aggregate categories from selector (#1742)

## Description

Adds a PathCategories() func to selectors which returns
all the path categories exhibited by the scopes within the
selector.

## Type of change

- [x] 🌻 Feature

## Issue(s)

* #1725

## Test Plan

- [x] ⚡ Unit test

src/internal/connector/exchange/service_iterators.go

@@ -157,28 +157,7 @@ func FilterContainersAndFillCollections(
 		collections[metadataKey] = col
 	}
 
-	// TODO(ashmrtn): getFetchIDFunc functions should probably just return a
-	// multierror and all of the error handling should just use those so that it
-	// all ends up more consistent.
-	merrs := multierror.Append(nil, errs)
-
-	col, err = makeMetadataCollection(
-		qp.Credentials.AzureTenantID,
-		qp.ResourceOwner,
-		qp.Category,
-		deltaTokens,
-		statusUpdater,
-	)
-	if err != nil {
-		merrs = multierror.Append(
-			merrs,
-			errors.Wrap(err, "making metadata collection"),
-		)
-	} else if col != nil {
-		collections[metadataKey] = col
-	}
-
-	return merrs.ErrorOrNil()
+	return errs
 }
 
 func IterativeCollectContactContainers(

src/pkg/selectors/exchange.go

@@ -40,6 +40,7 @@ var (
 	_ Reducer         = &ExchangeRestore{}
 	_ printabler      = &ExchangeRestore{}
 	_ resourceOwnerer = &ExchangeRestore{}
+	_ pathCategorier  = &ExchangeRestore{}
 )
 
 // NewExchange produces a new Selector with the service set to ServiceExchange.
@@ -103,6 +104,15 @@ func (s exchange) ResourceOwners() selectorResourceOwners {
 	}
 }
 
+// PathCategories produces the aggregation of discrete users described by each type of scope.
+func (s exchange) PathCategories() selectorPathCategories {
+	return selectorPathCategories{
+		Excludes: pathCategoriesIn[ExchangeScope, exchangeCategory](s.Excludes),
+		Filters:  pathCategoriesIn[ExchangeScope, exchangeCategory](s.Filters),
+		Includes: pathCategoriesIn[ExchangeScope, exchangeCategory](s.Includes),
+	}
+}
+
 // -------------------
 // Exclude/Includes
 
@@ -210,7 +220,7 @@ func (s *exchange) Contacts(users, folders, contacts []string, opts ...option) [
 func (s *exchange) ContactFolders(users, folders []string, opts ...option) []ExchangeScope {
 	var (
 		scopes = []ExchangeScope{}
-		os     = append([]option{pathType()}, opts...)
+		os     = append([]option{pathComparator()}, opts...)
 	)
 
 	scopes = append(
@@ -247,7 +257,7 @@ func (s *exchange) Events(users, calendars, events []string, opts ...option) []E
 func (s *exchange) EventCalendars(users, events []string, opts ...option) []ExchangeScope {
 	var (
 		scopes = []ExchangeScope{}
-		os     = append([]option{pathType()}, opts...)
+		os     = append([]option{pathComparator()}, opts...)
 	)
 
 	scopes = append(
@@ -283,7 +293,7 @@ func (s *exchange) Mails(users, folders, mails []string, opts ...option) []Excha
 func (s *exchange) MailFolders(users, folders []string, opts ...option) []ExchangeScope {
 	var (
 		scopes = []ExchangeScope{}
-		os     = append([]option{pathType()}, opts...)
+		os     = append([]option{pathComparator()}, opts...)
 	)
 
 	scopes = append(
@@ -663,7 +673,7 @@ func (s ExchangeScope) Get(cat exchangeCategory) []string {
 func (s ExchangeScope) set(cat exchangeCategory, v []string, opts ...option) ExchangeScope {
 	os := []option{}
 	if cat == ExchangeContactFolder || cat == ExchangeEventCalendar || cat == ExchangeMailFolder {
-		os = append(os, pathType())
+		os = append(os, pathComparator())
 	}
 
 	return set(s, cat, v, append(os, opts...)...)

