Add plugins.py module with load_plugin_on_server helper (#1600)

* Add plugins.py module with load_plugin_on_server helper.

Signed-off-by: paul.profizi <paul.profizi@ansys.com>

* Retro-compatible importlib import

---------

Signed-off-by: paul.profizi <paul.profizi@ansys.com>

src/ansys/dpf/core/__init__.py

@@ -57,6 +57,7 @@
     config_options
     )
 from ansys.dpf.core import help
+from ansys.dpf.core import plugins
 from ansys.dpf.core.core import (
     BaseService,
     load_library,

src/ansys/dpf/core/plugins.py

@@ -0,0 +1,80 @@
+"""
+Python DPF plugins utilities
+============================
+
+Contains the utilities specific to installing and using Python DPF plugins.
+"""
+import os.path
+try:
+    import importlib.metadata as importlib_metadata
+except ImportError:  # Python < 3.10 (backport)
+    import importlib_metadata as importlib_metadata
+
+import ansys.dpf.core as dpf
+from ansys.dpf.core import server as server_module
+
+
+def load_plugin_on_server(plugin, server=None, symbol="load_operators"):
+    """Load a DPF Python plugin on the global or given DPF server.
+
+        Parameters
+    ----------
+    plugin:
+        DPF Python plugin to load.
+    server:
+        DPF server to load the plugin onto.
+    symbol:
+        Name of the function recording the operators in the plugin.
+    """
+    server = server_module.get_or_create_server(server)
+    plugin_name = plugin.split("-")[-1]
+    tmp_folder = dpf.make_tmp_dir_server(server=server)
+
+    # Get the path to the plugin from the package installation
+    if len([p for p in importlib_metadata.files(plugin) if "__init__.py" in str(p)]) > 0:
+        file_path = [p for p in importlib_metadata.files(plugin) if "__init__.py" in str(p)][0]
+        plugin_path = str(os.path.dirname(file_path.locate()))
+        # For some reason the "locate()" function returns a path with src doubled
+        plugin_path = plugin_path.replace("src"+os.path.sep+"src", "src")
+    elif len([p for p in importlib_metadata.files(plugin) if ".pth" in str(p)]) > 0:
+        path_file = [p for p in importlib_metadata.files(plugin) if ".pth" in str(p)][0].locate()
+        with open(path_file, "r") as file:
+            plugin_path = file.readline()[:-1]
+        plugin_path = os.path.join(plugin_path, "ansys", "dpf", "plugins", plugin_name)
+    else:
+        raise ModuleNotFoundError(f"Could not locate files for plugin {plugin}")
+
+    target_plugin_path = dpf.path_utilities.join(tmp_folder, "ansys", "dpf", "plugins", plugin_name)
+    target_xml_path = dpf.path_utilities.join(tmp_folder, "ansys", "dpf", "plugins")
+
+    # Upload python files
+    _ = dpf.upload_files_in_folder(
+        target_plugin_path,
+        plugin_path,
+        specific_extension=".py",
+        server=server,
+    )
+
+    # upload zip files (site-packages)
+    _ = dpf.upload_files_in_folder(
+        target_plugin_path,
+        plugin_path,
+        specific_extension=".zip",
+        server=server,
+    )
+
+    # Upload xml file for the plugin
+    _ = dpf.upload_files_in_folder(
+        target_xml_path,
+        os.path.join(plugin_path, os.pardir),
+        specific_extension=".xml",
+        server=server,
+    )
+
+    # Load the plugin on the server
+    dpf.load_library(
+        filename=target_plugin_path,
+        name=f"py_{plugin_name}",
+        symbol=symbol,
+        server=server,
+    )