# Copyright 2022 Memgraph Ltd.
#
# Use of this software is governed by the Business Source License
# included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
# License, and you may not use this file except in compliance with the Business Source License.
#
# As of the Change Date specified in that file, in accordance with
# the Business Source License, use of this software will be governed
# by the Apache License, Version 2.0, included in the file
# licenses/APL.txt.

"""
This module provides the API for usage in custom openCypher procedures.
"""

# C API using `mgp_memory` is not exposed in Python, instead the usage of such
# API is hidden behind Python API. Any function requiring an instance of
# `mgp_memory` should go through a `ProcCtx` instance.
#
# `mgp_value` does not exist as such in Python, instead all `mgp_value`
# instances are marshalled to an appropriate Python object. This implies that
# `mgp_list` and `mgp_map` are mapped to `list` and `dict` respectively.
#
# Only the public API is stubbed out here. Any private details are left for the
# actual implementation. Functions have type annotations as supported by Python
# 3.5, but variable type annotations are only available with Python 3.6+

import datetime
import inspect
import sys
import typing
from collections import namedtuple
from functools import wraps

import _mgp


class InvalidContextError(Exception):
    """
    Signals using a graph element instance outside of the registered procedure.
    """

    pass


class UnknownError(_mgp.UnknownError):
    """
    Signals unspecified failure.
    """

    pass


class UnableToAllocateError(_mgp.UnableToAllocateError):
    """
    Signals failed memory allocation.
    """

    pass


class InsufficientBufferError(_mgp.InsufficientBufferError):
    """
    Signals that some buffer is not big enough.
    """

    pass


class OutOfRangeError(_mgp.OutOfRangeError):
    """
    Signals that an index-like parameter has a value that is outside its
    possible values.
    """

    pass


class LogicErrorError(_mgp.LogicErrorError):
    """
    Signals faulty logic within the program such as violating logical
    preconditions or class invariants and may be preventable.
    """

    pass


class DeletedObjectError(_mgp.DeletedObjectError):
    """
    Signals accessing an already deleted object.
    """

    pass


class InvalidArgumentError(_mgp.InvalidArgumentError):
    """
    Signals that some of the arguments have invalid values.
    """

    pass


class KeyAlreadyExistsError(_mgp.KeyAlreadyExistsError):
    """
    Signals that a key already exists in a container-like object.
    """

    pass


class ImmutableObjectError(_mgp.ImmutableObjectError):
    """
    Signals modification of an immutable object.
    """

    pass


class ValueConversionError(_mgp.ValueConversionError):
    """
    Signals that the conversion failed between python and cypher values.
    """

    pass


class SerializationError(_mgp.SerializationError):
    """
    Signals serialization error caused by concurrent modifications from
    different transactions.
    """

    pass


class AuthorizationError(_mgp.AuthorizationError):
    """
    Signals that the user doesn't have sufficient permissions to perform
    procedure call.
    """

    pass


class Label:
    """Label of a `Vertex`."""

    __slots__ = ("_name",)

    def __init__(self, name: str):
        self._name = name

    @property
    def name(self) -> str:
        """
        Get the name of the label.

        Returns:
            A string that represents the name of the label.

        Example:
            ```label.name```
        """
        return self._name

    def __eq__(self, other) -> bool:
        if isinstance(other, Label):
            return self._name == other.name
        if isinstance(other, str):
            return self._name == other
        return NotImplemented


# Named property value of a Vertex or an Edge.
# It would be better to use typing.NamedTuple with typed fields, but that is
# not available in Python 3.5.
Property = namedtuple("Property", ("name", "value"))


class Properties:
    """
    A collection of properties either on a `Vertex` or an `Edge`.
    """

    __slots__ = (
        "_vertex_or_edge",
        "_len",
    )

    def __init__(self, vertex_or_edge):
        if not isinstance(vertex_or_edge, (_mgp.Vertex, _mgp.Edge)):
            raise TypeError("Expected '_mgp.Vertex' or '_mgp.Edge', got {}".format(type(vertex_or_edge)))
        self._len = None
        self._vertex_or_edge = vertex_or_edge

    def __deepcopy__(self, memo):
        # This is the same as the shallow copy, as the underlying C API should
        # not support deepcopy. Besides, it doesn't make much sense to actually
        # copy _mgp.Edge and _mgp.Vertex types as they are actually references
        # to graph elements and not proper values.
        return Properties(self._vertex_or_edge)

    def get(self, property_name: str, default=None) -> object:
        """
        Get the value of a property with the given name or return default value.

        Args:
            property_name: String that represents property name.
            default: Default value return if there is no property.

        Returns:
            Any object value that property under `property_name` has or default value otherwise.

        Raises:
            InvalidContextError: If `edge` or `vertex` is out of context.
            UnableToAllocateError: If unable to allocate a `mgp.Value`.
            DeletedObjectError: If the `object` has been deleted.

        Examples:
            ```
            vertex.properties.get(property_name)
            edge.properties.get(property_name)
            ```

        """
        if not self._vertex_or_edge.is_valid():
            raise InvalidContextError()
        try:
            return self[property_name]
        except KeyError:
            return default

    def set(self, property_name: str, value: object) -> None:
        """
        Set the value of the property. When the value is `None`, then the
        property is removed.

        Args:
            property_name: String that represents property name.
            value: Object that represents value to be set.

        Raises:
            UnableToAllocateError: If unable to allocate memory for storing the property.
            ImmutableObjectError: If the object is immutable.
            DeletedObjectError: If the object has been deleted.
            SerializationError: If the object has been modified by another transaction.
            ValueConversionError: If `value` is vertex, edge or path.

        Examples:
            ```
            vertex.properties.set(property_name, value)
            edge.properties.set(property_name, value)
            ```

        """
        self[property_name] = value

    def items(self) -> typing.Iterable[Property]:
        """
        Iterate over the properties. Doesn’t return a dynamic view of the properties but copies the
        current properties.

        Returns:
            Iterable `Property` of names and values.

        Raises:
            InvalidContextError: If edge or vertex is out of context.
            UnableToAllocateError: If unable to allocate an iterator.
            DeletedObjectError: If the object has been deleted.

        Examples:
            ```
            items = vertex.properties.items()
            for it in items:
                name = it.name
                value = it.value
            ```
            ```
            items = edge.properties.items()
            for it in items:
                name = it.name
                value = it.value
            ```

        """
        if not self._vertex_or_edge.is_valid():
            raise InvalidContextError()
        properties_it = self._vertex_or_edge.iter_properties()
        prop = properties_it.get()
        while prop is not None:
            yield Property(*prop)
            if not self._vertex_or_edge.is_valid():
                raise InvalidContextError()
            prop = properties_it.next()

    def keys(self) -> typing.Iterable[str]:
        """
        Iterate over property names. Doesn’t return a dynamic view of the property names but copies the
        name of the current properties.

        Returns:
            Iterable list of strings that represent names/keys of properties.

        Raises:
            InvalidContextError: If edge or vertex is out of context.
            UnableToAllocateError: If unable to allocate an iterator.
            DeletedObjectError: If the object has been deleted.

        Examples:
            ```
            graph.vertex.properties.keys()
            graph.edge.properties.keys()
            ```
        """
        if not self._vertex_or_edge.is_valid():
            raise InvalidContextError()
        for item in self.items():
            yield item.name

    def values(self) -> typing.Iterable[object]:
        """
        Iterate over property values. Doesn’t return a dynamic view of the property values but copies the
        value of the current properties.

        Returns:
            Iterable list of property values.

        Raises:
            InvalidContextError: If edge or vertex is out of context.
            UnableToAllocateError: If unable to allocate an iterator.
            DeletedObjectError: If the object has been deleted.

