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/eviction_internal_test.go

@@ -16,6 +16,7 @@ import (
 	_ "modernc.org/sqlite"
 	"sneak.berlin/go/pixa/internal/database"
 	"sneak.berlin/go/pixa/internal/httpfetcher"
+	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
 // sqliteTimestampFormat matches the format SQLite's CURRENT_TIMESTAMP
@@ -27,10 +28,10 @@ const sqliteTimestampFormat = "2006-01-02 15:04:05"
 // keys reused across the eviction tests, in the order the tests store
 // them.
 const (
-	testVariantKeyOne   VariantKey = "aabbccdd0001"
-	testVariantKeyTwo   VariantKey = "aabbccdd0002"
-	testVariantKeyThree VariantKey = "aabbccdd0003"
-	testVariantKeyFour  VariantKey = "aabbccdd0004"
+	testVariantKeyOne   imagerequest.VariantKey = "aabbccdd0001"
+	testVariantKeyTwo   imagerequest.VariantKey = "aabbccdd0002"
+	testVariantKeyThree imagerequest.VariantKey = "aabbccdd0003"
+	testVariantKeyFour  imagerequest.VariantKey = "aabbccdd0004"
 )
 
 // evictionTestDB creates an in-memory SQLite database with the real
@@ -88,12 +89,16 @@ func storeEvictionTestSource(
 ) ContentHash {
 	t.Helper()
 
-	req := &ImageRequest{
-		SourceHost: host,
-		SourcePath: path,
-		Format:     FormatJPEG,
-		Quality:    85,
-		FitMode:    FitCover,
+	req := &imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: host,
+			Path: path,
+		},
+		Transform: imagerequest.Transform{
+			Format:  imagerequest.FormatJPEG,
+			Quality: 85,
+			FitMode: imagerequest.FitCover,
+		},
 	}
 
 	result := &httpfetcher.FetchResult{
@@ -118,7 +123,7 @@ func storeEvictionTestSource(
 // storeEvictionTestVariant stores content as a processed variant under
 // the given cache key.
 func storeEvictionTestVariant(
-	t *testing.T, cache *Cache, key VariantKey, content []byte,
+	t *testing.T, cache *Cache, key imagerequest.VariantKey, content []byte,
 ) {
 	t.Helper()
 
@@ -131,7 +136,7 @@ func storeEvictionTestVariant(
 // setVariantLastAccessed backdates the last access time of a tracked
 // variant, to make LRU ordering deterministic in tests.
 func setVariantLastAccessed(
-	t *testing.T, cache *Cache, key VariantKey, when time.Time,
+	t *testing.T, cache *Cache, key imagerequest.VariantKey, when time.Time,
 ) {
 	t.Helper()
 
@@ -244,7 +249,7 @@ func assertNoDanglingReferences(t *testing.T, cache *Cache) {
 			t.Fatalf("failed to scan cache_key: %v", err)
 		}
 
-		if !cache.variants.Exists(VariantKey(key)) {
+		if !cache.variants.Exists(imagerequest.VariantKey(key)) {
 			t.Errorf("variant_content references key %s but the file is missing", key)
 		}
 	}
@@ -343,7 +348,7 @@ func TestEvictToLimitEvictsLeastRecentlyUsedFirst(t *testing.T) {
 	cache, _ := newEvictionTestCache(t, limit)
 
 	now := time.Now()
-	keys := []VariantKey{
+	keys := []imagerequest.VariantKey{
 		testVariantKeyOne, testVariantKeyTwo,
 		testVariantKeyThree, testVariantKeyFour,
 	}
@@ -516,12 +521,16 @@ func TestZeroMaxBytesDisablesDiskCache(t *testing.T) {
 
 	cache, tmpDir := newEvictionTestCache(t, 0)
 
