From 49a39c567ae834d3a99ba93a55f564ce4c2b4af5 Mon Sep 17 00:00:00 2001
From: Kyle Nelli <knelli@caltech.edu>
Date: Wed, 11 Sep 2024 16:37:28 -0700
Subject: [PATCH] Add executable to write CCE worldtube coords to a file

---
 src/Executables/CMakeLists.txt                |  1 +
 .../CMakeLists.txt                            | 24 ++++++
 .../WriteCceWorldtubeCoordsToFile.cpp         | 79 +++++++++++++++++++
 3 files changed, 104 insertions(+)
 create mode 100644 src/Executables/WriteCceWorldtubeCoordsToFile/CMakeLists.txt
 create mode 100644 src/Executables/WriteCceWorldtubeCoordsToFile/WriteCceWorldtubeCoordsToFile.cpp

diff --git a/src/Executables/CMakeLists.txt b/src/Executables/CMakeLists.txt
index c9595dfc0839..d7cfdbdfd98c 100644
--- a/src/Executables/CMakeLists.txt
+++ b/src/Executables/CMakeLists.txt
@@ -10,3 +10,4 @@ add_subdirectory(ExportCoordinates)
 add_subdirectory(ParallelInfo)
 add_subdirectory(ReduceCceWorldtube)
 add_subdirectory(TimeStepperSummary)
+add_subdirectory(WriteCceWorldtubeCoordsToFile)
diff --git a/src/Executables/WriteCceWorldtubeCoordsToFile/CMakeLists.txt b/src/Executables/WriteCceWorldtubeCoordsToFile/CMakeLists.txt
new file mode 100644
index 000000000000..33c49662dcc2
--- /dev/null
+++ b/src/Executables/WriteCceWorldtubeCoordsToFile/CMakeLists.txt
@@ -0,0 +1,24 @@
+# Distributed under the MIT License.
+# See LICENSE.txt for details.
+
+set(EXECUTABLE WriteCceWorldtubeCoordsToFile)
+
+add_spectre_executable(
+  ${EXECUTABLE}
+  EXCLUDE_FROM_ALL
+  WriteCceWorldtubeCoordsToFile.cpp
+  )
+
+target_link_libraries(
+  ${EXECUTABLE}
+  PRIVATE
+  Boost::boost
+  Boost::program_options
+  Printf
+  SphericalHarmonics
+  SphericalHarmonicsIO
+  )
+
+if(BUILD_TESTING)
+  add_dependencies(test-executables ${EXECUTABLE})
+endif()
diff --git a/src/Executables/WriteCceWorldtubeCoordsToFile/WriteCceWorldtubeCoordsToFile.cpp b/src/Executables/WriteCceWorldtubeCoordsToFile/WriteCceWorldtubeCoordsToFile.cpp
new file mode 100644
index 000000000000..3cd327f3193f
--- /dev/null
+++ b/src/Executables/WriteCceWorldtubeCoordsToFile/WriteCceWorldtubeCoordsToFile.cpp
@@ -0,0 +1,79 @@
+// Distributed under the MIT License.
+// See LICENSE.txt for details.
+
+#include <array>
+#include <boost/program_options.hpp>
+#include <boost/program_options/value_semantic.hpp>
+#include <cstddef>
+#include <exception>
+#include <string>
+
+#include "NumericalAlgorithms/SphericalHarmonics/AngularOrdering.hpp"
+#include "NumericalAlgorithms/SphericalHarmonics/IO/StrahlkorperCoordsToTextFile.hpp"
+#include "Parallel/Printf/Printf.hpp"
+
+// Charm looks for this function but since we build without a main function or
+// main module we just have it be empty
+extern "C" void CkRegisterMainModule(void) {}
+
+/*
+ * This executable is used for writing the collocation points of a CCE
+ * Strahlkorper to a text file. This is useful for other NR codes so they can
+ * write data to certain points and we do the necessary transformations.
+ */
+int main(int argc, char** argv) {
+  boost::program_options::options_description desc(
+      "Program for writing the collocation points (coordinates) of a worldtube "
+      "sphere that SpECTRE CCE is able to read and interpret to a "
+      "file.\nDetails about the output file:\n"
+      " * There are no header or comment lines\n"
+      " * Each point is written to a new line of the output file\n"
+      " * The delimiter for the x, y, z components of each point is a space\n"
+      " * The points are written in scientific notation\n"
+      " * The sphere is centered on the origin (0, 0, 0)");
+  desc.add_options()("help,h", "show this help message")(
+      "radius,r", boost::program_options::value<double>()->required(),
+      "Radius of the worltube.")(
+      "lmax,L", boost::program_options::value<size_t>()->required(),
+      "The spherical harmonic L of the surface. The surface will have (L + 1) "
+      "* (2L + 1) total points")(
+      "output_file,o", boost::program_options::value<std::string>()->required(),
+      "Output filename for the points. No extension will be added.")(
+      "force,f", boost::program_options::bool_switch(),
+      "Overwrite the output file if it already exists");
+
+  boost::program_options::variables_map vars;
+
+  boost::program_options::store(
+      boost::program_options::command_line_parser(argc, argv)
+          .options(desc)
+          .run(),
+      vars);
+
+  if (vars.contains("help")) {
+    Parallel::printf("%s\n", desc);
+    return 0;
+  }
+
+  for (const auto& option : {"radius", "lmax", "output_file"}) {
+    if (not vars.contains(option)) {
+      Parallel::printf("Missing option: %s\n\n%s", option, desc);
+      return 1;
+    }
+  }
+
+  const double radius = vars["radius"].as<double>();
+  const size_t l_max = vars["lmax"].as<size_t>();
+  const std::array<double, 3> center{0.0, 0.0, 0.0};
+  const std::string output_file = vars["output_file"].as<std::string>();
+  const bool overwrite = vars["force"].as<bool>();
+
+  try {
+    ylm::write_strahlkorper_coords_to_text_file(
+        radius, l_max, center, output_file, ylm::AngularOrdering::Cce,
+        overwrite);
+  } catch (const std::exception& exception) {
+    Parallel::printf("%s\n", exception.what());
+    return 1;
+  }
+}