#-*- coding: utf-8 -*-

import importlib
import warnings
import copy

from lodel.context import LodelContext

LodelContext.expose_modules(globals(), {
    'lodel.logger': 'logger',
    'lodel.settings': 'Settings',
    'lodel.settings.utils': 'SettingsError',
    'lodel.leapi.query': ['LeInsertQuery', 'LeUpdateQuery', 'LeDeleteQuery',
                          'LeGetQuery'],
    'lodel.leapi.exceptions': ['LeApiError', 'LeApiErrors',
                               'LeApiDataCheckError', 'LeApiDataCheckErrors', 'LeApiQueryError',
                               'LeApiQueryErrors'],
    'lodel.plugin.exceptions': ['PluginError', 'PluginTypeError',
                                'LodelScriptError', 'DatasourcePluginError'],
    'lodel.exceptions': ['LodelFatalError'],
    'lodel.plugin.hooks': ['LodelHook'],
    'lodel.plugin': ['Plugin', 'DatasourcePlugin'],
    'lodel.leapi.datahandlers.base_classes': ['DatasConstructor', 'Reference']})

# @brief Stores the name of the field present in each LeObject that indicates
# the name of LeObject subclass represented by this object
CLASS_ID_FIELDNAME = "classname"

# @brief Wrapper class for LeObject getter & setter
#
# This class intend to provide easy & friendly access to LeObject fields values
# without name collision problems
# @note Wrapped methods are : LeObject.data() & LeObject.set_data()


class LeObjectValues(object):

    # @brief Construct a new LeObjectValues
    # @param fieldnames_callback method
    # @param set_callback method : The LeObject.set_datas() method of corresponding LeObject class
    # @param get_callback method : The LeObject.get_datas() method of corresponding LeObject class
    def __init__(self, fieldnames_callback, set_callback, get_callback):
        self._setter = set_callback
        self._getter = get_callback

    # @brief Provide read access to datas values
    # @note Read access should be provided for all fields
    # @param fname str : Field name
    def __getattribute__(self, fname):
        getter = super().__getattribute__('_getter')
        return getter(fname)

    # @brief Provide write access to datas values
    # @note Write acces shouldn't be provided for internal or immutable fields
    # @param fname str : Field name
    # @param fval * : the field value
    def __setattribute__(self, fname, fval):
        setter = super().__getattribute__('_setter')
        return setter(fname, fval)


class LeObject(object):

    # @brief boolean that tells if an object is abtract or not
    _abstract = None
    # @brief A dict that stores DataHandler instances indexed by field name
    _fields = None
    # @brief A tuple of fieldname (or a uniq fieldname) representing uid
    _uid = None
    # @brief Read only datasource ( see @ref lodel2_datasources )
    _ro_datasource = None
    # @brief Read & write datasource ( see @ref lodel2_datasources )
    _rw_datasource = None
    # @brief Store the list of child classes
    _child_classes = None
    # @brief Name of the datasource plugin
    _datasource_name = None

    def __new__(cls, **kwargs):

        self = object.__new__(cls)
        # @brief A dict that stores fieldvalues indexed by fieldname
        self.__datas = {fname: None for fname in self._fields}
        # @brief Store a list of initianilized fields when instanciation not complete else store True
        self.__initialized = list()
        # @brief Datas accessor. Instance of @ref LeObjectValues
        self.d = LeObjectValues(self.fieldnames, self.set_data, self.data)
        for fieldname, fieldval in kwargs.items():
            self.__datas[fieldname] = fieldval
            self.__initialized.append(fieldname)
        self.__is_initialized = False
        self.__set_initialized()
        return self

    # @brief Construct an object representing an Editorial component
    # @note Can be considered as EmClass instance
    def __init__(self, **kwargs):
        if self._abstract:
            raise NotImplementedError(
                "%s is abstract, you cannot instanciate it." % self.__class__.__name__)

        # Checks that uid is given
        for uid_name in self._uid:
            if uid_name not in kwargs:
                raise LeApiError("Cannot instanciate a LeObject without it's identifier")
            self.__datas[uid_name] = kwargs[uid_name]
            del(kwargs[uid_name])
            self.__initialized.append(uid_name)

        # Processing given fields
        allowed_fieldnames = self.fieldnames(include_ro=False)
        err_list = dict()
        for fieldname, fieldval in kwargs.items():
            if fieldname not in allowed_fieldnames:
                if fieldname in self._fields:
                    err_list[fieldname] = LeApiError(
                        "Value given but the field is internal")
                else:
                    err_list[fieldname] = LeApiError(
                        "Unknown fieldname : '%s'" % fieldname)
            else:
                self.__datas[fieldname] = fieldval
                self.__initialized.append(fieldname)
        if len(err_list) > 0:
            raise LeApiErrors(msg="Unable to __init__ %s" % self.__class__,
                              exceptions=err_list)
        self.__set_initialized()

