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middleware.go
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middleware.go
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package middleware
import (
"mime"
"net/http"
"strings"
)
type Middleware interface {
Wrap(http.Handler) http.Handler
}
type MiddlewareFunc func(http.Handler) http.Handler
func (mf MiddlewareFunc) Wrap(next http.Handler) http.Handler {
return mf(next)
}
type MiddlewareProvider interface {
Middleware() Middleware
}
type Middlewares []Middleware
func (ms Middlewares) Wrap(next http.Handler) http.Handler {
for i := len(ms) - 1; i >= 0; i-- {
m := ms[i]
next = m.Wrap(next)
}
return next
}
var NopHandler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {})
func Compose(mws ...Middleware) http.Handler {
return Middlewares(mws).Wrap(NopHandler)
}
func Wrap(h http.Handler, mws ...Middleware) http.Handler {
return Middlewares(mws).Wrap(h)
}
func RequireMethods(methods ...string) Middleware {
allowed := make(map[string]bool)
for _, m := range methods {
allowed[strings.ToUpper(m)] = true
}
return MiddlewareFunc(func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if allowed[r.Method] {
next.ServeHTTP(w, r)
return
}
code := http.StatusMethodNotAllowed
http.Error(w, http.StatusText(code), code)
})
})
}
func RequireMimeTypes(mimes ...string) Middleware {
allowed := make(map[string]bool)
for _, m := range mimes {
allowed[m] = true
}
return MiddlewareFunc(func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
mimetype, _, err := mime.ParseMediaType(r.Header.Get("Content-Type"))
if err != nil {
http.Error(w, err.Error(), http.StatusBadRequest)
return
}
if allowed[mimetype] {
next.ServeHTTP(w, r)
return
}
code := http.StatusUnsupportedMediaType
http.Error(w, http.StatusText(code), code)
})
})
}