package middleware

import "net/http"

// Middleware wraps an http.RoundTripper to add behavior.
// This is the fundamental building block of the httpx library.
type Middleware func(http.RoundTripper) http.RoundTripper

// Chain composes middlewares so that Chain(A, B, C)(base) == A(B(C(base))).
// Middlewares are applied from right to left: C wraps base first, then B wraps
// the result, then A wraps last. This means A is the outermost layer and sees
// every request first.
func Chain(mws ...Middleware) Middleware {
	return func(rt http.RoundTripper) http.RoundTripper {
		for i := len(mws) - 1; i >= 0; i-- {
			rt = mws[i](rt)
		}
		return rt
	}
}

// RoundTripperFunc is an adapter to allow the use of ordinary functions as
// http.RoundTripper. It works exactly like http.HandlerFunc for handlers.
type RoundTripperFunc func(*http.Request) (*http.Response, error)

// RoundTrip implements http.RoundTripper.
func (f RoundTripperFunc) RoundTrip(req *http.Request) (*http.Response, error) {
	return f(req)
}