[Optimization] On-chain indexing of GetApplicationsDelegatingToGateway

[Olshansk]

Objective

Enable a potentially common operations the shannon-sdk will need.

Origin Document

This came up in a conversation with @adshmh and @commodity. The diff at the bottom of

Goals

• Use on-chain indexing to enable a potentially common operations gateways will need
• Avoid off-chain tools resolving the same issue

Deliverables

• A PR that indexes applications based on the gateway they delegate to
• A PR that updates QueryAllApps with a filter on "gateway_addr_delegated_to`
• Follow the same patterns as in QueryAllProofs

General deliverables

• Comments: Add/update TODOs and comments alongside the source code so it is easier to follow.
• Testing: Add new tests (unit and/or E2E) to the test suite.
• Makefile: Add new targets to the Makefile to make the new functionality easier to use.
• Documentation: Update architectural or development READMEs; use mermaid diagrams where appropriate.

---

Creator: @Olshansk
Co-Owners: @adshmh @commodity

diff --git a/proto/poktroll/application/query.proto b/proto/poktroll/application/query.proto
index 0707ea6f..56e51b00 100644
--- a/proto/poktroll/application/query.proto
+++ b/proto/poktroll/application/query.proto
@@ -52,6 +52,11 @@ message QueryGetApplicationResponse {
 
 message QueryAllApplicationsRequest {
   cosmos.base.query.v1beta1.PageRequest pagination = 1;
+
+  oneof filter {
+    string gateway_address = 2;
+  }
+
 }
 
 message QueryAllApplicationsResponse {
diff --git a/x/application/keeper/application.go b/x/application/keeper/application.go
index e48068f3..028a8c90 100644
--- a/x/application/keeper/application.go
+++ b/x/application/keeper/application.go
@@ -2,10 +2,12 @@ package keeper
 
 import (
 	"context"
+	"fmt"
 
 	"cosmossdk.io/store/prefix"
 	storetypes "cosmossdk.io/store/types"
 	"github.com/cosmos/cosmos-sdk/runtime"
+	"github.com/docker/docker/daemon/logger"
 
 	"github.com/pokt-network/poktroll/x/application/types"
 )
@@ -13,9 +15,18 @@ import (
 // SetApplication set a specific application in the store from its index
 func (k Keeper) SetApplication(ctx context.Context, application types.Application) {
 	storeAdapter := runtime.KVStoreAdapter(k.storeService.OpenKVStore(ctx))
-	store := prefix.NewStore(storeAdapter, types.KeyPrefix(types.ApplicationKeyPrefix))
+
+	primaryStore := prefix.NewStore(storeAdapter, types.KeyPrefix(types.ApplicationKeyPrefix))
 	appBz := k.cdc.MustMarshal(&application)
-	store.Set(types.ApplicationKey(application.Address), appBz)
+	primaryStore.Set(types.ApplicationKey(application.Address), appBz)
+
+	// Update the address index: supplierOperatorAddress -> [ProofPrimaryKey]
+	gatewayAddrStore := prefix.NewStore(storeAdapter, types.KeyPrefix(types.GatewayApplicationKeyPrefix))
+	// supplierOperatorAddrKey := types.ProofSupplierOperatorAddressKey(proof.GetSupplierOperatorAddress(), primaryKey)
+	// gatewayAddrStore.Set(supplierOperatorAddrKey, primaryKey)
+
+	logger.Info(fmt.Sprintf("indexed Proof for supplier %s with primaryKey %s", proof.GetSupplierOperatorAddress(), primaryKey))
+
 }
 
 // GetApplication returns a application from its index
diff --git a/x/application/keeper/query_application.go b/x/application/keeper/query_application.go
index 446449d2..ab0b8494 100644
--- a/x/application/keeper/query_application.go
+++ b/x/application/keeper/query_application.go
@@ -38,6 +38,8 @@ func (k Keeper) AllApplications(ctx context.Context, req *types.QueryAllApplicat
 		return nil
 	})
 
+	// Look at `query_proof.go`
+
 	if err != nil {
 		return nil, status.Error(codes.Internal, err.Error())
 	}
diff --git a/x/application/types/key_application.go b/x/application/types/key_application.go
index cb11774e..06214902 100644
--- a/x/application/types/key_application.go
+++ b/x/application/types/key_application.go
@@ -6,7 +6,8 @@ var _ binary.ByteOrder
 
 const (
 	// ApplicationKeyPrefix is the prefix to retrieve all Application
-	ApplicationKeyPrefix = "Application/address/"
+	ApplicationKeyPrefix        = "Application/address/"
+	GatewayApplicationKeyPrefix = "Application/gateway_address/"
 )
 
 // ApplicationKey returns the store key to retrieve a Application from the index fields