package main

import (
	"net/http"
	"time"
)

// An HTTPGetter can GET over HTTP
type HTTPGetter interface {
	Get(URL string) (*http.Response, error)
}

type simpleHTTPGetter struct{}

// NewHTTPGetter returns the simplest object that can GET over HTTP
func NewHTTPGetter() HTTPGetter {
	return &simpleHTTPGetter{}
}

func (g *simpleHTTPGetter) Get(URL string) (*http.Response, error) {
	return http.Get(URL)
}

type rateLimitedHTTPGetter struct {
	tokens chan bool
	window time.Duration
}

// NewRateLimitedGetter returns an HTTPGetter that is limited by a
// maximal amount of request over a time window
func NewRateLimitedGetter(maxRequest uint, window time.Duration) HTTPGetter {
	return &rateLimitedHTTPGetter{
		tokens: make(chan bool, maxRequest),
		window: window,
	}
}

func (g *rateLimitedHTTPGetter) Get(URL string) (*http.Response, error) {
	g.tokens <- true
	defer func() {
		go func() {
			time.Sleep(g.window)
			<-g.tokens
		}()
	}()
	return http.Get(URL)
}