package reverseproxy

import (
	"context"
	"net/http"
	"net/http/httputil"
	"net/url"
	"strings"
)

type ReverseProxy struct {
	context.Context
	*httputil.ReverseProxy
}

type CtxKey string

func New(ctx context.Context, host string) *ReverseProxy {

	ctxKey := CtxKey("host")
	ctx = context.WithValue(ctx, ctxKey, host)

	reverseProxySTDLIB := &httputil.ReverseProxy{
		Director: func(r *http.Request) {
			r = r.WithContext(ctx)
			hostFromCtx := ctx.Value(ctxKey).(string)
			target, _ := url.Parse(hostFromCtx)
			targetQuery := target.RawQuery
			r.URL.Scheme = target.Scheme
			r.URL.Host = target.Host
			r.URL.Path, r.URL.RawPath = joinURLPath(target, r.URL)
			if targetQuery == "" || r.URL.RawQuery == "" {
				r.URL.RawQuery = targetQuery + r.URL.RawQuery
			} else {
				r.URL.RawQuery = targetQuery + "&" + r.URL.RawQuery
			}
		},
	}
	reverseProxy := &ReverseProxy{}
	reverseProxy.Context = ctx
	reverseProxy.ReverseProxy = reverseProxySTDLIB
	return reverseProxy
}
func (revereProxy *ReverseProxy) SetContext(ctx context.Context) {
	revereProxy.Context = ctx
}
func (revereProxy *ReverseProxy) DirectorFunc(df func(jup JoinURLPathFunc) DirectorFunc) {
	d := df(joinURLPath)
	revereProxy.Director = d
}

func singleJoiningSlash(a, b string) string {
	aslash := strings.HasSuffix(a, "/")
	bslash := strings.HasPrefix(b, "/")
	switch {
	case aslash && bslash:
		return a + b[1:]
	case !aslash && !bslash:
		return a + "/" + b
	}
	return a + b
}

func joinURLPath(a, b *url.URL) (path, rawpath string) {
	if a.RawPath == "" && b.RawPath == "" {
		return singleJoiningSlash(a.Path, b.Path), ""
	}
	// Same as singleJoiningSlash, but uses EscapedPath to determine
	// whether a slash should be added
	apath := a.EscapedPath()
	bpath := b.EscapedPath()

	aslash := strings.HasSuffix(apath, "/")
	bslash := strings.HasPrefix(bpath, "/")

	switch {
	case aslash && bslash:
		return a.Path + b.Path[1:], apath + bpath[1:]
	case !aslash && !bslash:
		return a.Path + "/" + b.Path, apath + "/" + bpath
	}
	return a.Path + b.Path, apath + bpath
}

type JoinURLPathFunc func(*url.URL, *url.URL) (string, string)

// type SingleJoiningSlashFunc func(string, string) string
type DirectorFunc func(*http.Request)