basic functionality - terrible performance

Grok didn't do a terribly greate job on this one.

I'll clean it up with actually good code later.

main.go

@@ -0,0 +1,155 @@
+package main
+
+import (
+	"encoding/json"
+	"flag"
+	"log"
+	"net/http"
+	"os"
+	"strings"
+	"time"
+
+	"github.com/aws/aws-sdk-go/aws"
+	"github.com/aws/aws-sdk-go/aws/session"
+	"github.com/aws/aws-sdk-go/service/s3"
+)
+
+var (
+	useS3    bool
+	s3Bucket string
+	s3Region string
+	localDir string
+	port     string
+)
+
+func init() {
+	flag.BoolVar(&useS3, "s3", false, "Use S3")
+	flag.StringVar(&s3Bucket, "bucket", "", "S3 bucket name")
+	flag.StringVar(&s3Region, "region", "", "S3 region")
+	flag.StringVar(&localDir, "dir", "", "Local directory")
+	flag.StringVar(&port, "port", "8080", "Server port")
+	flag.Parse()
+}
+
+func main() {
+	if useS3 && (s3Bucket == "" || s3Region == "") {
+		log.Fatal("S3 bucket and region must be provided when using S3")
+	}
+	if !useS3 && localDir == "" {
+		log.Fatal("Local directory must be provided when not using S3")
+	}
+
+	http.HandleFunc("/api/pairs", pairsHandler)
+	if !useS3 {
+		http.Handle("/images/", http.StripPrefix("/images/", http.FileServer(http.Dir(localDir))))
+	}
+	http.Handle("/", http.FileServer(http.Dir("web"))) // Serve static files from 'web' directory
+	log.Println("Server starting on port", port)
+	log.Fatal(http.ListenAndServe(":"+port, nil))
+}
+
+func pairsHandler(w http.ResponseWriter, r *http.Request) {
+	var pairs []Pair
+	if useS3 {
+		pairs = listS3Pairs()
+	} else {
+		pairs = listLocalPairs(r.Host)
+	}
+	w.Header().Set("Content-Type", "application/json")
+	json.NewEncoder(w).Encode(pairs)
+}
+
+type Pair struct {
+	Name  string `json:"name"`
+	Left  string `json:"left"`
+	Right string `json:"right"`
+}
+
+func listS3Pairs() []Pair {
+	sess, err := session.NewSession(&aws.Config{
+		Region: aws.String(s3Region),
+	})
+	if err != nil {
+		log.Println("Error creating AWS session:", err)
+		return nil
+	}
+	s3Client := s3.New(sess)
+	resp, err := s3Client.ListObjectsV2(&s3.ListObjectsV2Input{
+		Bucket: aws.String(s3Bucket),
+	})
+	if err != nil {
+		log.Println("Error listing S3 objects:", err)
+		return nil
+	}
+
+	pairMap := make(map[string][2]string)
+	for _, obj := range resp.Contents {
+		key := *obj.Key
+		if strings.HasSuffix(key, "_left.jpg") {
+			prefix := strings.TrimSuffix(key, "_left.jpg")
+			pairMap[prefix] = [2]string{key, ""}
+		} else if strings.HasSuffix(key, "_right.jpg") {
+			prefix := strings.TrimSuffix(key, "_right.jpg")
+			if val, ok := pairMap[prefix]; ok {
+				pairMap[prefix] = [2]string{val[0], key}
+			} else {
+				pairMap[prefix] = [2]string{"", key}
+			}
+		}
+	}
+
+	var pairs []Pair
+	for prefix, keys := range pairMap {
+		if keys[0] != "" && keys[1] != "" {
+			leftReq, _ := s3Client.GetObjectRequest(&s3.GetObjectInput{
+				Bucket: aws.String(s3Bucket),
+				Key:    aws.String(keys[0]),
+			})
+			leftURL, _ := leftReq.Presign(1 * time.Hour)
+			rightReq, _ := s3Client.GetObjectRequest(&s3.GetObjectInput{
+				Bucket: aws.String(s3Bucket),
+				Key:    aws.String(keys[1]),
+			})
+			rightURL, _ := rightReq.Presign(1 * time.Hour)
+			pairs = append(pairs, Pair{Name: prefix, Left: leftURL, Right: rightURL})
+		}
+	}
+	return pairs
+}
+
+func listLocalPairs(host string) []Pair {
+	files, err := os.ReadDir(localDir)
+	if err != nil {
+		log.Println("Error reading local directory:", err)
+		return nil
+	}
+
+	pairMap := make(map[string][2]string)
+	for _, file := range files {
+		name := file.Name()
+		if strings.HasSuffix(name, "_left.jpg") {
+			prefix := strings.TrimSuffix(name, "_left.jpg")
+			pairMap[prefix] = [2]string{name, ""}
+		} else if strings.HasSuffix(name, "_right.jpg") {
+			prefix := strings.TrimSuffix(name, "_right.jpg")
+			if val, ok := pairMap[prefix]; ok {
+				pairMap[prefix] = [2]string{val[0], name}
+			} else {
+				pairMap[prefix] = [2]string{"", name}
+			}
+		}
+	}
+
+	baseURL := "http://" + host + "/images/"
+	var pairs []Pair
+	for prefix, names := range pairMap {
+		if names[0] != "" && names[1] != "" {
+			pairs = append(pairs, Pair{
+				Name:  prefix,
+				Left:  baseURL + names[0],
+				Right: baseURL + names[1],
+			})
+		}
+	}
+	return pairs
+}