        Examples:
            ```
            vertex.properties.values()
            edge.properties.values()
            ```

        """
        if not self._vertex_or_edge.is_valid():
            raise InvalidContextError()
        for item in self.items():
            yield item.value

    def __len__(self) -> int:
        """
        Get the number of properties.

        Returns:
            A number of properties on vertex or edge.

        Raises:
            InvalidContextError: If edge or vertex is out of context.
            UnableToAllocateError: If unable to allocate an iterator.
            DeletedObjectError: If the object has been deleted.

        Examples:
            ```
            len(vertex.properties)
            len(edge.properties)
            ```

        """
        if not self._vertex_or_edge.is_valid():
            raise InvalidContextError()
        if self._len is None:
            self._len = sum(1 for item in self.items())
        return self._len

    def __iter__(self) -> typing.Iterable[str]:
        """
        Iterate over property names.

        Returns:
            Iterable list of strings that represent names of properties.

        Raises:
            InvalidContextError: If edge or vertex is out of context.
            UnableToAllocateError: If unable to allocate an iterator.
            DeletedObjectError: If the object has been deleted.

        Examples:
            ```
            iter(vertex.properties)
            iter(edge.properties)
            ```

        """
        if not self._vertex_or_edge.is_valid():
            raise InvalidContextError()
        for item in self.items():
            yield item.name

    def __getitem__(self, property_name: str) -> object:
        """
        Get the value of a property with the given name or raise KeyError.

        Args:
            property_name: String that represents property name.

        Returns:
            Any value that property under property_name have.

        Raises:
            InvalidContextError: If edge or vertex is out of context.
            UnableToAllocateError: If unable to allocate a mgp.Value.
            DeletedObjectError: If the object has been deleted.

        Examples:
            ```
            vertex.properties[property_name]
            edge.properties[property_name]
            ```

        """
        if not self._vertex_or_edge.is_valid():
            raise InvalidContextError()
        prop = self._vertex_or_edge.get_property(property_name)
        if prop is None:
            raise KeyError()
        return prop

    def __setitem__(self, property_name: str, value: object) -> None:
        """
        Set the value of the property. When the value is `None`, then the
        property is removed.

        Args:
            property_name: String that represents property name.
            value: Object that represents value to be set.

        Raises:
            UnableToAllocateError: If unable to allocate memory for storing the property.
            ImmutableObjectError: If the object is immutable.
            DeletedObjectError: If the object has been deleted.
            SerializationError: If the object has been modified by another transaction.
            ValueConversionError: If `value` is vertex, edge or path.

        Examples:
            ```
            vertex.properties[property_name] = value
            edge.properties[property_name] = value
            ```
        """
        if not self._vertex_or_edge.is_valid():
            raise InvalidContextError()

        self._vertex_or_edge.set_property(property_name, value)

    def __contains__(self, property_name: str) -> bool:
        """
        Check if there is a property with the given name.

        Args:
            property_name: String that represents property name

        Returns:
            Bool value that depends if there is with a given name.

        Raises:
            InvalidContextError: If edge or vertex is out of context.
            UnableToAllocateError: If unable to allocate a mgp.Value.
            DeletedObjectError: If the object has been deleted.

        Examples:
            ```
            if property_name in vertex.properties:
            ```
            ```
            if property_name in edge.properties:
            ```
        """
        if not self._vertex_or_edge.is_valid():
            raise InvalidContextError()
        try:
            _ = self[property_name]
            return True
        except KeyError:
            return False

    def set_properties(self, properties: dict) -> None:
        if not self._vertex_or_edge.is_valid():
            raise InvalidContextError()

        self._vertex_or_edge.set_properties(properties)


class EdgeType:
    """Type of an Edge."""

    __slots__ = ("_name",)

    def __init__(self, name):
        self._name = name

    @property
    def name(self) -> str:
        """
        Get the name of EdgeType.

        Returns:
            A string that represents the name of EdgeType.

        Example:
            ```edge.type.name```
        """
        return self._name

    def __eq__(self, other) -> bool:
        if isinstance(other, EdgeType):
            return self.name == other.name
        if isinstance(other, str):
            return self.name == other
        return NotImplemented


if sys.version_info >= (3, 5, 2):
    EdgeId = typing.NewType("EdgeId", int)
else:
    EdgeId = int


class Edge:
    """Edge in the graph database.

    Access to an Edge is only valid during a single execution of a procedure in
    a query. You should not globally store an instance of an Edge. Using an
    invalid Edge instance will raise InvalidContextError.

    """

    __slots__ = ("_edge",)

    def __init__(self, edge):
        if not isinstance(edge, _mgp.Edge):
            raise TypeError("Expected '_mgp.Edge', got '{}'".format(type(edge)))
        self._edge = edge

    def __deepcopy__(self, memo):
        # This is the same as the shallow copy, because we want to share the
        # underlying C struct. Besides, it doesn't make much sense to actually
        # copy _mgp.Edge as that is actually a reference to a graph element
        # and not a proper value.
        return Edge(self._edge)

    def is_valid(self) -> bool:
        """
        Check if `edge` is in a valid context and may be used.

        Returns:
            A `bool` value depends on if the `edge` is in a valid context.

        Examples:
            ```edge.is_valid()```

        """
        return self._edge.is_valid()

    def underlying_graph_is_mutable(self) -> bool:
        """
        Check if the `graph` can be modified.

        Returns:
            A `bool` value depends on if the `graph` is mutable.

        Examples:
            ```edge.underlying_graph_is_mutable()```

        """
        if not self.is_valid():
            raise InvalidContextError()
        return self._edge.underlying_graph_is_mutable()

    @property
    def id(self) -> EdgeId:
        """
        Get the ID of the edge.

        Returns:
            `EdgeId` represents ID of the edge.

        Raises:
            InvalidContextError: If edge is out of context.

        Examples:
            ```edge.id```
        """
        if not self.is_valid():
            raise InvalidContextError()
        return self._edge.get_id()

    @property
    def type(self) -> EdgeType:
        """
        Get the type of edge.

        Returns:
            `EdgeType` describing the type of edge.

        Raises:
            InvalidContextError: If edge is out of context.

        Examples:
            ```edge.type```
        """
        if not self.is_valid():
            raise InvalidContextError()
        return EdgeType(self._edge.get_type_name())

    @property
    def from_vertex(self) -> "Vertex":
        """
        Get the source vertex.

        Returns:
            `Vertex` from where the edge is directed.

        Raises:
            InvalidContextError: If edge is out of context.

        Examples:
            ```edge.from_vertex```
        """
        if not self.is_valid():
            raise InvalidContextError()
        return Vertex(self._edge.from_vertex())

    @property
    def to_vertex(self) -> "Vertex":
        """
        Get the destination vertex.

        Returns:
            `Vertex` to where the edge is directed.

        Raises:
            InvalidContextError: If edge is out of context.

        Examples:
            ```edge.to_vertex```
        """
        if not self.is_valid():
            raise InvalidContextError()
        return Vertex(self._edge.to_vertex())

    @property
    def properties(self) -> Properties:
        """
        Get the properties of the edge.

        Returns:
            All `Properties` of edge.

        Raises:
            InvalidContextError: If edge is out of context.

        Examples:
            ```edge.properties```
        """
        if not self.is_valid():
            raise InvalidContextError()
        return Properties(self._edge)

    def __eq__(self, other) -> bool:
        """Raise InvalidContextError."""
        if not self.is_valid():
            raise InvalidContextError()
        if not isinstance(other, Edge):
            return NotImplemented
        return self._edge == other._edge

    def __hash__(self) -> int:
        return hash(self.id)


if sys.version_info >= (3, 5, 2):
    VertexId = typing.NewType("VertexId", int)
else:
    VertexId = int


class Vertex:
    """Vertex in the graph database.

