From 8dab11d5362255e3711ba0bce85b5da359c53f44 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fr=C3=A9d=C3=A9ric=20BRIOL?= <fbriol@gmail.com>
Date: Thu, 7 Nov 2024 22:45:58 +0100
Subject: [PATCH] Add custom build backend and update documentation to use
 build option with pip.

---
 .pre-commit-config.yaml     |  2 +
 _custom_build/backend.py    | 75 +++++++++++++++++++++++++++++++++++++
 docs/source/conf.py         |  4 +-
 docs/source/setup/build.rst |  9 +++++
 pyproject.toml              |  4 ++
 setup.cfg                   |  3 --
 6 files changed, 92 insertions(+), 5 deletions(-)
 create mode 100644 _custom_build/backend.py
 create mode 100644 pyproject.toml

diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index c0d3dae7..edc60915 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -35,6 +35,8 @@ repos:
     rev: v0.32.0
     hooks:
       - id: yapf
+        additional_dependencies:
+          - toml
         files: \.py(?:i)?
   # - repo: https://github.com/myint/docformatter
   #   rev: "v1.7.5"
diff --git a/_custom_build/backend.py b/_custom_build/backend.py
new file mode 100644
index 00000000..ac99b95b
--- /dev/null
+++ b/_custom_build/backend.py
@@ -0,0 +1,75 @@
+# Copyright (c) 2024 CNES
+#
+# All rights reserved. Use of this source code is governed by a
+# BSD-style license that can be found in the LICENSE file.
+import argparse
+import sys
+
+import setuptools.build_meta
+
+
+def usage(args: dict[str, str | list[str] | None]) -> argparse.Namespace:
+    """Parse the command line arguments."""
+    parser = argparse.ArgumentParser('Custom build backend')
+    parser.add_argument('--c-compiler', help='Preferred C compiler')
+    parser.add_argument('--cxx-compiler', help='Preferred C++ compiler')
+    parser.add_argument('--generator', help='Selected CMake generator')
+    parser.add_argument('--cmake-args', help='Additional arguments for CMake')
+    parser.add_argument('--mkl', help='Using MKL as BLAS library')
+    return parser.parse_args(args=[f"--{k}={v}" for k, v in args.items()])
+
+
+def decode_bool(value: str | None) -> bool:
+    """Decode a boolean value."""
+    if value is None:
+        return False
+    value = value.lower()
+    return value in {'1', 'true', 'yes'}
+
+
+class _CustomBuildMetaBackend(setuptools.build_meta._BuildMetaBackend):
+    """Custom build backend.
+
+    This class is used to pass the option from pip to the setup.py script.
+
+    Reference: https://setuptools.pypa.io/en/latest/build_meta.html
+    """
+
+    def run_setup(self, setup_script='setup.py'):
+        """Run the setup script."""
+        args = usage(self.config_settings or {})  # type: ignore[arg-type]
+        setuptools_args = []
+        if args.c_compiler:
+            setuptools_args.append(f"--c-compiler={args.c_compiler}")
+        if args.cxx_compiler:
+            setuptools_args.append(f"--cxx-compiler={args.cxx_compiler}")
+        if args.generator:
+            setuptools_args.append(f"--generator={args.generator}")
+        if args.cmake_args:
+            setuptools_args.append(f"--cmake-args={args.cmake_args}")
+        if args.parallel:
+            setuptools_args.append(f"--parallel={args.parallel}")
+        if decode_bool(args.mkl):
+            setuptools_args.append('--mkl=yes')
+
+        if setuptools_args:
+            sys.argv = (sys.argv[:1] + ['build_ext'] + setuptools_args +
+                        sys.argv[1:])
+        return super().run_setup(setup_script)
+
+    def build_wheel(
+        self,
+        wheel_directory,
+        config_settings=None,
+        metadata_directory=None,
+    ):
+        """Build the wheel."""
+        self.config_settings = config_settings
+        return super().build_wheel(
+            wheel_directory,
+            config_settings,
+            metadata_directory,
+        )
+
+
+build_wheel = _CustomBuildMetaBackend().build_wheel
diff --git a/docs/source/conf.py b/docs/source/conf.py
index c8cee777..2c977410 100644
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -39,9 +39,9 @@ def get_build_dirname():
 author = 'CNES/CLS'
 
 # The short X.Y version
-version = '2024.11.0'
+version = '2024.11.0.dev1'
 # The full version, including alpha/beta/rc tags
-release = '2024.11.0'
+release = '2024.11.0.dev1'
 
 # -- General configuration ---------------------------------------------------
 
diff --git a/docs/source/setup/build.rst b/docs/source/setup/build.rst
index 8e6ed167..2ab7e796 100644
--- a/docs/source/setup/build.rst
+++ b/docs/source/setup/build.rst
@@ -172,3 +172,12 @@ Install
 =======
 
 To install this library, type the command ``python3 -m pip install .``.
+
+If you want to pass some options to the ``build_ext`` command, you can use the
+``--config-settings``or ``-C`` option. For example, to compile the library using
+MKL as BLAS library and the Visual Studio 17 2022 generator, type the following
+command:
+
+.. code-block:: bash
+
+    python3 -m pip install . -Cmkl=yes -Cgenerator="Visual Studio 17 2022"
diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 00000000..5f5ee837
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,4 @@
+[build-system]
+requires = ["setuptools", "cmake"]
+build-backend = "backend"
+backend-path = ["_custom_build"]
diff --git a/setup.cfg b/setup.cfg
index f3fa1935..3f2d0a65 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -1,6 +1,3 @@
-[build-system]
-requires = ["setuptools", "cmake"]
-
 [flake8]
 exclude = docs,tests
 max-line-length = 80