src/pkg/selectors/onedrive.go

@@ -39,6 +39,7 @@ var (
 	_ Reducer         = &OneDriveRestore{}
 	_ printabler      = &OneDriveRestore{}
 	_ resourceOwnerer = &OneDriveRestore{}
+	_ pathCategorier  = &OneDriveRestore{}
 )
 
 // NewOneDriveBackup produces a new Selector with the service set to ServiceOneDrive.
@@ -102,6 +103,15 @@ func (s oneDrive) ResourceOwners() selectorResourceOwners {
 	}
 }
 
+// PathCategories produces the aggregation of discrete users described by each type of scope.
+func (s oneDrive) PathCategories() selectorPathCategories {
+	return selectorPathCategories{
+		Excludes: pathCategoriesIn[OneDriveScope, oneDriveCategory](s.Excludes),
+		Filters:  pathCategoriesIn[OneDriveScope, oneDriveCategory](s.Filters),
+		Includes: pathCategoriesIn[OneDriveScope, oneDriveCategory](s.Includes),
+	}
+}
+
 // -------------------
 // Scope Factories
 
@@ -197,7 +207,7 @@ func (s *oneDrive) Users(users []string) []OneDriveScope {
 func (s *oneDrive) Folders(users, folders []string, opts ...option) []OneDriveScope {
 	var (
 		scopes = []OneDriveScope{}
-		os     = append([]option{pathType()}, opts...)
+		os     = append([]option{pathComparator()}, opts...)
 	)
 
 	scopes = append(
@@ -447,7 +457,7 @@ func (s OneDriveScope) Get(cat oneDriveCategory) []string {
 func (s OneDriveScope) set(cat oneDriveCategory, v []string, opts ...option) OneDriveScope {
 	os := []option{}
 	if cat == OneDriveFolder {
-		os = append(os, pathType())
+		os = append(os, pathComparator())
 	}
 
 	return set(s, cat, v, append(os, opts...)...)

src/pkg/selectors/selectors.go

@@ -84,6 +84,19 @@ type resourceOwnerer interface {
 	ResourceOwners() selectorResourceOwners
 }
 
+// selectorResourceOwners aggregates all discrete path category types described
+// in the selector.  Category sets are grouped by their scope type (includes,
+// excludes, filters).
+type selectorPathCategories struct {
+	Includes []path.CategoryType
+	Excludes []path.CategoryType
+	Filters  []path.CategoryType
+}
+
+type pathCategorier interface {
+	PathCategories() selectorPathCategories
+}
+
 // ---------------------------------------------------------------------------
 // Selector
 // ---------------------------------------------------------------------------
@@ -205,6 +218,7 @@ func (s Selector) Reduce(ctx context.Context, deets *details.Details) (*details.
 	return r.Reduce(ctx, deets), nil
 }
 
+// returns the sets of resource owners identified in each scope set.
 func (s Selector) ResourceOwners() (selectorResourceOwners, error) {
 	ro, err := selectorAsIface[resourceOwnerer](s)
 	if err != nil {
@@ -214,6 +228,16 @@ func (s Selector) ResourceOwners() (selectorResourceOwners, error) {
 	return ro.ResourceOwners(), nil
 }
 
+// returns the sets of path categories identified in each scope set.
+func (s Selector) PathCategories() (selectorPathCategories, error) {
+	ro, err := selectorAsIface[pathCategorier](s)
+	if err != nil {
+		return selectorPathCategories{}, err
+	}
+
+	return ro.PathCategories(), nil
+}
+
 // transformer for arbitrary selector interfaces
 func selectorAsIface[T any](s Selector) (T, error) {
 	var (
@@ -388,6 +412,30 @@ func resourceOwnersIn(s []scope, rootCat string) []string {
 	return rs
 }
 
+// produces the discrete set of path categories in the slice of scopes.
+func pathCategoriesIn[T scopeT, C categoryT](ss []scope) []path.CategoryType {
+	rm := map[path.CategoryType]struct{}{}
+
+	for _, s := range ss {
+		t := T(s)
+
+		lc := t.categorizer().leafCat()
+		if lc == lc.unknownCat() {
+			continue
+		}
+
+		rm[lc.PathType()] = struct{}{}
+	}
+
+	rs := []path.CategoryType{}
+
+	for k := range rm {
+		rs = append(rs, k)
+	}
+
+	return rs
+}
+
 // ---------------------------------------------------------------------------
 // scope helpers
 // ---------------------------------------------------------------------------
@@ -424,10 +472,10 @@ func SuffixMatch() option {
 	}
 }
 
