internal/api: implement module packages endpoint

- Implement the ServeModulePackages handler and introduce
  GetModulePackages to return the list of packages for a given module
  version.

Change-Id: I20c1618e2fdbf0126cb913665a1d7457b8951177
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/754863
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
kokoro-CI: kokoro <noreply+kokoro@google.com>
Auto-Submit: Ethan Lee <ethanalee@google.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>

1 files changed, 29 insertions, 0 deletions

diff --git a/internal/fetchdatasource/fetchdatasource.go b/internal/fetchdatasource/fetchdatasource.go
index 41573ae5..1643d009 100644
--- a/internal/fetchdatasource/fetchdatasource.go
+++ b/internal/fetchdatasource/fetchdatasource.go
@@ -404,3 +404,32 @@ func (ds *FetchDataSource) Search(ctx context.Context, q string, opts internal.S
 
 	return results, nil
 }
+
+// GetModulePackages returns a list of packages in the given module version.
+func (ds *FetchDataSource) GetModulePackages(ctx context.Context, modulePath, version string) ([]*internal.PackageMeta, error) {
+	m, err := ds.getModule(ctx, modulePath, version)
+	if err != nil {
+		return nil, err
+	}
+	var metas []*internal.PackageMeta
+	for _, um := range m.UnitMetas {
+		if um.IsPackage() {
+			u, err := ds.findUnit(ctx, m, um.Path)
+			if err != nil {
+				return nil, err
+			}
+			var synopsis string
+			if len(u.Documentation) > 0 {
+				synopsis = u.Documentation[0].Synopsis
+			}
+			metas = append(metas, &internal.PackageMeta{
+				Path:              u.Path,
+				Name:              u.Name,
+				Synopsis:          synopsis,
+				IsRedistributable: u.IsRedistributable,
+				Licenses:          u.Licenses,
+			})
+		}
+	}
+	return metas, nil
+}