Add URL-support for images

Signed-off-by: Knut Ahlers <knut@ahlers.me>

cmd/streamdeck/display_image.go

@@ -2,10 +2,15 @@ package main
 
 import (
 	"context"
+	"crypto/sha256"
+	"fmt"
 	"image"
 	_ "image/jpeg"
 	_ "image/png"
+	"io"
+	"net/http"
 	"os"
+	"path"
 
 	"github.com/pkg/errors"
 )
@@ -19,7 +24,36 @@ type displayElementImage struct{}
 func (d displayElementImage) Display(ctx context.Context, idx int, attributes map[string]interface{}) error {
 	filename, ok := attributes["path"].(string)
 	if !ok {
-		return errors.New("No path attribute specified")
+		url, ok := attributes["url"].(string)
+		if !ok {
+			return errors.New("No path or url attribute specified")
+		}
+
+		var err error
+		filename, err = d.getCacheFileName(url)
+		if err != nil {
+			return errors.Wrap(err, "Unable to get cache filename for image url")
+		}
+
+		if _, err := os.Stat(filename); os.IsNotExist(err) {
+			resp, err := http.Get(url)
+			if err != nil {
+				return errors.Wrap(err, "Unable to request image url")
+			}
+			defer resp.Body.Close()
+
+			imgFile, err := os.Create(filename)
+			if err != nil {
+				return errors.Wrap(err, "Unable to create cache file")
+			}
+
+			if _, err = io.Copy(imgFile, resp.Body); err != nil {
+				imgFile.Close()
+				return errors.Wrap(err, "Unable to download file")
+			}
+
+			imgFile.Close()
+		}
 	}
 
 	f, err := os.Open(filename)
@@ -42,3 +76,17 @@ func (d displayElementImage) Display(ctx context.Context, idx int, attributes ma
 
 	return errors.Wrap(sd.FillImage(idx, img), "Unable to set image")
 }
+
+func (d displayElementImage) getCacheFileName(url string) (string, error) {
+	ucd, err := os.UserCacheDir()
+	if err != nil {
+		return "", errors.Wrap(err, "Unable to get user cache dir")
+	}
+
+	cacheDir := path.Join(ucd, "io.luzifer.streamdeck")
+	if err = os.MkdirAll(cacheDir, 0750); err != nil {
+		return "", errors.Wrap(err, "Unable to create cache dir")
+	}
+
+	return path.Join(cacheDir, fmt.Sprintf("%x", sha256.Sum256([]byte(url)))), nil
+}