WIP: implementing asset.Loader

the image loader is implemented, working on the archive loader, I left a
note in the HTTP code with that was left off.

Once implemented then the get asset methods in both http and gmi should
use the loader directly, rather than loading from the store and doing
transforms. This way gmi will also gain the image transformations and
archive loading that http has (though I dunno if it really needs it).

src/cmd/load-test-data/main.go

@@ -9,6 +9,7 @@ import (
 
 	cfgpkg "github.com/mediocregopher/blog.mediocregopher.com/srv/cfg"
 	"github.com/mediocregopher/blog.mediocregopher.com/srv/post"
+	"github.com/mediocregopher/blog.mediocregopher.com/srv/post/asset"
 	"github.com/mediocregopher/mediocre-go-lib/v2/mctx"
 	"github.com/mediocregopher/mediocre-go-lib/v2/mlog"
 	"gopkg.in/yaml.v3"
@@ -99,7 +100,7 @@ func main() {
 	}
 
 	{
-		assetStore := post.NewAssetStore(postDB)
+		assetStore := asset.NewStore(postDB)
 
 		setAsset := func(assetID, assetPath string) error {
 			assetFullPath := filepath.Join(testDataDir, assetPath)

src/cmd/mediocre-blog/main.go

@@ -13,6 +13,7 @@ import (
 	"github.com/mediocregopher/blog.mediocregopher.com/srv/http"
 	"github.com/mediocregopher/blog.mediocregopher.com/srv/mailinglist"
 	"github.com/mediocregopher/blog.mediocregopher.com/srv/post"
+	"github.com/mediocregopher/blog.mediocregopher.com/srv/post/asset"
 	"github.com/mediocregopher/blog.mediocregopher.com/srv/pow"
 	"github.com/mediocregopher/mediocre-go-lib/v2/mctx"
 	"github.com/mediocregopher/mediocre-go-lib/v2/mlog"
@@ -100,7 +101,7 @@ func main() {
 	defer postSQLDB.Close()
 
 	postStore := post.NewStore(postSQLDB)
-	postAssetStore := post.NewAssetStore(postSQLDB)
+	postAssetStore := asset.NewStore(postSQLDB)
 	postDraftStore := post.NewDraftStore(postSQLDB)
 
 	cache := cache.New(5000)

src/gmi/gmi.go

@@ -16,6 +16,7 @@ import (
 	"github.com/mediocregopher/blog.mediocregopher.com/srv/cache"
 	"github.com/mediocregopher/blog.mediocregopher.com/srv/cfg"
 	"github.com/mediocregopher/blog.mediocregopher.com/srv/post"
+	"github.com/mediocregopher/blog.mediocregopher.com/srv/post/asset"
 	"github.com/mediocregopher/mediocre-go-lib/v2/mctx"
 	"github.com/mediocregopher/mediocre-go-lib/v2/mlog"
 )
@@ -27,7 +28,7 @@ type Params struct {
 	Cache  cache.Cache
 
 	PostStore      post.Store
-	PostAssetStore post.AssetStore
+	PostAssetStore asset.Store
 
 	PublicURL        *url.URL
 	ListenAddr       string
@@ -218,7 +219,7 @@ func (a *api) assetsMiddleware() gemini.Handler {
 
 		err := a.params.PostAssetStore.Get(id, rw)
 
-		if errors.Is(err, post.ErrAssetNotFound) {
+		if errors.Is(err, asset.ErrNotFound) {
 			rw.WriteHeader(gemini.StatusNotFound, "Asset not found, sorry!")
 			return
 

src/http/assets.go

@@ -5,64 +5,17 @@ import (
 	"compress/gzip"
 	"errors"
 	"fmt"
-	"image"
-	"image/jpeg"
-	"image/png"
 	"io"
 	"io/fs"
 	"net/http"
 	"path/filepath"
-	"strings"
 	"time"
 
 	"github.com/mediocregopher/blog.mediocregopher.com/srv/http/apiutil"
-	"github.com/mediocregopher/blog.mediocregopher.com/srv/post"
+	"github.com/mediocregopher/blog.mediocregopher.com/srv/post/asset"
 	"github.com/omeid/go-tarfs"
-	"golang.org/x/image/draw"
 )
 
