From 8733d84ef685cfd4f0f89945171af196e4a7d4da Mon Sep 17 00:00:00 2001
From: Umputun <umputun@gmail.com>
Date: Thu, 8 Apr 2021 23:27:57 -0500
Subject: [PATCH] support extension of rules

---
 app/discovery/discovery.go      | 25 ++++++++++++++++
 app/discovery/discovery_test.go | 51 +++++++++++++++++++++++++++++----
 2 files changed, 71 insertions(+), 5 deletions(-)

diff --git a/app/discovery/discovery.go b/app/discovery/discovery.go
index 3c3709d..67faf1d 100644
--- a/app/discovery/discovery.go
+++ b/app/discovery/discovery.go
@@ -7,6 +7,7 @@ package discovery
 import (
 	"context"
 	"regexp"
+	"strings"
 	"sync"
 
 	log "github.com/go-pkgz/lgr"
@@ -124,6 +125,7 @@ func (s *Service) mergeLists() (res []UrlMapper) {
 			continue
 		}
 		for i := range lst {
+			lst[i] = s.extendRule(lst[i])
 			lst[i].ProviderID = p.ID()
 		}
 		res = append(res, lst...)
@@ -131,6 +133,29 @@ func (s *Service) mergeLists() (res []UrlMapper) {
 	return res
 }
 
+// extendRule from /something/blah->http://example.com/api to ^/something/blah/(.*)->http://example.com/api/$1
+func (s *Service) extendRule(m UrlMapper) UrlMapper {
+
+	src := m.SrcMatch.String()
+	if strings.Contains(m.Dst, "$1") || strings.Contains(src, "(") || !strings.HasSuffix(src, "/") {
+		return m
+	}
+	res := UrlMapper{
+		Server:     m.Server,
+		Dst:        strings.TrimSuffix(m.Dst, "/") + "/$1",
+		ProviderID: m.ProviderID,
+		PingURL:    m.PingURL,
+	}
+
+	rx, err := regexp.Compile("^" + strings.TrimSuffix(src, "/") + "/(.*)")
+	if err != nil {
+		log.Printf("[WARN] can't extend %s, %v", m.SrcMatch.String(), err)
+		return m
+	}
+	res.SrcMatch = *rx
+	return res
+}
+
 func (s *Service) mergeEvents(ctx context.Context, chs ...<-chan struct{}) <-chan struct{} {
 	var wg sync.WaitGroup
 	out := make(chan struct{})
diff --git a/app/discovery/discovery_test.go b/app/discovery/discovery_test.go
index 859af82..719a4cd 100644
--- a/app/discovery/discovery_test.go
+++ b/app/discovery/discovery_test.go
@@ -49,11 +49,12 @@ func TestService_Do(t *testing.T) {
 	err := svc.Run(ctx)
 	require.Error(t, err)
 	assert.Equal(t, context.DeadlineExceeded, err)
-	assert.Equal(t, 3, len(svc.mappers))
-	assert.Equal(t, PIFile, svc.mappers[0].ProviderID)
-	assert.Equal(t, "*", svc.mappers[0].Server)
-	assert.Equal(t, "^/api/svc1/(.*)", svc.mappers[0].SrcMatch.String())
-	assert.Equal(t, "http://127.0.0.1:8080/blah1/$1", svc.mappers[0].Dst)
+	mappers := svc.Mappers()
+	assert.Equal(t, 3, len(mappers))
+	assert.Equal(t, PIFile, mappers[0].ProviderID)
+	assert.Equal(t, "*", mappers[0].Server)
+	assert.Equal(t, "^/api/svc1/(.*)", mappers[0].SrcMatch.String())
+	assert.Equal(t, "http://127.0.0.1:8080/blah1/$1", mappers[0].Dst)
 
 	assert.Equal(t, 1, len(p1.EventsCalls()))
 	assert.Equal(t, 1, len(p2.EventsCalls()))
@@ -172,3 +173,43 @@ func TestService_Servers(t *testing.T) {
 	assert.Equal(t, []string{"m.example.com", "xx.reproxy.io"}, servers)
 
 }
+
+func TestService_extendRule(t *testing.T) {
+
+	tbl := []struct {
+		inp UrlMapper
+		out UrlMapper
+	}{
+		{
+			UrlMapper{SrcMatch: *regexp.MustCompile("/")},
+			UrlMapper{SrcMatch: *regexp.MustCompile("^/(.*)"), Dst: "/$1"},
+		},
+		{
+			UrlMapper{Server: "m.example.com", PingURL: "http://example.com/ping", ProviderID: "docker",
+				SrcMatch: *regexp.MustCompile("/api/blah/"), Dst: "http://localhost:8080/"},
+			UrlMapper{Server: "m.example.com", PingURL: "http://example.com/ping", ProviderID: "docker",
+				SrcMatch: *regexp.MustCompile("^/api/blah/(.*)"), Dst: "http://localhost:8080/$1"},
+		},
+		{
+			UrlMapper{Server: "m.example.com", PingURL: "http://example.com/ping", ProviderID: "docker",
+				SrcMatch: *regexp.MustCompile("/api/blah/(.*)/xxx/(.*_)"), Dst: "http://localhost:8080/$1/$2"},
+			UrlMapper{Server: "m.example.com", PingURL: "http://example.com/ping", ProviderID: "docker",
+				SrcMatch: *regexp.MustCompile("/api/blah/(.*)/xxx/(.*_)"), Dst: "http://localhost:8080/$1/$2"},
+		},
+		{
+			UrlMapper{Server: "m.example.com", PingURL: "http://example.com/ping", ProviderID: "docker",
+				SrcMatch: *regexp.MustCompile("/api/blah"), Dst: "http://localhost:8080/xxx"},
+			UrlMapper{Server: "m.example.com", PingURL: "http://example.com/ping", ProviderID: "docker",
+				SrcMatch: *regexp.MustCompile("/api/blah"), Dst: "http://localhost:8080/xxx"},
+		},
+	}
+
+	svc := &Service{}
+	for i, tt := range tbl {
+		t.Run(strconv.Itoa(i), func(t *testing.T) {
+			res := svc.extendRule(tt.inp)
+			assert.Equal(t, tt.out, res)
+		})
+	}
+
+}