dont download if file already present

if a file is already i the file system and it validates, we do not need to download it again.

Update resource.go

added comment back to the code

Update resource.go

removed os.Remove(fileName) which was previously on line 82

Update resource.go

deleted my code under the geturltodir function and added the missing line that was requested

dont download if file already present

if a file is already i the file system and it validates, we do not need to download it again.

fixed the too less calls in lock.Download go included a missing boolean value for the lock.Download call.

dont download if file already present

if a file is already i the file system and it validates, we do not need to download it again.

Update resource.go

added comment back to the code

Update resource.go

removed os.Remove(fileName) which was previously on line 82

Update resource.go

deleted my code under the geturltodir function and added the missing line that was requested

dont download if file already present

if a file is already i the file system and it validates, we do not need to download it again.

fixed the too less calls in lock.Download go included a missing boolean value for the lock.Download call.

cmd/dowload_test.go

@@ -4,10 +4,16 @@ import (
 	"crypto/sha256"
 	"encoding/base64"
 	"fmt"
+	"github.com/cisco-open/grabit/internal"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"path/filepath"
 	"testing"
 
 	"github.com/cisco-open/grabit/test"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func getSha256Integrity(content string) string {
@@ -124,6 +130,56 @@ func TestRunDownloadFailsIntegrityTest(t *testing.T) {
 	assert.Contains(t, err.Error(), "integrity mismatch")
 }
 
+func TestOptimization(t *testing.T) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		_, err := w.Write([]byte("test content"))
+		if err != nil {
+			return
+		}
+	}))
+	defer ts.Close()
+
+	t.Run("Valid_File_Not_Redownloaded", func(t *testing.T) {
+		tmpDir := test.TmpDir(t)
+		testUrl := ts.URL + "/valid_test.txt"
+
+		lockPath := test.TmpFile(t, "")
+		lock, err := internal.NewLock(lockPath, true)
+		require.NoError(t, err)
+
+		err = lock.AddResource([]string{testUrl}, internal.RecommendedAlgo, nil, "valid_test.txt")
+		require.NoError(t, err)
+
+		// Update the Download call to match the new signature
+		err = lock.Download(tmpDir, nil, nil, "", false) // Added 'false' for the new boolean argument
+		require.NoError(t, err)
+	})
+
+	t.Run("Invalid_File_Redownloaded", func(t *testing.T) {
+		tmpDir := test.TmpDir(t)
+		testUrl := ts.URL + "/invalid_test.txt"
+
+		lockPath := test.TmpFile(t, "")
+		lock, err := internal.NewLock(lockPath, true)
+		require.NoError(t, err)
+
+		err = lock.AddResource([]string{testUrl}, internal.RecommendedAlgo, nil, "invalid_test.txt")
+		require.NoError(t, err)
+
+		err = lock.Save()
+		require.NoError(t, err)
+
+		invalidPath := filepath.Join(tmpDir, "invalid_test.txt")
+		err = os.WriteFile(invalidPath, []byte("corrupted"), 0644)
+		require.NoError(t, err)
+
+		// Update the Download call to match the new signature
+		err = lock.Download(tmpDir, nil, nil, "", false) // Added 'false' for the new boolean argument
+		require.Error(t, err)
+		assert.Contains(t, err.Error(), "integrity mismatch")
+	})
+}
+
 func TestRunDownloadTriesAllUrls(t *testing.T) {
 	content := `abcdef`
 	contentIntegrity := getSha256Integrity(content)

internal/resource.go

@@ -92,15 +92,7 @@ func (l *Resource) Download(dir string, mode os.FileMode, ctx context.Context) e
 	for _, u := range l.Urls {
 		// Download file in the target directory so that the call to
 		// os.Rename is atomic.
-		lpath, err := GetUrlToDir(u, dir, ctx)
-		if err != nil {
-			downloadError = err
-			continue
-		}
-		err = checkIntegrityFromFile(lpath, algo, l.Integrity, u)
-		if err != nil {
-			return err
-		}
+		log.Debug().Str("URL", u).Msg("Downloading")
 
 		localName := ""
 		if l.Filename != "" {
@@ -109,27 +101,61 @@ func (l *Resource) Download(dir string, mode os.FileMode, ctx context.Context) e
 			localName = path.Base(u)
 		}
 		resPath := filepath.Join(dir, localName)
-		err = os.Rename(lpath, resPath)
+
+		// Check existing file first
+		if _, err := os.Stat(resPath); err == nil {
+			// File exists, validate its integrity
+			if !ValidateLocalFile(resPath, l.Integrity) {
+				return fmt.Errorf("integrity mismatch for '%s'", resPath)
+			}
+			// Set file permissions if needed
+			if mode != NoFileMode {
+				if err := os.Chmod(resPath, mode.Perm()); err != nil {
+					return err
+				}
+			}
+			ok = true
+			continue
+		} else if !os.IsNotExist(err) {
+			// Handle other potential errors from os.Stat
+			return fmt.Errorf("failed to stat file '%s': %v", resPath, err)
+		}
+
+		// Download new file
+		lpath, err := GetUrlToDir(u, dir, ctx)
 		if err != nil {
-			return err
+			downloadError = fmt.Errorf("failed to download '%s': %v", u, err)
+			continue
+		}
+
+		// Validate downloaded file
+		if err := checkIntegrityFromFile(lpath, algo, l.Integrity, u); err != nil {
+			os.Remove(lpath)
+			downloadError = err
+			continue
 		}
+
+		// Move to final location
+		if err := os.Rename(lpath, resPath); err != nil {
+			os.Remove(lpath)
+			downloadError = err
+			continue
+		}
+
 		if mode != NoFileMode {
-			err = os.Chmod(resPath, mode.Perm())
-			if err != nil {
+			if err := os.Chmod(resPath, mode.Perm()); err != nil {
 				return err
 			}
 		}
 		ok = true
+		break
 	}
+
 	if !ok {
-		if downloadError != nil {
-			return downloadError
-		}
-		return err
+		return downloadError
 	}
 	return nil
 }
-
 func (l *Resource) Contains(url string) bool {
 	for _, u := range l.Urls {
 		if u == url {
@@ -138,3 +164,21 @@ func (l *Resource) Contains(url string) bool {
 	}
 	return false
 }
+
+func ValidateLocalFile(filePath string, expectedIntegrity string) bool {
+	if _, err := os.Stat(filePath); os.IsNotExist(err) {
+		return false
+	}
+
+	algo, err := getAlgoFromIntegrity(expectedIntegrity)
+	if err != nil {
+		return false
+	}
+
+	fileIntegrity, err := getIntegrityFromFile(filePath, algo)
+	if err != nil {
+		return false
+	}
+
+	return fileIntegrity == expectedIntegrity
+}