-	req := &ImageRequest{
-		SourceHost: "src.example.com",
-		SourcePath: "/a.jpg",
-		Format:     FormatJPEG,
-		Quality:    85,
-		FitMode:    FitCover,
+	req := &imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: "src.example.com",
+			Path: "/a.jpg",
+		},
+		Transform: imagerequest.Transform{
+			Format:  imagerequest.FormatJPEG,
+			Quality: 85,
+			FitMode: imagerequest.FitCover,
+		},
 	}
 
 	assertDisabledCacheWritesAreNoOps(t, cache, req)
@@ -533,14 +542,14 @@ func TestZeroMaxBytesDisablesDiskCache(t *testing.T) {
 // assertDisabledCacheWritesAreNoOps verifies that stores against a
 // disabled cache report success without recording anything.
 func assertDisabledCacheWritesAreNoOps(
-	t *testing.T, cache *Cache, req *ImageRequest,
+	t *testing.T, cache *Cache, req *imagerequest.Request,
 ) {
 	t.Helper()
 
 	ctx := t.Context()
 
 	err := cache.StoreVariant(
-		ctx, CacheKey(req), bytes.NewReader([]byte("data")), "image/webp",
+		ctx, imagerequest.CacheKey(req), bytes.NewReader([]byte("data")), "image/webp",
 	)
 	if err != nil {
 		t.Fatalf("StoreVariant on disabled cache must be a no-op, got error: %v", err)
@@ -566,7 +575,7 @@ func assertDisabledCacheWritesAreNoOps(
 // assertDisabledCacheReadsAlwaysMiss verifies that lookups against a
 // disabled cache never report a hit.
 func assertDisabledCacheReadsAlwaysMiss(
-	t *testing.T, cache *Cache, req *ImageRequest,
+	t *testing.T, cache *Cache, req *imagerequest.Request,
 ) {
 	t.Helper()
 
@@ -661,7 +670,7 @@ func TestEvictionRunsUnderWritePressure(t *testing.T) {
 	cache.StartEviction(time.Hour)
 	defer func() { _ = cache.StopEviction(t.Context()) }()
 
-	keys := []VariantKey{
+	keys := []imagerequest.VariantKey{
 		testVariantKeyOne, testVariantKeyTwo, testVariantKeyThree,
 	}
 	fills := []byte{0x11, 0x12, 0x13}
@@ -715,7 +724,7 @@ func TestEvictionRunsOnPeriodicSchedule(t *testing.T) {
 		time.Sleep(10 * time.Millisecond)
 	}
 
-	keys := []VariantKey{
+	keys := []imagerequest.VariantKey{
 		testVariantKeyOne, testVariantKeyTwo, testVariantKeyThree,
 	}
 	fills := []byte{0x21, 0x22, 0x23}
@@ -1308,9 +1317,11 @@ func TestEvictSourceBlobExcludesConcurrentStoreOfIdenticalContent(t *testing.T)
 
 	assertNoDanglingReferences(t, cache)
 
-	dupHash, _, err := cache.LookupSource(ctx, &ImageRequest{
-		SourceHost: "race.example.com",
-		SourcePath: "/dup.jpg",
+	dupHash, _, err := cache.LookupSource(ctx, &imagerequest.Request{
+		Source: imagerequest.Source{
+			Host: "race.example.com",
+			Path: "/dup.jpg",
+		},
 	})
 	if err != nil {
 		t.Fatalf("LookupSource failed: %v", err)
@@ -1336,12 +1347,16 @@ func storeIdenticalContentConcurrently(
 	storeDone := make(chan error, 1)
 
 	go func() {
-		req := &ImageRequest{
-			SourceHost: "race.example.com",
-			SourcePath: "/dup.jpg",
-			Format:     FormatJPEG,
-			Quality:    85,
-			FitMode:    FitCover,
+		req := &imagerequest.Request{
+			Source: imagerequest.Source{
+				Host: "race.example.com",
+				Path: "/dup.jpg",
+			},
+			Transform: imagerequest.Transform{
+				Format:  imagerequest.FormatJPEG,
+				Quality: 85,
+				FitMode: imagerequest.FitCover,
+			},
 		}
 		result := &httpfetcher.FetchResult{
 			StatusCode:    200,