loader logic revised

client/loader/download.go

@@ -1,19 +1,84 @@
 package loader
 
 import (
+	"errors"
+	"fmt"
 	"galaxy/connector"
 	"galaxy/util"
 )
 
-func (l *loader) newerVersion(version string) bool {
-	return util.CompareSemver(util.MustParseSemver(l.client.Version()), util.MustParseSemver(version)) > 0
+func (l *loader) checkAndDownloadPluginVersion() error {
+	versions, err := l.connector.CheckVersion()
+	if err != nil {
+		return err
+	} else if latest, ok, err := latestVersion(versions); err != nil {
+		return err
+	} else if ok {
+		return l.preparePluginVersion(latest)
+	} else {
+		return errors.New("Server did not respond with a suitable client version")
+	}
 }
 
-// downloadVersion fetches given version artifact, when newer to the current version,
-// and stores at the App's local storage with a pre-defined name with semver suffix
-func (l *loader) downloadVersion(v connector.VersionInfo) {
-	if !l.newerVersion(v.Version) {
-		return
+// preparePluginVersion fetches and stores given version of plugin artifact, if newer to the current known version.
+func (l *loader) preparePluginVersion(v connector.VersionInfo) error {
+	s, exists, err := l.loadCurrentState()
+	if err != nil {
+		return err
 	}
-	l.connector.DownloadVersion(v.URL)
+	version, err := util.ParseSemver(v.Version)
+	if err != nil {
+		return err
+	}
+	if exists {
+		currentVersion, err := util.ParseSemver(s.ClientCurrentVersion)
+		if err != nil {
+			return err
+		}
+		if util.CompareSemver(currentVersion, version) > 0 {
+			return nil
+		}
+	}
+	err = l.downloadPlugin(v.URL, v.Version, v.Checksum)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+// downloadPlugin downloads and stores at the App's local storage with a pre-defined name with semver suffix.
+func (l *loader) downloadPlugin(url, version string, checksum [32]byte) error {
+	data, err := l.connector.DownloadVersion(url)
+	if err != nil {
+		return fmt.Errorf("Plugin v%s download error: %w", version, err)
+	}
+	dataChecksum := SumSHA256(data)
+	if !EqualSHA256(checksum, dataChecksum) {
+		return errors.New("Downloaded pligin checksum incorrect")
+	}
+	versionFileName := resolvePluginFile(version)
+	versionFileExists, _, err := l.storage.FileExists(versionFileName)
+	if err != nil {
+		return fmt.Errorf("Check plugin v%s exists error: %w", version, err)
+	}
+	if versionFileExists {
+		storedData, err := l.storage.ReadFile(versionFileName)
+		if err != nil {
+			return err
+		}
+		if EqualSHA256(dataChecksum, SumSHA256(storedData)) {
+			return nil
+		}
+		if err := l.storage.DeleteFile(versionFileName); err != nil {
+			return fmt.Errorf("Plugin v%s delete error: %w", version, err)
+		}
+	}
+	err = l.storage.WriteFile(versionFileName, data)
+	if err != nil {
+		return fmt.Errorf("Plugin file write error: %w", err)
+	}
+	if err := l.setNextVersion(&version); err != nil {
+		return err
+	}
+	return nil
 }