    Access to a Vertex is only valid during a single execution of a procedure
    in a query. You should not globally store an instance of a Vertex. Using an
    invalid Vertex instance will raise InvalidContextError.
    """

    __slots__ = ("_vertex",)

    def __init__(self, vertex):
        if not isinstance(vertex, _mgp.Vertex):
            raise TypeError("Expected '_mgp.Vertex', got '{}'".format(type(vertex)))
        self._vertex = vertex

    def __deepcopy__(self, memo):
        # This is the same as the shallow copy, because we want to share the
        # underlying C struct. Besides, it doesn't make much sense to actually
        # copy _mgp.Vertex as that is actually a reference to a graph element
        # and not a proper value.
        return Vertex(self._vertex)

    def is_valid(self) -> bool:
        """
        Checks if `Vertex` is in valid context and may be used.

        Returns:
            A `bool` value depends on if the `Vertex` is in a valid context.

        Examples:
            ```vertex.is_valid()```

        """
        return self._vertex.is_valid()

    def underlying_graph_is_mutable(self) -> bool:
        """
        Check if the `graph` is mutable.

        Returns:
            A `bool` value depends on if the `graph` is mutable.

        Examples:
            ```vertex.underlying_graph_is_mutable()```

        """
        if not self.is_valid():
            raise InvalidContextError()
        return self._vertex.underlying_graph_is_mutable()

    @property
    def id(self) -> VertexId:
        """
         Get the ID of the Vertex.

        Returns:
            `VertexId` represents ID of the vertex.

        Raises:
            InvalidContextError: If vertex is out of context.

        Examples:
            ```vertex.id```
        """
        if not self.is_valid():
            raise InvalidContextError()
        return self._vertex.get_id()

    @property
    def labels(self) -> typing.Tuple[Label]:
        """
        Get the labels of the vertex.

        Returns:
            A tuple of `Label` representing vertex Labels

        Raises:
            InvalidContextError: If vertex is out of context.
            OutOfRangeError: If some of the labels are removed while collecting the labels.
            DeletedObjectError: If `Vertex` has been deleted.

        Examples:
            ```vertex.labels```
        """
        if not self.is_valid():
            raise InvalidContextError()
        return tuple(Label(self._vertex.label_at(i)) for i in range(self._vertex.labels_count()))

    def add_label(self, label: str) -> None:
        """
        Add the label to the vertex.

        Args:
            label: String label to be added.

        Raises:
            InvalidContextError: If `Vertex` is out of context.
            UnableToAllocateError: If unable to allocate memory for storing the label.
            ImmutableObjectError: If `Vertex` is immutable.
            DeletedObjectError: If `Vertex` has been deleted.
            SerializationError: If `Vertex` has been modified by another transaction.

        Examples:
            ```vertex.add_label(label)```
        """
        if not self.is_valid():
            raise InvalidContextError()
        return self._vertex.add_label(label)

    def remove_label(self, label: str) -> None:
        """
        Remove the label from the vertex.

        Args:
            label: String label to be deleted
        Raises:
            InvalidContextError: If `Vertex` is out of context.
            ImmutableObjectError: If `Vertex` is immutable.
            DeletedObjectError: If `Vertex` has been deleted.
            SerializationError: If `Vertex` has been modified by another transaction.

        Examples:
            ```vertex.remove_label(label)```
        """
        if not self.is_valid():
            raise InvalidContextError()
        return self._vertex.remove_label(label)

    @property
    def properties(self) -> Properties:
        """
        Get the properties of the vertex.

        Returns:
            `Properties` on a current vertex.

        Raises:
            InvalidContextError: If `Vertex` is out of context.

        Examples:
            ```vertex.properties```
        """
        if not self.is_valid():
            raise InvalidContextError()
        return Properties(self._vertex)

    @property
    def in_edges(self) -> typing.Iterable[Edge]:
        """
        Iterate over inbound edges of the vertex.
        Doesn’t return a dynamic view of the edges but copies the
        current inbound edges.

        Returns:
            Iterable list of `Edge` objects that are directed in towards the current vertex.

        Raises:
            InvalidContextError: If `Vertex` is out of context.
            UnableToAllocateError: If unable to allocate an iterator.
            DeletedObjectError: If `Vertex` has been deleted.

        Examples:
            ```for edge in vertex.in_edges:```
        """
        if not self.is_valid():
            raise InvalidContextError()
        edges_it = self._vertex.iter_in_edges()
        edge = edges_it.get()
        while edge is not None:
            yield Edge(edge)
            if not self.is_valid():
                raise InvalidContextError()
            edge = edges_it.next()

    @property
    def out_edges(self) -> typing.Iterable[Edge]:
        """
        Iterate over outbound edges of the vertex.

        Doesn’t return a dynamic view of the edges but copies the
        current outbound edges.

        Returns:
            Iterable list of `Edge` objects that are directed out of the current vertex.

        Raises:
            InvalidContextError: If `Vertex` is out of context.
            UnableToAllocateError: If unable to allocate an iterator.
            DeletedObjectError: If `Vertex` has been deleted.

        Examples:
            ```for edge in vertex.out_edges:```
        """
        if not self.is_valid():
            raise InvalidContextError()
        edges_it = self._vertex.iter_out_edges()
        edge = edges_it.get()
        while edge is not None:
            yield Edge(edge)
            if not self.is_valid():
                raise InvalidContextError()
            edge = edges_it.next()

    def __eq__(self, other) -> bool:
        """Raise InvalidContextError"""
        if not self.is_valid():
            raise InvalidContextError()
        if not isinstance(other, Vertex):
            return NotImplemented
        return self._vertex == other._vertex

    def __hash__(self) -> int:
        return hash(self.id)


class Path:
    """Path containing Vertex and Edge instances."""

    __slots__ = ("_path", "_vertices", "_edges")

    def __init__(self, starting_vertex_or_path: typing.Union[_mgp.Path, Vertex]):
        """Initialize with a starting Vertex.

        Raises:
            InvalidContextError: If passed in Vertex is invalid.
            UnableToAllocateError: If cannot allocate a path.
        """
        # We cache calls to `vertices` and `edges`, so as to avoid needless
        # allocations at the C level.
        self._vertices = None
        self._edges = None
        # Accepting _mgp.Path is just for internal usage.
        if isinstance(starting_vertex_or_path, _mgp.Path):
            self._path = starting_vertex_or_path
        elif isinstance(starting_vertex_or_path, Vertex):
            vertex = starting_vertex_or_path._vertex
            if not vertex.is_valid():
                raise InvalidContextError()
            self._path = _mgp.Path.make_with_start(vertex)
        else:
            raise TypeError("Expected '_mgp.Vertex' or '_mgp.Path', got '{}'".format(type(starting_vertex_or_path)))

    def __copy__(self):
        if not self.is_valid():
            raise InvalidContextError()
        assert len(self.vertices) >= 1
        path = Path(self.vertices[0])
        for e in self.edges:
            path.expand(e)
        return path

    def __deepcopy__(self, memo):
        try:
            return Path(memo[id(self._path)])
        except KeyError:
            pass
        # This is the same as the shallow copy, as the underlying C API should
        # not support deepcopy. Besides, it doesn't make much sense to actually
        # copy _mgp.Edge and _mgp.Vertex types as they are actually references
        # to graph elements and not proper values.
        path = self.__copy__()
        memo[id(self._path)] = path._path
        return path

    def is_valid(self) -> bool:
        """
        Check if `Path` is in valid context and may be used.

        Returns:
            A `bool` value depends on if the `Path` is in a valid context.

        Examples:
            ```path.is_valid()```
        """
        return self._path.is_valid()

    def expand(self, edge: Edge):
        """
        Append an edge continuing from the last vertex on the path.

        The last vertex on the path will become the other endpoint of the given
        edge, as continued from the current last vertex.

