Contacts delta endpoint fetch (#1644)

## Description

Use delta endpoint to get contacts in each folder

## Type of change

<!--- Please check the type of change your PR introduces: --->
- [x] 🌻 Feature
- [ ] 🐛 Bugfix
- [ ] 🗺️ Documentation
- [ ] 🤖 Test
- [ ] 💻 CI/Deployment
- [ ] 🐹 Trivial/Minor

## Issue(s)

part of:
* #1612 

merge after:
* #1620 

## Test Plan

<!-- How will this be tested prior to merging.-->
- [x] 💪 Manual
- [x] ⚡ Unit test
- [ ] 💚 E2E

src/internal/connector/exchange/delta_get.go

@@ -81,7 +81,6 @@ func sendMessagesDeltaGet(
 	return res.(msmaildelta.DeltaResponseable), nil
 }
 
-//nolint:unused
 func sendContactsDeltaGet(
 	ctx context.Context,
 	m *mscontactdelta.DeltaRequestBuilder,

src/internal/connector/exchange/query_options.go

@@ -9,7 +9,6 @@ import (
 	mscontactfolder "github.com/microsoftgraph/msgraph-sdk-go/users/item/contactfolders"
 	mscontactfolderitem "github.com/microsoftgraph/msgraph-sdk-go/users/item/contactfolders/item"
 	mscontactfolderchild "github.com/microsoftgraph/msgraph-sdk-go/users/item/contactfolders/item/childfolders"
-	mscontactfolderitemcontact "github.com/microsoftgraph/msgraph-sdk-go/users/item/contactfolders/item/contacts"
 	mscontacts "github.com/microsoftgraph/msgraph-sdk-go/users/item/contacts"
 	msevents "github.com/microsoftgraph/msgraph-sdk-go/users/item/events"
 	msfolder "github.com/microsoftgraph/msgraph-sdk-go/users/item/mailfolders"
@@ -300,19 +299,18 @@ func optionsForMailFoldersItem(
 }
 
 // optionsForContactFoldersItem is the same as optionsForContacts.
-// TODO: Remove after Issue #828; requires updating msgraph to v0.34
 func optionsForContactFoldersItem(
 	moreOps []string,
-) (*mscontactfolderitemcontact.ContactsRequestBuilderGetRequestConfiguration, error) {
+) (*DeltaRequestBuilderGetRequestConfiguration, error) {
 	selecting, err := buildOptions(moreOps, contacts)
 	if err != nil {
 		return nil, err
 	}
 
-	requestParameters := &mscontactfolderitemcontact.ContactsRequestBuilderGetQueryParameters{
+	requestParameters := &DeltaRequestBuilderGetQueryParameters{
 		Select: selecting,
 	}
-	options := &mscontactfolderitemcontact.ContactsRequestBuilderGetRequestConfiguration{
+	options := &DeltaRequestBuilderGetRequestConfiguration{
 		QueryParameters: requestParameters,
 	}
 

src/internal/connector/exchange/service_iterators.go

@@ -8,6 +8,7 @@ import (
 	multierror "github.com/hashicorp/go-multierror"
 	msgraphgocore "github.com/microsoftgraph/msgraph-sdk-go-core"
 	"github.com/microsoftgraph/msgraph-sdk-go/models"
+	cdelta "github.com/microsoftgraph/msgraph-sdk-go/users/item/contactfolders/item/contacts/delta"
 	mdelta "github.com/microsoftgraph/msgraph-sdk-go/users/item/mailfolders/item/messages/delta"
 	"github.com/pkg/errors"
 
@@ -217,61 +218,54 @@ func FetchEventIDsFromCalendar(
 // FetchContactIDsFromDirectory function that returns a list of  all the m365IDs of the contacts
 // of the targeted directory
 func FetchContactIDsFromDirectory(ctx context.Context, gs graph.Service, user, directoryID string) ([]string, error) {
+	var (
+		errs *multierror.Error
+		ids  []string
+	)
+
 	options, err := optionsForContactFoldersItem([]string{"parentFolderId"})
 	if err != nil {
-		return nil, err
+		return nil, errors.Wrap(err, "getting query options")
 	}
 
-	ids := []string{}
-
-	response, err := gs.Client().
+	builder := gs.Client().
 		UsersById(user).
 		ContactFoldersById(directoryID).
 		Contacts().
-		Get(ctx, options)
-	if err != nil {
-		return nil, errors.Wrap(err, support.ConnectorStackErrorTrace(err))
-	}
+		Delta()
 
-	pageIterator, err := msgraphgocore.NewPageIterator(
-		response,
-		gs.Adapter(),
-		models.CreateContactCollectionResponseFromDiscriminatorValue,
-	)
-	if err != nil {
-		return nil, errors.Wrap(err, "iterator creation during FetchContactIDs")
-	}
-
-	var errs *multierror.Error
-
-	err = pageIterator.Iterate(ctx, func(pageItem any) bool {
-		entry, ok := pageItem.(graph.Idable)
-		if !ok {
-			errs = multierror.Append(
-				errs,
-				errors.New("casting pageItem to models.Contactable"),
-			)
-
-			return true
+	for {
+		// TODO(ashmrtn): Update to pass options once graph SDK dependency is updated.
+		resp, err := sendContactsDeltaGet(ctx, builder, options, gs.Adapter())
+		if err != nil {
+			return nil, errors.Wrap(err, support.ConnectorStackErrorTrace(err))
 		}
 
-		if entry.GetId() == nil {
-			errs = multierror.Append(errs, errors.New("item with nil ID"))
-			return true
+		for _, item := range resp.GetValue() {
+			if item.GetId() == nil {
+				errs = multierror.Append(
+					errs,
+					errors.Errorf("contact with nil ID in folder %s", directoryID),
+				)
+
+				// TODO(ashmrtn): Handle fail-fast.
+				continue
+			}
+
+			ids = append(ids, *item.GetId())
 		}
 
-		ids = append(ids, *entry.GetId())
+		nextLinkIface := resp.GetAdditionalData()[nextLinkKey]
+		if nextLinkIface == nil {
+			break
+		}
 
-		return true
-	})
+		nextLink := nextLinkIface.(*string)
+		if len(*nextLink) == 0 {
+			break
+		}
 
-	if err != nil {
-		return nil,
-			errors.Wrap(
-				err,
-				support.ConnectorStackErrorTrace(err)+
-					" :fetching contactIDs from directory "+directoryID,
-			)
+		builder = cdelta.NewDeltaRequestBuilder(*nextLink, gs.Adapter())
 	}
 
 	return ids, errs.ErrorOrNil()