Simplify random.Int64 usage with generics

model/share.go

@@ -42,7 +42,7 @@ func (s Share) CoverArtID() ArtworkID {
 	case "artist":
 		return Artist{ID: ids[0]}.CoverArtID()
 	}
-	rnd := random.Int64(int64(len(s.Tracks)))
+	rnd := random.Int64(len(s.Tracks))
 	return s.Tracks[rnd].CoverArtID()
 }
 

server/backgrounds/handler.go

@@ -51,7 +51,7 @@ func (h *Handler) getRandomImage(ctx context.Context) (string, error) {
 	if len(list) == 0 {
 		return "", errors.New("no images available")
 	}
-	rnd := random.Int64(int64(len(list)))
+	rnd := random.Int64(len(list))
 	return list[rnd], nil
 }
 

utils/random/number.go

@@ -3,9 +3,11 @@ package random
 import (
 	"crypto/rand"
 	"math/big"
+
+	"golang.org/x/exp/constraints"
 )
 
-func Int64(max int64) int64 {
+func Int64[T constraints.Integer](max T) int64 {
-	rnd, _ := rand.Int(rand.Reader, big.NewInt(max))
+	rnd, _ := rand.Int(rand.Reader, big.NewInt(int64(max)))
 	return rnd.Int64()
 }

utils/random/weighted_random_chooser.go

@@ -39,7 +39,7 @@ func (w *WeightedChooser) weightedChoice() (int, error) {
 	if w.totalWeight == 0 {
 		return 0, errors.New("no choices available")
 	}
-	rnd := Int64(int64(w.totalWeight))
+	rnd := Int64(w.totalWeight)
 	for i, weight := range w.weights {
 		rnd -= int64(weight)
 		if rnd < 0 {