One image request type instead of five (closes #307)

The new package internal/imagerequest holds the request type, its two
parts Source and Transform, the Format and Fit types, the dimension and
fit checks, the /v1/image/ path parsing and the variant key; it imports
no other package of pixa. imgcache.ParsedURL, imgcache.ImageRequest,
signature.Request, imageprocessor.Request, the second Size, format and
fit types and the conversions between them are gone. The image
processor takes a Transform only. encurl keeps a private struct with the
token's CBOR field names, so tokens made before still decode. VariantKey
moves with the function that makes it. Tests follow the moved and
renamed code; the tests of the removed conversions go with them.

Model: opus-5-5

internal/handlers/format_auto_internal_test.go

@@ -12,8 +12,7 @@ import (
 
 	"github.com/go-chi/chi/v5"
 
-	"sneak.berlin/go/pixa/internal/encurl"
-	"sneak.berlin/go/pixa/internal/imgcache"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // The content types the tests below expect.
@@ -33,24 +32,24 @@ func TestFormatForAccept(t *testing.T) {
 	tests := []struct {
 		name    string
 		accept  string
-		want    imgcache.ImageFormat
+		want    imagerequest.Format
 		wantErr error
 	}{
 		{"AVIF-capable browser",
 			"image/avif,image/webp,image/apng,image/svg+xml,image/*,*/*;q=0.8",
-			imgcache.FormatAVIF, nil},
+			imagerequest.FormatAVIF, nil},
 		{"WebP-capable browser",
 			"image/webp,image/png,image/svg+xml,image/*;q=0.8,*/*;q=0.5",
-			imgcache.FormatWebP, nil},
-		{"WebP only", webpType, imgcache.FormatWebP, nil},
-		{"neither", "image/png,image/*;q=0.8,*/*;q=0.5", imgcache.FormatJPEG, nil},
-		{"wildcard only", "*/*", imgcache.FormatJPEG, nil},
-		{"image wildcard only", "image/*", imgcache.FormatJPEG, nil},
-		{"absent", "", imgcache.FormatJPEG, nil},
-		{"q=0 on AVIF", "image/avif;q=0,image/webp,*/*", imgcache.FormatWebP, nil},
+			imagerequest.FormatWebP, nil},
+		{"WebP only", webpType, imagerequest.FormatWebP, nil},
+		{"neither", "image/png,image/*;q=0.8,*/*;q=0.5", imagerequest.FormatJPEG, nil},
+		{"wildcard only", "*/*", imagerequest.FormatJPEG, nil},
+		{"image wildcard only", "image/*", imagerequest.FormatJPEG, nil},
+		{"absent", "", imagerequest.FormatJPEG, nil},
+		{"q=0 on AVIF", "image/avif;q=0,image/webp,*/*", imagerequest.FormatWebP, nil},
 		{"AVIF named twice, once with q=0", "image/avif,image/avif;q=0.0,*/*",
-			imgcache.FormatJPEG, nil},
-		{"upper case and spaces", " Image/AVIF ; Q=0.5 ", imgcache.FormatAVIF, nil},
+			imagerequest.FormatJPEG, nil},
+		{"upper case and spaces", " Image/AVIF ; Q=0.5 ", imagerequest.FormatAVIF, nil},
 		{"q=0 on JPEG", "image/jpeg;q=0,image/*", "", errNotAcceptable},
 		{"q=0 on everything", "*/*;q=0", "", errNotAcceptable},
 		{"PNG only", "image/png", "", errNotAcceptable},
@@ -80,23 +79,30 @@ func TestFormatForAccept(t *testing.T) {
 func autoPhotoURLs(t *testing.T, h *Handlers) (string, string) {
 	t.Helper()
 
-	signedURL, err := h.imgSvc.GenerateSignedURL("", &imgcache.ImageRequest{
-		SourceHost: signedHost,
-		SourcePath: photoPath,
-		Size:       imgcache.Size{Width: 50, Height: 50},
-		Format:     imgcache.FormatAuto,
+	signedURL, err := h.imgSvc.GenerateSignedURL("", &imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: signedHost,
+			Path: photoPath,
+		},
+		Transform: imagerequest.Transform{
+			Size:   imagerequest.Size{Width: 50, Height: 50},
+			Format: imagerequest.FormatAuto,
+		},
 	}, time.Minute)
 	if err != nil {
 		t.Fatalf("GenerateSignedURL() error = %v", err)
 	}
 
-	token, err := h.encGen.Generate(&encurl.Payload{
-		SourceHost: signedHost,
-		SourcePath: photoPath,
-		Width:      50,
-		Height:     50,
-		Format:     imgcache.FormatAuto,
-		ExpiresAt:  time.Now().Add(time.Minute).Unix(),
+	token, err := h.encGen.Generate(&imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: signedHost,
+			Path: photoPath,
+		},
+		Transform: imagerequest.Transform{
+			Size:   imagerequest.Size{Width: 50, Height: 50},
+			Format: imagerequest.FormatAuto,
+		},
+		Expires: time.Now().Add(time.Minute),
 	})
 	if err != nil {
 		t.Fatalf("Generate() error = %v", err)
@@ -184,11 +190,15 @@ func TestFormatAuto_SignatureCoversAuto(t *testing.T) {
 
 	h, srv := newSignedHostServer(t, slog.New(slog.DiscardHandler))
 
-	signedForAVIF, err := h.imgSvc.GenerateSignedURL("", &imgcache.ImageRequest{
-		SourceHost: signedHost,
-		SourcePath: photoPath,
-		Size:       imgcache.Size{Width: 50, Height: 50},
-		Format:     imgcache.FormatAVIF,
+	signedForAVIF, err := h.imgSvc.GenerateSignedURL("", &imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: signedHost,
+			Path: photoPath,
+		},
+		Transform: imagerequest.Transform{
+			Size:   imagerequest.Size{Width: 50, Height: 50},
+			Format: imagerequest.FormatAVIF,
+		},
 	}, time.Minute)
 	if err != nil {
 		t.Fatalf("GenerateSignedURL() error = %v", err)