From 15b2ab246ffa974a15c4da080d9100c56b9594ce Mon Sep 17 00:00:00 2001
From: Melissa DeLucchi <delucchi@andrew.cmu.edu>
Date: Fri, 24 May 2024 15:17:06 -0400
Subject: [PATCH] scikit build

---
 CMakeLists.txt                           | 11 +++++++++
 pyproject.toml                           |  8 +++++--
 src/cpp/pixel_math.cpp                   | 16 +++++++++++++
 src/cpp/pixel_math.h                     | 30 ++++++++++++++++++++++++
 tests/hipscat/pixel_math/test_the_cpp.py |  9 +++++++
 5 files changed, 72 insertions(+), 2 deletions(-)
 create mode 100644 CMakeLists.txt
 create mode 100644 src/cpp/pixel_math.cpp
 create mode 100644 src/cpp/pixel_math.h
 create mode 100644 tests/hipscat/pixel_math/test_the_cpp.py

diff --git a/CMakeLists.txt b/CMakeLists.txt
new file mode 100644
index 00000000..55cca0bf
--- /dev/null
+++ b/CMakeLists.txt
@@ -0,0 +1,11 @@
+cmake_minimum_required(VERSION 3.15...3.26)
+project(${SKBUILD_PROJECT_NAME} LANGUAGES CXX)
+
+set(PYBIND11_NEWPYTHON ON)
+find_package(pybind11 CONFIG REQUIRED)
+set(TARGET pixel_math_ext)
+
+pybind11_add_module(${TARGET} src/cpp/pixel_math.cpp )
+
+target_include_directories(${TARGET} PUBLIC src/cpp)
+install(TARGETS ${TARGET} LIBRARY DESTINATION ${SKBUILD_PROJECT_NAME})
\ No newline at end of file
diff --git a/pyproject.toml b/pyproject.toml
index 1e783288..1044cf74 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -52,10 +52,14 @@ dev = [
 
 [build-system]
 requires = [
-    "setuptools>=62", # Used to build and package the Python project
     "setuptools_scm>=6.2", # Gets release version from git. Makes it available programmatically
+    "scikit-build-core", "pybind11"
 ]
-build-backend = "setuptools.build_meta"
+build-backend = "scikit_build_core.build"
+
+[tool.scikit-build]
+metadata.version.provider = "scikit_build_core.metadata.setuptools_scm"
+sdist.include = ["src/hipscat/_version.py"]
 
 [tool.setuptools_scm]
 write_to = "src/hipscat/_version.py"
diff --git a/src/cpp/pixel_math.cpp b/src/cpp/pixel_math.cpp
new file mode 100644
index 00000000..6d8f243c
--- /dev/null
+++ b/src/cpp/pixel_math.cpp
@@ -0,0 +1,16 @@
+#include <pybind11/numpy.h>
+#include <pybind11/pybind11.h>
+#include <pybind11/stl.h>
+
+#include <vector>
+#include "pixel_math.h"
+
+std::vector<std::vector<unsigned long long int> > generate_alignment(
+    const std::vector<unsigned long long int> &histogram,
+    unsigned short highest_order,
+    unsigned short lowest_order,
+    unsigned long long int threshold
+){
+    std::vector<std::vector<unsigned long long int> > result (order2npix(highest_order));
+    return result;
+}
diff --git a/src/cpp/pixel_math.h b/src/cpp/pixel_math.h
new file mode 100644
index 00000000..da987a50
--- /dev/null
+++ b/src/cpp/pixel_math.h
@@ -0,0 +1,30 @@
+#ifndef PIXEL_MATH_H_
+#define  PIXEL_MATH_H_
+
+#include <pybind11/pybind11.h>
+
+#include <vector>
+
+namespace py = pybind11;
+
+
+float square(float x) { return x * x; }
+
+unsigned long order2npix(unsigned short pix) {
+    return 12 * 1 << (2 * pix);
+}
+
+std::vector<std::vector<unsigned long long int> > generate_alignment(
+    const std::vector<unsigned long long int> &histogram,
+    unsigned short highest_order,
+    unsigned short lowest_order,
+    unsigned long long int threshold
+);
+
+PYBIND11_MODULE(pixel_math_ext, m) {
+    m.def("square", &square);
+    m.def("order2npix", &order2npix);
+    m.def("generate_alignment", &generate_alignment);
+}
+
+#endif
\ No newline at end of file
diff --git a/tests/hipscat/pixel_math/test_the_cpp.py b/tests/hipscat/pixel_math/test_the_cpp.py
new file mode 100644
index 00000000..67841cf8
--- /dev/null
+++ b/tests/hipscat/pixel_math/test_the_cpp.py
@@ -0,0 +1,9 @@
+from hipscat.pixel_math_ext import order2npix, generate_alignment
+import numpy as np
+
+def test_order2npix():
+    assert order2npix(0) == 12
+    assert order2npix(4) == 3072
+
+def test_generate_alignment():
+    assert len(generate_alignment(np.arange(12), 0, 0, 4)) == 12
\ No newline at end of file