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 short CBOR field names. 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/auth.go

@@ -16,7 +16,7 @@ import (
 
 	"sneak.berlin/go/pixa/internal/clientip"
 	"sneak.berlin/go/pixa/internal/encurl"
-	"sneak.berlin/go/pixa/internal/imgcache"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 	"sneak.berlin/go/pixa/internal/templates"
 )
 
@@ -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)
@@ -154,9 +154,8 @@ func (s *Handlers) HandleGenerateURL() http.HandlerFunc {
 		}
 
 		// The image URL must fetch the source URL as it was written
-		sourceRequest := payload.ToImageRequest()
-		sourceRequest.AllowHTTP = s.config.AllowHTTP
-		fetchURL := sourceRequest.SourceURL()
+		req.AllowHTTP = s.config.AllowHTTP
+		fetchURL := req.SourceURL()
 
 		if !fetchedAsWritten(parsed, fetchURL) {
 			s.renderGeneratorWithForm(w, r, "Source URL cannot be fetched as "+
@@ -167,7 +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,
@@ -240,14 +239,15 @@ func fetchedAsWritten(source *url.URL, fetchURL string) bool {
 		fetched.RawQuery == source.RawQuery
 }
 
-// buildGeneratePayload parses the numeric form fields and assembles the
-// encrypted URL payload. ttl=0 means never expires (ExpiresAt stays 0). 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(
+// 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 buildGenerateRequest(
 	parsed *url.URL, form url.Values,
-) (*encurl.Payload, time.Time, int, error) {
+) (*imagerequest.Request, time.Time, int, error) {
 	width, err := parseFormDimension(form, "width")
 	if err != nil {
 		return nil, time.Time{}, 0, err
@@ -269,42 +269,40 @@ func buildGeneratePayload(
 		return nil, time.Time{}, 0, err
 	}
 
-	fitMode := imgcache.FitMode(form.Get("fit"))
+	fitMode := imagerequest.Fit(form.Get("fit"))
 
-	err = imgcache.ValidateFitMode(fitMode)
+	err = imagerequest.ValidateFitMode(fitMode)
 	if err != nil {
 		return nil, time.Time{}, 0,
-			fmt.Errorf("%w: %s", imgcache.ErrInvalidFitMode, form.Get("fit"))
+			fmt.Errorf("%w: %s", imagerequest.ErrInvalidFitMode, form.Get("fit"))
 	}
 
-	var (
-		expiresAt     time.Time
-		expiresAtUnix int64
-	)
-
+	var expiresAt time.Time
 	if ttl > 0 {
 		expiresAt = time.Now().Add(time.Duration(ttl) * time.Second)
-		expiresAtUnix = expiresAt.Unix()
 	}
 
-	payload := &encurl.Payload{
-		SourceHost:  parsed.Host,
-		SourcePath:  parsed.Path,
-		SourceQuery: parsed.RawQuery,
-		Width:       width,
-		Height:      height,
-		Format:      imgcache.ImageFormat(form.Get("format")),
-		Quality:     quality,
-		FitMode:     fitMode,
-		ExpiresAt:   expiresAtUnix,
+	req := &imagerequest.Request{
+		Source: imagerequest.Source{
+			Host:  parsed.Host,
+			Path:  parsed.Path,
+			Query: parsed.RawQuery,
+		},
+		Transform: imagerequest.Transform{
+			Size:    imagerequest.Size{Width: width, Height: height},
+			Format:  imagerequest.Format(form.Get("format")),
+			Quality: quality,
+			FitMode: fitMode,
+		},
+		Expires: expiresAt,
 	}
 
-	return payload, expiresAt, ttl, nil
+	return req, expiresAt, ttl, nil
 }
 
 // parseFormDimension reads an optional width or height form field. An empty
 // value means "original size" (0). A non-numeric value, or one
-// imgcache.ValidateDimension rejects, is an error naming the field.
+// imagerequest.ValidateDimension rejects, is an error naming the field.
 func parseFormDimension(form url.Values, field string) (int, error) {
 	raw := form.Get(field)
 	if raw == "" {
@@ -316,7 +314,7 @@ func parseFormDimension(form url.Values, field string) (int, error) {
 		return 0, fmt.Errorf("%w %s: not a number", errInvalidFormField, field)
 	}
 
-	err = imgcache.ValidateDimension(field, value)
+	err = imagerequest.ValidateDimension(field, value)
 	if err != nil {
 		return 0, err
 	}