offline tool: add wire-fee cmd

tools/offline_impl.ml

@@ -167,3 +167,33 @@ let disable_auditor ~output ~master_key ~auditor_pub ~validity_end =
   let* s = Api.encode Api.AuditorTeardownMessage.jsont v in
   let* () = write_file output s in
   Ok ()
+
+let wire_fee ~output ~master_key ~wire_method ~fee_start ~fee_end ~closing_fee
+    ~wire_fee =
+  let open Crypto in
+  let* key = read_master_key_file master_key in
+  let master_sig_wire =
+    let open Bin_sig.MasterWireFee in
+    sign_f ~f:(EddsaSignature.sign ~key)
+      {
+        h_wire_method= Bin_type.Hash_64_cstr.hash wire_method;
+        start_date= fee_start;
+        end_date= fee_end;
+        closing_fee;
+        wire_fee;
+      }
+  in
+  let v =
+    Api.WireFeeSetupMessage.
+      {
+        wire_method;
+        fee_start;
+        fee_end;
+        closing_fee;
+        wire_fee;
+        master_sig_wire;
+      }
+  in
+  let* s = Api.encode Api.WireFeeSetupMessage.jsont v in
+  let* () = write_file output s in
+  Ok ()