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 code; the
tests of the removed conversions go with them.

Model: opus-5-5

internal/handlers/auth.go

@@ -145,7 +145,7 @@ func (s *Handlers) HandleGenerateURL() http.HandlerFunc {
 			return
 		}
 
-		payload, expiresAt, ttl, err := buildGeneratePayload(parsed, r.Form)
+		req, expiresAt, ttl, err := buildGenerateRequest(parsed, r.Form)
 		if err != nil {
 			s.renderGeneratorWithForm(w, r, err.Error(), r.Form,
 				http.StatusBadRequest)
@@ -154,8 +154,8 @@ func (s *Handlers) HandleGenerateURL() http.HandlerFunc {
 		}
 
 		// The image URL must fetch the source URL as it was written
-		payload.AllowHTTP = s.config.AllowHTTP
-		fetchURL := payload.SourceURL()
+		req.AllowHTTP = s.config.AllowHTTP
+		fetchURL := req.SourceURL()
 
 		if !fetchedAsWritten(parsed, fetchURL) {
 			s.renderGeneratorWithForm(w, r, "Source URL cannot be fetched as "+
@@ -166,7 +166,7 @@ func (s *Handlers) HandleGenerateURL() http.HandlerFunc {
 		}
 
 		// Generate encrypted token
-		token, err := s.encGen.Generate(payload)
+		token, err := s.encGen.Generate(req)
 		if err != nil {
 			s.log.Error("failed to generate encrypted URL", "error", err)
 			s.renderGeneratorWithForm(w, r, "Failed to generate URL", r.Form,
@@ -239,13 +239,13 @@ func fetchedAsWritten(source *url.URL, fetchURL string) bool {
 		fetched.RawQuery == source.RawQuery
 }
 
-// buildGeneratePayload parses the numeric form fields and assembles the
+// buildGenerateRequest parses the numeric form fields and assembles the
 // image request the encrypted URL's token is made from. ttl=0 means never
 // expires (Expires stays the zero time). A non-numeric or out-of-range
 // width, height, quality or ttl, or an unrecognized fit mode, is a client
 // error naming the offending field. The format field is passed through
 // unchecked.
-func buildGeneratePayload(
+func buildGenerateRequest(
 	parsed *url.URL, form url.Values,
 ) (*imagerequest.Request, time.Time, int, error) {
 	width, err := parseFormDimension(form, "width")
@@ -282,7 +282,7 @@ func buildGeneratePayload(
 		expiresAt = time.Now().Add(time.Duration(ttl) * time.Second)
 	}
 
-	payload := &imagerequest.Request{
+	req := &imagerequest.Request{
 		Source: imagerequest.Source{
 			Host:  parsed.Host,
 			Path:  parsed.Path,
@@ -297,7 +297,7 @@ func buildGeneratePayload(
 		Expires: expiresAt,
 	}
 
-	return payload, expiresAt, ttl, nil
+	return req, expiresAt, ttl, nil
 }
 
 // parseFormDimension reads an optional width or height form field. An empty

internal/handlers/auth_generate_internal_test.go

@@ -125,10 +125,10 @@ func TestGeneratePostRejectsBadField(t *testing.T) {
 	}
 }
 
-// TestBuildGeneratePayloadDefaultAndLimits verifies that an empty quality
+// TestBuildGenerateRequestDefaultAndLimits verifies that an empty quality
 // takes the default, and that the largest accepted width, height, quality and
 // ttl are accepted with an expiry still in the future.
-func TestBuildGeneratePayloadDefaultAndLimits(t *testing.T) {
+func TestBuildGenerateRequestDefaultAndLimits(t *testing.T) {
 	t.Parallel()
 
 	parsed, err := url.Parse(testSourceURL)
@@ -136,17 +136,17 @@ func TestBuildGeneratePayloadDefaultAndLimits(t *testing.T) {
 		t.Fatalf("url.Parse() error = %v", err)
 	}
 
-	payload, _, _, err := buildGeneratePayload(parsed, url.Values{})
+	req, _, _, err := buildGenerateRequest(parsed, url.Values{})
 	if err != nil {
 		t.Fatalf("empty form: error = %v", err)
 	}
 
-	if payload.Transform.Quality != encurl.DefaultQuality {
+	if req.Transform.Quality != encurl.DefaultQuality {
 		t.Errorf("empty quality gave %d, want %d",
-			payload.Transform.Quality, encurl.DefaultQuality)
+			req.Transform.Quality, encurl.DefaultQuality)
 	}
 
-	_, expiresAt, _, err := buildGeneratePayload(parsed, url.Values{
+	_, expiresAt, _, err := buildGenerateRequest(parsed, url.Values{
 		widthField:   {strconv.Itoa(imagerequest.MaxDimension)},
 		heightField:  {strconv.Itoa(imagerequest.MaxDimension)},
 		qualityField: {strconv.Itoa(maxQuality)},

internal/imgcache/service_internal_test.go

@@ -381,6 +381,7 @@ func TestService_Get_InvalidFile(t *testing.T) {
 
 	req := photoVariant(fixtures, 85, imagerequest.FitCover)
 	req.Source.Path = "/images/fake.jpg"
+	req.Transform.Size = imagerequest.Size{Width: 50, Height: 50}
 
 	// Should fail because magic bytes don't match
 	_, err := svc.Get(ctx, req)
@@ -397,6 +398,7 @@ func TestService_Get_NotFound(t *testing.T) {
 
 	req := photoVariant(fixtures, 85, imagerequest.FitCover)
 	req.Source.Path = "/images/nonexistent.jpg"
+	req.Transform.Size = imagerequest.Size{Width: 50, Height: 50}
 
 	_, err := svc.Get(ctx, req)
 	if err == nil {