feat: add release asset downloading of tar/zip

cmd/helpers.go

@@ -1,7 +1,9 @@
 package cmd
 
 import (
+	"encoding/json"
 	"errors"
+	"io"
 	"os"
 	"strings"
 
@@ -60,3 +62,12 @@ func setLogLevel(level string) {
 		log.Fatalf("Invalid log level: %s", logLevel)
 	}
 }
+
+func prettyEncode(data interface{}, out io.Writer) error {
+	enc := json.NewEncoder(out)
+	enc.SetIndent("", "    ")
+	if err := enc.Encode(data); err != nil {
+		return err
+	}
+	return nil
+}

internal/gh/assets.go

@@ -1,21 +1,42 @@
 package gh
 
 import (
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
 	"strings"
+	"time"
 
 	"github.com/google/go-github/v44/github"
+	log "github.com/sirupsen/logrus"
 )
 
-type OsAssetSuffix int64
+func getOsAssetSuffix(os string) osAssetSuffix {
+	switch os {
+	case "linux":
+		return linuxamd64
+	case "darwin":
+		return macos
+	case "windows":
+		return win
+	default:
+		return unknown
+	}
+}
+
+type osAssetSuffix int64
 
 const (
-	unknown OsAssetSuffix = iota
+	unknown osAssetSuffix = iota
 	linuxamd64
 	macos
 	win
 )
 
-func (o OsAssetSuffix) String() string {
+func (o osAssetSuffix) String() string {
 	switch o {
 	case linuxamd64:
 		return "linux-amd64.tar.gz"
@@ -28,17 +49,51 @@ func (o OsAssetSuffix) String() string {
 	}
 }
 
-func GetTarballForOs(assets []github.ReleaseAsset, suffix OsAssetSuffix) string {
+// DownloadReleaseAsset downloads the release asset for a given platform to a temp
+// file and returns the file handle.
+// targetOs should be "windows", "darwin", "linux"
+func DownloadReleaseAsset(client *github.Client, tag string, targetOs string) (*os.File, error) {
+	release, err := GetRelease(client, tag)
+	if err != nil {
+		return nil, err
+	}
+	asset := findAssetForOs(release.Assets, getOsAssetSuffix(targetOs))
+	if asset == nil {
+		return nil, errors.New("no release asset found")
+	}
+	// shouldn't need the redirect url given should follow redirects with the http client
+	log.Tracef("fetching information to download release asset from %s\n", asset.GetBrowserDownloadURL())
+	start := time.Now()
+	rc, _, err := client.Repositories.DownloadReleaseAsset(context.Background(), "quarto-dev", "quarto-cli", asset.GetID(), http.DefaultClient)
+	log.Tracef("done fetching release asset information in %s\n", time.Since(start))
+	if err != nil {
+		return nil, err
+	}
+	defer rc.Close()
+	tmpFile, err := os.CreateTemp("", fmt.Sprintf("*-%s", asset.GetName()))
+	if err != nil {
+		return tmpFile, err
+	}
+	log.Tracef("starting to copy release asset to %s\n", tmpFile.Name())
+	start = time.Now()
+	wb, err := io.Copy(tmpFile, rc)
+	log.Tracef("done copying release asset in %s\n", time.Since(start))
+	if err != nil {
+		return tmpFile, err
+	}
+	log.Debugf("downloaded %d bytes from release asset at url %s\n", wb, asset.GetBrowserDownloadURL())
+	return tmpFile, nil
+}
+
+func findAssetForOs(assets []*github.ReleaseAsset, suffix osAssetSuffix) *github.ReleaseAsset {
 	if suffix == unknown {
-		return ""
+		return nil
 	}
-	var dlUrl string
 	for _, asset := range assets {
 		name := asset.GetName()
 		if strings.HasSuffix(name, suffix.String()) {
-			dlUrl = asset.GetBrowserDownloadURL()
-			break
+			return asset
 		}
 	}
-	return dlUrl
+	return nil
 }

internal/gh/releases.go

@@ -8,6 +8,20 @@ import (
 	log "github.com/sirupsen/logrus"
 )
 
+func GetRelease(client *github.Client, release string) (*github.RepositoryRelease, error) {
+	rel, resp, err := client.Repositories.GetReleaseByTag(
+		context.Background(),
+		"quarto-dev",
+		"quarto-cli",
+		release,
+	)
+	log.WithField("resp", resp).Trace("get-latest-release")
+	if err != nil {
+		return nil, err
+	}
+	return rel, err
+}
+
 func GetLatestRelease(client *github.Client) (*github.RepositoryRelease, error) {
 	rel, resp, err := client.Repositories.GetLatestRelease(
 		context.Background(),