package simpleproxy

import (
	"io"
	"net/http"
	"net/url"
)

type Proxy struct {
	ListenAddr string
	ServerAddr string

	u *url.URL
}

// NewProxy creates a new proxy server.
func NewProxy(listenAddr, serverAddr string) *Proxy {
	u, err := url.Parse(serverAddr)
	if err != nil {
		panic(err)
	}

	return &Proxy{
		ListenAddr: listenAddr,
		ServerAddr: serverAddr,
		u:          u,
	}
}

// ListenAndServe starts the proxy server.
func (p *Proxy) ListenAndServe() error {
	srv := &http.Server{
		Addr:    p.ListenAddr,
		Handler: p,
	}

	return srv.ListenAndServe()

}

// ServeHTTP is the main handler for the proxy server.
// all requests here should be proxied to the server.
func (p *Proxy) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	// all requests should be proxied to the server.
	req, err := http.NewRequest(r.Method, p.ServerAddr+r.URL.String(), r.Body)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	// copy headers
	for k, v := range r.Header {
		req.Header[k] = v
	}

	// make the request
	resp, err := http.DefaultClient.Do(req)

	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	mirrorResponse(w, resp)

}

func mirrorResponse(w http.ResponseWriter, resp *http.Response) {
	// Copy all headers from the original response
	for key, values := range resp.Header {
		for _, value := range values {
			w.Header().Add(key, value)
		}
	}

	// Copy the status code from the original response
	w.WriteHeader(resp.StatusCode)

	// Copy the response body
	io.Copy(w, resp.Body)
	resp.Body.Close()
}