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/imgcache/cache.go

@@ -17,6 +17,7 @@ import (
 
 	lru "github.com/hashicorp/golang-lru/v2"
 	"sneak.berlin/go/pixa/internal/httpfetcher"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // Cache errors.
@@ -111,7 +112,7 @@ type Cache struct {
 	// metaCache holds the content types of the variants most recently
 	// stored or served, so a hit does not read the variant's .meta file.
 	// It never stands in for the variant file, which is always opened.
-	metaCache *lru.Cache[VariantKey, string]
+	metaCache *lru.Cache[imagerequest.VariantKey, string]
 
 	// contentLocks serializes StoreSource and evictSourceBlob per
 	// content hash, closing the race window between an eviction's row
@@ -153,7 +154,7 @@ func newCache(
 		log = slog.Default()
 	}
 
-	metaCache, err := lru.New[VariantKey, string](metaCacheSize)
+	metaCache, err := lru.New[imagerequest.VariantKey, string](metaCacheSize)
 	if err != nil {
 		return nil, fmt.Errorf("failed to create variant content type cache: %w", err)
 	}
@@ -223,7 +224,7 @@ func newCache(
 // LookupResult contains the result of a cache lookup.
 type LookupResult struct {
 	Hit         bool
-	CacheKey    VariantKey
+	CacheKey    imagerequest.VariantKey
 	ContentType string
 	SizeBytes   int64
 	CacheStatus CacheStatus
@@ -231,8 +232,10 @@ type LookupResult struct {
 
 // Lookup checks if a processed variant exists on disk. Hits touch the
 // variant's LRU timestamp; a disabled cache always misses.
-func (c *Cache) Lookup(ctx context.Context, req *ImageRequest) (*LookupResult, error) {
-	cacheKey := CacheKey(req)
+func (c *Cache) Lookup(
+	ctx context.Context, req *imagerequest.Request,
+) (*LookupResult, error) {
+	cacheKey := imagerequest.CacheKey(req)
 
 	// Check variant storage directly - no DB needed for cache hits
 	if !c.disabled && c.variants.Exists(cacheKey) {
@@ -257,7 +260,9 @@ func (c *Cache) Lookup(ctx context.Context, req *ImageRequest) (*LookupResult, e
 // variant's .meta file and is then kept in metaCache. A variant with
 // no .meta file is served as application/octet-stream, which is not
 // kept.
-func (c *Cache) GetVariant(cacheKey VariantKey) (io.ReadCloser, int64, string, error) {
+func (c *Cache) GetVariant(
+	cacheKey imagerequest.VariantKey,
+) (io.ReadCloser, int64, string, error) {
 	if c.disabled {
 		return nil, 0, "", ErrNotFound
 	}
@@ -282,7 +287,7 @@ func (c *Cache) GetVariant(cacheKey VariantKey) (io.ReadCloser, int64, string, e
 // disabled cache it is a no-op returning an empty hash.
 func (c *Cache) StoreSource(
 	ctx context.Context,
-	req *ImageRequest,
+	req *imagerequest.Request,
 	content io.Reader,
 	result *httpfetcher.FetchResult,
 ) (ContentHash, error) {
@@ -322,7 +327,7 @@ func (c *Cache) StoreSource(
 	}
 
 	// Store in database
-	pathHash := HashPath(req.SourcePath + "?" + req.SourceQuery)
+	pathHash := HashPath(req.Source.Path + "?" + req.Source.Query)
 
 	headersJSON, err := json.Marshal(result.Headers)
 	if err != nil {
@@ -349,7 +354,7 @@ func (c *Cache) StoreSource(
 			content_type = excluded.content_type,
 			response_headers = excluded.response_headers,
 			fetched_at = CURRENT_TIMESTAMP
-	`, req.SourceHost, req.SourcePath, req.SourceQuery, pathHash,
+	`, req.Source.Host, req.Source.Path, req.Source.Query, pathHash,
 		contentHash, httpStatusOK, result.ContentType, string(headersJSON))
 	if err != nil {
 		return "", fmt.Errorf("failed to insert source metadata: %w", err)
@@ -367,7 +372,8 @@ func (c *Cache) StoreSource(
 // accounting insert is best-effort (the startup reconciliation pass
 // adopts any variant file that misses its accounting row).
 func (c *Cache) StoreVariant(
-	ctx context.Context, cacheKey VariantKey, content io.Reader, contentType string,
+	ctx context.Context, cacheKey imagerequest.VariantKey,
+	content io.Reader, contentType string,
 ) error {
 	if c.disabled {
 		return nil
@@ -403,7 +409,7 @@ func (c *Cache) StoreVariant(
 // if not. Hits touch the blob's LRU timestamp; a disabled cache always
 // reports no cached source.
 func (c *Cache) LookupSource(
-	ctx context.Context, req *ImageRequest,
+	ctx context.Context, req *imagerequest.Request,
 ) (ContentHash, string, error) {
 	if c.disabled {
 		return "", "", nil
@@ -414,7 +420,7 @@ func (c *Cache) LookupSource(
 	err := c.db.QueryRowContext(ctx, `
 		SELECT content_hash, content_type FROM source_metadata
 		WHERE source_host = ? AND source_path = ? AND source_query = ?
-	`, req.SourceHost, req.SourcePath, req.SourceQuery).Scan(&hashStr, &contentType)
+	`, req.Source.Host, req.Source.Path, req.Source.Query).Scan(&hashStr, &contentType)
 
 	if errors.Is(err, sql.ErrNoRows) {
 		return "", "", nil
@@ -438,7 +444,7 @@ func (c *Cache) LookupSource(
 
