start fixing up emoji processing code

internal/media/util.go

@@ -0,0 +1,123 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package media
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+
+	"github.com/h2non/filetype"
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+)
+
+// parseContentType parses the MIME content type from a file, returning it as a string in the form (eg., "image/jpeg").
+// Returns an error if the content type is not something we can process.
+func parseContentType(content []byte) (string, error) {
+	// read in the first bytes of the file
+	fileHeader := make([]byte, maxFileHeaderBytes)
+	if _, err := bytes.NewReader(content).Read(fileHeader); err != nil {
+		return "", fmt.Errorf("could not read first magic bytes of file: %s", err)
+	}
+
+	kind, err := filetype.Match(fileHeader)
+	if err != nil {
+		return "", err
+	}
+
+	if kind == filetype.Unknown {
+		return "", errors.New("filetype unknown")
+	}
+
+	return kind.MIME.Value, nil
+}
+
+// supportedImage checks mime type of an image against a slice of accepted types,
+// and returns True if the mime type is accepted.
+func supportedImage(mimeType string) bool {
+	acceptedImageTypes := []string{
+		mimeImageJpeg,
+		mimeImageGif,
+		mimeImagePng,
+	}
+	for _, accepted := range acceptedImageTypes {
+		if mimeType == accepted {
+			return true
+		}
+	}
+	return false
+}
+
+// supportedEmoji checks that the content type is image/png -- the only type supported for emoji.
+func supportedEmoji(mimeType string) bool {
+	acceptedEmojiTypes := []string{
+		mimeImageGif,
+		mimeImagePng,
+	}
+	for _, accepted := range acceptedEmojiTypes {
+		if mimeType == accepted {
+			return true
+		}
+	}
+	return false
+}
+
+// ParseMediaType converts s to a recognized MediaType, or returns an error if unrecognized
+func ParseMediaType(s string) (Type, error) {
+	switch s {
+	case string(TypeAttachment):
+		return TypeAttachment, nil
+	case string(TypeHeader):
+		return TypeHeader, nil
+	case string(TypeAvatar):
+		return TypeAvatar, nil
+	case string(TypeEmoji):
+		return TypeEmoji, nil
+	}
+	return "", fmt.Errorf("%s not a recognized MediaType", s)
+}
+
+// ParseMediaSize converts s to a recognized MediaSize, or returns an error if unrecognized
+func ParseMediaSize(s string) (Size, error) {
+	switch s {
+	case string(SizeSmall):
+		return SizeSmall, nil
+	case string(SizeOriginal):
+		return SizeOriginal, nil
+	case string(SizeStatic):
+		return SizeStatic, nil
+	}
+	return "", fmt.Errorf("%s not a recognized MediaSize", s)
+}
+
+// putOrUpdate is just a convenience function for first trying to PUT the attachment or emoji in the database,
+// and then if that doesn't work because the attachment/emoji already exists, updating it instead.
+func putOrUpdate(ctx context.Context, database db.DB, i interface{}) error {
+	if err := database.Put(ctx, i); err != nil {
+		if err != db.ErrAlreadyExists {
+			return fmt.Errorf("putOrUpdate: proper error while putting: %s", err)
+		}
+		if err := database.UpdateByPrimaryKey(ctx, i); err != nil {
+			return fmt.Errorf("putOrUpdate: error while updating: %s", err)
+		}
+	}
+
+	return nil
+}