Implemented config functionality

Signed-off-by: Jim Martens <github@2martens.de>

src/twomartens/masterthesis/config.py

@@ -18,26 +18,95 @@
 """
 Takes care of config functionality.
 
+Constants:
+    CONFIG_FILE: name of config file relative to working directory
+
 Functions:
-    get_property(key: str): returns the value of given property
+    get_property(key: str): returns the value of given property (e.g. "section.option")
     set_property(key: str, value: str): sets the given property to given value
     list_property_values(): prints out list of config values
     get_config(): returns key-value store
 """
-from typing import Union, Dict
+import configparser
+import os
+
+
+CONFIG_FILE = "tm-masterthesis-config.ini"
+_CONFIG_PROPS = {
+    "Paths": {
+        "coco": (str, ""),
+        "scenenet": (str, ""),
+        "scenenet_gt_train": (str, ""),
+        "scenenet_gt_val": (str, ""),
+        "scenenet_gt_test": (str, ""),
+        "output": (str, ""),
+        "summaries": (str, ""),
+        "weights": (str, "")
+    },
+    "Debug": {
+        "summaries": (bool, True),
+        "train_images": (bool, False)
+    }
+}
 
 
 def get_property(key: str) -> str:
-    raise NotImplementedError
+    parser = configparser.ConfigParser()
+    config_file = f"{os.getcwd()}/{CONFIG_FILE}"
+    
+    _initialise_config(config_file)
+    parser.read(config_file)
+    
+    section, prop = tuple(key.split("."))
+    return str(parser.get(section, prop))
 
 
 def set_property(key: str, value: str) -> None:
-    raise NotImplementedError
+    parser = configparser.ConfigParser()
+    config_file = f"{os.getcwd()}/{CONFIG_FILE}"
+    
+    _initialise_config(config_file)
+    parser.read(config_file)
+    
+    section, prop = tuple(key.split("."))
+    cast_method = _CONFIG_PROPS[section][key][0]
+    parser.set(section, prop, cast_method(value))
 
 
 def list_property_values() -> None:
-    raise NotImplementedError
+    parser = configparser.ConfigParser()
+    config_file = f"{os.getcwd()}/{CONFIG_FILE}"
+    
+    _initialise_config(config_file)
+    parser.read(config_file)
+    
+    print(parser)  # simple implementation, more sophisticated might follow
 
 
-def get_config() -> Dict[str, Union[str, int, float, bool]]:
-    raise NotImplementedError
+def get_config() -> configparser.ConfigParser:
+    parser = configparser.ConfigParser()
+    config_file = f"{os.getcwd()}/{CONFIG_FILE}"
+    _initialise_config(config_file)
+    parser.read(config_file)
+    
+    return parser
+
+
+def _initialise_config(config_file: str) -> None:
+    # work-around for implementation detail of config parser
+    # a non-existing file does not lead to an exception but is simply ignored
+    # therefore a manual check via this construction is required
+    
+    try:
+        with open(config_file, "r"):
+            pass
+    except FileNotFoundError:
+        with open(config_file, "w") as file:
+            parser = configparser.ConfigParser()
+            for section in _CONFIG_PROPS:
+                parser[section] = {}
+                for option in _CONFIG_PROPS[section]:
+                    _, default = _CONFIG_PROPS[section][option]
+                    parser[section][option] = default
+                    
+            parser.write(file)