from django.utils.translation import ugettext
from livesettings import values
from livesettings.models import SettingNotSet
from livesettings.utils import is_string_like

import logging

log = logging.getLogger('configuration')

_NOTSET = object()

class ConfigurationSettings(object):
    """A singleton manager for ConfigurationSettings"""

    class __impl(object):
        def __init__(self):
            self.settings = values.SortedDotDict()
            self.prereg = {}

        def __getitem__(self, key):
            """Get an element either by ConfigurationGroup object or by its key"""
            key = self._resolve_key(key)
            return self.settings.get(key)

        def __getattr__(self, key):
            """Get an element either by ConfigurationGroup object or by its key"""
            try:
                return self[key]
            except:
                raise AttributeError, key

        def __iter__(self):
            for v in self.groups():
                yield v

        def __len__(self):
            return len(self.settings)

        def __contains__(self, key):
            try:
                key = self._resolve_key(key)
                return self.settings.has_key(key)
            except:
                return False

        def _resolve_key(self, raw):
            if is_string_like(raw):
                key = raw

            elif isinstance(raw, values.ConfigurationGroup):
                key = raw.key

            else:
                group = self.groups()[raw]
                key = group.key

            return key

        def get_config(self, group, key):
            try:
                if isinstance(group, values.ConfigurationGroup):
                    group = group.key

                cg = self.settings.get(group, None)
                if not cg:
                    raise SettingNotSet('%s config group does not exist' % group)

                else:
                    return cg[key]
            except KeyError:
                raise SettingNotSet('%s.%s' % (group, key))

        def groups(self):
            """Return ordered list"""
            return self.settings.values()

        def has_config(self, group, key):
            if isinstance(group, values.ConfigurationGroup):
                group = group.key

            cfg = self.settings.get(group, None)
            if cfg and key in cfg:
                return True
            else:
                return False

        def preregister_choice(self, group, key, choice):
            """Setup a choice for a group/key which hasn't been instantiated yet."""
            k = (group, key)
            if self.prereg.has_key(k):
                self.prereg[k].append(choice)
            else:
                self.prereg[k] = [choice]

        def register(self, value):
            g = value.group
            if not isinstance(g, values.ConfigurationGroup):
                raise ValueError('value.group should be an instance of ConfigurationGroup')

            groupkey = g.key
            valuekey = value.key

            k = (groupkey, valuekey)
            if self.prereg.has_key(k):
                for choice in self.prereg[k]:
                    value.add_choice(choice)

            if not groupkey in self.settings:
                self.settings[groupkey] = g

            self.settings[groupkey][valuekey] = value

            return value

    __instance = None

    def __init__(self):
        if ConfigurationSettings.__instance is None:
            ConfigurationSettings.__instance = ConfigurationSettings.__impl()
            #ConfigurationSettings.__instance.load_app_configurations()

        self.__dict__['_ConfigurationSettings__instance'] = ConfigurationSettings.__instance

    def __getattr__(self, attr):
            """ Delegate access to implementation """
            return getattr(self.__instance, attr)

    def __getitem__(self, key):
        return self.__instance[key]

    def __len__(self):
        return len(self.__instance)

    def __setattr__(self, attr, value):
        """ Delegate access to implementation """
        return setattr(self.__instance, attr, value)

    def __unicode__(self):
        return u"ConfigurationSettings: " + unicode(self.groups())

def config_exists(group, key):
    """Test to see if a setting has been registered"""

    return ConfigurationSettings().has_config(group, key)

def config_get(group, key):
    """Get a configuration setting"""
    try:
        return ConfigurationSettings().get_config(group, key)
    except SettingNotSet:
        log.debug('SettingNotSet: %s.%s', group, key)
        raise

def config_get_group(group):
    return ConfigurationSettings()[group]

def config_collect_values(group, groupkey, key, unique=True, skip_missing=True):
    """Look up (group, groupkey) from config, then take the values returned and
    use them as groups for a second-stage lookup.

    For example:

    config_collect_values(PAYMENT, MODULES, CREDITCHOICES)

    Stage 1: ['PAYMENT_GOOGLE', 'PAYMENT_AUTHORIZENET']
    Stage 2: config_value('PAYMENT_GOOGLE', 'CREDITCHOICES')
           + config_value('PAYMENT_AUTHORIZENET', 'CREDITCHOICES')
    Stage 3: (if unique is true) remove dupes
    """
    groups = config_value(group, groupkey)

    ret = []
    for g in groups:
        try:
            ret.append(config_value(g, key))
        except KeyError, ke:
            if not skip_missing:
                raise SettingNotSet('No config %s.%s' % (g, key))

    if unique:
        out = []
        for x in ret:
            if not x in out:
                out.append(x)
        ret = out

    return ret

def config_register(value):
    """Register a value or values.

    Parameters:
        -A Value
    """
    return ConfigurationSettings().register(value)

def config_register_list(*args):
    for value in args:
        config_register(value)

def config_value(group, key, default=_NOTSET):
    """Get a value from the configuration system"""
    try:
        return config_get(group, key).value
    except SettingNotSet:
        if default != _NOTSET:
            return default
        raise

def config_value_safe(group, key, default_value):
    """Get a config value with a default fallback, safe for use during SyncDB."""
    raw = default_value

    try:
        raw = config_value(group, key)
    except SettingNotSet:
        pass
    except ImportError, e:
        log.warn("Error getting %s.%s, OK if you are in SyncDB.", group, key)

    return raw


def config_choice_values(group, key, skip_missing=True, translate=False):
    """Get pairs of key, label from the setting."""
    try:
        cfg = config_get(group, key)
        choices = cfg.choice_values

    except SettingNotSet:
        if skip_missing:
            return []
        else:
            raise SettingNotSet('%s.%s' % (group, key))

    if translate:
        choices = [(k, ugettext(v)) for k, v in choices]

    return choices

def config_add_choice(group, key, choice):
    """Add a choice to a value"""
    if config_exists(group, key):
        cfg = config_get(group, key)
        cfg.add_choice(choice)
    else:
        ConfigurationSettings().preregister_choice(group, key, choice)