GC: Restore: SharePoint: Collection logic (#2227)

## Description
Updates SharePoint Restore Collection Logic.
Test Suite included.
Restore Pipeline is not connected in this PR for ease of parsing. 

It is noted that there is a large amount of code duplication between Lists and Pages. Code Clean-Up will address these issues once issue #2174 has been handled.  As this will require the use of an HTTP client that is not necessary for other services. 
<!-- Insert PR description-->

## Does this PR need a docs update or release note?

- [x] ⛔ No 

## Type of change

<!--- Please check the type of change your PR introduces: --->
- [x] 🌻 Feature


## Issue(s)

<!-- Can reference multiple issues. Use one of the following "magic words" - "closes, fixes" to auto-close the Github issue. -->
* related to  #2169<issue>

## Test Plan

- [x] ⚡ Unit test

src/internal/connector/graph_connector.go

@@ -293,7 +293,7 @@ func (gc *GraphConnector) RestoreDataCollections(
 	case selectors.ServiceOneDrive:
 		status, err = onedrive.RestoreCollections(ctx, backupVersion, gc.Service, dest, opts, dcs, deets)
 	case selectors.ServiceSharePoint:
-		status, err = sharepoint.RestoreCollections(ctx, backupVersion, gc.Service, dest, dcs, deets)
+		status, err = sharepoint.RestoreCollections(ctx, backupVersion, creds, gc.Service, dest, dcs, deets)
 	default:
 		err = errors.Errorf("restore data from service %s not supported", selector.Service.String())
 	}

src/internal/connector/sharepoint/restore.go

@@ -9,11 +9,14 @@ import (
 	"github.com/microsoftgraph/msgraph-sdk-go/models"
 	"github.com/pkg/errors"
 
+	discover "github.com/alcionai/corso/src/internal/connector/discovery/api"
 	"github.com/alcionai/corso/src/internal/connector/graph"
 	"github.com/alcionai/corso/src/internal/connector/onedrive"
+	"github.com/alcionai/corso/src/internal/connector/sharepoint/api"
 	"github.com/alcionai/corso/src/internal/connector/support"
 	"github.com/alcionai/corso/src/internal/data"
 	D "github.com/alcionai/corso/src/internal/diagnostics"
+	"github.com/alcionai/corso/src/pkg/account"
 	"github.com/alcionai/corso/src/pkg/backup/details"
 	"github.com/alcionai/corso/src/pkg/control"
 	"github.com/alcionai/corso/src/pkg/logger"
@@ -37,6 +40,7 @@ import (
 func RestoreCollections(
 	ctx context.Context,
 	backupVersion int,
+	creds account.M365Config,
 	service graph.Servicer,
 	dest control.RestoreDestination,
 	dcs []data.Collection,
@@ -74,7 +78,7 @@ func RestoreCollections(
 				false,
 			)
 		case path.ListsCategory:
-			metrics, canceled = RestoreCollection(
+			metrics, canceled = RestoreListCollection(
 				ctx,
 				service,
 				dc,
@@ -83,11 +87,14 @@ func RestoreCollections(
 				errUpdater,
 			)
 		case path.PagesCategory:
-			errorMessage := fmt.Sprintf("restore of %s not supported", dc.FullPath().Category())
+			metrics, canceled = RestorePageCollection(
-			logger.Ctx(ctx).Error(errorMessage)
+				ctx,
-
+				creds,
-			return nil, errors.New(errorMessage)
+				dc,
-
+				dest.ContainerName,
+				deets,
+				errUpdater,
+			)
 		default:
 			return nil, errors.Errorf("category %s not supported", dc.FullPath().Category())
 		}
@@ -209,7 +216,7 @@ func restoreListItem(
 	return dii, nil
 }
 
-func RestoreCollection(
+func RestoreListCollection(
 	ctx context.Context,
 	service graph.Servicer,
 	dc data.Collection,
@@ -217,7 +224,7 @@ func RestoreCollection(
 	deets *details.Builder,
 	errUpdater func(string, error),
 ) (support.CollectionMetrics, bool) {
-	ctx, end := D.Span(ctx, "gc:sharepoint:restoreCollection", D.Label("path", dc.FullPath()))
+	ctx, end := D.Span(ctx, "gc:sharepoint:restoreListCollection", D.Label("path", dc.FullPath()))
 	defer end()
 
 	var (
@@ -225,7 +232,7 @@ func RestoreCollection(
 		directory = dc.FullPath()
 	)
 
-	trace.Log(ctx, "gc:sharepoint:restoreCollection", directory.String())
+	trace.Log(ctx, "gc:sharepoint:restoreListCollection", directory.String())
 	siteID := directory.ResourceOwner()
 
 	// Restore items from the collection
@@ -276,3 +283,83 @@ func RestoreCollection(
 		}
 	}
 }
+
+// RestorePageCollection handles restoration of an individual site page collection.
+// returns:
+// - the collection's item and byte count metrics
+// - the context cancellation station. True iff context is canceled.
+func RestorePageCollection(
+	ctx context.Context,
+	creds account.M365Config,
+	dc data.Collection,
+	restoreContainerName string,
+	deets *details.Builder,
+	errUpdater func(string, error),
+) (support.CollectionMetrics, bool) {
+	ctx, end := D.Span(ctx, "gc:sharepoint:restorePageCollection", D.Label("path", dc.FullPath()))
+	defer end()
+
+	var (
+		metrics   = support.CollectionMetrics{}
+		directory = dc.FullPath()
+	)
+
+	adpt, err := graph.CreateAdapter(creds.AzureTenantID, creds.AzureClientID, creds.AzureClientSecret)
+	if err != nil {
+		return metrics, false
+	}
+
+	service := discover.NewBetaService(adpt)
+
+	trace.Log(ctx, "gc:sharepoint:restorePageCollection", directory.String())
+	siteID := directory.ResourceOwner()
+
+	// Restore items from collection
+	items := dc.Items()
+
+	for {
+		select {
+		case <-ctx.Done():
+			errUpdater("context canceled", ctx.Err())
+			return metrics, true
+
+		case itemData, ok := <-items:
+			if !ok {
+				return metrics, false
+			}
+			metrics.Objects++
+
+			itemInfo, err := api.RestoreSitePage(
+				ctx,
+				service,
+				itemData,
+				siteID,
+				restoreContainerName,
+			)
+			if err != nil {
+				errUpdater(itemData.UUID(), err)
+				continue
+			}
+
+			metrics.TotalBytes += itemInfo.SharePoint.Size
+
+			itemPath, err := dc.FullPath().Append(itemData.UUID(), true)
+			if err != nil {
+				logger.Ctx(ctx).Errorw("transforming item to full path", "error", err)
+				errUpdater(itemData.UUID(), err)
+
+				continue
+			}
+
+			deets.Add(
+				itemPath.String(),
+				itemPath.ShortRef(),
+				"",
+				true,
+				itemInfo,
+			)
+
+			metrics.Successes++
+		}
+	}
+}