More code re-organizing

src/engines/core/base_engine.py

@@ -0,0 +1,56 @@
+import logging
+import os
+import subprocess
+
+logger = logging.getLogger()
+SUBPROCESS_TIMEOUT = 5
+
+
+class BaseRenderEngine(object):
+
+    install_paths = []
+    supported_extensions = []
+
+    def __init__(self, custom_path=None):
+        self.custom_renderer_path = custom_path
+        if not self.renderer_path():
+            raise FileNotFoundError(f"Cannot find path to renderer for {self.name()} instance")
+
+    def renderer_path(self):
+        return self.custom_renderer_path or self.default_renderer_path()
+
+    @classmethod
+    def name(cls):
+        return cls.__name__.lower()
+
+    @classmethod
+    def default_renderer_path(cls):
+        path = None
+        try:  # Linux and macOS
+            path = subprocess.check_output(['which', cls.name()], timeout=SUBPROCESS_TIMEOUT).decode('utf-8').strip()
+        except (subprocess.CalledProcessError, FileNotFoundError):
+            for p in cls.install_paths:
+                if os.path.exists(p):
+                    path = p
+        except Exception as e:
+            logger.exception(e)
+        return path
+
+    def version(self):
+        raise NotImplementedError("version not implemented")
+
+    def get_help(self):
+        path = self.renderer_path()
+        if not path:
+            raise FileNotFoundError("renderer path not found")
+        help_doc = subprocess.check_output([path, '-h'], stderr=subprocess.STDOUT,
+                                           timeout=SUBPROCESS_TIMEOUT).decode('utf-8')
+        return help_doc
+
+    @classmethod
+    def get_output_formats(cls):
+        raise NotImplementedError(f"get_output_formats not implemented for {cls.__name__}")
+
+    @classmethod
+    def get_arguments(cls):
+        pass