    #-----------------------------------#
    #   Fields datas handling methods   #
    #-----------------------------------#

    # @brief Property method True if LeObject is initialized else False
    @property
    def initialized(self):
        return self.__is_initialized

    # @return The uid field name
    @classmethod
    def uid_fieldname(cls):
        return cls._uid

    # @brief Return a list of fieldnames
    # @param include_ro bool : if True include read only field names
    # @return a list of str
    @classmethod
    def fieldnames(cls, include_ro=False):
        if not include_ro:
            return [fname for fname in cls._fields if not cls._fields[fname].is_internal()]
        else:
            return list(cls._fields.keys())

    @classmethod
    def name2objname(cls, name):
        return name.title()

    # @brief Return the datahandler asssociated with a LeObject field
    # @param fieldname str : The fieldname
    # @return A data handler instance
    #@todo update class of exception raised
    @classmethod
    def data_handler(cls, fieldname):
        if not fieldname in cls._fields:
            raise NameError("No field named '%s' in %s" % (fieldname, cls.__name__))
        return cls._fields[fieldname]

    # @brief Getter for references datahandlers
    #@param with_backref bool : if true return only references with back_references
    #@return <code>{'fieldname': datahandler, ...}</code>
    @classmethod
    def reference_handlers(cls, with_backref=True):
        return {fname: fdh
                for fname, fdh in cls.fields(True).items()
                if fdh.is_reference() and
                (not with_backref or fdh.back_reference is not None)}

    # @brief Return a LeObject child class from a name
    # @warning This method has to be called from dynamically generated LeObjects
    # @param leobject_name str : LeObject name
    # @return A LeObject child class
    # @throw NameError if invalid name given
    @classmethod
    def name2class(cls, leobject_name):
        if cls.__module__ == 'lodel.leapi.leobject':
            raise NotImplementedError("Abstract method")
        mod = importlib.import_module(cls.__module__)
        try:
            return getattr(mod, leobject_name)
        except (AttributeError, TypeError):
            raise LeApiError("No LeObject named '%s'" % leobject_name)

    @classmethod
    def is_abstract(cls):
        return cls._abstract

    # @brief Field data handler getter
    #@param fieldname str : The field name
    #@return A datahandler instance
    #@throw NameError if the field doesn't exist
    @classmethod
    def field(cls, fieldname):
        try:
            return cls._fields[fieldname]
        except KeyError:
            raise NameError("No field named '%s' in %s" % (fieldname,
                                                           cls.__name__))
    # @return A dict with fieldname as key and datahandler as instance

    @classmethod
    def fields(cls, include_ro=False):
        if include_ro:
            return copy.copy(cls._fields)
        else:
            return {fname: cls._fields[fname] for fname in cls._fields\
                    if not cls._fields[fname].is_internal()}

    # @brief Return the list of parents classes
    #
    #@note the first item of the list is the current class, the second is it's
    # parent etc...
    #@param cls
    #@warning multiple inheritance broken by this method
    #@return a list of LeObject child classes
    #@todo multiple parent capabilities implementation
    @classmethod
    def hierarch(cls):
        res = [cls]
        cur = cls
        while True:
            cur = cur.__bases__[0]  # Multiple inheritance broken HERE
            if cur in (LeObject, object):
                break
            else:
                res.append(cur)
        return res

    # @brief Return a tuple a child classes
    #@return a tuple of child classes
    @classmethod
    def child_classes(cls):
        return copy.copy(cls._child_classes)

    # @brief Return the parent class that is the "source" of uid
    #
    # The method goal is to return the parent class that defines UID.
    #@return a LeObject child class or false if no UID defined
    @classmethod
    def uid_source(cls):
        if cls._uid is None or len(cls._uid) == 0:
            return False
        hierarch = cls.hierarch()
        prev = hierarch[0]
        uid_handlers = set(cls._fields[name] for name in cls._uid)
        for pcls in cls.hierarch()[1:]:
            puid_handlers = set(cls._fields[name] for name in pcls._uid)
            if set(pcls._uid) != set(prev._uid) \
                    or puid_handlers != uid_handlers:
                break
            prev = pcls
        return prev

