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/signature/signature.go

@@ -12,6 +12,8 @@ import (
 	"strconv"
 	"strings"
 	"time"
+
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // Signature errors.
@@ -22,37 +24,6 @@ var (
 	ErrMissingExpiration = errors.New("signature expiration is required")
 )
 
-// Request carries the components an image request signature covers. It is a
-// standalone type so that this package does not depend on imgcache, keeping
-// the import edge one-way (imgcache depends on signature, never the reverse).
-type Request struct {
-	// SourceHost is the origin host (e.g. "cdn.example.com").
-	SourceHost string
-	// SourcePath is the path on the origin (e.g. "/photos/cat.jpg").
-	SourcePath string
-	// SourceQuery is the optional query string for the origin URL.
-	SourceQuery string
-	// Width is the requested output width in pixels.
-	Width int
-	// Height is the requested output height in pixels.
-	Height int
-	// Format is the requested output format (e.g. "webp").
-	Format string
-	// Quality is the requested output quality (1-100) for lossy formats.
-	// It is the effective value the request resolves to: callers pass the
-	// default quality when the request omits the parameter, so an omitted
-	// quality signs identically to that same value stated explicitly.
-	Quality int
-	// FitMode is how the image is fit into the requested dimensions
-	// (e.g. "cover"). Like Quality it is the effective value: callers pass
-	// the default fit mode when the request omits the parameter.
-	FitMode string
-	// Signature is the HMAC signature to verify.
-	Signature string
-	// Expires is the signature expiration timestamp.
-	Expires time.Time
-}
-
 // Signer handles HMAC-SHA256 signature generation and verification.
 type Signer struct {
 	secretKey []byte
@@ -67,8 +38,11 @@ func New(secretKey string) *Signer {
 
 // Sign generates an HMAC-SHA256 signature for the given request.
 // The signature covers: host + path + query + width + height + format +
-// expiration + quality + fit.
-func (s *Signer) Sign(req *Request) string {
+// expiration + quality + fit. The quality and fit mode are the effective
+// values the request resolves to: callers pass the defaults when the request
+// omits those parameters, so an omitted quality or fit mode signs
+// identically to that same value stated explicitly.
+func (s *Signer) Sign(req *imagerequest.Request) string {
 	data := s.buildSignatureData(req)
 	mac := hmac.New(sha256.New, s.secretKey)
 	mac.Write([]byte(data))
@@ -84,7 +58,7 @@ func (s *Signer) Sign(req *Request) string {
 // No suffix matching, wildcard matching, or partial matching is supported.
 // A signature for "cdn.example.com" will NOT verify for "example.com" or
 // "other.cdn.example.com", and vice versa.
-func (s *Signer) Verify(req *Request) error {
+func (s *Signer) Verify(req *imagerequest.Request) error {
 	// Check expiration first
 	if req.Expires.IsZero() {
 		return ErrMissingExpiration
@@ -108,7 +82,7 @@ func (s *Signer) Verify(req *Request) error {
 // GenerateSignedURL creates a complete URL with signature and expiration.
 // Returns the path portion that should be appended to the base URL.
 func (s *Signer) GenerateSignedURL(
-	req *Request, ttl time.Duration,
+	req *imagerequest.Request, ttl time.Duration,
 ) (string, string, int64) {
 	// Set expiration
 	req.Expires = time.Now().Add(ttl)
@@ -120,10 +94,11 @@ func (s *Signer) GenerateSignedURL(
 
 	// Build the size component
 	var sizeStr string
-	if req.Width == 0 && req.Height == 0 {
+	if req.Transform.Size.Width == 0 && req.Transform.Size.Height == 0 {
 		sizeStr = "orig"
 	} else {
-		sizeStr = fmt.Sprintf("%dx%d", req.Width, req.Height)
+		sizeStr = fmt.Sprintf("%dx%d",
+			req.Transform.Size.Width, req.Transform.Size.Height)
 	}
 
 	// Build the path. A source query follows the source path after a "?".
@@ -131,13 +106,13 @@ func (s *Signer) GenerateSignedURL(
 	// written in Go's own percent-encoding of a URL path, which writes "?"
 	// as %3F and "%" as %25, and leaves "/", ";", ",", "=" and "&" as they
 	// are.
-	sourcePathAndQuery := req.SourcePath
-	if req.SourceQuery != "" {
-		sourcePathAndQuery += "?" + req.SourceQuery
+	sourcePathAndQuery := req.Source.Path
+	if req.Source.Query != "" {
+		sourcePathAndQuery += "?" + req.Source.Query
 	}
 
 	unescapedPath := fmt.Sprintf("/v1/image/%s%s/%s.%s",
-		req.SourceHost, sourcePathAndQuery, sizeStr, req.Format)
+		req.Source.Host, sourcePathAndQuery, sizeStr, req.Transform.Format)
 
 	return (&url.URL{Path: unescapedPath}).EscapedPath(), sig, exp
 }
@@ -150,17 +125,17 @@ func (s *Signer) GenerateSignedURL(
 // expansion is performed. Quality and fit are the effective transform
 // values, so replaying a signed URL with a different quality or fit mode
 // fails verification.
-func (s *Signer) buildSignatureData(req *Request) string {
+func (s *Signer) buildSignatureData(req *imagerequest.Request) string {
 	return fmt.Sprintf("%s:%s:%s:%d:%d:%s:%d:%d:%s",
-		req.SourceHost,
-		escapePercentAndColon(req.SourcePath),
-		escapePercentAndColon(req.SourceQuery),
-		req.Width,
-		req.Height,
-		req.Format,
+		req.Source.Host,
+		escapePercentAndColon(req.Source.Path),
+		escapePercentAndColon(req.Source.Query),
+		req.Transform.Size.Width,
+		req.Transform.Size.Height,
+		req.Transform.Format,
 		req.Expires.Unix(),
-		req.Quality,
-		req.FitMode,
+		req.Transform.Quality,
+		req.Transform.FitMode,
 	)
 }