1 files changed, 151 insertions, 0 deletions
diff --git a/beku.go b/beku.go
index 9ca8500..fe1796d 100644
--- a/beku.go
+++ b/beku.go
@@ -6,7 +6,13 @@ package beku
 
 import (
 	"errors"
+	"fmt"
+	"go/build"
 	"os"
+	"path/filepath"
+	"strings"
+
+	libhttp "git.sr.ht/~shulhan/pakakeh.go/lib/http"
 )
 
 const (
@@ -87,3 +93,148 @@ var (
 	defStdout = os.Stdout //nolint: gochecknoglobals
 	defStderr = os.Stderr //nolint: gochecknoglobals
 )
+
+type Beku struct {
+	env   *Env
+	httpc *libhttp.Client
+}
+
+func NewBeku(env *Env) (beku *Beku) {
+	beku = &Beku{
+		env: env,
+	}
+	return beku
+}
+
+// Install the Go binary or a module.
+func (beku *Beku) Install(module string) (err error) {
+	module = strings.ToLower(module)
+
+	var (
+		nameVersion = strings.Split(module, "@")
+		modName     = nameVersion[0]
+		modVersion  string
+	)
+
+	if len(nameVersion) > 1 {
+		modVersion = nameVersion[1]
+	}
+
+	if modName == "go" {
+		if len(modVersion) == 0 {
+			return beku.installGoFromSource()
+		}
+		return beku.installGo(modVersion)
+	}
+
+	return nil
+}
+
+// checkInstalledGo check if specific Go tools version already installed.
+// It will return nil if it not exist.
+func (beku *Beku) checkInstalledGo(version string) (err error) {
+	pathGo := filepath.Join(beku.env.prefix, "beku", "share", "go"+version)
+	_, err = os.Stat(pathGo)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil
+		}
+		return err
+	}
+	return fmt.Errorf("%s already installed", pathGo)
+}
+
+func (beku *Beku) downloadGo(version string) (err error) {
+	var (
+		logp        = "downloadGo"
+		compression = "tar.gz"
+	)
+
+	if build.Default.GOOS == "windows" {
+		compression = "zip"
+	}
+
+	goDownload := fmt.Sprintf("go%s.%s-%s.%s", version,
+		build.Default.GOOS, build.Default.GOARCH,
+		compression)
+
+	pathCache := filepath.Join(beku.env.prefix, "beku", "cache", goDownload)
+
+	fi, err := os.Stat(pathCache)
+	if err != nil {
+		if !os.IsNotExist(err) {
+			return fmt.Errorf("%s: %w", logp, err)
+		}
+		err = nil
+	}
+	if fi != nil {
+		// The downloaded file already exist on cache directory.
+		return nil
+	}
+
+	fout, err := os.Create(pathCache)
+	if err != nil {
+		return fmt.Errorf("%s: %w", logp, err)
+	}
+
+	beku.initHttpClient()
+
+	downloadReq := libhttp.DownloadRequest{
+		ClientRequest: libhttp.ClientRequest{
+			Path: "/dl/" + goDownload,
+		},
+		Output: fout,
+	}
+
+	_, err = beku.httpc.Download(downloadReq)
+	if err != nil {
+		errClose := fout.Close()
+		if errClose != nil {
+			err = fmt.Errorf("%s: %w: %s", logp, err, errClose)
+		} else {
+			err = fmt.Errorf("%s: %w", logp, err)
+		}
+		return err
+	}
+
+	err = fout.Close()
+	if err != nil {
+		return fmt.Errorf("%s: %w", logp, err)
+	}
+
+	return nil
+}
+
+func (beku *Beku) initHttpClient() {
+	if beku.httpc != nil {
+		return
+	}
+	opts := libhttp.ClientOptions{
+		ServerURL: "https://go.dev",
+	}
+	beku.httpc = libhttp.NewClient(opts)
+}
+
+// installGo install specific Go tools version by downloading the binary from
+// official server and extract it into $GOPATH/beku/share/go{version}.
+func (beku *Beku) installGo(version string) (err error) {
+	var (
+		logp = "installGo " + version
+	)
+
+	err = beku.checkInstalledGo(version)
+	if err != nil {
+		return fmt.Errorf("%s: %w", logp, err)
+	}
+
+	err = beku.downloadGo(version)
+	if err != nil {
+		return fmt.Errorf("%s: %w", logp, err)
+	}
+
+	return nil
+}
+
+func (beku *Beku) installGoFromSource() (err error) {
+	return nil
+}