 // StoreNegative stores a negative cache entry for a failed fetch.
 func (c *Cache) StoreNegative(
-	ctx context.Context, req *ImageRequest, statusCode int, errMsg string,
+	ctx context.Context, req *imagerequest.Request, statusCode int, errMsg string,
 ) error {
 	expiresAt := time.Now().UTC().Add(c.config.NegativeTTL)
 
@@ -452,7 +458,7 @@ func (c *Cache) StoreNegative(
 			error_message = excluded.error_message,
 			fetched_at = CURRENT_TIMESTAMP,
 			expires_at = excluded.expires_at
-	`, req.SourceHost, req.SourcePath, req.SourceQuery, statusCode, errMsg, expiresAt)
+	`, req.Source.Host, req.Source.Path, req.Source.Query, statusCode, errMsg, expiresAt)
 	if err != nil {
 		return fmt.Errorf("failed to insert negative cache: %w", err)
 	}
@@ -462,14 +468,14 @@ func (c *Cache) StoreNegative(
 
 // GetSourceMetadataID returns the source metadata ID for a request.
 func (c *Cache) GetSourceMetadataID(
-	ctx context.Context, req *ImageRequest,
+	ctx context.Context, req *imagerequest.Request,
 ) (int64, error) {
 	var id int64
 
 	err := c.db.QueryRowContext(ctx, `
 		SELECT id FROM source_metadata
 		WHERE source_host = ? AND source_path = ? AND source_query = ?
-	`, req.SourceHost, req.SourcePath, req.SourceQuery).Scan(&id)
+	`, req.Source.Host, req.Source.Path, req.Source.Query).Scan(&id)
 	if err != nil {
 		return 0, fmt.Errorf("failed to get source metadata ID: %w", err)
 	}
@@ -665,7 +671,7 @@ func (c *Cache) readHitAndMissCounts(ctx context.Context, stats *CacheStats) err
 // application/octet-stream and keeps nothing, so metaCache only ever
 // holds a type read from a .meta file or passed to StoreVariant.
 func (c *Cache) loadVariantWithMeta(
-	cacheKey VariantKey,
+	cacheKey imagerequest.VariantKey,
 ) (io.ReadCloser, int64, string, error) {
 	reader, size, contentType, err := c.variants.LoadWithMeta(cacheKey)
 	if err != nil {
@@ -685,15 +691,15 @@ func (c *Cache) loadVariantWithMeta(
 // A failure is logged and is otherwise non-fatal; the metadata is in the
 // database.
 func (c *Cache) writeMetadataSidecar(
-	req *ImageRequest,
+	req *imagerequest.Request,
 	pathHash PathHash,
 	contentHash ContentHash,
 	result *httpfetcher.FetchResult,
 ) {
 	meta := &SourceMetadata{
-		Host:            req.SourceHost,
-		Path:            req.SourcePath,
-		Query:           req.SourceQuery,
+		Host:            req.Source.Host,
+		Path:            req.Source.Path,
+		Query:           req.Source.Query,
 		ContentHash:     string(contentHash),
 		StatusCode:      result.StatusCode,
 		ContentType:     result.ContentType,
@@ -704,16 +710,16 @@ func (c *Cache) writeMetadataSidecar(
 		RemoteAddr:      result.RemoteAddr,
 	}
 
-	err := c.srcMetadata.Store(req.SourceHost, pathHash, meta)
+	err := c.srcMetadata.Store(req.Source.Host, pathHash, meta)
 	if err != nil {
 		c.log.Warn("failed to write metadata sidecar",
-			"host", req.SourceHost, "path_hash", pathHash, "error", err)
+			"host", req.Source.Host, "path_hash", pathHash, "error", err)
 	}
 }
 
 // touchVariant updates the LRU timestamp of a variant, best-effort:
 // a failed touch only makes the entry look colder to eviction.
-func (c *Cache) touchVariant(ctx context.Context, cacheKey VariantKey) {
+func (c *Cache) touchVariant(ctx context.Context, cacheKey imagerequest.VariantKey) {
 	_, err := c.db.ExecContext(ctx, `
 		UPDATE variant_content SET last_accessed_at = CURRENT_TIMESTAMP
 		WHERE cache_key = ?
@@ -739,14 +745,14 @@ func (c *Cache) touchSourceContent(ctx context.Context, contentHash ContentHash)
 
 // checkNegativeCache checks if a request is in the negative cache.
 func (c *Cache) checkNegativeCache(
-	ctx context.Context, req *ImageRequest,
+	ctx context.Context, req *imagerequest.Request,
 ) (bool, error) {
 	var expiresAt time.Time
 
 	err := c.db.QueryRowContext(ctx, `
 		SELECT expires_at FROM negative_cache
 		WHERE source_host = ? AND source_path = ? AND source_query = ?
-	`, req.SourceHost, req.SourcePath, req.SourceQuery).Scan(&expiresAt)
+	`, req.Source.Host, req.Source.Path, req.Source.Query).Scan(&expiresAt)
 
 	if errors.Is(err, sql.ErrNoRows) {
 		return false, nil
@@ -762,10 +768,10 @@ func (c *Cache) checkNegativeCache(
 		_, err = c.db.ExecContext(ctx, `
 			DELETE FROM negative_cache
 			WHERE source_host = ? AND source_path = ? AND source_query = ?
-		`, req.SourceHost, req.SourcePath, req.SourceQuery)
+		`, req.Source.Host, req.Source.Path, req.Source.Query)
 		if err != nil {
 			c.log.Warn("failed to delete expired negative cache entry",
-				"host", req.SourceHost, "path", req.SourcePath, "error", err)
+				"host", req.Source.Host, "path", req.Source.Path, "error", err)
 		}
 
 		return false, nil