        Args:
            edge: `Edge` that is added to the path

        Raises:
            InvalidContextError: If using an invalid `Path` instance or if passed in `Edge` is invalid.
            LogicErrorError: If the current last vertex in the path is not part of the given edge.
            UnableToAllocateError: If unable to allocate memory for path extension.

        Examples:
            ```path.expand(edge)```
        """
        if not isinstance(edge, Edge):
            raise TypeError("Expected '_mgp.Edge', got '{}'".format(type(edge)))
        if not self.is_valid() or not edge.is_valid():
            raise InvalidContextError()
        self._path.expand(edge._edge)
        # Invalidate our cached tuples
        self._vertices = None
        self._edges = None

    def pop(self):
        """
        Remove the last node and the last relationship from the path.

        Raises:
            InvalidContextError: If using an invalid `Path` instance
            OutOfRangeError: If the path contains no relationships.

        Examples:
            ```path.pop()```
        """
        if not self.is_valid():
            raise InvalidContextError()
        self._path.pop()
        # Invalidate our cached tuples
        self._vertices = None
        self._edges = None

    @property
    def vertices(self) -> typing.Tuple[Vertex, ...]:
        """
        Vertices are ordered from the start to the end of the path.

        Returns:
            A tuple of `Vertex` objects order from start to end of the path.

        Raises:
            InvalidContextError: If using an invalid Path instance.

        Examples:
            ```path.vertices```
        """
        if not self.is_valid():
            raise InvalidContextError()
        if self._vertices is None:
            num_vertices = self._path.size() + 1
            self._vertices = tuple(Vertex(self._path.vertex_at(i)) for i in range(num_vertices))
        return self._vertices

    @property
    def edges(self) -> typing.Tuple[Edge, ...]:
        """
        Edges are ordered from the start to the end of the path.

        Returns:
            A tuple of `Edge` objects order from start to end of the path
        Raises:
            InvalidContextError: If using an invalid `Path` instance.
        Examples:
            ```path.edges```
        """
        if not self.is_valid():
            raise InvalidContextError()
        if self._edges is None:
            num_edges = self._path.size()
            self._edges = tuple(Edge(self._path.edge_at(i)) for i in range(num_edges))
        return self._edges

    @property
    def length(self) -> int:
        return self._path.size()


class Record:
    """Represents a record of resulting field values."""

    __slots__ = ("fields",)

    def __init__(self, **kwargs):
        """Initialize with name=value fields in kwargs."""
        self.fields = kwargs


class Vertices:
    """Iterable over vertices in a graph."""

    __slots__ = ("_graph", "_len")

    def __init__(self, graph):
        if not isinstance(graph, _mgp.Graph):
            raise TypeError("Expected '_mgp.Graph', got '{}'".format(type(graph)))
        self._graph = graph
        self._len = None

    def __deepcopy__(self, memo):
        # This is the same as the shallow copy, because we want to share the
        # underlying C struct. Besides, it doesn't make much sense to actually
        # copy _mgp.Graph as that always references the whole graph state.
        return Vertices(self._graph)

    def is_valid(self) -> bool:
        """
        Check if `Vertices` is in valid context and may be used.

        Returns:
            A `bool` value depends on if the `Vertices` is in valid context.

        Examples:
            ```vertices.is_valid()```
        """
        return self._graph.is_valid()

    def __iter__(self) -> typing.Iterable[Vertex]:
        """
        Iterate over vertices.

        Returns:
            Iterable list of `Vertex` objects.

        Raises:
            InvalidContextError: If context is invalid.
            UnableToAllocateError: If unable to allocate an iterator or a vertex.

        Examples:
            ```
            for vertex in graph.vertices:
            ```
            ```
            iter(graph.vertices)
            ```

        """
        if not self.is_valid():
            raise InvalidContextError()
        vertices_it = self._graph.iter_vertices()
        vertex = vertices_it.get()
        while vertex is not None:
            yield Vertex(vertex)
            if not self.is_valid():
                raise InvalidContextError()
            vertex = vertices_it.next()

    def __contains__(self, vertex):
        """
        Check if Vertices contain the given vertex.

        Args:
            vertex: `Vertex` to be checked if it is a part of graph `Vertices`.

        Returns:
            Bool value depends if there is `Vertex` in graph `Vertices`.

        Raises:
            UnableToAllocateError: If unable to allocate the vertex.

        Examples:
            ```if vertex in graph.vertices:```
        """
        try:
            _ = self._graph.get_vertex_by_id(vertex.id)
            return True
        except IndexError:
            return False

    def __len__(self):
        """
        Get the number of vertices.

        Returns:
            A number of vertices in the graph.

        Raises:
            InvalidContextError: If context is invalid.
            UnableToAllocateError: If unable to allocate an iterator or a vertex.

        Examples:
            ```len(graph.vertices)```
        """
        if not self._len:
            self._len = sum(1 for _ in self)
        return self._len


class Graph:
    """State of the graph database in current ProcCtx."""

    __slots__ = ("_graph",)

    def __init__(self, graph):
        if not isinstance(graph, _mgp.Graph):
            raise TypeError("Expected '_mgp.Graph', got '{}'".format(type(graph)))
        self._graph = graph

    def __deepcopy__(self, memo):
        # This is the same as the shallow copy, because we want to share the
        # underlying C struct. Besides, it doesn't make much sense to actually
        # copy _mgp.Graph as that always references the whole graph state.
        return Graph(self._graph)

    def is_valid(self) -> bool:
        """
        Check if `graph` is in a valid context and may be used.

        Returns:
            A `bool` value depends on if the `graph` is in a valid context.

        Examples:
            ```graph.is_valid()```

        """
        return self._graph.is_valid()

    def get_vertex_by_id(self, vertex_id: VertexId) -> Vertex:
        """
        Return the Vertex corresponding to the given vertex_id from the graph.

        Access to a Vertex is only valid during a single execution of a
        procedure in a query. You should not globally store the returned
        Vertex.

        Args:
            vertex_id: Memgraph Vertex ID

        Returns:
            `Vertex`corresponding to `vertex_id`

        Raises:
            IndexError: If unable to find the given vertex_id.
            InvalidContextError: If context is invalid.

        Examples:
            ```graph.get_vertex_by_id(vertex_id)```


        """
        if not self.is_valid():
            raise InvalidContextError()
        vertex = self._graph.get_vertex_by_id(vertex_id)
        return Vertex(vertex)

    @property
    def vertices(self) -> Vertices:
        """
        Get all vertices in the graph.

        Access to a Vertex is only valid during a single execution of a
        procedure in a query. You should not globally store the returned Vertex
        instances.

        Returns:
            `Vertices` that contained in the graph.

        Raises:
            InvalidContextError: If context is invalid.

        Examples:
            Iteration over all graph `Vertices`.

            ```
            graph = context.graph
            for vertex in graph.vertices:
            ```

        """
        if not self.is_valid():
            raise InvalidContextError()
        return Vertices(self._graph)

    def is_mutable(self) -> bool:
        """
        Check if the graph is mutable. Thus it can be used to modify vertices and edges.

        Returns:
            A `bool` value that depends if the graph is mutable or not.

        Examples:
            ```graph.is_mutable()```
        """
        if not self.is_valid():
            raise InvalidContextError()
        return self._graph.is_mutable()

    def create_vertex(self) -> Vertex:
        """
        Create an empty vertex.

        Returns:
            Created `Vertex`.

        Raises:
            ImmutableObjectError: If `graph` is immutable.
            UnableToAllocateError: If unable to allocate a vertex.

        Examples:
            Creating an empty vertex.
            ```vertex = graph.create_vertex()```

        """
        if not self.is_valid():
            raise InvalidContextError()
        return Vertex(self._graph.create_vertex())

    def delete_vertex(self, vertex: Vertex) -> None:
        """
        Delete a vertex if there are no edges.

