import yaml
from http import HTTPStatus
from copy import deepcopy

__author__ = "Alfonso Tierno <alfonso.tiernosepulveda@telefonica.com>"


class DbException(Exception):

    def __init__(self, message, http_code=HTTPStatus.NOT_FOUND):
        # TODO change to http.HTTPStatus instead of int that allows .value and .name
        self.http_code = http_code
        Exception.__init__(self, "database exception " + message)


class DbBase(object):

    def __init__(self):
        pass

    def db_connect(self, config):
        pass

    def db_disconnect(self):
        pass

    def get_list(self, table, filter={}):
        raise DbException("Method 'get_list' not implemented")

    def get_one(self, table, filter={}, fail_on_empty=True, fail_on_more=True):
        raise DbException("Method 'get_one' not implemented")

    def create(self, table, indata):
        raise DbException("Method 'create' not implemented")

    def del_list(self, table, filter={}):
        raise DbException("Method 'del_list' not implemented")

    def del_one(self, table, filter={}, fail_on_empty=True):
        raise DbException("Method 'del_one' not implemented")


def deep_update(dict_to_change, dict_reference, key_list=None):
    """
    Modifies one dictionary with the information of the other following https://tools.ietf.org/html/rfc7396
    Basically is a recursive python 'dict_to_change.update(dict_reference)', but a value of None is used to delete.
    It implements an extra feature that allows modifying an array. RFC7396 only allows replacing the entire array.
    For that, dict_reference should contains a dict with keys starting by "$" with the following meaning:
        $[index]    <index> is an integer for targeting a concrete index from dict_to_change array. If the value is None
                    the element of the array is deleted, otherwise it is edited.
        $+[index]   The value is inserted at this <index>. A value of None has not sense and an exception is raised.
        $+          The value is appended at the end. A value of None has not sense and an exception is raised.
        $val        It looks for all the items in the array dict_to_change equal to <val>. <val> is evaluated as yaml,
                    that is, numbers are taken as type int, true/false as boolean, etc. Use quotes to force string.
                    Nothing happens if no match is found. If the value is None the matched elements are deleted.
        $key: val   In case a dictionary is passed in yaml format, if looks for all items in the array dict_to_change
                    that are dictionaries and contains this <key> equal to <val>. Several keys can be used by yaml
                    format '{key: val, key: val, ...}'; and all of them mast match. Nothing happens if no match is
                    found. If value is None the matched items are deleted, otherwise they are edited.
        $+val       If no match if found (see '$val'), the value is appended to the array. If any match is found nothing
                    is changed. A value of None has not sense.
        $+key: val  If no match if found (see '$key: val'), the value is appended to the array. If any match is found
                    nothing is changed. A value of None has not sense.
    If there are several editions, insertions and deletions; editions and deletions are done first in reverse index
        order; then insertions also in reverse index order; and finally appends in any order. So indexes used at
        insertions must take into account the deleted items.
    :param dict_to_change:  Target dictionary to be changed.
    :param dict_reference: Dictionary that contains changes to be applied.
    :param key_list: This is used internally for recursive calls. Do not fill this parameter.
    :return: none or raises and exception only at array modification when there is a bad format or conflict.
    """
    def _deep_update_array(array_to_change, _dict_reference, _key_list):
        to_append = {}
        to_insert_at_index = {}
        values_to_edit_delete = {}
        indexes_to_edit_delete = []
        array_edition = None
        _key_list.append("")
        for k in _dict_reference:
            _key_list[-1] = str(k)
            if not isinstance(k, str) or not k.startswith("$"):
                if array_edition is True:
                    raise DbException("Found array edition (keys starting with '$') and pure dictionary edition in the"
                                      " same dict at '{}'".format(":".join(_key_list[:-1])))
                array_edition = False
                continue
            else:
                if array_edition is False:
                    raise DbException("Found array edition (keys starting with '$') and pure dictionary edition in the"
                                      " same dict at '{}'".format(":".join(_key_list[:-1])))
                array_edition = True
            insert = False
            indexes = []  # indexes to edit or insert
            kitem = k[1:]
            if kitem.startswith('+'):
                insert = True
                kitem = kitem[1:]
                if _dict_reference[k] is None:
                    raise DbException("A value of None has not sense for insertions at '{}'".format(
                        ":".join(_key_list)))

            if kitem.startswith('[') and kitem.endswith(']'):
                try:
                    index = int(kitem[1:-1])
                    if index < 0:
                        index += len(array_to_change)
                    if index < 0:
                        index = 0  # skip outside index edition
                    indexes.append(index)
                except Exception:
                    raise DbException("Wrong format at '{}'. Expecting integer index inside quotes".format(
                        ":".join(_key_list)))
            elif kitem:
                # match_found_skip = False
                try:
                    filter_in = yaml.safe_load(kitem)
                except Exception:
                    raise DbException("Wrong format at '{}'. Expecting '$<yaml-format>'".format(":".join(_key_list)))
                if isinstance(filter_in, dict):
                    for index, item in enumerate(array_to_change):
                        for filter_k, filter_v in filter_in.items():
                            if not isinstance(item, dict) or filter_k not in item or item[filter_k] != filter_v:
                                break
                        else:  # match found
                            if insert:
                                # match_found_skip = True
                                insert = False
                                break
                            else:
                                indexes.append(index)
                else:
                    index = 0
                    try:
                        while True:  # if not match a ValueError exception will be raise
                            index = array_to_change.index(filter_in, index)
                            if insert:
                                # match_found_skip = True
                                insert = False
                                break
                            indexes.append(index)
                            index += 1
                    except ValueError:
                        pass

