From 0aeeaf289ec31da902a9a5e614c1686baf880a29 Mon Sep 17 00:00:00 2001
From: Aaron LI <aaronly.me@outlook.com>
Date: Tue, 27 Sep 2016 21:34:42 +0800
Subject: Implement the basic ConfigManger()

This is very basic at the moment, and needs many improvements.

Thanks: https://github.com/pazz/alot

TODO: Add config specifications with default values
---
 fg21sim/configs/__init__.py |  6 ++++
 fg21sim/configs/manager.py  | 74 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 80 insertions(+)
 create mode 100644 fg21sim/configs/__init__.py
 create mode 100644 fg21sim/configs/manager.py

diff --git a/fg21sim/configs/__init__.py b/fg21sim/configs/__init__.py
new file mode 100644
index 0000000..b1fe70f
--- /dev/null
+++ b/fg21sim/configs/__init__.py
@@ -0,0 +1,6 @@
+# Copyright (c) 2016 Weitian LI <liweitianux@live.com>
+# MIT license
+
+from .manager import ConfigManager
+
+configs = ConfigManager()
diff --git a/fg21sim/configs/manager.py b/fg21sim/configs/manager.py
new file mode 100644
index 0000000..933a63d
--- /dev/null
+++ b/fg21sim/configs/manager.py
@@ -0,0 +1,74 @@
+# Copyright (c) 2016 Weitian LI <liweitianux@live.com>
+# MIT license
+#
+# References:
+# [1] https://configobj.readthedocs.io/en/latest/configobj.html
+# [2] https://github.com/pazz/alot/blob/master/alot/settings/manager.py
+
+"""
+Configuration manager.
+"""
+
+import os
+from glob import glob
+from errors import ConfigError
+
+from configobj import ConfigObj, ConfigObjError, flatten_errors
+from validate import Validator
+
+
+CONFIGS_PATH = os.path.dirname(__file__)
+
+
+class ConfigManager:
+    """Manager the configurations"""
+    def __init__(self, configs=None):
+        """
+        :param configs: (optional) list of user configs to load
+        """
+        configs_spec = sorted(glob(os.path.join(CONFIGS_PATH, "*.conf.spec")))
+        spec = "\n".join([open(f).read() for f in configs_spec]).split("\n")
+        self._configspec = ConfigObj(spec, interpolation=False,
+                                     list_values=False, _inspec=True)
+        self._validator = Validator()
+        configs_default = ConfigObj(configspec=self._configspec)
+        self._config = self.validate(configs_default)
+        if configs:
+            for config in configs:
+                self.read_config(config)
+
+    def read_config(self, config):
+        newconfig = ConfigObj(config, configspec=self._configspec)
+        newconfig = self.validate(newconfig)
+        self._config.merge(newconfig)
+
+    def validate(self, config):
+        try:
+            results = config.validate(self._validator, preserve_errors=True)
+        except ConfigObjError as e:
+            raise ConfigError(e.message)
+        if not results:
+            error_msg = ''
+            for (section_list, key, res) in flatten_errors(config, results):
+                if key is not None:
+                    if res is False:
+                        msg = 'key "%s" in section "%s" is missing.'
+                        msg = msg % (key, ', '.join(section_list))
+                    else:
+                        msg = 'key "%s" in section "%s" failed validation: %s'
+                        msg = msg % (key, ', '.join(section_list), res)
+                else:
+                    msg = 'section "%s" is missing' % '.'.join(section_list)
+                error_msg += msg + '\n'
+            raise ConfigError(error_msg)
+        return config
+
+    def get(self, key, fallback=None):
+        if key in self._config:
+            value = self._config[key]
+        else:
+            value = fallback
+        return value
+
+    def set(self, key, value):
+        self._config[key] = value
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