-// pathType is an internal-facing option.  It is assumed that scope
-// constructors will provide the pathType option whenever a folder-
+// pathComparator is an internal-facing option.  It is assumed that scope
+// constructors will provide the pathComparator option whenever a folder-
 // level scope (ie, a scope that compares path hierarchies) is created.
-func pathType() option {
+func pathComparator() option {
 	return func(sc *scopeConfig) {
 		sc.usePathFilter = true
 	}

src/pkg/selectors/selectors_test.go

@@ -8,6 +8,7 @@ import (
 	"github.com/stretchr/testify/suite"
 
 	"github.com/alcionai/corso/src/pkg/filters"
+	"github.com/alcionai/corso/src/pkg/path"
 )
 
 type SelectorSuite struct {
@@ -208,6 +209,39 @@ func (suite *SelectorSuite) TestResourceOwnersIn() {
 	}
 }
 
+func (suite *SelectorSuite) TestPathCategoriesIn() {
+	leafCat := leafCatStub.String()
+	f := filters.Identity(leafCat)
+
+	table := []struct {
+		name   string
+		input  []scope
+		expect []path.CategoryType
+	}{
+		{
+			name:   "nil",
+			input:  nil,
+			expect: []path.CategoryType{},
+		},
+		{
+			name:   "empty",
+			input:  []scope{},
+			expect: []path.CategoryType{},
+		},
+		{
+			name:   "single",
+			input:  []scope{{leafCat: f, scopeKeyCategory: f}},
+			expect: []path.CategoryType{leafCatStub.PathType()},
+		},
+	}
+	for _, test := range table {
+		suite.T().Run(test.name, func(t *testing.T) {
+			result := pathCategoriesIn[mockScope, mockCategorizer](test.input)
+			assert.ElementsMatch(t, test.expect, result)
+		})
+	}
+}
+
 func (suite *SelectorSuite) TestContains() {
 	t := suite.T()
 	key := rootCatStub

src/pkg/selectors/sharepoint.go

@@ -37,6 +37,7 @@ var (
 	_ Reducer         = &SharePointRestore{}
 	_ printabler      = &SharePointRestore{}
 	_ resourceOwnerer = &SharePointRestore{}
+	_ pathCategorier  = &SharePointRestore{}
 )
 
 // NewSharePointBackup produces a new Selector with the service set to ServiceSharePoint.
@@ -100,6 +101,15 @@ func (s sharePoint) ResourceOwners() selectorResourceOwners {
 	}
 }
 
+// PathCategories produces the aggregation of discrete users described by each type of scope.
+func (s sharePoint) PathCategories() selectorPathCategories {
+	return selectorPathCategories{
+		Excludes: pathCategoriesIn[SharePointScope, sharePointCategory](s.Excludes),
+		Filters:  pathCategoriesIn[SharePointScope, sharePointCategory](s.Filters),
+		Includes: pathCategoriesIn[SharePointScope, sharePointCategory](s.Includes),
+	}
+}
+
 // -------------------
 // Scope Factories
 
@@ -210,7 +220,7 @@ func (s *sharePoint) Sites(sites []string) []SharePointScope {
 func (s *sharePoint) Libraries(sites, libraries []string, opts ...option) []SharePointScope {
 	var (
 		scopes = []SharePointScope{}
-		os     = append([]option{pathType()}, opts...)
+		os     = append([]option{pathComparator()}, opts...)
 	)
 
 	scopes = append(
@@ -397,7 +407,7 @@ func (s SharePointScope) Get(cat sharePointCategory) []string {
 func (s SharePointScope) set(cat sharePointCategory, v []string, opts ...option) SharePointScope {
 	os := []option{}
 	if cat == SharePointLibrary {
-		os = append(os, pathType())
+		os = append(os, pathComparator())
 	}
 
 	return set(s, cat, v, append(os, opts...)...)