implement /in

fetches a given list of globs from the assets.

also be durable to 'v' prefixing version tags

Signed-off-by: Alex Suraci <asuraci@pivotal.io>

in_command.go

@@ -0,0 +1,116 @@
+package resource
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"path/filepath"
+	"sort"
+
+	"github.com/google/go-github/github"
+)
+
+type InCommand struct {
+	github GitHub
+}
+
+func NewInCommand(github GitHub) *InCommand {
+	return &InCommand{
+		github: github,
+	}
+}
+
+func (c *InCommand) Run(destDir string, request InRequest) (InResponse, error) {
+	releases, err := c.github.ListReleases()
+	if err != nil {
+		return InResponse{}, nil
+	}
+
+	sort.Sort(byVersion(releases))
+
+	if len(releases) == 0 {
+		return InResponse{}, errors.New("no releases")
+	}
+
+	var foundRelease *github.RepositoryRelease
+
+	if request.Version == nil {
+		foundRelease = &releases[len(releases)-1]
+	} else {
+		for _, release := range releases {
+			if *release.TagName == request.Version.Tag {
+				foundRelease = &release
+				break
+			}
+		}
+	}
+
+	if foundRelease == nil {
+		return InResponse{}, fmt.Errorf("could not find release with tag: %s", request.Version.Tag)
+	}
+
+	assets, err := c.github.ListReleaseAssets(foundRelease)
+	if err != nil {
+		return InResponse{}, nil
+	}
+
+	for _, asset := range assets {
+		url := *asset.BrowserDownloadURL
+		path := filepath.Join(destDir, *asset.Name)
+
+		var matchFound bool
+		if len(request.Params.Globs) == 0 {
+			matchFound = true
+		} else {
+			for _, glob := range request.Params.Globs {
+				matches, err := filepath.Match(glob, *asset.Name)
+				if err != nil {
+					return InResponse{}, err
+				}
+
+				if matches {
+					matchFound = true
+					break
+				}
+			}
+		}
+
+		if !matchFound {
+			continue
+		}
+
+		err := c.downloadFile(url, path)
+		if err != nil {
+			return InResponse{}, nil
+		}
+	}
+
+	return InResponse{
+		Version: Version{
+			Tag: *foundRelease.TagName,
+		},
+	}, nil
+}
+
+func (c *InCommand) downloadFile(url, destPath string) error {
+	out, err := os.Create(destPath)
+	if err != nil {
+		return err
+	}
+	defer out.Close()
+
+	resp, err := http.Get(url)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	_, err = io.Copy(out, resp.Body)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}