feat: add getLastAcceptedEpoch to repository and jsonrpc

Author: mpolitzer

internal/jsonrpc/jsonrpc-discover.json

@@ -138,6 +138,27 @@
 				}
 			}
 		},
+		{
+			"name": "cartesi_getLastAcceptedEpoch",
+			"summary": "Get the last accepted epoch",
+			"description": "Fetches the latest accepted epoch by application.",
+			"params": [
+				{
+					"name": "application",
+					"description": "The application's name or hex encoded address.",
+					"schema": {
+						"type": "string"
+					},
+					"required": true
+				}
+			],
+			"result": {
+				"name": "result",
+				"schema": {
+					"$ref": "#/components/schemas/EpochGetResult"
+				}
+			}
+		},
 		{
 			"name": "cartesi_listInputs",
 			"summary": "Retrieve a List of Inputs",

internal/jsonrpc/jsonrpc.go

@@ -69,6 +69,8 @@ func (s *Service) handleRPC(w http.ResponseWriter, r *http.Request) {
 		s.handleListEpochs(w, r, req)
 	case "cartesi_getEpoch":
 		s.handleGetEpoch(w, r, req)
+	case "cartesi_getLastAcceptedEpoch":
+		s.handleGetLastAcceptedEpoch(w, r, req)
 	case "cartesi_listInputs":
 		s.handleListInputs(w, r, req)
 	case "cartesi_getInput":
@@ -320,6 +322,40 @@ func (s *Service) handleGetEpoch(w http.ResponseWriter, r *http.Request, req RPC
 	writeRPCResult(w, req.ID, result)
 }
 
+func (s *Service) handleGetLastAcceptedEpoch(w http.ResponseWriter, r *http.Request, req RPCRequest) {
+	var params GetEpochParams
+	if err := json.Unmarshal(req.Params, &params); err != nil {
+		writeRPCError(w, req.ID, JSONRPC_INVALID_PARAMS, "Invalid params", nil)
+		return
+	}
+
+	// Validate application parameter
+	if err := validateNameOrAddress(params.Application); err != nil {
+		writeRPCError(w, req.ID, JSONRPC_INVALID_PARAMS, fmt.Sprintf("Invalid application identifier: %v", err), nil)
+		return
+	}
+
+	epoch, err := s.repository.GetLastAcceptedEpoch(r.Context(), params.Application)
+	if err != nil {
+		s.Logger.Error("Unable to retrieve epoch from repository", "err", err)
+		writeRPCError(w, req.ID, JSONRPC_INTERNAL_ERROR, "Internal server error", nil)
+		return
+	}
+	if epoch == nil {
+		writeRPCError(w, req.ID, JSONRPC_RESOURCE_NOT_FOUND, "Epoch not found", nil)
+		return
+	}
+
+	// Format response according to spec
+	result := struct {
+		Data *model.Epoch `json:"data"`
+	}{
+		Data: epoch,
+	}
+
+	writeRPCResult(w, req.ID, result)
+}
+
 func (s *Service) handleListInputs(w http.ResponseWriter, r *http.Request, req RPCRequest) {
 	var params ListInputsParams
 	if err := json.Unmarshal(req.Params, &params); err != nil {

internal/repository/postgres/epoch.go

@@ -280,6 +280,67 @@ func (r *PostgresRepository) GetEpoch(
 	return &ep, nil
 }
 
+func (r *PostgresRepository) GetLastAcceptedEpoch(
+	ctx context.Context,
+	nameOrAddress string,
+) (*model.Epoch, error) {
+
+	whereClause, err := getWhereClauseFromNameOrAddress(nameOrAddress)
+	if err != nil {
+		return nil, err
+	}
+
+	stmt := table.Epoch.
+		SELECT(
+			table.Epoch.ApplicationID,
+			table.Epoch.Index,
+			table.Epoch.FirstBlock,
+			table.Epoch.LastBlock,
+			table.Epoch.ClaimHash,
+			table.Epoch.ClaimTransactionHash,
+			table.Epoch.Status,
+			table.Epoch.VirtualIndex,
+			table.Epoch.CreatedAt,
+			table.Epoch.UpdatedAt,
+		).
+		FROM(
+			table.Epoch.
+				INNER_JOIN(table.Application,
+					table.Epoch.ApplicationID.EQ(table.Application.ID),
+				),
+		).
+		WHERE(
+			whereClause.
+				AND(table.Epoch.Status.EQ(postgres.NewEnumValue(model.EpochStatus_ClaimAccepted.String()))),
+		).
+		ORDER_BY(table.Epoch.Index.DESC()).
+		LIMIT(1)
+
+	sqlStr, args := stmt.Sql()
+	row := r.db.QueryRow(ctx, sqlStr, args...)
+
+	var ep model.Epoch
+	err = row.Scan(
+		&ep.ApplicationID,
+		&ep.Index,
+		&ep.FirstBlock,
+		&ep.LastBlock,
+		&ep.ClaimHash,
+		&ep.ClaimTransactionHash,
+		&ep.Status,
+		&ep.VirtualIndex,
+		&ep.CreatedAt,
+		&ep.UpdatedAt,
+	)
+	if errors.Is(err, sql.ErrNoRows) {
+		return nil, nil
+	}
+	if err != nil {
+		return nil, err
+	}
+	return &ep, nil
+}
+
 func (r *PostgresRepository) GetEpochByVirtualIndex(
 	ctx context.Context,
 	nameOrAddress string,

internal/repository/repository.go

@@ -74,6 +74,7 @@ type EpochRepository interface {
 	CreateEpochsAndInputs(ctx context.Context, nameOrAddress string, epochInputMap map[*Epoch][]*Input, blockNumber uint64) error
 
 	GetEpoch(ctx context.Context, nameOrAddress string, index uint64) (*Epoch, error)
+	GetLastAcceptedEpoch(ctx context.Context, nameOrAddress string) (*Epoch, error)
 	GetEpochByVirtualIndex(ctx context.Context, nameOrAddress string, index uint64) (*Epoch, error)
 
 	UpdateEpoch(ctx context.Context, nameOrAddress string, e *Epoch) error