# 
# 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 sys
import os.path
import re
import socket
import inspect
import copy
from lodel.context import LodelContext


LodelContext.expose_modules(globals(), {
    'lodel.mlnamedobject.mlnamedobject': ['MlNamedObject'],
    'lodel.exceptions': ['LodelException', 'LodelExceptions',
                         'LodelFatalError', 'FieldValidationError']})


##
# @package lodel.settings.validator Lodel2 settings validators/cast module.
#
# Validator are registered in the Validator class.
# @note to get a list of registered default validators just run
# <pre>$ python scripts/settings_validator.py</pre>
#
# @remarks Should we reconsider specifying conf right in this module?


##
# @brief Exception class that should be raised when a validation fails
class ValidationError(Exception):
    pass


##
# @brief Handles settings validators
#
# Class instance are callable objects that takes a value argument (the value
# to validate). It raises a ValidationError if validation fails, else it returns
# a properly cast value.
#
#@todo Implement an IP validator for use in the multisite confspec
class Validator(MlNamedObject):

    _validators = dict()
    _description = dict()

    ##
    # @brief Instantiate a validator
    #
    #@param name str: validator name
    #@param none_is_valid bool: if True None will be validated
    #@param **kwargs: more arguments for the validator
    def __init__(self, name, none_is_valid=False, display_name=None, help_text=None, **kwargs):
        if name is not None and name not in self._validators:
            raise LodelFatalError("No validator named '%s'" % name)
        self.__none_is_valid = none_is_valid
        self.__name = name
        self._opt_args = kwargs
        if display_name is None:
            display_name = name
        super().__init__(display_name, help_text)

    ##
    # @brief Calls the validator.
    #
    # @param value mixed:
    # @return mixed: The properly casted value
    # @throw ValidationError
    def __call__(self, value):
        if value is None:
            if self.__none_is_valid:
                return None
            else:
                raise ValidationError('None is not a valid value')
        if self.__none_is_valid and value is None:
            return None
        try:
            ret = self._validators[self.__name](value, **self._opt_args)
            return ret
        except Exception as exp:
            raise ValidationError(exp)

    ##
    # @brief Register a new validator
    #
    # @param name string: validator name
    # @param callback callable: the function that will validate a value
    # @param description string:
    @classmethod
    def register_validator(cls, name, callback, description=None):
        if name in cls._validators:
            raise NameError("A validator named '%s' allready exists" % name)
        ##
        # @todo Broken test for callable.
        if not inspect.isfunction(callback) and not inspect.ismethod(callback) and not hasattr(callback, '__call__'):
            raise TypeError("Callable expected but got %s" % type(callback))
        cls._validators[name] = callback
        cls._description[name] = description

    ##
    # @brief Get the validator list associated with description
    @classmethod
    def validators_list(cls):
        return copy.copy(cls._description)

    ##
    # @brief Creates and registers an iterative list validator
    #
    # @param elt_validator callable: The validator that will be used to validate
    #         each of the list values.
    # @param validator_name string:
    # @param description None | string:
    # @param separator string: The element separator.
    # @return A Validator instance.
    @classmethod
    def create_list_validator(cls, validator_name, elt_validator, description=None, separator=','):
        def list_validator(value):
            res = list()
            if value is None:
                return res
            errors = list()
            for elt in value.split(separator):
                elt = elt_validator(elt)
                if len(elt) > 0:
                    res.append(elt)
            return res
        description = "Convert value to an array" if description is None else description
        cls.register_validator(validator_name, list_validator, description)
        return cls(validator_name)

    ##
    # @brief Creates and registers a list validator that reads an array
    #        and returns a string
    # @param elt_validator callable: The validator that will be used to validate
    #        each elt value
    # @param validator_name string:
    # @param description None | string:
    # @param separator string: The element separator
    # @return A Validator instance
    @classmethod
    def create_write_list_validator(cls, validator_name, elt_validator, description=None, separator=','):
        def write_list_validator(value):
            res = ''
            for elt in value:
                res += elt_validator(elt) + ','
            return res[:len(res) - 1]
        description = "Convert value to a string" if description is None else description
        cls.register_validator(validator_name, write_list_validator, description)
        return cls(validator_name)

    ##
    # @brief Create and register a regular expression validator
    #
    # @param pattern str: regex pattern
    # @param validator_name str: The validator name
    # @param description str: Validator description
    # @return a Validator instance
    @classmethod
    def create_re_validator(cls, pattern, validator_name, description=None):
        def re_validator(value):
            if not re.match(pattern, value):
                raise ValidationError(
                    "The value '%s' doesn't match the following pattern '%s'"
                    % pattern)
            return value
        # registering the validator
        cls.register_validator(validator_name, re_validator,
                               ("Match value to '%s'" % pattern)
                               if description is None else description)
        return cls(validator_name)