-func isImgResizable(path string) bool {
-	switch strings.ToLower(filepath.Ext(path)) {
-	case ".jpg", ".jpeg", ".png":
-		return true
-	default:
-		return false
-	}
-}
-
-func resizeImage(out io.Writer, in io.Reader, maxWidth float64) error {
-
-	img, format, err := image.Decode(in)
-	if err != nil {
-		return fmt.Errorf("decoding image: %w", err)
-	}
-
-	imgRect := img.Bounds()
-	imgW, imgH := float64(imgRect.Dx()), float64(imgRect.Dy())
-
-	if imgW > maxWidth {
-
-		newH := imgH * maxWidth / imgW
-		newImg := image.NewRGBA(image.Rect(0, 0, int(maxWidth), int(newH)))
-
-		// Resize
-		draw.BiLinear.Scale(
-			newImg, newImg.Bounds(), img, img.Bounds(), draw.Over, nil,
-		)
-
-		img = newImg
-	}
-
-	switch format {
-	case "jpeg":
-		return jpeg.Encode(out, img, nil)
-	case "png":
-		return png.Encode(out, img)
-	default:
-		return fmt.Errorf("unknown image format %q", format)
-	}
-}
-
 func (a *api) managePostAssetsHandler() http.Handler {
 
 	tpl := a.mustParseBasedTpl("post-assets-manage.html")
@@ -88,38 +41,6 @@ func (a *api) managePostAssetsHandler() http.Handler {
 	})
 }
 
-type postAssetArchiveInfo struct {
-	path      string
-	id        string
-	subPath   string
-	isGzipped bool
-}
-
-func extractPostAssetArchiveInfo(path string) (postAssetArchiveInfo, bool) {
-
-	var info postAssetArchiveInfo
-
-	info.path = strings.TrimPrefix(path, "/")
-
-	info.id, info.subPath, _ = strings.Cut(info.path, "/")
-
-	switch {
-
-	case strings.HasSuffix(info.id, ".tar.gz"),
-		strings.HasSuffix(info.id, ".tgz"):
-		info.isGzipped = true
-
-	case strings.HasSuffix(info.id, ".tar"):
-		// ok
-
-	default:
-		// unsupported
-		return postAssetArchiveInfo{}, false
-	}
-
-	return info, true
-}
-
 func (a *api) writePostAsset(
 	rw http.ResponseWriter,
 	r *http.Request,
@@ -170,7 +91,7 @@ func (a *api) handleGetPostAssetArchive(
 
 	err := a.params.PostAssetStore.Get(info.id, buf)
 
-	if errors.Is(err, post.ErrAssetNotFound) {
+	if errors.Is(err, asset.ErrNotFound) {
 		http.Error(rw, "asset not found", 404)
 		return
 	} else if err != nil {
@@ -194,6 +115,8 @@ func (a *api) handleGetPostAssetArchive(
 		}
 	}
 
+	// TODO everything from here down needs to be moved to the archive loader
+
 	tarFS, err := tarfs.New(from)
 
 	if err != nil {
@@ -244,7 +167,7 @@ func (a *api) getPostAssetHandler() http.Handler {
 
 		err := a.params.PostAssetStore.Get(id, buf)
 
-		if errors.Is(err, post.ErrAssetNotFound) {
+		if errors.Is(err, asset.ErrNotFound) {
 			http.Error(rw, "Asset not found", 404)
 			return
 		} else if err != nil {
@@ -297,7 +220,7 @@ func (a *api) deletePostAssetHandler() http.Handler {
 
 		err := a.params.PostAssetStore.Delete(id)
 
-		if errors.Is(err, post.ErrAssetNotFound) {
+		if errors.Is(err, asset.ErrNotFound) {
 			http.Error(rw, "Asset not found", 404)
 			return
 		} else if err != nil {

src/http/http.go

@@ -20,6 +20,7 @@ import (
 	"github.com/mediocregopher/blog.mediocregopher.com/srv/http/apiutil"
 	"github.com/mediocregopher/blog.mediocregopher.com/srv/mailinglist"
 	"github.com/mediocregopher/blog.mediocregopher.com/srv/post"
+	"github.com/mediocregopher/blog.mediocregopher.com/srv/post/asset"
 	"github.com/mediocregopher/blog.mediocregopher.com/srv/pow"
 	"github.com/mediocregopher/mediocre-go-lib/v2/mctx"
 	"github.com/mediocregopher/mediocre-go-lib/v2/mlog"
@@ -36,7 +37,7 @@ type Params struct {
 	Cache      cache.Cache
 
