feat: check screenshot image type (#278)

* feat: check screenshot image type

* ref: add test for all image types, check svg

pkg/analysis/passes/screenshots/screenshots.go

@@ -1,34 +1,48 @@
 package screenshots
 
 import (
+	"bytes"
 	"encoding/json"
 	"fmt"
+	"net/http"
+	"os"
+	"path/filepath"
 	"strings"
 
 	"github.com/grafana/plugin-validator/pkg/analysis"
+	"github.com/grafana/plugin-validator/pkg/analysis/passes/archive"
 	"github.com/grafana/plugin-validator/pkg/analysis/passes/metadata"
+	"github.com/grafana/plugin-validator/pkg/logme"
 )
 
 var (
-	screenshots = &analysis.Rule{Name: "screenshots", Severity: analysis.Warning}
+	screenshots     = &analysis.Rule{Name: "screenshots", Severity: analysis.Warning}
+	screenshotsType = &analysis.Rule{Name: "screenshots-image-type", Severity: analysis.Error}
 )
 
 var Analyzer = &analysis.Analyzer{
 	Name:     "screenshots",
-	Run:      checkScreenshotsExist,
-	Requires: []*analysis.Analyzer{metadata.Analyzer},
-	Rules:    []*analysis.Rule{screenshots},
+	Run:      checkScreenshots,
+	Requires: []*analysis.Analyzer{metadata.Analyzer, archive.Analyzer},
+	Rules:    []*analysis.Rule{screenshots, screenshotsType},
 	ReadmeInfo: analysis.ReadmeInfo{
 		Name:        "Screenshots",
 		Description: "Screenshots are specified in `plugin.json` that will be used in the Grafana plugin catalog.",
 	},
 }
 
-func checkScreenshotsExist(pass *analysis.Pass) (interface{}, error) {
+var svgImage = "image/svg+xml"
+var acceptedImageTypes = []string{"image/jpeg", "image/png", "image/gif", svgImage}
+
+func checkScreenshots(pass *analysis.Pass) (interface{}, error) {
 	metadataBody, ok := pass.ResultOf[metadata.Analyzer].([]byte)
 	if !ok {
 		return nil, nil
 	}
+	archiveDir, ok := pass.ResultOf[archive.Analyzer].(string)
+	if !ok {
+		return nil, nil
+	}
 
 	var data metadata.Metadata
 	if err := json.Unmarshal(metadataBody, &data); err != nil {
@@ -39,24 +53,73 @@ func checkScreenshotsExist(pass *analysis.Pass) (interface{}, error) {
 		explanation := "Screenshots are displayed in the Plugin catalog. Please add at least one screenshot to your plugin.json."
 		pass.ReportResult(pass.AnalyzerName, screenshots, "plugin.json: should include screenshots for the Plugin catalog", explanation)
 		return data.Info.Screenshots, nil
-	} else {
-		reportCount := 0
-		for _, screenshot := range data.Info.Screenshots {
-			if strings.TrimSpace(screenshot.Path) == "" {
-				reportCount++
-				pass.ReportResult(pass.AnalyzerName, screenshots, fmt.Sprintf("plugin.json: invalid empty screenshot path: %q", screenshot.Name), "The screenshot path must not be empty.")
-			}
-		}
+	}
 
-		if reportCount > 0 {
-			return nil, nil
+	reportCount := 0
+	for _, screenshot := range data.Info.Screenshots {
+		if strings.TrimSpace(screenshot.Path) == "" {
+			reportCount++
+			pass.ReportResult(pass.AnalyzerName, screenshots, fmt.Sprintf("plugin.json: invalid empty screenshot path: %q", screenshot.Name), "The screenshot path must not be empty.")
+		} else if err := validateImage(filepath.Join(archiveDir, screenshot.Path)); err != nil {
+			reportCount++
+			logme.Debugln(err)
+			pass.ReportResult(pass.AnalyzerName, screenshotsType, err.Error(), "The screenshot image is of an unsupported format.")
 		}
+	}
 
-		if screenshots.ReportAll {
-			screenshots.Severity = analysis.OK
-			pass.ReportResult(pass.AnalyzerName, screenshots, "plugin.json: includes screenshots for the Plugin catalog", "")
-		}
+	if reportCount > 0 {
+		return nil, nil
+	}
+
+	if screenshots.ReportAll {
+		screenshots.Severity = analysis.OK
+		pass.ReportResult(pass.AnalyzerName, screenshots, "plugin.json: includes screenshots for the Plugin catalog", "")
+	}
+
+	if screenshotsType.ReportAll {
+		screenshotsType.Severity = analysis.OK
+		pass.ReportResult(pass.AnalyzerName, screenshotsType, "screenshots are valid image type", "")
 	}
 
 	return data.Info.Screenshots, nil
 }
+
+// We can use mimetype but it does too much for our case
+// https://github.com/gabriel-vasile/mimetype/blob/master/internal/magic/text.go#L298
+func checkSVG(raw []byte) bool {
+	return bytes.Contains(raw, []byte("<svg"))
+}
+
+func validateImage(imgPath string) error {
+	file, err := os.Open(imgPath)
+	if err != nil {
+		logme.DebugFln("cannot open file: %v", err)
+		return fmt.Errorf("invalid screenshot path: %q", imgPath)
+	}
+	defer file.Close()
+
+	// 512 is enough for getting the content type
+	// https://pkg.go.dev/net/http#DetectContentType
+	buffer := make([]byte, 512)
+	// files less than 512 it will read all the file
+	// won't throw errors
+	if _, err := file.Read(buffer); err != nil {
+		logme.DebugFln("cannot read file: %v", err)
+		return fmt.Errorf("cannot read file: %v", err)
+	}
+
+	// returns text/plain or text/xml for svg files
+	mimeType := http.DetectContentType(buffer)
+	// logo.svg returns text/plain, valid.svg returns text/xml
+	if (strings.Contains(mimeType, "text/plain") || strings.Contains(mimeType, "text/xml")) && checkSVG(buffer) {
+		mimeType = svgImage
+	}
+
+	for _, accepted := range acceptedImageTypes {
+		if accepted == mimeType {
+			return nil
+		}
+	}
+
+	return fmt.Errorf("invalid screenshot image: %q. Accepted image types: %q", imgPath, acceptedImageTypes)
+}