        Args:
            vertex: `Vertex` to be deleted
        Raises:
            ImmutableObjectError: If `graph` is immutable.
            LogicErrorError: If `vertex` has edges.
            SerializationError: If `vertex` has been modified by
            another transaction.
        Examples:
            ```graph.delete_vertex(vertex)```

        """
        if not self.is_valid():
            raise InvalidContextError()
        self._graph.delete_vertex(vertex._vertex)

    def detach_delete_vertex(self, vertex: Vertex) -> None:
        """
        Delete a vertex and all of its edges.

        Args:
             vertex: `Vertex` to be deleted with all of its edges

        Raises:
            ImmutableObjectError: If `graph` is immutable.
            SerializationError: If `vertex` has been modified by another transaction.
        Examples:
            ```graph.detach_delete_vertex(vertex)```
        """
        if not self.is_valid():
            raise InvalidContextError()
        self._graph.detach_delete_vertex(vertex._vertex)

    def create_edge(self, from_vertex: Vertex, to_vertex: Vertex, edge_type: EdgeType) -> Edge:
        """
        Create an edge.

        Args:
            from_vertex: `Vertex` from where edge is directed.
            to_vertex: `Vertex'  to where edge is directed.
            edge_type:  `EdgeType` defines the type of edge.

        Returns:
            Created `Edge`.

        Raises:
            ImmutableObjectError: If `graph` is immutable.
            UnableToAllocateError: If unable to allocate an edge.
            DeletedObjectError: If `from_vertex` or `to_vertex` has been deleted.
            SerializationError: If `from_vertex` or `to_vertex` has been modified by another transaction.
        Examples:
            ```edge = graph.create_edge(from_vertex, vertex, edge_type)```
        """
        if not self.is_valid():
            raise InvalidContextError()
        return Edge(self._graph.create_edge(from_vertex._vertex, to_vertex._vertex, edge_type.name))

    def delete_edge(self, edge: Edge) -> None:
        """
        Delete an edge.

        Args:
            edge: `Edge` to be deleted

        Raises:
            ImmutableObjectError if `graph` is immutable.
            Raise SerializationError if `edge`, its source or destination vertex has been modified by another transaction.
        """
        if not self.is_valid():
            raise InvalidContextError()
        self._graph.delete_edge(edge._edge)


class AbortError(Exception):
    """Signals that the procedure was asked to abort its execution."""

    pass


class ProcCtx:
    """Context of a procedure being executed.

    Access to a ProcCtx is only valid during a single execution of a procedure
    in a query. You should not globally store a ProcCtx instance.
    """

    __slots__ = ("_graph",)

    def __init__(self, graph):
        if not isinstance(graph, _mgp.Graph):
            raise TypeError("Expected '_mgp.Graph', got '{}'".format(type(graph)))
        self._graph = Graph(graph)

    def is_valid(self) -> bool:
        return self._graph.is_valid()

    @property
    def graph(self) -> Graph:
        """
        Access to `Graph` object.

        Returns:
            Graph object.

        Raises:
            InvalidContextError:  If context is invalid.

        Examples:
            ```context.graph```
        """
        if not self.is_valid():
            raise InvalidContextError()
        return self._graph

    def must_abort(self) -> bool:
        if not self.is_valid():
            raise InvalidContextError()
        return self._graph._graph.must_abort()

    def check_must_abort(self):
        if self.must_abort():
            raise AbortError


# Additional typing support

Number = typing.Union[int, float]

Map = typing.Union[dict, Edge, Vertex]

Date = datetime.date

LocalTime = datetime.time

LocalDateTime = datetime.datetime

Duration = datetime.timedelta

Any = typing.Union[bool, str, Number, Map, Path, list, Date, LocalTime, LocalDateTime, Duration]

List = typing.List

Nullable = typing.Optional


class UnsupportedTypingError(Exception):
    """Signals a typing annotation is not supported as a _mgp.CypherType."""

    def __init__(self, type_):
        super().__init__("Unsupported typing annotation '{}'".format(type_))


class UnequalTypesError(Exception):
    """Signals a typing annotation is not equal between types"""

    def __init__(self, type1_: typing.Any, type2_: typing.Any):
        super().__init__(f"Unequal typing annotation '{type1_}' and '{type2_}'")


def _typing_to_cypher_type(type_):
    """Convert typing annotation to a _mgp.CypherType instance."""
    simple_types = {
        typing.Any: _mgp.type_nullable(_mgp.type_any()),
        object: _mgp.type_nullable(_mgp.type_any()),
        list: _mgp.type_list(_mgp.type_nullable(_mgp.type_any())),
        Any: _mgp.type_any(),
        bool: _mgp.type_bool(),
        str: _mgp.type_string(),
        int: _mgp.type_int(),
        float: _mgp.type_float(),
        Number: _mgp.type_number(),
        Map: _mgp.type_map(),
        Vertex: _mgp.type_node(),
        Edge: _mgp.type_relationship(),
        Path: _mgp.type_path(),
        Date: _mgp.type_date(),
        LocalTime: _mgp.type_local_time(),
        LocalDateTime: _mgp.type_local_date_time(),
        Duration: _mgp.type_duration(),
    }
    try:
        return simple_types[type_]
    except KeyError:
        pass
    if sys.version_info >= (3, 8):
        complex_type = typing.get_origin(type_)
        type_args = typing.get_args(type_)
        if complex_type == typing.Union:
            # If we have a Union with NoneType inside, it means we are building
            # a nullable type.
            # isinstance doesn't work here because subscripted generics cannot
            # be used with class and instance checks. type comparison should be
            # fine because subclasses are not used.
            if type(None) in type_args:
                types = tuple(t for t in type_args if t is not type(None))  # noqa E721
                if len(types) == 1:
                    (type_arg,) = types
                else:
                    # We cannot do typing.Union[*types], so do the equivalent
                    # with __getitem__ which does not even need arg unpacking.
                    type_arg = typing.Union.__getitem__(types)
                return _mgp.type_nullable(_typing_to_cypher_type(type_arg))
        elif complex_type == list:
            (type_arg,) = type_args
            return _mgp.type_list(_typing_to_cypher_type(type_arg))
        raise UnsupportedTypingError(type_)
    else:
        # We cannot get to type args in any reliable way prior to 3.8, but we
        # still want to support typing.Optional and typing.List, so just parse
        # their string representations. Hopefully, that is always pretty
        # printed the same way. `typing.List[type]` is printed as such, while
        # `typing.Optional[type]` is printed as 'typing.Union[type, NoneType]'
        def parse_type_args(type_as_str):
            return tuple(
                map(
                    str.strip,
                    type_as_str[type_as_str.index("[") + 1 : -1].split(","),
                )
            )

        def fully_qualified_name(cls):
            if cls.__module__ is None or cls.__module__ == "builtins":
                return cls.__name__
            return cls.__module__ + "." + cls.__name__

        def get_simple_type(type_as_str):
            for simple_type, cypher_type in simple_types.items():
                if type_as_str == str(simple_type):
                    return cypher_type
                # Fallback to comparing to __name__ if it exits. This handles
                # the cases like when we have 'object' which is
                # `object.__name__`, but `str(object)` is "<class 'object'>"
                try:
                    if type_as_str == fully_qualified_name(simple_type):
                        return cypher_type
                except AttributeError:
                    pass

