Use originally requested service if not using URL redirect

The specified service (i.e. whoogle) should be used for the redirect if
explicitly stated, rather than randomly fetching an instance for the
provided URL.

For instance:

- farside.link/https://google.com/search?q=balatro can redirect to a
  whoogle or searxng instance.
- farside.link/whoogle/search?q=balatro will always redirect to a
  whoogle instance.

services/mappings.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 	"math/rand"
 	"regexp"
+	"strings"
 )
 
 type RegexMapping struct {
@@ -30,7 +31,7 @@ var regexMap = []RegexMapping{
 	{
 		// Google Search
 		Pattern: regexp.MustCompile(`google\.com|whoogle|searx|searxng`),
-		Targets: []string{"whoogle", "searx", "searxng"},
+		Targets: []string{"whoogle", "searxng"},
 	},
 	{
 		// Instagram
@@ -122,12 +123,17 @@ var regexMap = []RegexMapping{
 }
 
 func MatchRequest(service string) (string, error) {
+
 	for _, mapping := range regexMap {
 		hasMatch := mapping.Pattern.MatchString(service)
 		if !hasMatch {
 			continue
 		}
 
+		if !strings.Contains(service, ".") {
+			return service, nil
+		}
+
 		index := rand.Intn(len(mapping.Targets))
 		value := mapping.Targets[index]
 		return value, nil