 	PostStore      post.Store
-	PostAssetStore post.AssetStore
+	PostAssetStore asset.Store
 	PostDraftStore post.DraftStore
 
 	MailingList mailinglist.MailingList

src/post/asset/asset.go

@@ -1,4 +1,4 @@
-package post
+package asset
 
 import (
 	"bytes"
@@ -6,23 +6,25 @@ import (
 	"errors"
 	"fmt"
 	"io"
+
+	"github.com/mediocregopher/blog.mediocregopher.com/srv/post"
 )
 
 var (
-	// ErrAssetNotFound is used to indicate an Asset could not be found in the
+	// ErrNotFound is used to indicate an Asset could not be found in the
-	// AssetStore.
+	// Store.
-	ErrAssetNotFound = errors.New("asset not found")
+	ErrNotFound = errors.New("asset not found")
 )
 
-// AssetStore implements the storage and retrieval of binary assets, which are
+// Store implements the storage and retrieval of binary assets, which are
 // intended to be used by posts (e.g. images).
-type AssetStore interface {
+type Store interface {
 
 	// Set sets the id to the contents of the given io.Reader.
 	Set(id string, from io.Reader) error
 
 	// Get writes the id's body to the given io.Writer, or returns
-	// ErrAssetNotFound.
+	// ErrNotFound.
 	Get(id string, into io.Writer) error
 
 	// Delete's the body stored for the id, if any.
@@ -32,18 +34,18 @@ type AssetStore interface {
 	List() ([]string, error)
 }
 
-type assetStore struct {
+type store struct {
-	db *sql.DB
+	db *post.SQLDB
 }
 
-// NewAssetStore initializes a new AssetStore using an existing SQLDB.
+// NewStore initializes a new Store using an existing SQLDB.
-func NewAssetStore(db *SQLDB) AssetStore {
+func NewStore(db *post.SQLDB) Store {
-	return &assetStore{
+	return &store{
-		db: db.db,
+		db: db,
 	}
 }
 
-func (s *assetStore) Set(id string, from io.Reader) error {
+func (s *store) Set(id string, from io.Reader) error {
 
 	body, err := io.ReadAll(from)
 	if err != nil {
@@ -64,14 +66,14 @@ func (s *assetStore) Set(id string, from io.Reader) error {
 	return nil
 }
 
-func (s *assetStore) Get(id string, into io.Writer) error {
+func (s *store) Get(id string, into io.Writer) error {
 
 	var body []byte
 
 	err := s.db.QueryRow(`SELECT body FROM assets WHERE id = ?`, id).Scan(&body)
 
 	if errors.Is(err, sql.ErrNoRows) {
-		return ErrAssetNotFound
+		return ErrNotFound
 	} else if err != nil {
 		return fmt.Errorf("selecting from assets: %w", err)
 	}
@@ -83,12 +85,12 @@ func (s *assetStore) Get(id string, into io.Writer) error {
 	return nil
 }
 
-func (s *assetStore) Delete(id string) error {
+func (s *store) Delete(id string) error {
 	_, err := s.db.Exec(`DELETE FROM assets WHERE id = ?`, id)
 	return err
 }
 
-func (s *assetStore) List() ([]string, error) {
+func (s *store) List() ([]string, error) {
 
 	rows, err := s.db.Query(`SELECT id FROM assets ORDER BY id ASC`)
 

src/post/asset/asset_test.go

@@ -1,30 +1,31 @@
-package post
+package asset
 
 import (
 	"bytes"
 	"io"
 	"testing"
 
+	"github.com/mediocregopher/blog.mediocregopher.com/srv/post"
 	"github.com/stretchr/testify/assert"
 )
 
-type assetTestHarness struct {
+type testHarness struct {
-	store AssetStore
+	store Store
 }
 
