#! /usr/bin/env python3
# encoding: utf-8

import jsmin
import json

from . import aux

def _read_json(path):
	"""
	Reads a data structure from a JSON file pointed to by `path`.
	
	Removes any C/JS-like comments from it.
	"""
	
	with open(path) as f:
		return json.loads(jsmin.jsmin(f.read()))

class Config:
	"""
	A hierarchical key-value container that can be loaded from JSON or a Python dict.
	
	Any contained dicts are automatically converted to Config instances as well.
	
	Supports sequential overwriting - so one can load a default config and then
	progressively overlay more on top:
	
	>>> c = Config.from_file("/usr/lib/app/default.cfg")
	>>> c.update_from_file("/etc/app/config.cfg")
	>>> c.update({"key", value, "subtree": {"key": "value"}})
	"""
	
	def __init__(self, d=None, readonly=False):
		if d is None:
			d = {}
		
		assert type(d) == dict
		object.__setattr__(self, "raw", d)
		object.__setattr__(self, "readonly", readonly)
	
	@classmethod
	def from_file(cls, path, readonly=False):
		return cls(_read_json(path), readonly)
	
	def update(self, d):
		aux.overlay_tree(self.raw, d)
	
	def update_from_file(self, path):
		self.update(_read_json(path))
	
	def keys(self):
		return self.raw.keys()
	
	def values(self):
		return self.raw.values()
	
	def items(self):
		return self.raw.items()
	
	def __getitem__(self, name):
		return self.raw[name]
	
	def __setitem__(self, name, value):
		if self.readonly:
			raise AttributeError("config is read-only")
		
		self.raw[name] = value
	
	def __setattr__(self, name, value):
		if self.readonly:
			raise AttributeError("config is read-only")
		
		self.raw[name] = value
	
	def __getattr__(self, name):
		matches = [key for key in self.raw if key.replace("-", "_") == name]
		
		if matches:
			assert len(matches) == 1
			
			value = self.raw[matches[0]]
			
			if type(value) == dict:
				return Config(value)
			else:
				return value
		else:
			raise KeyError(name)
	
	def __contains__(self, name):
		return name in self.raw
	
	def __repr__(self):
		return "Config(%s)" %(" ".join("%s=%s" %(k, "…" if type(v) == dict else v) for k, v in self.raw.items()))