From 685d621556f77f897f7e2c7d7a36ad6e58131090 Mon Sep 17 00:00:00 2001
From: rasmus <rasmus@k-space.ee>
Date: Fri, 13 Sep 2024 21:48:41 +0300
Subject: [PATCH] ft: NOPATH redirect

---
 main.go | 65 ++++++++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 46 insertions(+), 19 deletions(-)

diff --git a/main.go b/main.go
index 05e00b3..4bc7fad 100644
--- a/main.go
+++ b/main.go
@@ -2,6 +2,13 @@ package main
 
 import (
 	"context"
+	"log"
+	"net/http"
+	"os"
+	"regexp"
+	"strings"
+	"time"
+
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promauto"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
@@ -10,39 +17,53 @@ import (
 	"go.mongodb.org/mongo-driver/mongo"
 	"go.mongodb.org/mongo-driver/mongo/options"
 	"go.mongodb.org/mongo-driver/x/mongo/driver/connstring"
-	"log"
-	"net/http"
-	"os"
-	"regexp"
-	"strings"
-	"time"
 )
 
 type inventoryItemType struct {
-	ID primitive.ObjectID `bson:"_id" json:"_id,omitempty"`
+	ID        primitive.ObjectID `bson:"_id" json:"_id,omitempty"`
 	Shortener struct {
 		Slug string `bson:"slug" json:"slug"`
 		URL  string `bson:"url" json:"url"`
 	} `bson:"shortener" json:"shortener"`
 }
 
-var reValid = regexp.MustCompile("^[a-zA-Z0-9]{4,6}$")
-var mongoURI string = "mongodb://127.0.0.1:27017/default?replicaSet=rs0"
-var collectionName string = "inventory"
-var redirectFound string = os.Getenv("GOREDIRECT_FOUND")
-var redirectNotFound string = os.Getenv("GOREDIRECT_NOT_FOUND")
+var (
+	mongoURI        = "mongodb://127.0.0.1:27017/default?replicaSet=rs0"
+	mongoCollection = "inventory"
+)
+
+var (
+	regexValid       = regexp.MustCompile("^[a-zA-Z0-9]{4,6}$")
+	redirectFound    = os.Getenv("GOREDIRECT_FOUND")
+	redirectNotFound = os.Getenv("GOREDIRECT_NOT_FOUND")
+	redirectNoPath   = os.Getenv("GOREDIRECT_NOPATH")
+)
 
 func wrapper(coll *mongo.Collection) func(w http.ResponseWriter, r *http.Request) {
 	return func(w http.ResponseWriter, r *http.Request) {
 		counterQueries.Inc()
 		slug := r.URL.Path[1:]
-		match := reValid.MatchString(slug)
-		if !match {
+
+		// Prevalidation
+
+		if slug == "" && redirectNoPath != "" {
+			counterNoPath.Inc()
+
+			log.Printf("Redirecting empty slug to %s\n", redirectNoPath)
+			http.Redirect(w, r, redirectNoPath, 302)
+
+			return
+		}
+
+		if match := regexValid.MatchString(slug); !match {
 			counterInvalidSlug.Inc()
+
 			http.Error(w, "Invalid slug", 400)
 			return
 		}
 
+		// Query
+
 		var doc inventoryItemType
 		err := coll.FindOne(context.TODO(), bson.M{"shortener.slug": slug}).Decode(&doc)
 		if err != nil {
@@ -57,12 +78,14 @@ func wrapper(coll *mongo.Collection) func(w http.ResponseWriter, r *http.Request
 		}
 
 		counterFound.Inc()
-		var u = doc.Shortener.URL
-		if u == "" {
-			u = strings.Replace(redirectFound, "%s", doc.ID.Hex(), 1)
+
+		redirURL := doc.Shortener.URL
+		if redirURL == "" {
+			redirURL = strings.Replace(redirectFound, "%s", doc.ID.Hex(), 1)
 		}
-		http.Redirect(w, r, u, 302)
-		log.Printf("Redirecting %s to %s\n", slug, doc.Shortener.URL)
+
+		http.Redirect(w, r, redirURL, 302)
+		log.Printf("Redirecting %s to %s\n", slug, redirURL)
 	}
 }
 
@@ -71,6 +94,10 @@ var (
 		Name: "goredirect_queries",
 		Help: "The total number of queries.",
 	})
+	counterNoPath = promauto.NewCounter(prometheus.CounterOpts{
+		Name: "goredirect_not_found",
+		Help: "The total number of queries with unknown slug.",
+	})
 	counterInvalidSlug = promauto.NewCounter(prometheus.CounterOpts{
 		Name: "goredirect_invalid_slug",
 		Help: "The total number of queries that did not match regex.",