package prxy

import (
	"fmt"
	"net"
	"net/http"
	"net/http/httputil"
	"net/url"

	"github.com/xlgmokha/x/pkg/log"
	"github.com/xlgmokha/x/pkg/x"
)

func New(routes map[string]string) http.Handler {
	mapped := map[string]*url.URL{}
	for source, destination := range routes {
		mapped[source] = x.Must(url.Parse(destination))
	}

	return &httputil.ReverseProxy{
		Rewrite: func(r *httputil.ProxyRequest) {
			host, _, err := net.SplitHostPort(r.In.Host)
			if err != nil {
				log.WithFields(r.In.Context(), log.Fields{"error": err})
				return
			}

			destination := mapped[host]
			r.SetXForwarded()
			r.SetURL(destination)
		},
		Transport:     http.DefaultTransport,
		FlushInterval: -1,
		ErrorLog:      nil,
		ModifyResponse: func(r *http.Response) error {
			r.Header.Add("Via", fmt.Sprintf("%v gtwy", r.Proto))
			return nil
		},
		ErrorHandler: func(w http.ResponseWriter, r *http.Request, err error) {
			log.WithFields(r.Context(), log.Fields{"error": err})
		},
	}
}