from typing import Any, Callable


class Graph:
    """
    represents an undirected and unweighted Graph
    """
    def __init__(self):
        self._adjacent: dict[int, set] = {}
        self._vertex_attribute: dict[int, dict] = {}

    def add_vertex(self, vertex:int):
        if vertex not in self._adjacent:
            if not isinstance(vertex, int):
                raise TypeError(f"Argument {vertex} is not a valid vertex")
            self._adjacent[vertex] = set()
            self._vertex_attribute[vertex] = {}
        pass

    def add_edge(self, u: int, v: int):
        self.add_vertex(u)
        self.add_vertex(v)
        v_neighbor = self._adjacent[v]
        if u not in v_neighbor:
            v_neighbor.add(u)
        u_neighbor = self._adjacent[u]
        if v not in u_neighbor:
            u_neighbor.add(v)
        pass

    def add_edges(self, u: int, adjacent: list[int]):
        for v in adjacent:
            self.add_edge(u, v)
        pass

    def merge_attribute(self, vertex: int, properties: dict):
        """
        merge a dict of attribute to a vertex. Usage example:
        ```
        g = Graph();
        g.add_vertex(1);
        g.mergeAttribute(1, {'color': 0});
        ```
        :param vertex:
        :param properties:
        :return: self
        """
        if vertex not in self._adjacent:
            raise ValueError(f"Graph does not include vertex {vertex}")
        old_attributes = self._vertex_attribute[vertex]
        self._vertex_attribute[vertex] = old_attributes | properties
        return self
        pass

    def get_attribute(self, vertex: int):
        if vertex in self._adjacent:
            return self._vertex_attribute[vertex]
        else:
            raise ValueError(f"Graph does not include vertex {vertex}")
        pass

    def vertices(self):
        """
        returns the set of vertices in not defined order.
        :return:
        """
        return self._adjacent.keys()

    def for_each_vertices(self, action: Callable[[int], Any]):
        """
        iterates over all vertices in this graph in ascending order.
        :param action:
        :return:
        """
        for v in sorted( self.vertices() ):
            action(v)

    def adjacent_of(self, vertex: int):
        if vertex not in self._adjacent:
            raise ValueError(f"Graph does not include vertex {vertex}")
        return sorted( self._adjacent[vertex] )

    def for_each_edges(self, action: Callable[[int, int], Any]):
        """
        iterates over all edges of the graph, executes the action on each edge.
        :param action: a binary function, its parameters are start and end vertices of the visited edges
        """
        visited_edges: dict[int, set] = {}
        for start in sorted( self.vertices() ):
            for end in self.adjacent_of(start):
                (first, second) = (start, end) if (start >= end) else (end, start)
            if first in visited_edges:
                #visited_adjacent = visited_edges.get(first)
                visited_adjacent = visited_edges[first]
                if second not in visited_adjacent:
                    visited_adjacent.add(second)
                    action(start, end)
            else:
                adjacent: set[int] = set()
                visited_edges[first] = adjacent
                adjacent.add(second)
                action(start, end)



    def __repr__(self):
        text = ""
        sorted_key = sorted(self._adjacent.keys())
        last_key = sorted_key.pop()
        def adjacent_fn(vertex): return "[" + ", ".join([str(v) for v in self._adjacent[vertex]]) + "]"
        for key in sorted_key:
            text += f"{key} → {adjacent_fn(key)}\n"
        text += f"{last_key} → {adjacent_fn(last_key)}"
        return text

    def to_dot(self) -> str:
        pass