package ieproxy

import (

	"net/http"

	"net/url"

	"golang.org/x/net/http/httpproxy"

)

func proxyMiddleman() func(req *http.Request) (i *url.URL, e error) {

	// Get the proxy configuration

	conf := GetConf()

	envcfg := httpproxy.FromEnvironment()

	if envcfg.HTTPProxy != "" || envcfg.HTTPSProxy != "" {

		// If the user manually specifies environment variables, prefer those over the Windows config.

		return http.ProxyFromEnvironment

	} else if conf.Automatic.Active {

		// If automatic proxy obtaining is specified

		return func(req *http.Request) (i *url.URL, e error) {

			host := conf.Automatic.FindProxyForURL(req.URL.String())

			if host == "" {

				return nil, nil

			}

			return &url.URL{Host: host}, nil

		}

	} else if conf.Static.Active {

		// If static proxy obtaining is specified

		prox := httpproxy.Config{

			HTTPSProxy: mapFallback("https", "", conf.Static.Protocols),

			HTTPProxy:  mapFallback("http", "", conf.Static.Protocols),

			NoProxy:    conf.Static.NoProxy,

		}

		return func(req *http.Request) (i *url.URL, e error) {

			return prox.ProxyFunc()(req.URL)

		}

	} else {

		// Final fallthrough case; use the environment variables.

		return http.ProxyFromEnvironment

	}

}

// Return oKey or fbKey if oKey doesn't exist in the map.

func mapFallback(oKey, fbKey string, m map[string]string) string {

	if v, ok := m[oKey]; ok {

		return v

	} else {

		return m[fbKey]

	}

}