-func newAssetTestHarness(t *testing.T) *assetTestHarness {
+func newTestHarness(t *testing.T) *testHarness {
 
-	db := NewInMemSQLDB()
+	db := post.NewInMemSQLDB()
 	t.Cleanup(func() { db.Close() })
 
-	store := NewAssetStore(db)
+	store := NewStore(db)
 
-	return &assetTestHarness{
+	return &testHarness{
 		store: store,
 	}
 }
 
-func (h *assetTestHarness) assertGet(t *testing.T, exp, id string) {
+func (h *testHarness) assertGet(t *testing.T, exp, id string) {
 	t.Helper()
 	buf := new(bytes.Buffer)
 	err := h.store.Get(id, buf)
@@ -32,15 +33,15 @@ func (h *assetTestHarness) assertGet(t *testing.T, exp, id string) {
 	assert.Equal(t, exp, buf.String())
 }
 
-func (h *assetTestHarness) assertNotFound(t *testing.T, id string) {
+func (h *testHarness) assertNotFound(t *testing.T, id string) {
 	t.Helper()
 	err := h.store.Get(id, io.Discard)
-	assert.ErrorIs(t, ErrAssetNotFound, err)
+	assert.ErrorIs(t, ErrNotFound, err)
 }
 
-func TestAssetStore(t *testing.T) {
+func TestStore(t *testing.T) {
 
-	testAssetStore := func(t *testing.T, h *assetTestHarness) {
+	testStore := func(t *testing.T, h *testHarness) {
 		t.Helper()
 
 		h.assertNotFound(t, "foo")
@@ -85,7 +86,7 @@ func TestAssetStore(t *testing.T) {
 	}
 
 	t.Run("sql", func(t *testing.T) {
-		h := newAssetTestHarness(t)
+		h := newTestHarness(t)
-		testAssetStore(t, h)
+		testStore(t, h)
 	})
 }

src/post/asset/loader.go

@@ -0,0 +1,43 @@
+package asset
+
+import (
+	"errors"
+	"io"
+	"path/filepath"
+)
+
+var (
+	ErrCannotResize = errors.New("cannot resize")
+)
+
+// LoadOpts are optional parameters to Loader's Load method. Some may only apply
+// to specific Loader implementations.
+type LoadOpts struct {
+
+	// ImageWidth is used by the ImageLoader to resize images on the fly.
+	ImageWidth int
+}
+
+// Loader is used to load an asset and write its body into the given io.Writer.
+//
+// Errors:
+//	- ErrNotFound
+//	- ErrCannotResize (only if ImageLoader is used)
+type Loader interface {
+	Load(path string, into io.Writer, opts LoadOpts) error
+}
+
+type storeLoader struct {
+	store Store
+}
+
+// NewStoreLoader returns a Loader which loads assets directly from the given
+// Store, with no transformation.
+func NewStoreLoader(store Store) Loader {
+	return &storeLoader{store}
+}
+
+func (l *storeLoader) Load(path string, into io.Writer, opts LoadOpts) error {
+	id := filepath.Base(path)
+	return l.store.Get(id, into)
+}

src/post/asset/loader_archive.go

@@ -0,0 +1,57 @@
+package asset
+
+import (
+	"bytes"
+	"compress/gzip"
+	"fmt"
+	"io"
+	"strings"
+)
+
+type archiveLoader struct {
+	loader Loader
+}
+
+func (l *archiveLoader) Load(path string, into io.Writer, opts LoadOpts) error {
+
+	id, subPath, ok := strings.Cut(strings.TrimPrefix(path, "/"), "/")
+
+	if !ok {
+		return l.loader.Load(path, into, opts)
+	}
+
+	var isGzipped bool
+
+	switch {
+
+	case strings.HasSuffix(id, ".tar.gz"),
+		strings.HasSuffix(id, ".tgz"):
+		isGzipped = true
+
+	case strings.HasSuffix(id, ".tar"):
+		// ok
+
+	default:
+		// unsupported
+		return l.loader.Load(path, into, opts)
+	}
+
+	buf := new(bytes.Buffer)
+
+	if err := l.loader.Load(id, buf, opts); err != nil {
+		return fmt.Errorf("loading archive into buffer: %w", err)
+	}
+
+	var (
+		from io.Reader = buf
+		err  error
+	)
+
+	if isGzipped {
+
+		if from, err = gzip.NewReader(from); err != nil {
+			return fmt.Errorf("decompressing archive asset with id %q: %w", id, err)
+		}
+	}
+
+}