        def parse_typing(type_as_str):
            if type_as_str.startswith("typing.Union"):
                type_args_as_str = parse_type_args(type_as_str)
                none_type_as_str = type(None).__name__
                if none_type_as_str in type_args_as_str:
                    types = tuple(t for t in type_args_as_str if t != none_type_as_str)
                    if len(types) == 1:
                        (type_arg_as_str,) = types
                    else:
                        type_arg_as_str = "typing.Union[" + ", ".join(types) + "]"
                    simple_type = get_simple_type(type_arg_as_str)
                    if simple_type is not None:
                        return _mgp.type_nullable(simple_type)
                    return _mgp.type_nullable(parse_typing(type_arg_as_str))
            elif type_as_str.startswith("typing.List"):
                type_arg_as_str = parse_type_args(type_as_str)

                if len(type_arg_as_str) > 1:
                    # Nested object could be a type consisting of a list of types (e.g. mgp.Map)
                    # so we need to join the parts.
                    type_arg_as_str = ", ".join(type_arg_as_str)
                else:
                    type_arg_as_str = type_arg_as_str[0]

                simple_type = get_simple_type(type_arg_as_str)
                if simple_type is not None:
                    return _mgp.type_list(simple_type)
                return _mgp.type_list(parse_typing(type_arg_as_str))
            raise UnsupportedTypingError(type_)

        return parse_typing(str(type_))


def _is_typing_same(type1_, type2_):
    """Convert typing annotation to a _mgp.CypherType instance."""
    simple_types = {
        typing.Any: 1,
        object: 2,
        list: 3,
        Any: 4,
        bool: 5,
        str: 6,
        int: 7,
        float: 8,
        Number: 9,
        Map: 10,
        Vertex: 11,
        Edge: 12,
        Path: 13,
        Date: 14,
        LocalTime: 15,
        LocalDateTime: 16,
        Duration: 17,
    }
    try:
        return simple_types[type1_] == simple_types[type2_]
    except KeyError:
        pass

    if sys.version_info < (3, 8):
        # skip type checks
        return True

    complex_type1 = typing.get_origin(type1_)
    type_args1 = typing.get_args(type2_)

    complex_type2 = typing.get_origin(type1_)
    type_args2 = typing.get_args(type2_)

    if complex_type2 != complex_type1:
        raise UnequalTypesError(type1_, type2_)

    if complex_type1 == typing.Union:
        contains_none_arg1 = type(None) in type_args1
        contains_none_arg2 = type(None) in type_args2

        if contains_none_arg1 != contains_none_arg2:
            raise UnequalTypesError(type1_, type2_)

        if contains_none_arg1:
            types1 = tuple(t for t in type_args1 if t is not type(None))  # noqa E721
            types2 = tuple(t for t in type_args2 if t is not type(None))  # noqa E721
            if len(types1) != len(types2):
                raise UnequalTypesError(types1, types2)
            if len(types1) == 1:
                (type_arg1,) = types1
                (type_arg2,) = types2
            else:
                type_arg1 = typing.Union.__getitem__(types1)
                type_arg2 = typing.Union.__getitem__(types2)
            return _is_typing_same(type_arg1, type_arg2)
    elif complex_type1 == list:
        (type_arg1,) = type_args1
        (type_arg2,) = type_args2
        return _is_typing_same(type_arg1, type_arg2)
    # skip type checks
    return True


# Procedure registration


class Deprecated:
    """Annotate a resulting Record's field as deprecated."""

    __slots__ = ("field_type",)

    def __init__(self, type_):
        self.field_type = type_


def raise_if_does_not_meet_requirements(func: typing.Callable[..., Record]):
    if not callable(func):
        raise TypeError("Expected a callable object, got an instance of '{}'".format(type(func)))
    if inspect.iscoroutinefunction(func):
        raise TypeError("Callable must not be 'async def' function")
    if sys.version_info >= (3, 6):
        if inspect.isasyncgenfunction(func):
            raise TypeError("Callable must not be 'async def' function")
    if inspect.isgeneratorfunction(func):
        raise NotImplementedError("Generator functions are not supported")


def _register_proc(func: typing.Callable[..., Record], is_write: bool):
    raise_if_does_not_meet_requirements(func)
    register_func = _mgp.Module.add_write_procedure if is_write else _mgp.Module.add_read_procedure
    sig = inspect.signature(func)
    params = tuple(sig.parameters.values())
    if params and params[0].annotation is ProcCtx:

        @wraps(func)
        def wrapper(graph, args):
            return func(ProcCtx(graph), *args)

        params = params[1:]
        mgp_proc = register_func(_mgp._MODULE, wrapper)
    else:

        @wraps(func)
        def wrapper(graph, args):
            return func(*args)

        mgp_proc = register_func(_mgp._MODULE, wrapper)
    for param in params:
        name = param.name
        type_ = param.annotation
        if type_ is param.empty:
            type_ = object
        cypher_type = _typing_to_cypher_type(type_)
        if param.default is param.empty:
            mgp_proc.add_arg(name, cypher_type)
        else:
            mgp_proc.add_opt_arg(name, cypher_type, param.default)
    if sig.return_annotation is not sig.empty:
        record = sig.return_annotation
        if not isinstance(record, Record):
            raise TypeError("Expected '{}' to return 'mgp.Record', got '{}'".format(func.__name__, type(record)))
        for name, type_ in record.fields.items():
            if isinstance(type_, Deprecated):
                cypher_type = _typing_to_cypher_type(type_.field_type)
                mgp_proc.add_deprecated_result(name, cypher_type)
            else:
                mgp_proc.add_result(name, _typing_to_cypher_type(type_))
    return func


def read_proc(func: typing.Callable[..., Record]):
    """
    Register `func` as a read-only procedure of the current module.

    The decorator `read_proc` is meant to be used to register module procedures.
    The registered `func` needs to be a callable which optionally takes
    `ProcCtx` as its first argument. Other arguments of `func` will be bound to
    values passed in the cypherQuery. The full signature of `func` needs to be
    annotated with types. The return type must be `Record(field_name=type, ...)`
    and the procedure must produce either a complete Record or None. To mark a
    field as deprecated, use `Record(field_name=Deprecated(type), ...)`.
    Multiple records can be produced by returning an iterable of them.
    Registering generator functions is currently not supported.

    Example usage.

    ```
    import mgp

    @mgp.read_proc
    def procedure(context: mgp.ProcCtx,
                  required_arg: mgp.Nullable[mgp.Any],
                  optional_arg: mgp.Nullable[mgp.Any] = None
                  ) -> mgp.Record(result=str, args=list):
        args = [required_arg, optional_arg]
        # Multiple rows can be produced by returning an iterable of mgp.Record
        return mgp.Record(args=args, result='Hello World!')
    ```

    The example procedure above returns 2 fields: `args` and `result`.
      * `args` is a copy of arguments passed to the procedure.
      * `result` is the result of this procedure, a "Hello World!" string.
    Any errors can be reported by raising an Exception.

    The procedure can be invoked in openCypher using the following calls:
      CALL example.procedure(1, 2) YIELD args, result;
      CALL example.procedure(1) YIELD args, result;
    Naturally, you may pass in different arguments or yield less fields.
    """
    return _register_proc(func, False)


def write_proc(func: typing.Callable[..., Record]):
    """
    Register `func` as a writeable procedure of the current module.

    The decorator `write_proc` is meant to be used to register module
    procedures. The registered `func` needs to be a callable which optionally
    takes `ProcCtx` as the first argument. Other arguments of `func` will be
    bound to values passed in the cypherQuery. The full signature of `func`
    needs to be annotated with types. The return type must be
    `Record(field_name=type, ...)` and the procedure must produce either a
    complete Record or None. To mark a field as deprecated, use
    `Record(field_name=Deprecated(type), ...)`. Multiple records can be produced
    by returning an iterable of them. Registering generator functions is
    currently not supported.

    Example usage.