    # @brief Initialise both datasources (ro and rw)
    #
    # This method is used once at dyncode load to replace the datasource string
    # by a datasource instance to avoid doing this operation for each query
    #@see LeObject::_init_datasource()
    @classmethod
    def _init_datasources(cls):
        if isinstance(cls._datasource_name, str):
            rw_ds = ro_ds = cls._datasource_name
        else:
            ro_ds, rw_ds = cls._datasource_name
        # Read only datasource initialisation
        cls._ro_datasource = DatasourcePlugin.init_datasource(ro_ds, True)
        if cls._ro_datasource is None:
            log_msg = "No read only datasource set for LeObject %s"
            log_msg %= cls.__name__
            logger.debug(log_msg)
        else:
            log_msg = "Read only datasource '%s' initialized for LeObject %s"
            log_msg %= (ro_ds, cls.__name__)
            logger.debug(log_msg)
        # Read write datasource initialisation
        cls._rw_datasource = DatasourcePlugin.init_datasource(rw_ds, False)
        if cls._ro_datasource is None:
            log_msg = "No read/write datasource set for LeObject %s"
            log_msg %= cls.__name__
            logger.debug(log_msg)
        else:
            log_msg = "Read/write datasource '%s' initialized for LeObject %s"
            log_msg %= (ro_ds, cls.__name__)
            logger.debug(log_msg)

    # @brief Return the uid of the current LeObject instance
    #@return the uid value
    #@warning Broke multiple uid capabilities
    def uid(self):
        return self.data(self._uid[0])

    # @brief Read only access to all datas
    # @note for fancy data accessor use @ref LeObject.g attribute @ref LeObjectValues instance
    # @param field_name str : field name
    # @return the Value
    # @throw RuntimeError if the field is not initialized yet
    # @throw NameError if name is not an existing field name
    def data(self, field_name):
        if field_name not in self._fields.keys():
            raise NameError("No such field in %s : %s" % (self.__class__.__name__, field_name))
        if not self.initialized and field_name not in self.__initialized:
            raise RuntimeError(
                "The field %s is not initialized yet (and have no value)" % field_name)
        return self.__datas[field_name]

    # @brief Read only access to all datas
    #@return a dict representing datas of current instance
    def datas(self, internal=False):
        return {fname: self.data(fname) for fname in self.fieldnames(internal)}

    # @brief Datas setter
    # @note for fancy data accessor use @ref LeObject.g attribute @ref LeObjectValues instance
    # @param fname str : field name
    # @param fval * : field value
    # @return the value that is really set
    # @throw NameError if fname is not valid
    # @throw AttributeError if the field is not writtable
    def set_data(self, fname, fval):
        if fname not in self.fieldnames(include_ro=False):
            if fname not in self._fields.keys():
                raise NameError("No such field in %s : %s" % (self.__class__.__name__, fname))
            else:
                raise AttributeError("The field %s is read only" % fname)
        self.__datas[fname] = fval
        if not self.initialized and fname not in self.__initialized:
            # Add field to initialized fields list
            self.__initialized.append(fname)
            self.__set_initialized()
        if self.initialized:
            # Running full value check
            ret = self.__check_modified_values()
            if ret is None:
                return self.__datas[fname]
            else:
                raise LeApiErrors("Data check error", ret)
        else:
            # Doing value check on modified field
            # We skip full validation here because the LeObject is not fully initialized yet
            val, err = self._fields[fname].check_data_value(fval)
            if isinstance(err, Exception):
                # Revert change to be in valid state
                del(self.__datas[fname])
                del(self.__initialized[-1])
                raise LeApiErrors("Data check error", {fname: err})
            else:
                self.__datas[fname] = val

    # @brief Update the __initialized attribute according to LeObject internal state
    #
    # Check the list of initialized fields and set __initialized to True if all fields initialized
    def __set_initialized(self):
        if isinstance(self.__initialized, list):
            expected_fields = self.fieldnames(include_ro=False) + self._uid
            if set(expected_fields) == set(self.__initialized):
                self.__is_initialized = True

