internal/api: add support for readme and licenses in ServeModule

- Utilize conditional fieldset in GetUnit to efficiently retrieve readme
  and license fields.
- Modify Module type to include HasGoMod.

Change-Id: Id22ac3f2485392749742332701d2e913f047b3da
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/763401
kokoro-CI: kokoro <noreply+kokoro@google.com>
Auto-Submit: Ethan Lee <ethanalee@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>

3 files changed, 97 insertions, 20 deletions

diff --git a/internal/api/api.go b/internal/api/api.go
index 49873c9b..5bf14eec 100644
--- a/internal/api/api.go
+++ b/internal/api/api.go
@@ -100,21 +100,45 @@ func ServeModule(w http.ResponseWriter, r *http.Request, ds internal.DataSource)
 	resp := Module{
 		Path:              um.ModulePath,
 		Version:           um.Version,
+		IsLatest:          um.Version == um.LatestVersion,
 		IsStandardLibrary: stdlib.Contains(um.ModulePath),
 		IsRedistributable: um.IsRedistributable,
+		HasGoMod:          um.HasGoMod,
 	}
 	// RepoURL needs to be extracted from source info if available
 	if um.SourceInfo != nil {
 		resp.RepoURL = um.SourceInfo.RepoURL()
 	}
 
+	if !params.Readme && !params.Licenses {
+		return serveJSON(w, http.StatusOK, resp)
+	}
+
+	fs := internal.MinimalFields
 	if params.Readme {
-		readme, err := ds.GetModuleReadme(r.Context(), um.ModulePath, um.Version)
-		if err == nil && readme != nil {
-			resp.Readme = &Readme{
-				Filepath: readme.Filepath,
-				Contents: readme.Contents,
-			}
+		fs |= internal.WithMain // WithMain includes Readme in GetUnit
+	}
+	if params.Licenses {
+		fs |= internal.WithLicenses
+	}
+	unit, err := ds.GetUnit(r.Context(), um, fs, internal.BuildContext{})
+	if err != nil {
+		return serveJSON(w, http.StatusOK, resp)
+	}
+
+	if params.Readme && unit.Readme != nil {
+		resp.Readme = &Readme{
+			Filepath: unit.Readme.Filepath,
+			Contents: unit.Readme.Contents,
+		}
+	}
+	if params.Licenses {
+		for _, l := range unit.LicenseContents {
+			resp.Licenses = append(resp.Licenses, License{
+				Types:    l.Metadata.Types,
+				FilePath: l.Metadata.FilePath,
+				Contents: string(l.Contents),
+			})
 		}
 	}
 
diff --git a/internal/api/api_test.go b/internal/api/api_test.go
index 15659c37..36066f46 100644
--- a/internal/api/api_test.go
+++ b/internal/api/api_test.go
@@ -230,20 +230,34 @@ func TestServeModule(t *testing.T) {
 		version    = "v1.2.3"
 	)
 
+	mi1 := sample.ModuleInfo(modulePath, version)
+	mi1.LatestVersion = "v1.2.4"
+	mi1.HasGoMod = true
+
 	ds.MustInsertModule(ctx, &internal.Module{
-		ModuleInfo: internal.ModuleInfo{
-			ModulePath: modulePath,
-			Version:    version,
-		},
+		ModuleInfo: *mi1,
+		Licenses:   sample.Licenses(),
 		Units: []*internal.Unit{{
 			UnitMeta: internal.UnitMeta{
-				Path: modulePath,
-				ModuleInfo: internal.ModuleInfo{
-					ModulePath: modulePath,
-					Version:    version,
-				},
+				Path:       modulePath,
+				ModuleInfo: *mi1,
+			},
+			Readme:   &internal.Readme{Filepath: "README.md", Contents: "Hello world"},
+			Licenses: sample.LicenseMetadata(),
+		}},
+	})
+
+	mi2 := sample.ModuleInfo(modulePath, "v1.2.4")
+	mi2.LatestVersion = "v1.2.4"
+	mi2.HasGoMod = true
+
+	ds.MustInsertModule(ctx, &internal.Module{
+		ModuleInfo: *mi2,
+		Units: []*internal.Unit{{
+			UnitMeta: internal.UnitMeta{
+				Path:       modulePath,
+				ModuleInfo: *mi2,
 			},
-			Readme: &internal.Readme{Filepath: "README.md", Contents: "Hello world"},
 		}},
 	})
 
@@ -258,8 +272,24 @@ func TestServeModule(t *testing.T) {
 			url:        "/v1/module/example.com?version=v1.2.3",
 			wantStatus: http.StatusOK,
 			want: &Module{
-				Path:    modulePath,
-				Version: version,
+				Path:              modulePath,
+				Version:           version,
+				IsRedistributable: true,
+				HasGoMod:          true,
+				RepoURL:           "https://example.com",
+			},
+		},
+		{
+			name:       "latest module metadata",
+			url:        "/v1/module/example.com?version=v1.2.4",
+			wantStatus: http.StatusOK,
+			want: &Module{
+				Path:              modulePath,
+				Version:           "v1.2.4",
+				IsLatest:          true,
+				IsRedistributable: true,
+				HasGoMod:          true,
+				RepoURL:           "https://example.com",
 			},
 		},
 		{
@@ -273,14 +303,36 @@ func TestServeModule(t *testing.T) {
 			url:        "/v1/module/example.com?version=v1.2.3&readme=true",
 			wantStatus: http.StatusOK,
 			want: &Module{
-				Path:    modulePath,
-				Version: version,
+				Path:              modulePath,
+				Version:           version,
+				IsRedistributable: true,
+				HasGoMod:          true,
+				RepoURL:           "https://example.com",
 				Readme: &Readme{
 					Filepath: "README.md",
 					Contents: "Hello world",
 				},
 			},
 		},
+		{
+			name:       "module with licenses",
+			url:        "/v1/module/example.com?version=v1.2.3&licenses=true",
+			wantStatus: http.StatusOK,
+			want: &Module{
+				Path:              modulePath,
+				Version:           version,
+				IsRedistributable: true,
+				HasGoMod:          true,
+				RepoURL:           "https://example.com",
+				Licenses: []License{
+					{
+						Types:    []string{"MIT"},
+						FilePath: "LICENSE",
+						Contents: "Lorem Ipsum",
+					},
+				},
+			},
+		},
 	} {
 		t.Run(test.name, func(t *testing.T) {
 			r := httptest.NewRequest("GET", test.url, nil)
diff --git a/internal/api/types.go b/internal/api/types.go
index 6af65e58..be923e4c 100644
--- a/internal/api/types.go
+++ b/internal/api/types.go
@@ -47,6 +47,7 @@ type Module struct {
 	IsLatest          bool      `json:"isLatest"`
 	IsRedistributable bool      `json:"isRedistributable"`
 	IsStandardLibrary bool      `json:"isStandardLibrary"`
+	HasGoMod          bool      `json:"hasGoMod"`
 	RepoURL           string    `json:"repoUrl"`
 	GoModContents     string    `json:"goModContents,omitempty"`
 	Readme            *Readme   `json:"readme,omitempty"`