    ##
    #  @return The list of registered validators.
    @classmethod
    def validators_list_str(cls):
        result = ''
        for name in sorted(cls._validators.keys()):
            result += "\t%016s" % name
            if name in cls._description and cls._description[name] is not None:
                result += ": %s" % cls._description[name]
            result += "\n"
        return result


##
# @brief Integer value validator callback
#
# @remarks Is it intended that this function simply tries casting to an integer?
#            Is it also intended that it does not use any try/catch block?
def int_val(value):
    return int(value)


##
# @brief Output file validator callback
#
# @return A file object (if filename is '-' return sys.stderr)
def file_err_output(value):
    if not isinstance(value, str):
        raise ValidationError("A string was expected but got '%s' " % value)
    if value == '-':
        return None
    return value


##
# @brief Boolean validator callback
def boolean_val(value):
    if isinstance(value, bool):
        return value
    if value.strip().lower() == 'true' or value.strip() == '1':
        value = True
    elif value.strip().lower() == 'false' or value.strip() == '0':
        value = False
    else:
        raise ValidationError("A boolean was expected but got '%s' " % value)
    return bool(value)


##
# @brief Validate a directory path
def directory_val(value):
    res = Validator('strip')(value)
    if not os.path.isdir(res):
        raise ValidationError("Following path don't exists or is not a directory : '%s'" % res)
    return res


##
# @brief Validates a loglevel value
def loglevel_val(value):
    valids = ['DEBUG', 'INFO', 'WARNING', 'SECURITY', 'ERROR', 'CRITICAL']
    if value.upper() not in valids:
        raise ValidationError(
            "The value '%s' is not a valid loglevel" % value)
    return value.upper()


##
# @brief Validates a path
#
# @remarks is it intended to have both @ref directory_val and this function
#            right here?
def path_val(value):
    if value is None or not os.path.exists(value):
        raise ValidationError(
            "path '%s' doesn't exists" % value)
    return value


##
# @brief Validates None
#
# @remarks Purpose?
def none_val(value):
    if value is None:
        return None
    raise ValidationError("This settings cannot be set in configuration file")


##
# @brief Validates a string
def str_val(value):
    try:
        return str(value)
    except Exception as exp:
        raise ValidationError("Can't to convert value to string: " + str(exp))


##
# @brief Validate using a regex
def regex_val(value, pattern):
    if re.match(pattern, value) is None:
        raise ValidationError("The value '%s' is not validated by : \
r\"%s\"" % (value, pattern))
    return value


##
# @brief Validate a hostname (ipv4 or ipv6)
def host_val(value):
    if value == 'localhost':
        return value
    ok = False
    try:
        socket.inet_aton(value)
        return value
    except (TypeError, OSError):
        pass
    try:
        socket.inet_pton(socket.AF_INET6, value)
        return value
    except (TypeError, OSError):
        pass
    try:
        socket.getaddrinfo(value, 80)
        return value
    except (TypeError, socket.gaierror):
        msg = "The value '%s' is not a valid host"
        raise ValidationError(msg % value)


def custom_list_validator(value, validator_name, validator_kwargs=None):
    validator_kwargs = dict() if validator_kwargs is None else validator_kwargs
    validator = Validator(validator_name, **validator_kwargs)
    for item in value.split():
        validator(item)
    return value.split()


#
#   Default validators registration
#
Validator.register_validator('custom_list', custom_list_validator,
                             'A list validator that takes a "validator_name" as argument')
Validator.register_validator('dummy', lambda value: value, 'Validate anything')
Validator.register_validator('none', none_val, 'Validate None')
Validator.register_validator('string', str_val, 'Validate string values')
Validator.register_validator('strip', str.strip, 'String trim')
Validator.register_validator('int', int_val, 'Integer value validator')
Validator.register_validator('bool', boolean_val, 'Boolean value validator')
Validator.register_validator('errfile', file_err_output,
                             'Error output file validator (return stderr if filename is "-")')
Validator.register_validator('directory', directory_val,
                             'Directory path validator')
Validator.register_validator('loglevel', loglevel_val, 'Loglevel validator')
Validator.register_validator('path', path_val, 'path validator')
Validator.register_validator('host', host_val, 'host validator')
Validator.register_validator('regex', regex_val,
                             'RegEx name validator (take re as argument)')
Validator.create_list_validator('list', Validator('strip'), description="Simple list validator. Validate a list of values separated by ','",
                                separator=',')
Validator.create_list_validator(
    'directory_list',
    Validator('directory'),
    description="Validator for a list of directory path separated with ','",
    separator=',')
Validator.create_write_list_validator(
    'write_list',
    Validator('directory'),
    description="Validator for an array of values \
        which will be set in a string, separated by ','",
    separator=',')
Validator.create_re_validator(
    r'^https?://[^\./]+.[^\./]+/?.*$',
    'http_url',
    'Url validator')