    ```
    import mgp

    @mgp.write_proc
    def procedure(context: mgp.ProcCtx,
                required_arg: str,
                optional_arg: mgp.Nullable[str] = None
                ) -> mgp.Record(result=mgp.Vertex):
        vertex = context.graph.create_vertex()
        vertex_properties = vertex.properties
        vertex_properties["required_arg"] = required_arg
        if optional_arg is not None:
            vertex_properties["optional_arg"] = optional_arg

        return mgp.Record(result=vertex)
    ```

    The example procedure above returns  a newly created vertex which has
    at most 2 properties:
      * `required_arg` is always present and its value is the first
        argument of the procedure.
      * `optional_arg` is present if the second argument of the procedure
        is not `null`.
    Any errors can be reported by raising an Exception.

    The procedure can be invoked in openCypher using the following calls:
      CALL example.procedure("property value", "another one") YIELD result;
      CALL example.procedure("single argument") YIELD result;
    Naturally, you may pass in different arguments.
    """
    return _register_proc(func, True)


def _register_batch_proc(
    func: typing.Callable[..., Record], initializer: typing.Callable, cleanup: typing.Callable, is_write: bool
):
    raise_if_does_not_meet_requirements(func)
    register_func = _mgp.Module.add_batch_write_procedure if is_write else _mgp.Module.add_batch_read_procedure
    func_sig = inspect.signature(func)
    func_params = tuple(func_sig.parameters.values())

    initializer_sig = inspect.signature(initializer)
    initializer_params = tuple(initializer_sig.parameters.values())

    assert (
        func_params and initializer_params or not func_params and not initializer_params
    ), "Both function params and initializer params must exist or not exist"

    assert len(func_params) == len(initializer_params), "Number of params must be same"

    assert initializer_sig.return_annotation is initializer_sig.empty, "Initializer can't return anything"

    if func_params and func_params[0].annotation is ProcCtx:
        assert (
            initializer_params and initializer_params[0].annotation is ProcCtx
        ), "Initializer must have mgp.ProcCtx as first parameter"

        @wraps(func)
        def wrapper_func(graph, args):
            return func(ProcCtx(graph), *args)

        @wraps(initializer)
        def wrapper_initializer(graph, args):
            return initializer(ProcCtx(graph), *args)

        func_params = func_params[1:]
        initializer_params = initializer_params[1:]
        mgp_proc = register_func(_mgp._MODULE, wrapper_func, wrapper_initializer, cleanup)
    else:

        @wraps(func)
        def wrapper_func(graph, args):
            return func(*args)

        @wraps(initializer)
        def wrapper_initializer(graph, args):
            return initializer(*args)

        mgp_proc = register_func(_mgp._MODULE, wrapper_func, wrapper_initializer, cleanup)

    for func_param, initializer_param in zip(func_params, initializer_params):
        func_param_name = func_param.name
        func_param_type_ = func_param.annotation
        if func_param_type_ is func_param.empty:
            func_param_type_ = object
        initializer_param_type_ = initializer_param.annotation
        if initializer_param.annotation is initializer_param.empty:
            initializer_param_type_ = object

        assert _is_typing_same(
            func_param_type_, initializer_param_type_
        ), "Types of initializer and function must be same"

        func_cypher_type = _typing_to_cypher_type(func_param_type_)
        if func_param.default is func_param.empty:
            mgp_proc.add_arg(func_param_name, func_cypher_type)
        else:
            mgp_proc.add_opt_arg(func_param_name, func_cypher_type, func_param.default)
    if func_sig.return_annotation is not func_sig.empty:
        record = func_sig.return_annotation
        if not isinstance(record, Record):
            raise TypeError("Expected '{}' to return 'mgp.Record', got '{}'".format(func.__name__, type(record)))
        for name, type_ in record.fields.items():
            if isinstance(type_, Deprecated):
                cypher_type = _typing_to_cypher_type(type_.field_type)
                mgp_proc.add_deprecated_result(name, cypher_type)
            else:
                mgp_proc.add_result(name, _typing_to_cypher_type(type_))
    return func


def add_batch_write_proc(func: typing.Callable[..., Record], initializer: typing.Callable, cleanup: typing.Callable):
    return _register_batch_proc(func, initializer, cleanup, True)


def add_batch_read_proc(func: typing.Callable[..., Record], initializer: typing.Callable, cleanup: typing.Callable):
    return _register_batch_proc(func, initializer, cleanup, False)


class InvalidMessageError(Exception):
    """
    Signals using a message instance outside of the registered transformation.
    """

    pass


SOURCE_TYPE_KAFKA = _mgp.SOURCE_TYPE_KAFKA
SOURCE_TYPE_PULSAR = _mgp.SOURCE_TYPE_PULSAR


class Message:
    """Represents a message from a stream."""

    __slots__ = ("_message",)

    def __init__(self, message):
        if not isinstance(message, _mgp.Message):
            raise TypeError("Expected '_mgp.Message', got '{}'".format(type(message)))
        self._message = message

    def __deepcopy__(self, memo):
        # This is the same as the shallow copy, because we want to share the
        # underlying C struct. Besides, it doesn't make much sense to actually
        # copy _mgp.Messages as that always references all the messages.
        return Message(self._message)

    def is_valid(self) -> bool:
        """Return True if `self` is in valid context and may be used."""
        return self._message.is_valid()

    def source_type(self) -> str:
        """
        Supported in all stream sources

        Raise InvalidArgumentError if the message is from an unsupported stream source.
        """
        if not self.is_valid():
            raise InvalidMessageError()
        return self._message.source_type()

    def payload(self) -> bytes:
        """
        Supported stream sources:
          - Kafka
          - Pulsar

        Raise InvalidArgumentError if the message is from an unsupported stream source.
        """
        if not self.is_valid():
            raise InvalidMessageError()
        return self._message.payload()

    def topic_name(self) -> str:
        """
        Supported stream sources:
          - Kafka
          - Pulsar

        Raise InvalidArgumentError if the message is from an unsupported stream source.
        """
        if not self.is_valid():
            raise InvalidMessageError()
        return self._message.topic_name()

    def key(self) -> bytes:
        """
        Supported stream sources:
          - Kafka

        Raise InvalidArgumentError if the message is from an unsupported stream source.
        """
        if not self.is_valid():
            raise InvalidMessageError()
        return self._message.key()

    def timestamp(self) -> int:
        """
        Supported stream sources:
          - Kafka

        Raise InvalidArgumentError if the message is from an unsupported stream source.
        """
        if not self.is_valid():
            raise InvalidMessageError()
        return self._message.timestamp()

    def offset(self) -> int:
        """
        Supported stream sources:
          - Kafka

        Raise InvalidArgumentError if the message is from an unsupported stream source.
        """
        if not self.is_valid():
            raise InvalidMessageError()
        return self._message.offset()


class InvalidMessagesError(Exception):
    """Signals using a messages instance outside of the registered transformation."""

    pass


class Messages:
    """Represents a list of messages from a stream."""

    __slots__ = ("_messages",)

    def __init__(self, messages):
        if not isinstance(messages, _mgp.Messages):
            raise TypeError("Expected '_mgp.Messages', got '{}'".format(type(messages)))
        self._messages = messages

    def __deepcopy__(self, memo):
        # This is the same as the shallow copy, because we want to share the
        # underlying C struct. Besides, it doesn't make much sense to actually
        # copy _mgp.Messages as that always references all the messages.
        return Messages(self._messages)

    def is_valid(self) -> bool:
        """Return True if `self` is in valid context and may be used."""
        return self._messages.is_valid()

    def message_at(self, id: int) -> Message:
        """Raise InvalidMessagesError if context is invalid."""
        if not self.is_valid():
            raise InvalidMessagesError()
        return Message(self._messages.message_at(id))

    def total_messages(self) -> int:
        """Raise InvalidContextError if context is invalid."""
        if not self.is_valid():
            raise InvalidMessagesError()
        return self._messages.total_messages()


class TransCtx:
    """Context of a transformation being executed.

