From a4b5f8e7c91eb004f6e55ecbb807bdd55d641360 Mon Sep 17 00:00:00 2001
From: Ryan Moran <rmoran@vmware.com>
Date: Mon, 29 Mar 2021 17:19:19 -0700
Subject: [PATCH] Add bill of materials entry facility for postal.Service

---
 postal/buildpack.go    | 12 ++++-----
 postal/service.go      | 27 ++++++++++++++++++++
 postal/service_test.go | 57 +++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 89 insertions(+), 7 deletions(-)

diff --git a/postal/buildpack.go b/postal/buildpack.go
index 9e46ba26..7161404a 100644
--- a/postal/buildpack.go
+++ b/postal/buildpack.go
@@ -16,15 +16,9 @@ type Dependency struct {
 	// ID is the identifier used to specify the dependency.
 	ID string `toml:"id"`
 
-	// Version is the specific version of the dependency.
-	Version string `toml:"version"`
-
 	// Name is the human-readable name of the dependency.
 	Name string `toml:"name"`
 
-	// URI is the uri location of the built dependency.
-	URI string `toml:"uri"`
-
 	// SHA256 is the hex-encoded SHA256 checksum of the built dependency.
 	SHA256 string `toml:"sha256"`
 
@@ -36,6 +30,12 @@ type Dependency struct {
 
 	// Stacks is a list of stacks for which the dependency is built.
 	Stacks []string `toml:"stacks"`
+
+	// URI is the uri location of the built dependency.
+	URI string `toml:"uri"`
+
+	// Version is the specific version of the dependency.
+	Version string `toml:"version"`
 }
 
 func parseBuildpack(path, name string) ([]Dependency, string, error) {
diff --git a/postal/service.go b/postal/service.go
index 233c0391..eb9bdd66 100644
--- a/postal/service.go
+++ b/postal/service.go
@@ -7,8 +7,10 @@ import (
 	"regexp"
 	"sort"
 	"strings"
+	"time"
 
 	"github.com/Masterminds/semver/v3"
+	"github.com/paketo-buildpacks/packit"
 	"github.com/paketo-buildpacks/packit/cargo"
 	"github.com/paketo-buildpacks/packit/postal/internal"
 	"github.com/paketo-buildpacks/packit/vacation"
@@ -177,3 +179,28 @@ func (s Service) Deliver(dependency Dependency, cnbPath, layerPath, platformPath
 func (s Service) Install(dependency Dependency, cnbPath, layerPath string) error {
 	return s.Deliver(dependency, cnbPath, layerPath, "/platform")
 }
+
+// GenerateBillOfMaterials will generate a list of BOMEntry values given a
+// collection of Dependency values.
+func (s Service) GenerateBillOfMaterials(dependencies ...Dependency) []packit.BOMEntry {
+	var entries []packit.BOMEntry
+	for _, dependency := range dependencies {
+		entry := packit.BOMEntry{
+			Name: dependency.Name,
+			Metadata: map[string]interface{}{
+				"sha256":  dependency.SHA256,
+				"stacks":  dependency.Stacks,
+				"uri":     dependency.URI,
+				"version": dependency.Version,
+			},
+		}
+
+		if (dependency.DeprecationDate != time.Time{}) {
+			entry.Metadata["deprecation-date"] = dependency.DeprecationDate
+		}
+
+		entries = append(entries, entry)
+	}
+
+	return entries
+}
diff --git a/postal/service_test.go b/postal/service_test.go
index 84827b0f..72fcd99d 100644
--- a/postal/service_test.go
+++ b/postal/service_test.go
@@ -14,6 +14,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/paketo-buildpacks/packit"
 	"github.com/paketo-buildpacks/packit/postal"
 	"github.com/paketo-buildpacks/packit/postal/fakes"
 	"github.com/sclevine/spec"
@@ -38,7 +39,6 @@ func testService(t *testing.T, context spec.G, it spec.S) {
 		Expect(err).NotTo(HaveOccurred())
 
 		path = file.Name()
-
 		_, err = file.WriteString(`
 [[metadata.dependencies]]
 deprecation_date = 2022-04-01T00:00:00Z
@@ -823,4 +823,59 @@ version = "this is super not semver"
 			})
 		})
 	})
+
+	context("GenerateBillOfMaterials", func() {
+		var deprecationDate time.Time
+
+		it.Before(func() {
+			var err error
+			deprecationDate, err = time.Parse(time.RFC3339, "2022-04-01T00:00:00Z")
+			Expect(err).NotTo(HaveOccurred())
+		})
+
+		it("returns a list of BOMEntry values", func() {
+			entries := service.GenerateBillOfMaterials(
+				postal.Dependency{
+					DeprecationDate: deprecationDate,
+					ID:              "some-entry",
+					Name:            "Some Entry",
+					SHA256:          "some-sha",
+					Source:          "some-source",
+					Stacks:          []string{"some-stack"},
+					URI:             "some-uri",
+					Version:         "1.2.3",
+				},
+				postal.Dependency{
+					ID:      "other-entry",
+					Name:    "Other Entry",
+					SHA256:  "other-sha",
+					Source:  "other-source",
+					Stacks:  []string{"other-stack"},
+					URI:     "other-uri",
+					Version: "4.5.6",
+				},
+			)
+			Expect(entries).To(Equal([]packit.BOMEntry{
+				{
+					Name: "Some Entry",
+					Metadata: map[string]interface{}{
+						"deprecation-date": deprecationDate,
+						"sha256":           "some-sha",
+						"stacks":           []string{"some-stack"},
+						"uri":              "some-uri",
+						"version":          "1.2.3",
+					},
+				},
+				{
+					Name: "Other Entry",
+					Metadata: map[string]interface{}{
+						"sha256":  "other-sha",
+						"stacks":  []string{"other-stack"},
+						"uri":     "other-uri",
+						"version": "4.5.6",
+					},
+				},
+			}))
+		})
+	})
 }