    # @brief Designed to be called when datas are modified
    #
    # Make different checks on the LeObject given it's state (fully initialized or not)
    # @return None if checks succeded else return an exception list
    def __check_modified_values(self):
        err_list = dict()
        if self.__initialized is True:
            # Data value check
            for fname in self.fieldnames(include_ro=False):
                val, err = self._fields[fname].check_data_value(self.__datas[fname])
                if err is not None:
                    err_list[fname] = err
                else:
                    self.__datas[fname] = val
            # Data construction
            if len(err_list) == 0:
                for fname in self.fieldnames(include_ro=True):
                    try:
                        field = self._fields[fname]
                        self.__datas[fname] = field.construct_data(self,
                                                                   fname,
                                                                   self.__datas,
                                                                   self.__datas[fname]
                                                                   )
                    except Exception as exp:
                        err_list[fname] = exp
            # Datas consistency check
            if len(err_list) == 0:
                for fname in self.fieldnames(include_ro=True):
                    field = self._fields[fname]
                    ret = field.check_data_consistency(self, fname, self.__datas)
                    if isinstance(ret, Exception):
                        err_list[fname] = ret
        else:
            # Data value check for initialized datas
            for fname in self.__initialized:
                val, err = self._fields[fname].check_data_value(self.__datas[fname])
                if err is not None:
                    err_list[fname] = err
                else:
                    self.__datas[fname] = val
        return err_list if len(err_list) > 0 else None

    #--------------------#
    #   Other methods    #
    #--------------------#

    # @brief Temporary method to set private fields attribute at dynamic code generation
    #
    # This method is used in the generated dynamic code to set the _fields attribute
    # at the end of the dyncode parse
    # @warning This method is deleted once the dynamic code loaded
    # @param field_list list : list of EmField instance
    # @param cls
    @classmethod
    def _set__fields(cls, field_list):
        cls._fields = field_list

    # @brief Check that datas are valid for this type
    # @param datas dict : key == field name value are field values
    # @param complete bool : if True expect that datas provide values for all non internal fields
    # @param allow_internal bool : if True don't raise an error if a field is internal
    # @param cls
    # @return Checked datas
    # @throw LeApiDataCheckError if errors reported during check
    @classmethod
    def check_datas_value(cls, datas, complete=False, allow_internal=True):
        err_l = dict()  # Error storing
        correct = set()  # valid fields name
        mandatory = set()  # mandatory fields name
        for fname, datahandler in cls._fields.items():
            if allow_internal or not datahandler.is_internal():
                correct.add(fname)
                if complete and not hasattr(datahandler, 'default'):
                    mandatory.add(fname)
        provided = set(datas.keys())
        # searching for unknow fields
        for u_f in provided - correct:
            # Here we can check if the field is invalid or rejected because
            # it is internel
            err_l[u_f] = AttributeError("Unknown or unauthorized field '%s'" % u_f)
        # searching for missing mandatory fieldsa
        for missing in mandatory - provided:
            err_l[missing] = AttributeError("The data for field '%s' is missing" % missing)
        # Checks datas
        checked_datas = dict()
        for name, value in [(name, value) for name, value in datas.items() if name in correct]:
            dh = cls._fields[name]
            res = dh.check_data_value(value)
            checked_datas[name], err = res
            if err:
                err_l[name] = err

        if len(err_l) > 0:
            raise LeApiDataCheckErrors("Error while checking datas", err_l)
        return checked_datas

    # @brief Check and prepare datas
    #
    # @warning when complete = False we are not able to make construct_datas() and _check_data_consistency()
    #
    # @param datas dict : {fieldname : fieldvalue, ...}
    # @param complete bool : If True you MUST give all the datas
    # @param allow_internal : Wether or not interal fields are expected in datas
    # @param cls
    # @return Datas ready for use
    # @todo: complete is very unsafe, find a way to get rid of it
    @classmethod
    def prepare_datas(cls, datas, complete=False, allow_internal=True):
        if not complete:
            warnings.warn("\nActual implementation can make broken datas \
construction and consitency when datas are not complete\n")
        ret_datas = cls.check_datas_value(datas, complete, allow_internal)
        if isinstance(ret_datas, Exception):
            raise ret_datas
        if complete:
            ret_datas = cls._construct_datas(ret_datas)
            cls._check_datas_consistency(ret_datas)
        return ret_datas

    # @brief Construct datas values
    #
    # @param cls
    # @param datas dict : Datas that have been returned by LeCrud.check_datas_value() methods
    # @return A new dict of datas
    # @todo IMPLEMENTATION
    @classmethod
    def _construct_datas(cls, datas):
        constructor = DatasConstructor(cls, datas, cls._fields)
        ret = {
            fname: constructor[fname]
            for fname, ftype in cls._fields.items()
            if not ftype.is_internal() or ftype.internal != 'autosql'
        }
        return ret