src/post/asset/loader_image.go

@@ -0,0 +1,83 @@
+package asset
+
+import (
+	"bytes"
+	"fmt"
+	"image"
+	"image/jpeg"
+	"image/png"
+	"io"
+	"path/filepath"
+	"strings"
+
+	"golang.org/x/image/draw"
+)
+
+func isImgResizable(path string) bool {
+	switch strings.ToLower(filepath.Ext(path)) {
+	case ".jpg", ".jpeg", ".png":
+		return true
+	default:
+		return false
+	}
+}
+
+type imageLoader struct {
+	loader Loader
+}
+
+// NewImageLoader wraps an existing Loader in order to perform various
+// image-related transformations on any image assets being loaded. Non-image
+// assets are loaded as-is.
+func NewImageLoader(loader Loader) Loader {
+	return &imageLoader{loader}
+}
+
+func (l *imageLoader) Load(path string, into io.Writer, opts LoadOpts) error {
+
+	if opts.ImageWidth == 0 {
+		return l.loader.Load(path, into, opts)
+	}
+
+	if !isImgResizable(path) {
+		return ErrCannotResize
+	}
+
+	buf := new(bytes.Buffer)
+
+	if err := l.loader.Load(path, buf, opts); err != nil {
+		return fmt.Errorf("loading image into buffer: %w", err)
+	}
+
+	img, format, err := image.Decode(buf)
+	if err != nil {
+		return fmt.Errorf("decoding image: %w", err)
+	}
+
+	maxWidth := float64(opts.ImageWidth)
+	imgRect := img.Bounds()
+	imgW, imgH := float64(imgRect.Dx()), float64(imgRect.Dy())
+
+	if imgW > maxWidth {
+
+		newH := imgH * maxWidth / imgW
+		newImg := image.NewRGBA(image.Rect(0, 0, int(maxWidth), int(newH)))
+
+		// Resize
+		draw.BiLinear.Scale(
+			newImg, newImg.Bounds(), img, img.Bounds(), draw.Over, nil,
+		)
+
+		img = newImg
+	}
+
+	switch format {
+	case "jpeg":
+		return jpeg.Encode(into, img, nil)
+	case "png":
+		return png.Encode(into, img)
+	default:
+		return fmt.Errorf("unknown image format %q", format)
+	}
+
+}

src/post/draft_post.go

@@ -47,7 +47,7 @@ func (s *draftStore) Set(post Post) error {
 		return fmt.Errorf("json marshaling tags %#v: %w", post.Tags, err)
 	}
 
-	_, err = s.db.db.Exec(
+	_, err = s.db.Exec(
 		`INSERT INTO post_drafts (
 				id, title, description, tags, series, body, format
 			)
@@ -145,7 +145,7 @@ func (s *draftStore) get(
 
 func (s *draftStore) Get(page, count int) ([]Post, bool, error) {
 
-	posts, err := s.get(s.db.db, count+1, page*count, ``)
+	posts, err := s.get(s.db, count+1, page*count, ``)
 
 	if err != nil {
 		return nil, false, fmt.Errorf("querying post_drafts: %w", err)
@@ -163,7 +163,7 @@ func (s *draftStore) Get(page, count int) ([]Post, bool, error) {
 
 func (s *draftStore) GetByID(id string) (Post, error) {
 
-	posts, err := s.get(s.db.db, 0, 0, `WHERE p.id=?`, id)
+	posts, err := s.get(s.db, 0, 0, `WHERE p.id=?`, id)
 
 	if err != nil {
 		return Post{}, fmt.Errorf("querying post_drafts: %w", err)
@@ -182,7 +182,7 @@ func (s *draftStore) GetByID(id string) (Post, error) {
 
 func (s *draftStore) Delete(id string) error {
 
-	if _, err := s.db.db.Exec(`DELETE FROM post_drafts WHERE id = ?`, id); err != nil {
+	if _, err := s.db.Exec(`DELETE FROM post_drafts WHERE id = ?`, id); err != nil {
 		return fmt.Errorf("deleting from post_drafts: %w", err)
 	}
 

src/post/post.go

@@ -96,7 +96,7 @@ func (s *store) Set(post Post, now time.Time) (bool, error) {
 
 	var first bool
 
-	err := s.db.withTx(func(tx *sql.Tx) error {
+	err := s.db.WithTx(func(tx *sql.Tx) error {
 
 		nowTS := now.Unix()
 
