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# Source code for networkx.readwrite.json_graph.node_link

    import warnings
    from itertools import count

    import networkx as nx

    __all__ = ["node_link_data", "node_link_graph"]

    def _to_tuple(x):
        """Converts lists to tuples, including nested lists.

        All other non-list inputs are passed through unmodified. This function is
        intended to be used to convert potentially nested lists from json files
        into valid nodes.

        Examples
        --------
        >>> _to_tuple([1, 2, [3, 4]])
        (1, 2, (3, 4))
        """
        if not isinstance(x, tuple | list):
            return x
        return tuple(map(_to_tuple, x))

    def node_link_data(
        G,
        *,
        source="source",
        target="target",
        name="id",
        key="key",
        edges=None,
        nodes="nodes",
        link=None,
    ):
        """Returns data in node-link format that is suitable for JSON serialization
        and use in JavaScript documents.

        Parameters
        ----------
        G : NetworkX graph
        source : string
            A string that provides the 'source' attribute name for storing NetworkX-internal graph data.
        target : string
            A string that provides the 'target' attribute name for storing NetworkX-internal graph data.
        name : string
            A string that provides the 'name' attribute name for storing NetworkX-internal graph data.
        key : string
            A string that provides the 'key' attribute name for storing NetworkX-internal graph data.
        edges : string
            A string that provides the 'edges' attribute name for storing NetworkX-internal graph data.
        nodes : string
            A string that provides the 'nodes' attribute name for storing NetworkX-internal graph data.
        link : string
            .. deprecated:: 3.4

               The `link` argument is deprecated and will be removed in version `3.6`.
               Use the `edges` keyword instead.

            A string that provides the 'edges' attribute name for storing NetworkX-internal graph data.

        Returns
        -------
        data : dict
           A dictionary with node-link formatted data.

        Raises
        ------
        NetworkXError
            If the values of 'source', 'target' and 'key' are not unique.

        Examples
        --------
        >>> from pprint import pprint
        >>> G = nx.Graph([("A", "B")])
        >>> data1 = nx.node_link_data(G, edges="edges")
        >>> pprint(data1)
        {'directed': False,
         'edges': [{'source': 'A', 'target': 'B'}],
         'graph': {},
         'multigraph': False,
         'nodes': [{'id': 'A'}, {'id': 'B'}]}

        To serialize with JSON

        >>> import json
        >>> s1 = json.dumps(data1)
        >>> s1
        '{"directed": false, "multigraph": false, "graph": {}, "nodes": [{"id": "A"}, {"id": "B"}], "edges": [{"source": "A", "target": "B"}]}'

        A graph can also be serialized by passing `node_link_data` as an encoder function.

        >>> s1 = json.dumps(G, default=nx.node_link_data)
        >>> s1
        '{"directed": false, "multigraph": false, "graph": {}, "nodes": [{"id": "A"}, {"id": "B"}], "links": [{"source": "A", "target": "B"}]}'

        The attribute names for storing NetworkX-internal graph data can
        be specified as keyword options.

        >>> H = nx.gn_graph(2)
        >>> data2 = nx.node_link_data(
        ...     H, edges="links", source="from", target="to", nodes="vertices"
        ... )
        >>> pprint(data2)
        {'directed': True,
         'graph': {},
         'links': [{'from': 1, 'to': 0}],
         'multigraph': False,
         'vertices': [{'id': 0}, {'id': 1}]}

        Notes
        -----
        Graph, node, and link attributes are stored in this format.  Note that
        attribute keys will be converted to strings in order to comply with JSON.

        Attribute 'key' is only used for multigraphs.

        To use `node_link_data` in conjunction with `node_link_graph`,
        the keyword names for the attributes must match.

        See Also
        --------
        node_link_graph, adjacency_data, tree_data
        """
        # TODO: Remove between the lines when `link` deprecation expires
        # -------------------------------------------------------------
        if link is not None:
            warnings.warn(
                "Keyword argument 'link' is deprecated; use 'edges' instead",
                DeprecationWarning,
                stacklevel=2,
            )
            if edges is not None:
                raise ValueError(
                    "Both 'edges' and 'link' are specified. Use 'edges', 'link' will be remove in a future release"
                )
            else:
                edges = link
        else:
            if edges is None:
                warnings.warn(
                    (
                        '\nThe default value will be `edges="edges" in NetworkX 3.6.\n\n'
                        "To make this warning go away, explicitly set the edges kwarg, e.g.:\n\n"
                        '  nx.node_link_data(G, edges="links") to preserve current behavior, or\n'
                        '  nx.node_link_data(G, edges="edges") for forward compatibility.'
                    ),
                    FutureWarning,
                )
                edges = "links"
        # ------------------------------------------------------------

        multigraph = G.is_multigraph()

        # Allow 'key' to be omitted from attrs if the graph is not a multigraph.
        key = None if not multigraph else key
        if len({source, target, key}) < 3:
            raise nx.NetworkXError("Attribute names are not unique.")
        data = {
            "directed": G.is_directed(),
            "multigraph": multigraph,
            "graph": G.graph,
            nodes: [{**G.nodes[n], name: n} for n in G],
        }
        if multigraph:
            data[edges] = [
                {**d, source: u, target: v, key: k}
                for u, v, k, d in G.edges(keys=True, data=True)
            ]
        else:
            data[edges] = [{**d, source: u, target: v} for u, v, d in G.edges(data=True)]
        return data

    @nx._dispatchable(graphs=None, returns_graph=True)
    def node_link_graph(
        data,
        directed=False,
        multigraph=True,
        *,
        source="source",
        target="target",
        name="id",
        key="key",
        edges=None,
        nodes="nodes",
        link=None,
    ):
        """Returns graph from node-link data format.