    # @brief Check datas consistency
    # 
    # @warning assert that datas is complete
    # @param cls
    # @param datas dict : Datas that have been returned by LeCrud._construct_datas() method
    # @throw LeApiDataCheckError if fails
    @classmethod
    def _check_datas_consistency(cls, datas):
        err_l = []
        err_l = dict()
        for fname, dh in cls._fields.items():
            ret = dh.check_data_consistency(cls, fname, datas)
            if isinstance(ret, Exception):
                err_l[fname] = ret

        if len(err_l) > 0:
            raise LeApiDataCheckError("Datas consistency checks fails", err_l)

    # @brief Check datas consistency
    # 
    # @warning assert that datas is complete
    # @param cls
    # @param datas dict : Datas that have been returned by LeCrud.prepare_datas() method
    # @param type_query str : Type of query to be performed , default value : insert
    @classmethod
    def make_consistency(cls, datas, type_query='insert'):
        for fname, dh in cls._fields.items():
            ret = dh.make_consistency(fname, datas, type_query)

    # @brief Add a new instance of LeObject
    # @return a new uid en case of success, False otherwise
    @classmethod
    def insert(cls, datas):
        query = LeInsertQuery(cls)
        return query.execute(datas)

    # @brief Update an instance of LeObject
    #
    #@param datas : list of new datas
    def update(self, datas=None):
        datas = self.datas(internal=False) if datas is None else datas
        uids = self._uid
        query_filter = list()
        for uid in uids:
            query_filter.append((uid, '=', self.data(uid)))
        try:
            query = LeUpdateQuery(self.__class__, query_filter)
        except Exception as err:
            raise err

        try:
            result = query.execute(datas)
        except Exception as err:
            raise err

        return result

    # @brief Delete an instance of LeObject
    #
    #@return 1 if the objet has been deleted
    def delete(self):
        uids = self._uid
        query_filter = list()
        for uid in uids:
            query_filter.append((uid, '=', self.data(uid)))

        query = LeDeleteQuery(self.__class__, query_filter)

        result = query.execute()

        return result

    # @brief Delete instances of LeObject
    #@param query_filters list
    #@returns the number of deleted items
    @classmethod
    def delete_bundle(cls, query_filters):
        deleted = 0
        try:
            query = LeDeleteQuery(cls, query_filters)
        except Exception as err:
            raise err

        try:
            result = query.execute()
        except Exception as err:
            raise err
        if not result is None:
            deleted += result
        return deleted

    # @brief Get instances of LeObject
    #
    #@param query_filters dict : (filters, relational filters), with filters is a list of tuples : (FIELD, OPERATOR, VALUE) )
    #@param field_list list|None : list of string representing fields see
    #@ref leobject_filters
    #@param order list : A list of field names or tuple (FIELDNAME,[ASC | DESC])
    #@param group list : A list of field names or tuple (FIELDNAME,[ASC | DESC])
    #@param limit int : The maximum number of returned results
    #@param offset int : offset
    #@return a list of items (lists of (fieldname, fieldvalue))
    @classmethod
    def get(cls, query_filters, field_list=None, order=None, group=None, limit=None, offset=0):
        if field_list is not None:
            for uid in [uidname
                        for uidname in cls.uid_fieldname()
                        if uidname not in field_list]:
                field_list.append(uid)
            if CLASS_ID_FIELDNAME not in field_list:
                field_list.append(CLASS_ID_FIELDNAME)
        try:
            query = LeGetQuery(
                cls, query_filters=query_filters, field_list=field_list,
                order=order, group=group, limit=limit, offset=offset)
        except ValueError as err:
            raise err

        try:
            result = query.execute()
        except Exception as err:
            raise err

        objects = list()
        for res in result:
            res_cls = cls.name2class(res[CLASS_ID_FIELDNAME])
            inst = res_cls.__new__(res_cls, **res)
            objects.append(inst)

        return objects

    # @brief Retrieve an object given an UID
    #@todo broken multiple UID
    @classmethod
    def get_from_uid(cls, uid):
        if cls.uid_fieldname() is None:
            raise LodelFatalError(
                "No uid defined for class %s" % cls.__name__)
        uidname = cls.uid_fieldname()[0]  # Brokes composed UID
        res = cls.get([(uidname, '=', uid)])

        # dedoublonnage vu que query ou la datasource est bugué
        if len(res) > 1:
            res_cp = res
            res = []
            while len(res_cp) > 0:
                cur_res = res_cp.pop()
                if cur_res.uid() in [r.uid() for r in res_cp]:
                    logger.error("DOUBLON detected in query results !!!")
                else:
                    res.append(cur_res)
        if len(res) > 1:
            raise LodelFatalError("Get from uid returned more than one \
object ! For class %s with uid value = %s" % (cls, uid))
        elif len(res) == 0:
            return None
        return res[0]