@@ -244,7 +244,7 @@ func (s *store) get(
 
 func (s *store) Get(page, count int) ([]StoredPost, bool, error) {
 
-	posts, err := s.get(s.db.db, count+1, page*count, ``)
+	posts, err := s.get(s.db, count+1, page*count, ``)
 
 	if err != nil {
 		return nil, false, fmt.Errorf("querying posts: %w", err)
@@ -262,7 +262,7 @@ func (s *store) Get(page, count int) ([]StoredPost, bool, error) {
 
 func (s *store) GetByID(id string) (StoredPost, error) {
 
-	posts, err := s.get(s.db.db, 0, 0, `WHERE p.id=?`, id)
+	posts, err := s.get(s.db, 0, 0, `WHERE p.id=?`, id)
 
 	if err != nil {
 		return StoredPost{}, fmt.Errorf("querying posts: %w", err)
@@ -280,14 +280,14 @@ func (s *store) GetByID(id string) (StoredPost, error) {
 }
 
 func (s *store) GetBySeries(series string) ([]StoredPost, error) {
-	return s.get(s.db.db, 0, 0, `WHERE p.series=?`, series)
+	return s.get(s.db, 0, 0, `WHERE p.series=?`, series)
 }
 
 func (s *store) GetByTag(tag string) ([]StoredPost, error) {
 
 	var posts []StoredPost
 
-	err := s.db.withTx(func(tx *sql.Tx) error {
+	err := s.db.WithTx(func(tx *sql.Tx) error {
 
 		rows, err := tx.Query(`SELECT post_id FROM post_tags WHERE tag = ?`, tag)
 
@@ -331,7 +331,7 @@ func (s *store) GetByTag(tag string) ([]StoredPost, error) {
 
 func (s *store) GetTags() ([]string, error) {
 
-	rows, err := s.db.db.Query(`SELECT tag FROM post_tags GROUP BY tag`)
+	rows, err := s.db.Query(`SELECT tag FROM post_tags GROUP BY tag`)
 	if err != nil {
 		return nil, fmt.Errorf("querying all tags: %w", err)
 	}
@@ -355,7 +355,7 @@ func (s *store) GetTags() ([]string, error) {
 
 func (s *store) Delete(id string) error {
 
-	return s.db.withTx(func(tx *sql.Tx) error {
+	return s.db.WithTx(func(tx *sql.Tx) error {
 
 		if _, err := tx.Exec(`DELETE FROM post_tags WHERE post_id = ?`, id); err != nil {
 			return fmt.Errorf("deleting from post_tags: %w", err)

src/post/sql.go

@@ -78,7 +78,7 @@ var migrations = &migrate.MemoryMigrationSource{Migrations: []*migrate.Migration
 // SQLDB is a sqlite3 database which can be used by storage interfaces within
 // this package.
 type SQLDB struct {
-	db *sql.DB
+	*sql.DB
 }
 
 // NewSQLDB initializes and returns a new sqlite3 database for storage
@@ -116,12 +116,14 @@ func NewInMemSQLDB() *SQLDB {
 
 // Close cleans up loose resources being held by the db.
 func (db *SQLDB) Close() error {
-	return db.db.Close()
+	return db.DB.Close()
 }
 
-func (db *SQLDB) withTx(cb func(*sql.Tx) error) error {
+// WithTx initializes a transaction, runs the callback using it, and either
+// commits or rolls it back depending on if the callback returns an error.
+func (db *SQLDB) WithTx(cb func(*sql.Tx) error) error {
 
-	tx, err := db.db.Begin()
+	tx, err := db.DB.Begin()
 
 	if err != nil {
 		return fmt.Errorf("starting transaction: %w", err)