    Access to a TransCtx is only valid during a single execution of a transformation.
    You should not globally store a TransCtx instance.
    """

    __slots__ = "_graph"

    def __init__(self, graph):
        if not isinstance(graph, _mgp.Graph):
            raise TypeError("Expected '_mgp.Graph', got '{}'".format(type(graph)))
        self._graph = Graph(graph)

    def is_valid(self) -> bool:
        return self._graph.is_valid()

    @property
    def graph(self) -> Graph:
        """Raise InvalidContextError if context is invalid."""
        if not self.is_valid():
            raise InvalidContextError()
        return self._graph


def transformation(func: typing.Callable[..., Record]):
    raise_if_does_not_meet_requirements(func)
    sig = inspect.signature(func)
    params = tuple(sig.parameters.values())
    if not params or not params[0].annotation is Messages:
        if not len(params) == 2 or not params[1].annotation is Messages:
            raise NotImplementedError("Valid signatures for transformations are (TransCtx, Messages) or (Messages)")
    if params[0].annotation is TransCtx:

        @wraps(func)
        def wrapper(graph, messages):
            return func(TransCtx(graph), messages)

        _mgp._MODULE.add_transformation(wrapper)
    else:

        @wraps(func)
        def wrapper(graph, messages):
            return func(messages)

        _mgp._MODULE.add_transformation(wrapper)
    return func


class FuncCtx:
    """Context of a function being executed.

    Access to a FuncCtx is only valid during a single execution of a function in
    a query. You should not globally store a FuncCtx instance. The graph object
    within the FuncCtx is not mutable.
    """

    __slots__ = "_graph"

    def __init__(self, graph):
        if not isinstance(graph, _mgp.Graph):
            raise TypeError("Expected '_mgp.Graph', got '{}'".format(type(graph)))
        self._graph = Graph(graph)

    def is_valid(self) -> bool:
        return self._graph.is_valid()


def function(func: typing.Callable):
    """
    Register `func` as a user-defined function in the current module.

    The decorator `function` is meant to be used to register module functions.
    The registered `func` needs to be a callable which optionally takes
    `FuncCtx` as its first argument. Other arguments of `func` will be bound to
    values passed in the Cypher query. Only the function arguments need to be
    annotated with types. The return type doesn't need to be specified, but it
    has to be supported by `mgp.Any`. Registering generator functions is
    currently not supported.

    Example usage.

    ```
    import mgp
    @mgp.function
    def func_example(context: mgp.FuncCtx,
        required_arg: str,
        optional_arg: mgp.Nullable[str] = None
        ):
        return_args = [required_arg]
        if optional_arg is not None:
            return_args.append(optional_arg)
        # Return any kind of result supported by mgp.Any
        return return_args
    ```

    The example function above returns a list of provided arguments:
      * `required_arg` is always present and its value is the first argument of
        the function.
      * `optional_arg` is present if the second argument of the function is not
        `null`.
    Any errors can be reported by raising an Exception.

    The function can be invoked in Cypher using the following calls:
      RETURN example.func_example("first argument", "second_argument");
      RETURN example.func_example("first argument");
    Naturally, you may pass in different arguments.
    """
    raise_if_does_not_meet_requirements(func)
    register_func = _mgp.Module.add_function
    sig = inspect.signature(func)
    params = tuple(sig.parameters.values())
    if params and params[0].annotation is FuncCtx:

        @wraps(func)
        def wrapper(graph, args):
            return func(FuncCtx(graph), *args)

        params = params[1:]
        mgp_func = register_func(_mgp._MODULE, wrapper)
    else:

        @wraps(func)
        def wrapper(graph, args):
            return func(*args)

        mgp_func = register_func(_mgp._MODULE, wrapper)

    for param in params:
        name = param.name
        type_ = param.annotation
        if type_ is param.empty:
            type_ = object
        cypher_type = _typing_to_cypher_type(type_)
        if param.default is param.empty:
            mgp_func.add_arg(name, cypher_type)
        else:
            mgp_func.add_opt_arg(name, cypher_type, param.default)
    return func


def _wrap_exceptions():
    def wrap_function(func):
        @wraps(func)
        def wrapped_func(*args, **kwargs):
            try:
                return func(*args, **kwargs)
            except _mgp.UnknownError as e:
                raise UnknownError(e)
            except _mgp.UnableToAllocateError as e:
                raise UnableToAllocateError(e)
            except _mgp.InsufficientBufferError as e:
                raise InsufficientBufferError(e)
            except _mgp.OutOfRangeError as e:
                raise OutOfRangeError(e)
            except _mgp.LogicErrorError as e:
                raise LogicErrorError(e)
            except _mgp.DeletedObjectError as e:
                raise DeletedObjectError(e)
            except _mgp.InvalidArgumentError as e:
                raise InvalidArgumentError(e)
            except _mgp.KeyAlreadyExistsError as e:
                raise KeyAlreadyExistsError(e)
            except _mgp.ImmutableObjectError as e:
                raise ImmutableObjectError(e)
            except _mgp.ValueConversionError as e:
                raise ValueConversionError(e)
            except _mgp.SerializationError as e:
                raise SerializationError(e)
            except _mgp.AuthorizationError as e:
                raise AuthorizationError(e)

        return wrapped_func

    def wrap_prop_func(func):
        return None if func is None else wrap_function(func)

    def wrap_member_functions(cls: type):
        for name, obj in inspect.getmembers(cls):
            if inspect.isfunction(obj):
                setattr(cls, name, wrap_function(obj))
            elif isinstance(obj, property):
                setattr(
                    cls,
                    name,
                    property(
                        wrap_prop_func(obj.fget),
                        wrap_prop_func(obj.fset),
                        wrap_prop_func(obj.fdel),
                        obj.__doc__,
                    ),
                )

    def defined_in_this_module(obj: object):
        return getattr(obj, "__module__", "") == __name__

    module = sys.modules[__name__]
    for name, obj in inspect.getmembers(module):
        if not defined_in_this_module(obj):
            continue
        if inspect.isclass(obj):
            wrap_member_functions(obj)
        elif inspect.isfunction(obj) and not name.startswith("_"):
            setattr(module, name, wrap_function(obj))


class Logger:
    """Represents a Logger through which it is possible
    to send logs via API to the graph database.

    The best way to use this Logger is to have one per query module."""

    __slots__ = ("_logger",)

    def __init__(self):
        self._logger = _mgp._LOGGER

    def info(self, out: str) -> None:
        """
        Log message on INFO level..
        Args:
            out: String message to be logged.

        Examples:
            ```logger.info("Hello from query module.")```
        """
        self._logger.info(out)

    def warning(self, out: str) -> None:
        """
        Log message on WARNING level..
        Args:
            out: String message to be logged.

        Examples:
            ```logger.warning("Hello from query module.")```
        """
        self._logger.warning(out)

    def critical(self, out: str) -> None:
        """
        Log message on CRITICAL level..
        Args:
            out: String message to be logged.

        Examples:
            ```logger.critical("Hello from query module.")```
        """
        self._logger.critical(out)

    def error(self, out: str) -> None:
        """
        Log message on ERROR level..
        Args:
            out: String message to be logged.

        Examples:
            ```logger.error("Hello from query module.")```
        """
        self._logger.error(out)

    def trace(self, out: str) -> None:
        """
        Log message on TRACE level..
        Args:
            out: String message to be logged.

        Examples:
            ```logger.trace("Hello from query module.")```
        """
        self._logger.trace(out)

    def debug(self, out: str) -> None:
        """
        Log message on DEBUG level..
        Args:
            out: String message to be logged.

        Examples:
            ```logger.debug("Hello from query module.")```
        """
        self._logger.debug(out)


_wrap_exceptions()