better file organization

internal/utils/utils.go

@@ -0,0 +1,68 @@
+package utils
+
+import (
+	"archive/tar"
+	"io"
+	"log"
+	"net/http"
+	"os"
+	"packets/configs"
+	errors_packets "packets/internal/errors"
+	"path/filepath"
+
+	"github.com/klauspost/compress/zstd"
+	"github.com/pelletier/go-toml/v2"
+)
+
+func DownloadPackageHTTP(url string) (*[]byte, error) {
+
+	resp, err := http.Get(url)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, errors_packets.ErrResponseNot200OK
+	}
+
+	fileBytes, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	return &fileBytes, nil
+}
+
+// ReadManifest is crucial to get package metadata it reads manifest.toml from a package file (tar.zst)
+func ReadManifest(file *os.File) (*configs.Manifest, error) {
+	zstdReader, err := zstd.NewReader(file)
+	if err != nil {
+		return nil, err
+	}
+	defer zstdReader.Close()
+
+	tarReader := tar.NewReader(zstdReader)
+	for {
+		header, err := tarReader.Next()
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			return nil, err
+		}
+
+		if filepath.Base(header.Name) == "manifest.toml" {
+			decoder := toml.NewDecoder(tarReader)
+
+			var manifest configs.Manifest
+
+			if err := decoder.Decode(&manifest); err != nil {
+				log.Fatal(err)
+			}
+
+			return &manifest, nil
+		}
+
+	}
+	return nil, errors_packets.ErrCantFindManifestTOML
+}