#
# Settings.py -- Simple class to manage stateful user preferences.
#
# Eric Jeschke (eric@naoj.org)
#
# Copyright (c) Eric R. Jeschke.  All rights reserved.
# This is open-source software licensed under a BSD license.
# Please see the file LICENSE.txt for details.
#
import os
import pprint
import numpy

from . import Callback
from . import Bunch


unset_value = ("^^UNSET^^")

class SettingError(Exception):
    pass

class Setting(Callback.Callbacks):

    def __init__(self, value=unset_value, name=None, logger=None,
                 check_fn=None):
        Callback.Callbacks.__init__(self)

        self.value = value
        self._unset = (value == unset_value)
        self.name = name
        self.logger = logger
        if check_fn == None:
            check_fn = self._check_none
        self.check_fn = check_fn

        # For callbacks
        for name in ('set', ):
            self.enable_callback(name)

    def _check_none(self, value):
        return value
    
    def set(self, value, callback=True):
        self.value = self.check_fn(value)
        if callback:
            self.make_callback('set', value)
        
    def get(self, *args):
        if self._unset:
            if len(args) == 0:
                raise KeyError("setting['%s'] value is not set!" % (
                    self.name))
            else:
                assert len(args) == 1, \
                       SettingError("Illegal parameter use to get(): %s" % (
                    str(args)))
                return args[0]
        return self.value
    
    def __repr__(self):
        return repr(self.value)

    def __str__(self):
        return str(self.value)
    

class SettingGroup(object):

    def __init__(self, name=None, logger=None, preffile=None):
        self.name = name
        self.logger = logger
        self.preffile = preffile

        self.group = Bunch.Bunch()

    def addSettings(self, **kwdargs):
        for key, value in kwdargs.items():
            self.group[key] = Setting(value=value, name=key,
                                      logger=self.logger)
            # TODO: add group change callback?
        
    def getSetting(self, key):
        return self.group[key]

    def shareSettings(self, other, keylist=None):
        if keylist == None:
            keylist = self.group.keys()
        for key in keylist:
            other.group[key] = self.group[key]

    def copySettings(self, other, keylist=None):
        if keylist == None:
            keylist = self.group.keys()
        d = {}
        for key in keylist:
            d[key] = self.get(key)
        other.setDict(d)

    def setdefault(self, key, value):
        if key in self.group:
            return self.group[key].get(value)
        else:
            d = { key: value }
            self.addSettings(**d)
            return self.group[key].get(value)

    def addDefaults(self, **kwdargs):
        for key, value in kwdargs.items():
            self.setdefault(key, value)

    def setDefaults(self, **kwdargs):
        return self.addDefaults(**kwdargs)
    
    def get(self, *args):
        key = args[0]
        if len(args) == 1:
            return self.group[key].get()
        if len(args) == 2:
            return self.setdefault(key, args[1])

    def getDict(self):
        return dict([[name, self.group[name].value] for name in self.group.keys()])
            
    def setDict(self, d, callback=True):
        for key, value in d.items():
            if key not in self.group:
                self.setdefault(key, value)
            else:
                self.group[key].set(value, callback=callback)
        
    def set(self, callback=True, **kwdargs):
        self.setDict(kwdargs, callback=callback)
        
    def __getitem__(self, key):
        return self.group[key].value
        
    def __setitem__(self, key, value):
        self.group[key].set(value)

    def has_key(self, key):
        return key in self.group

    def load(self, onError='raise'):
        try:
            d = {}
            with open(self.preffile, 'r') as in_f:
                buf = in_f.read()
            for line in buf.split('\n'):
                line = line.strip()
                # skip comments and anything that doesn't look like an
                # assignment
                if line.startswith('#') or (not ('=' in line)):
                    continue
                else:
                    try:
                        i = line.index('=')
                        key = line[:i].strip()
                        val = eval(line[i+1:].strip())
                        d[key] = val
                    except Exception as e:
                        # silently skip parse errors, for now
                        continue
                        
            self.setDict(d)
        except Exception as e:
            errmsg = "Error opening settings file (%s): %s" % (
                self.preffile, str(e))
            if onError == 'silent':
                pass
            elif onError == 'warn':
                self.logger.warn(errmsg)
            else:
                raise SettingError(errmsg)
            
    def _check(self, d):
        if isinstance(d, dict):
            for key, value in d.items():
                d[key] = self._check(value)
            return d
        try:
            if numpy.isnan(d):
                return 0.0
            elif numpy.isinf(d):
                return 0.0
        except Exception:
            pass
        return d
        
    def save(self):
        d = self.getDict()
        # sanitize data -- hard to parse NaN or Inf
        self._check(d)
        try:
            # sort keys for easy reading/editing
            keys = list(d.keys())
            keys.sort()
            with open(self.preffile, 'w') as out_f:
                for key in keys:
                    out_f.write("%s = %s\n" % (key, repr(d[key])))
                        
        except Exception as e:
            errmsg = "Error opening settings file (%s): %s" % (
                self.preffile, str(e))
            self.logger.error(errmsg)
        

class Preferences(object):

    def __init__(self, basefolder="/tmp", logger=None):
        self.folder = basefolder
        self.logger = logger
        self.settings = Bunch.Bunch(caseless=True)

    def setDefaults(self, category, **kwdargs):
        self.settings[category].addDefaults(**kwdargs)

    def getSettings(self, category):
        return self.settings[category]
    
    def getDict(self, category):
        return self.settings[category].getDict()
    
    def createCategory(self, category):
        if category not in self.settings:
            suffix = '.cfg'
            path = os.path.join(self.folder, category + suffix)
            self.settings[category] = SettingGroup(logger=self.logger,
                                                   name=category,
                                                   preffile=path)
        return self.settings[category]

    def get_baseFolder(self):
        return self.folder

    def getDict(self):
        return dict([[name, self.settings[name].getDict()] for name in
                     self.settings.keys()])
            
        
#END