        Useful for de-serialization from JSON.

        Parameters
        ----------
        data : dict
            node-link formatted graph data

        directed : bool
            If True, and direction not specified in data, return a directed graph.

        multigraph : bool
            If True, and multigraph not specified in data, return a multigraph.

        source : string
            A string that provides the 'source' attribute name for storing NetworkX-internal graph data.
        target : string
            A string that provides the 'target' attribute name for storing NetworkX-internal graph data.
        name : string
            A string that provides the 'name' attribute name for storing NetworkX-internal graph data.
        key : string
            A string that provides the 'key' attribute name for storing NetworkX-internal graph data.
        edges : string
            A string that provides the 'edges' attribute name for storing NetworkX-internal graph data.
        nodes : string
            A string that provides the 'nodes' attribute name for storing NetworkX-internal graph data.
        link : string
            .. deprecated:: 3.4

               The `link` argument is deprecated and will be removed in version `3.6`.
               Use the `edges` keyword instead.

            A string that provides the 'edges' attribute name for storing NetworkX-internal graph data.

        Returns
        -------
        G : NetworkX graph
            A NetworkX graph object

        Examples
        --------

        Create data in node-link format by converting a graph.

        >>> from pprint import pprint
        >>> G = nx.Graph([("A", "B")])
        >>> data = nx.node_link_data(G, edges="edges")
        >>> pprint(data)
        {'directed': False,
         'edges': [{'source': 'A', 'target': 'B'}],
         'graph': {},
         'multigraph': False,
         'nodes': [{'id': 'A'}, {'id': 'B'}]}

        Revert data in node-link format to a graph.

        >>> H = nx.node_link_graph(data, edges="edges")
        >>> print(H.edges)
        [('A', 'B')]

        To serialize and deserialize a graph with JSON,

        >>> import json
        >>> d = json.dumps(nx.node_link_data(G, edges="edges"))
        >>> H = nx.node_link_graph(json.loads(d), edges="edges")
        >>> print(G.edges, H.edges)
        [('A', 'B')] [('A', 'B')]

        Notes
        -----
        Attribute 'key' is only used for multigraphs.

        To use `node_link_data` in conjunction with `node_link_graph`,
        the keyword names for the attributes must match.

        See Also
        --------
        node_link_data, adjacency_data, tree_data
        """
        # TODO: Remove between the lines when `link` deprecation expires
        # -------------------------------------------------------------
        if link is not None:
            warnings.warn(
                "Keyword argument 'link' is deprecated; use 'edges' instead",
                DeprecationWarning,
                stacklevel=2,
            )
            if edges is not None:
                raise ValueError(
                    "Both 'edges' and 'link' are specified. Use 'edges', 'link' will be remove in a future release"
                )
            else:
                edges = link
        else:
            if edges is None:
                warnings.warn(
                    (
                        '\nThe default value will be changed to `edges="edges" in NetworkX 3.6.\n\n'
                        "To make this warning go away, explicitly set the edges kwarg, e.g.:\n\n"
                        '  nx.node_link_graph(data, edges="links") to preserve current behavior, or\n'
                        '  nx.node_link_graph(data, edges="edges") for forward compatibility.'
                    ),
                    FutureWarning,
                )
                edges = "links"
        # -------------------------------------------------------------

        multigraph = data.get("multigraph", multigraph)
        directed = data.get("directed", directed)
        if multigraph:
            graph = nx.MultiGraph()
        else:
            graph = nx.Graph()
        if directed:
            graph = graph.to_directed()

        # Allow 'key' to be omitted from attrs if the graph is not a multigraph.
        key = None if not multigraph else key
        graph.graph = data.get("graph", {})
        c = count()
        for d in data[nodes]:
            node = _to_tuple(d.get(name, next(c)))
            nodedata = {str(k): v for k, v in d.items() if k != name}
            graph.add_node(node, **nodedata)
        for d in data[edges]:
            src = tuple(d[source]) if isinstance(d[source], list) else d[source]
            tgt = tuple(d[target]) if isinstance(d[target], list) else d[target]
            if not multigraph:
                edgedata = {str(k): v for k, v in d.items() if k != source and k != target}
                graph.add_edge(src, tgt, **edgedata)
            else:
                ky = d.get(key, None)
                edgedata = {
                    str(k): v
                    for k, v in d.items()
                    if k != source and k != target and k != key
                }
                graph.add_edge(src, tgt, ky, **edgedata)
        return graph