From 7c242819bc13d1d0aac94a417176e3d1c5691843 Mon Sep 17 00:00:00 2001
From: ryanfkeepers <ryanfkeepers@gmail.com>
Date: Fri, 11 Aug 2023 11:14:27 -0600
Subject: [PATCH] Add 'halves()' to path interface

Adds a func to the path interface which breaks up the path
into its two distinct halves: the prefix builder, and the folder
and item elements.  Likely to be useful in the future where
prefixes will be of arbitrary length, and downstream consumers
are primarly focused on the non-prefix portion of the path.
---
 .../restore_path_transformer_test.go          |  8 +--
 src/pkg/path/path.go                          |  4 ++
 src/pkg/path/resource_path.go                 | 14 +++++
 src/pkg/path/resource_path_test.go            | 54 +++++++++++++++++++
 4 files changed, 74 insertions(+), 6 deletions(-)

diff --git a/src/internal/operations/pathtransformer/restore_path_transformer_test.go b/src/internal/operations/pathtransformer/restore_path_transformer_test.go
index 49173785a..eead601f5 100644
--- a/src/internal/operations/pathtransformer/restore_path_transformer_test.go
+++ b/src/internal/operations/pathtransformer/restore_path_transformer_test.go
@@ -36,12 +36,8 @@ func (suite *RestorePathTransformerUnitSuite) TestGetPaths() {
 		repoRef path.Path,
 		unescapedFolders ...string,
 	) string {
-		return path.Builder{}.
-			Append(
-				repoRef.Tenant(),
-				repoRef.Service().String(),
-				repoRef.ResourceOwner(),
-				repoRef.Category().String()).
+		pfx, _ := repoRef.Halves()
+		return pfx.
 			Append(unescapedFolders...).
 			String()
 	}
diff --git a/src/pkg/path/path.go b/src/pkg/path/path.go
index 8138f0f75..3454d1e9e 100644
--- a/src/pkg/path/path.go
+++ b/src/pkg/path/path.go
@@ -115,6 +115,10 @@ type Path interface {
 	ShortRef() string
 	// ToBuilder returns a Builder instance that represents the current Path.
 	ToBuilder() *Builder
+	// Halves breaks the path into its prefix (tenant, services, resources, category)
+	// and suffix (all parts after the prefix).  If either half is empty, that half
+	// returns an empty, non-nil, value.
+	Halves() (*Builder, Elements)
 
 	// Every path needs to comply with these funcs to ensure that PII
 	// is appropriately hidden from logging, errors, and other outputs.
diff --git a/src/pkg/path/resource_path.go b/src/pkg/path/resource_path.go
index 37738131a..1bd380286 100644
--- a/src/pkg/path/resource_path.go
+++ b/src/pkg/path/resource_path.go
@@ -156,3 +156,17 @@ func (rp dataLayerResourcePath) ToBuilder() *Builder {
 func (rp *dataLayerResourcePath) UpdateParent(prev, cur Path) bool {
 	return rp.Builder.UpdateParent(prev.ToBuilder(), cur.ToBuilder())
 }
+
+func (rp *dataLayerResourcePath) Halves() (*Builder, Elements) {
+	pfx, sfx := &Builder{}, Elements{}
+
+	b := rp.Builder
+	if len(b.elements) > 0 {
+		lenPfx := 2 + (len(rp.serviceResources) * 2)
+
+		pfx = &Builder{elements: append(Elements{}, b.elements[:lenPfx]...)}
+		sfx = append(Elements{}, b.elements[lenPfx-1:]...)
+	}
+
+	return pfx, sfx
+}
diff --git a/src/pkg/path/resource_path_test.go b/src/pkg/path/resource_path_test.go
index 3a7dfd3c3..bc350612c 100644
--- a/src/pkg/path/resource_path_test.go
+++ b/src/pkg/path/resource_path_test.go
@@ -678,3 +678,57 @@ func (suite *PopulatedDataLayerResourcePath) TestUpdateParent_NoopsNils() {
 		})
 	}
 }
+
+func (suite *PopulatedDataLayerResourcePath) TestHalves() {
+	t := suite.T()
+
+	onlyPrefix, err := path.BuildPrefix(
+		"titd",
+		[]path.ServiceResource{{path.ExchangeService, "pr"}},
+		path.ContactsCategory)
+	require.NoError(t, err, clues.ToCore(err))
+
+	fullPath, err := path.Build(
+		"tid",
+		[]path.ServiceResource{{path.ExchangeService, "pr"}},
+		path.ContactsCategory,
+		true,
+		"fld", "item")
+	require.NoError(t, err, clues.ToCore(err))
+
+	table := []struct {
+		name      string
+		dlrp      path.Path
+		expectPfx *path.Builder
+		expectSfx path.Elements
+	}{
+		{
+			name: "only prefix",
+			dlrp: onlyPrefix,
+			expectPfx: path.Builder{}.Append(
+				"tid",
+				path.ExchangeService.String(),
+				"pr",
+				path.ContactsCategory.String()),
+			expectSfx: path.Elements{},
+		},
+		{
+			name: "full path",
+			dlrp: fullPath,
+			expectPfx: path.Builder{}.Append(
+				"tid",
+				path.ExchangeService.String(),
+				"pr",
+				path.ContactsCategory.String()),
+			expectSfx: path.Elements{"foo", "bar"},
+		},
+	}
+	for _, test := range table {
+		suite.Run(test.name, func() {
+			t := suite.T()
+			pfx, sfx := test.dlrp.Halves()
+			assert.Equal(t, test.expectPfx, pfx, "prefix")
+			assert.Equal(t, test.expectSfx, sfx, "suffix")
+		})
+	}
+}