from PyQt4 import QtCore
from config import get_data_path

class SettingsWrapper(object):
    """Wrapper for QSettings using attribute access with conversion functions"""
    _known_settings = {
        #'setting':                     (conversionFuncRead, conversionFuncReadAttr, default),
    }
    def __init__(self, settings, subtree=None):
        self._settings = settings
        self._subtree = subtree

    def __repr__(self):
        return "<%s wrapping %s with subtree %s>"%(self.__class__, self._settings, self._subtree)

    def rewrite_settings(self):
        """Writes out the complete reparsed settings file"""
        if self._subtree:
            raise Exception("May only be called on main settings object")
        for setting in self._known_settings:
            section, name = setting.split('/')
            sec = getattr(self, section)
            setattr(sec, name, getattr(sec, name))

    def __getattr__(self, name):
        if self._subtree is None:
            #Top level, need to return a wrapper for child
            return self.__class__(self._settings, name + '/')
        fullname = self._subtree + name
        raw = self._settings.value(fullname, None)
        if raw.isNull():
            if fullname in self._known_settings:
                return self._known_settings[fullname][2] #Default
            return None
        if fullname in self._known_settings:
            return self._known_settings[fullname][0](getattr(raw, self._known_settings[fullname][1])())
        return unicode(raw.toString()) #By default, return strings

    def __setattr__(self, name, value):
        if name.startswith('_'):
            return super(SettingsWrapper, self).__setattr__(name, value)
        if self._subtree is None:
            raise ValueError("You cannot set an attribute outside of a section")
        fullname = self._subtree + name
        self._settings.setValue(fullname, value)

class SampleSettingsWrapper(SettingsWrapper):
    _known_settings = {
        'main/examplestr':          (unicode, 'toString',   'default.db'),
        'main/somebool':                     (bool,    'toBool',     False),

        'ab/cd':                        (bool, 'toBool', False),
    }