                # if match_found_skip:
                #     continue
            elif not insert:
                raise DbException("Wrong format at '{}'. Expecting '$+', '$[<index]' or '$[<filter>]'".format(
                    ":".join(_key_list)))
            for index in indexes:
                if insert:
                    if index in to_insert_at_index and to_insert_at_index[index] != _dict_reference[k]:
                        # Several different insertions on the same item of the array
                        raise DbException("Conflict at '{}'. Several insertions on same array index {}".format(
                            ":".join(_key_list), index))
                    to_insert_at_index[index] = _dict_reference[k]
                else:
                    if index in indexes_to_edit_delete and values_to_edit_delete[index] != _dict_reference[k]:
                        # Several different editions on the same item of the array
                        raise DbException("Conflict at '{}'. Several editions on array index {}".format(
                            ":".join(_key_list), index))
                    indexes_to_edit_delete.append(index)
                    values_to_edit_delete[index] = _dict_reference[k]
            if not indexes:
                if insert:
                    to_append[k] = _dict_reference[k]
                # elif _dict_reference[k] is not None:
                #     raise DbException("Not found any match to edit in the array, or wrong format at '{}'".format(
                #         ":".join(_key_list)))

        # edition/deletion is done before insertion
        indexes_to_edit_delete.sort(reverse=True)
        for index in indexes_to_edit_delete:
            _key_list[-1] = str(index)
            try:
                if values_to_edit_delete[index] is None:  # None->Anything
                    try:
                        del (array_to_change[index])
                    except IndexError:
                        pass  # it is not consider an error if this index does not exist
                elif not isinstance(values_to_edit_delete[index], dict):  # NotDict->Anything
                    array_to_change[index] = deepcopy(values_to_edit_delete[index])
                elif isinstance(array_to_change[index], dict):  # Dict->Dict
                    deep_update(array_to_change[index], values_to_edit_delete[index], _key_list)
                else:  # Dict->NotDict
                    if isinstance(array_to_change[index], list):  # Dict->List. Check extra array edition
                        if _deep_update_array(array_to_change[index], values_to_edit_delete[index], _key_list):
                            continue
                    array_to_change[index] = deepcopy(values_to_edit_delete[index])
                    # calling deep_update to delete the None values
                    deep_update(array_to_change[index], values_to_edit_delete[index], _key_list)
            except IndexError:
                raise DbException("Array edition index out of range at '{}'".format(":".join(_key_list)))

        # insertion with indexes
        to_insert_indexes = list(to_insert_at_index.keys())
        to_insert_indexes.sort(reverse=True)
        for index in to_insert_indexes:
            array_to_change.insert(index, to_insert_at_index[index])

        # append
        for k, insert_value in to_append.items():
            _key_list[-1] = str(k)
            insert_value_copy = deepcopy(insert_value)
            if isinstance(insert_value_copy, dict):
                # calling deep_update to delete the None values
                deep_update(insert_value_copy, insert_value, _key_list)
            array_to_change.append(insert_value_copy)

        _key_list.pop()
        if array_edition:
            return True
        return False

    if key_list is None:
        key_list = []
    key_list.append("")
    for k in dict_reference:
        key_list[-1] = str(k)
        if dict_reference[k] is None:   # None->Anything
            if k in dict_to_change:
                del dict_to_change[k]
        elif not isinstance(dict_reference[k], dict):  # NotDict->Anything
            dict_to_change[k] = deepcopy(dict_reference[k])
        elif k not in dict_to_change:  # Dict->Empty
            dict_to_change[k] = deepcopy(dict_reference[k])
            # calling deep_update to delete the None values
            deep_update(dict_to_change[k], dict_reference[k], key_list)
        elif isinstance(dict_to_change[k], dict):  # Dict->Dict
            deep_update(dict_to_change[k], dict_reference[k], key_list)
        else:       # Dict->NotDict
            if isinstance(dict_to_change[k], list):  # Dict->List. Check extra array edition
                if _deep_update_array(dict_to_change[k], dict_reference[k], key_list):
                    continue
            dict_to_change[k] = deepcopy(dict_reference[k])
            # calling deep_update to delete the None values
            deep_update(dict_to_change[k], dict_reference[k], key_list)
    key_list.pop()