# 
# This file is part of Lodel 2 (https://github.com/OpenEdition)
#
# Copyright (C) 2015-2017 Cléo UMS-3287
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published
# by the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#


import configparser
import os
import glob
import copy

from lodel.context import LodelContext

#  @package lodel.settings.settings_loader Lodel2 loader of configuration options
#
# From a filesystem directory, all ini files are loaded in a dict (key/value) for each option
# The options are called one by one by lodel bootstrap, if one or more options remains 
# then an exception is raised

LodelContext.expose_modules(globals(), {
    'lodel.logger': 'logger',
    'lodel.settings.utils': ['SettingsError', 'SettingsErrors'],
    'lodel.validator.validator': ['ValidationError']})

##@brief Merges and loads configuration files
class SettingsLoader(object):

    ## To avoid the DEFAULT section whose values are found in all sections, we
    # have to give it an unsual name
    DEFAULT_SECTION = 'lodel2_default_passaway_tip'

    ## @brief Virtual filename when default value is used
    DEFAULT_FILENAME = 'default_value'

    ##@brief Constructor
    # @param conf_path str : conf.d path
    def __init__(self, conf_path):
        self.__conf_path = conf_path
        self.__conf_sv = dict()
        self.__conf = self.__merge()
        # Stores errors
        self.__errors_list = []

    ##@brief Lists and merges files in settings_loader.conf_path
    # @return dict()
    def __merge(self):
        conf = dict()
        l_dir = glob.glob(self.__conf_path+'/*.ini')
        logger.debug("SettingsLoader found those settings files : %s" % (
            ', '.join(l_dir)))
        for f_ini in l_dir:
            config = configparser.ConfigParser(
	    	default_section = self.DEFAULT_SECTION ,interpolation=None)
            config.read(f_ini)
            for section in [s for s in config if s != self.DEFAULT_SECTION]:
                if section not in conf:
                    conf[section] = dict()
                for param in config[section]:
                    if param not in conf[section]:
                        conf[section][param] = dict()
                        conf[section][param]['value'] = config[section][param]
                        conf[section][param]['file'] = f_ini
                        self.__conf_sv[section + ':' + param] = f_ini
                    else:
                        raise SettingsError("Error redeclaration of key %s \
                            in section %s. Found in %s and %s" % (\
                            section, param, f_ini, conf[section][param]['file']))
        return conf

    ##@brief Returns option if exists default_value else and validates
    # @param section str : name of the section
    # @param keyname str
    # @param validator callable : takes one argument value and raises validation fail
    # @param default_value *
    # @return the option
    def getoption(self,section,keyname,validator,default_value=None):
        conf=self.__conf
        if section not in conf:
            conf[section] = dict()

        sec = conf[section]
        if keyname in sec:
            result = sec[keyname]['value']
            try:
                del self.__conf_sv[section + ':' + keyname]
            except KeyError: #allready fetched
                pass
        else:
            #default values
            sec[keyname] = dict()
            result = sec[keyname]['value'] = default_value
            sec[keyname]['file'] = SettingsLoader.DEFAULT_FILENAME

        try:
            return validator(result)
        except Exception as e:
            # Generating nice exceptions
            if False and sec[keyname]['file'] == SettingsLoader.DEFAULT_FILENAME:
                expt = SettingsError(msg='Mandatory settings not found', \
                                    key_id=section+'.'+keyname)
                self.__errors_list.append(expt)
            else:
                expt = ValidationError("For %s.%s : %s" % (section, keyname, e))
                expt2 = SettingsError(msg=str(expt), \
                                        key_id=section+'.'+keyname, \
                                        filename=sec[keyname]['file'])
                self.__errors_list.append(expt2)
            return

    ##@brief Sets option in a config section. Writes in the conf file
    # @param section str : name of the section
    # @param keyname str
    # @param value str
    # @param validator callable : takes one argument value and raises validation fail
    # @return the option
    def setoption(self, section, keyname, value, validator):
        f_conf = copy.copy(self.__conf[section][keyname]['file'])
        if f_conf == SettingsLoader.DEFAULT_FILENAME:
            f_conf = self.__conf_path + '/generated.ini'

        conf = self.__conf
        conf[section][keyname] = value
        config = configparser.ConfigParser()
        config.read(f_conf)
        if section not in config:
            config[section] = {}
        config[section][keyname] = validator(value)

        with open(f_conf, 'w') as configfile:
            config.write(configfile)

    ##@brief Saves new partial configuration. Writes in the conf files corresponding
    # @param sections dict
    # @param validators dict of callable : takes one argument value and raises validation fail
    def saveconf(self, sections, validators):
        for sec in sections:
            for kname in sections[sec]:
                self.setoption(sec, kname, sections[sec][kname], validators[sec][kname])

    ##@brief Returns the section to be configured
    # @param section_prefix str
    # @param default_section str
    # @return the section as dict()
    def getsection(self, section_prefix, default_section=None):
        conf = copy.copy(self.__conf)

        sections = []
        if section_prefix in conf:
            sections.append(section_prefix)
        for sect_names in conf:
            if sect_names in sections:
                pass
            elif sect_names.startswith(section_prefix + '.'):
                sections.append(sect_names)
        if sections == [] and default_section:
            sections.append(section_prefix + '.' + default_section)
        elif sections == []:
            raise NameError("Not existing settings section : %s" % section_prefix)

        return sections

    ##@brief Return invalid settings
    #
    # This method returns all the settings that was not fetched by
    # getsection() method. For the Settings object it allows to know
    # the list of invalids settings keys
    # @return a dict with SECTION_NAME+":"+KEY_NAME as key and the filename
    # where the settings was found as value
    def getremains(self):
        return self.__conf_sv

    ##@brief Raise a SettingsErrors exception if some confs remain
    #@note typically used at the end of Settings bootstrap
    def raise_errors(self):
        remains = self.getremains()
        err_l = self.__errors_list
        for key_id, filename in remains.items():
            err_l.append(SettingsError(msg="Invalid configuration key", \
                                    key_id=key_id, \
                                    filename =filename))
        if len(err_l) > 0:
            raise SettingsErrors(err_l)
        else:
            return