleware

for _, mw = range w.middlewares {

h = mw(h)

}

return h

}