added SPM

spm/download.go

@@ -0,0 +1,91 @@
+package spm
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"path/filepath"
+	"runtime"
+)
+
+type Package struct {
+	Name        string
+	Arch        string
+	OS          string
+	DownloadURL string
+}
+
+func DownloadPackage(pkg Package, destDir string) error {
+	UpdateProgress(0, fmt.Sprintf("Downloading %s", pkg.Name))
+	resp, err := http.Get(pkg.DownloadURL)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	filePath := filepath.Join(destDir, filepath.Base(pkg.DownloadURL))
+	out, err := os.Create(filePath)
+	if err != nil {
+		return err
+	}
+	defer out.Close()
+
+	totalSize := resp.ContentLength
+	var downloaded int64
+
+	// Track progress as bytes are downloaded
+	buf := make([]byte, 1024)
+	for {
+		n, err := resp.Body.Read(buf)
+		if n > 0 {
+			downloaded += int64(n)
+			percentage := int(float64(downloaded) / float64(totalSize) * 100)
+			UpdateProgress(percentage, fmt.Sprintf("Downloading %s", pkg.Name))
+			if _, err := out.Write(buf[:n]); err != nil {
+				return err
+			}
+		}
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			return err
+		}
+	}
+
+	UpdateProgress(100, fmt.Sprintf("%s downloaded", pkg.Name))
+	return nil
+}
+
+func FindPackage(entries []AppIndexEntry, name, release, arch, os string) (*AppIndexEntry, error) {
+	for _, entry := range entries {
+		if entry.Name == name && entry.Release == release && entry.Arch == arch && entry.OS == os {
+			return &entry, nil
+		}
+	}
+	return nil, errors.New("package not found")
+}
+
+func DownloadPackageFromAppIndex(appIndexPath, packageName, release, destDir string) error {
+	arch := runtime.GOARCH
+	osName := runtime.GOOS
+
+	entries, err := ParseAppIndex(appIndexPath)
+	if err != nil {
+		return err
+	}
+
+	entry, err := FindPackage(entries, packageName, release, arch, osName)
+	if err != nil {
+		return err
+	}
+
+	return DownloadPackage(Package{
+		Name:        entry.Name,
+		Arch:        entry.Arch,
+		OS:          entry.OS,
+		DownloadURL: entry.DownloadURL,
+	}, destDir)
+}