text: from __future__ import annotations
  import networkx as nx
  from .node import VNode, CNode
  import numpy as np
  import numpy.typing as npt
  from typing import Callable
  
  
  class TannerGraph:
      def __init__(self):
          self.v_nodes: dict[int, VNode] = {}
          self.c_nodes: dict[int, CNode] = {}
          self.edges = set()
  
      def add_v_node(self, channel_model: Callable, ordering_key: int, name: str = "") -> VNode:
          """
          :param ordering_key: should reflect order according to parity check matrix, channel symbols in order
          :param name: name of node.
          :param channel_model: add an exiting node to graph. If not used a new node is created.
          """
          node = VNode(channel_model, ordering_key, name)
          self.v_nodes[node.uid] = node
          return node
  
      def add_c_node(self, name: str = "", ordering_key: int = None) -> CNode:
          """
          :param ordering_key: use only for debug purposes
          :param name: name of node
          """
          node = CNode(name, ordering_key)
          self.c_nodes[node.uid] = node
          return node
  
      def add_edge(self, vnode_uid: int, cnode_uid: int) -> None:
          if vnode_uid not in self.v_nodes:
              raise ValueError()
          if cnode_uid not in self.c_nodes:
              raise ValueError()
          self.c_nodes.get(cnode_uid).register_neighbor(self.v_nodes.get(vnode_uid))
          self.v_nodes.get(vnode_uid).register_neighbor(self.c_nodes.get(cnode_uid))
          self.edges.update({(vnode_uid, cnode_uid)})
  
      def add_edges_by_uid(self, edges_set: set[tuple[int, int]]) -> None:
          """
          :param edges_set: each element in the set is a tuple. In the tuple first element is a v-node uid and second is
          c-node uid
          """
          for v_uid, c_uid in edges_set:
              if v_uid not in self.v_nodes:
                  raise ValueError("No v-node with uid " + str(v_uid) + " in graph")
              if c_uid not in self.c_nodes:
                  raise ValueError("No c-node with uid " + str(c_uid) + " in graph")
              self.add_edge(v_uid, c_uid)
  
      def add_edges_by_name(self, edges_set: set[tuple[str, str]]) -> None:
          """
          :param edges_set: each element in the set is a tuple. In the tuple first element is a v-node name and second is
          c-node name
          """
          for v_name, c_name in edges_set:
              v_uid = [node.uid for node in self.v_nodes.values() if node.name == v_name]
              if not v_uid:
                  raise ValueError("No v-node with name " + v_name + " in graph")
              c_uid = [node.uid for node in self.c_nodes.values() if node.name == c_name]
              if not c_uid:
                  raise ValueError("No c-node with name " + c_name + " in graph")
              self.add_edge(v_uid[0], c_uid[0])
  
      def get_edges(self, by_name=False) -> set:
          """
          :param by_name: if true nodes are referred to by name, otherwise by uid. Default to false
          :return: returns a set of edges. if by_name each element is a tuple of node names, else it is a tuple of uid's.
          """
          if not by_name:
              return self.edges
          return {(self.v_nodes.get(vnode).name, self.c_nodes.get(cnode).name) for vnode, cnode in self.edges}
  
      def to_nx(self) -> nx.Graph:
          g = nx.Graph()
          for uid, node in self.c_nodes.items():
              g.add_node(uid, label=node.name, bipartite=0, color="blue")
          for uid, node in self.v_nodes.items():
              g.add_node(uid, label=node.name, bipartite=1, color="red")
          g.add_edges_from(self.edges)
          return g
  
      @classmethod
      def from_biadjacency_matrix(cls, h: npt.ArrayLike, channel_model: Callable) -> TannerGraph:
          """
          :param channel_model: channel model to compute channel symbols llr within v nodes
          :param h: parity check matrix, shape MXN with M check nodes and N variable nodes. assumed binary matrix.
          """
          g = TannerGraph()
          h = np.array(h)
          m, n = h.shape
          for i in range(n):
              g.add_v_node(name="v" + str(i), channel_model=channel_model, ordering_key=i)
          for j in range(m):
              g.add_c_node(name="c" + str(j), ordering_key=j)
              for i in range(n):
                  if h[j, i] == 1:
                      g.add_edges_by_name({("v" + str(i), "c" + str(j))})
          return g
  
      def __str__(self) -> str:
          return "Graph with " + str(len(self.c_nodes) + len(self.v_nodes)) + " nodes and " + str(len(self.edges)) + \
                 " edges"
  
      def ordered_v_nodes(self) -> list[VNode]:
          return sorted(self.v_nodes.values())
  