##
# @brief Validator for Editorial Model components.
#
# Designed to validate a conf that indicates a class.field in an EM
#
# @todo modify the hardcoded dyncode import (it's a warning)
def emfield_val(value):
    LodelContext.expose_modules(globals(),
                                {'lodel.plugin.hooks': ['LodelHook']})
    spl = value.split('.')
    if len(spl) != 2:
        msg = "Expected a value in the form CLASSNAME.FIELDNAME but got : %s"
        raise ValidationError(msg % value)
    value = tuple(spl)
    # Late validation hook

    @LodelHook('lodel2_dyncode_bootstraped')
    def emfield_conf_check(hookname, caller, payload):
        import leapi_dyncode as dyncode  # <-- dirty & quick
        classnames = {cls.__name__.lower(): cls for cls in dyncode.dynclasses}
        if value[0].lower() not in classnames:
            msg = "Following dynamic class do not exists in current EM : %s"
            raise ValidationError(msg % value[0])
        ccls = classnames[value[0].lower()]
        if value[1].lower() not in ccls.fieldnames(True):
            msg = "Following field not found in class %s : %s"
            raise ValidationError(msg % value)
    return value


##
# @brief Validator for plugin name & its type optionally
#
# Able to check that the value is a plugin and if it is of a specific type
def plugin_validator(value, ptype=None):
    if value:
        LodelContext.expose_modules(globals(), {
            'lodel.plugin.hooks': ['LodelHook']})
        value = copy.copy(value)

        @LodelHook('lodel2_dyncode_bootstraped')
        def plugin_type_checker(hookname, caller, payload):
            LodelContext.expose_modules(globals(), {
                'lodel.plugin.plugins': ['Plugin'],
                'lodel.plugin.exceptions': ['PluginError']})
            if value is None:
                return
            try:
                plugin = Plugin.get(value)
            except PluginError:
                msg = "No plugin named %s found"
                msg %= value
                raise ValidationError(msg)
            if plugin._type_conf_name.lower() != ptype.lower():
                msg = "A plugin of type '%s' was expected but found a plugin \
    named  '%s' that is a '%s' plugin"
                msg %= (ptype, value, plugin._type_conf_name)
                raise ValidationError(msg)
        return value
    return None


Validator.register_validator(
    'plugin',
    plugin_validator,
    'plugin name & type validator')
Validator.register_validator(
    'emfield',
    emfield_val,
    'EmField name validator')


##
#   Lodel 2 configuration specification
#
# @brief Append a piece of confspec
#
# @param orig dict : the confspec to update
# @param section str : section name
# @param key str
# @param validator Validator : the validator to use to check this configuration key's value
# @param default
# @return new confspec
#
# @note orig is modified during the process
def confspec_append(orig, section, key, validator, default):
    if section not in orig:
        orig[section] = dict()
    if key not in orig[section]:
        orig[section][key] = (default, validator)
    return orig


##
# @brief Global specifications for lodel2 settings
LODEL2_CONF_SPECS = {
    'lodel2': {
        'debug': (True, Validator('bool')),
        'sitename': ('noname', Validator('strip')),
        'runtest': (False, Validator('bool')),
    },
    'lodel2.logging.*': {
        'level': ('ERROR', Validator('loglevel')),
        'context': (False, Validator('bool')),
        'filename': ("-", Validator('errfile', none_is_valid=False)),
        'backupcount': (5, Validator('int', none_is_valid=False)),
        'maxbytes': (1024 * 10, Validator('int', none_is_valid=False)),
    },
    'lodel2.editorialmodel': {
        'emfile': ('em.pickle', Validator('strip')),
        'emtranslator': ('picklefile', Validator('strip')),
        'dyncode': ('leapi_dyncode.py', Validator('strip')),
        'groups': ('', Validator('list')),
        'editormode': (False, Validator('bool')),
    },
    'lodel2.datasources.*': {
        'read_only': (False, Validator('bool')),
        'identifier': (None, Validator('string')),
    },
    'lodel2.auth': {
        'login_classfield': ('user.login', Validator('emfield')),
        'pass_classfield': ('user.password', Validator('emfield')),
    },
}