r"""
Kleber Trees

A Kleber tree is a tree of weights generated by Kleber's algorithm
[Kleber1]_. The nodes correspond to the weights in the positive Weyl chamber
obtained by subtracting a (non-zero) positive root. The edges are labeled by
the coefficients of the roots of the difference.

AUTHORS:

- Travis Scrimshaw (2011-05-03): Initial version
- Travis Scrimshaw (2013-02-13): Added support for virtual trees and improved
  `\LaTeX` output

EXAMPLES::

    sage: from sage.combinat.rigged_configurations.kleber_tree import KleberTree
    sage: KleberTree(['A', 3, 1], [[3,2], [2,1], [1,1], [1,1]])
    Kleber tree of Cartan type ['A', 3, 1] and B = ((3, 2), (2, 1), (1, 1), (1, 1))
    sage: KleberTree(['D', 4, 1], [[2,2]])
    Kleber tree of Cartan type ['D', 4, 1] and B = ((2, 2),)

TESTS::

    sage: from sage.combinat.rigged_configurations.kleber_tree import KleberTree
    sage: KT = KleberTree(['A', 3, 1], [[3,2], [2,1], [1,1], [1,1]])
    sage: sorted((x.weight.to_vector(), x.up_root.to_vector()) for x in KT.list())
    [((0, 0, 2), (1, 1, 0)),
     ((0, 0, 2), (2, 2, 1)),
     ((0, 1, 0), (0, 0, 1)),
     ((0, 1, 0), (1, 1, 1)),
     ((0, 2, 2), (1, 0, 0)),
     ((1, 0, 3), (1, 1, 0)),
     ((1, 1, 1), (1, 1, 1)),
     ((2, 0, 0), (0, 1, 1)),
     ((2, 1, 2), (0, 0, 0)),
     ((3, 0, 1), (0, 1, 1))]

    sage: KT = KleberTree(['A', 7, 1], [[3,2], [2,1], [1,1]])
    sage: KT
    Kleber tree of Cartan type ['A', 7, 1] and B = ((3, 2), (2, 1), (1, 1))
    sage: sorted((x.weight.to_vector(), x.up_root.to_vector()) for x in KT.list())
    [((0, 0, 0, 1, 1, 0, 0), (1, 1, 1, 0, 0, 0, 0)),
     ((0, 0, 1, 0, 0, 1, 0), (2, 3, 3, 2, 1, 0, 0)),
     ((0, 0, 3, 0, 0, 0, 0), (1, 1, 0, 0, 0, 0, 0)),
     ((0, 1, 1, 1, 0, 0, 0), (1, 1, 1, 0, 0, 0, 0)),
     ((1, 0, 0, 2, 0, 0, 0), (0, 1, 1, 0, 0, 0, 0)),
     ((1, 0, 1, 0, 1, 0, 0), (1, 2, 2, 1, 0, 0, 0)),
     ((1, 1, 2, 0, 0, 0, 0), (0, 0, 0, 0, 0, 0, 0)),
     ((2, 0, 1, 1, 0, 0, 0), (0, 1, 1, 0, 0, 0, 0))]
"""

#*****************************************************************************
#       Copyright (C) 2011, 2012 Travis Scrimshaw <tscrim@ucdavis.edu>
#
#  Distributed under the terms of the GNU General Public License (GPL)
#
#    This code is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
#    General Public License for more details.
#
#  The full text of the GPL is available at:
#
#                  http://www.gnu.org/licenses/
#*****************************************************************************

from six.moves import range
import itertools

from sage.misc.lazy_attribute import lazy_attribute
from sage.misc.cachefunc import cached_method
from sage.misc.latex import latex
from sage.arith.all import binomial
from sage.rings.integer import Integer
from sage.rings.all import ZZ

from sage.structure.parent import Parent
from sage.structure.element import Element
from sage.structure.unique_representation import UniqueRepresentation
from sage.structure.richcmp import richcmp_not_equal, richcmp
from sage.categories.finite_enumerated_sets import FiniteEnumeratedSets
from sage.modules.free_module import FreeModule

from sage.combinat.root_system.cartan_type import CartanType

from sage.graphs.digraph import DiGraph
from sage.graphs.dot2tex_utils import have_dot2tex

######################################
# Latex method for viewing the trees #
######################################

def _draw_tree(tree_node, node_label=True, style_point=None, style_node='fill=white', style_line=None,
               hspace=2.5, vspace=-2.5, start=[0.,0.], rpos=[0.,0.], node_id=0, node_prefix='T',
               edge_labels=True, use_vector_notation=False):
    r"""
    Return the tikz latex for drawing the Kleber tree.

    AUTHORS:

    - Viviane Pons (2013-02-13): Initial version
    - Travis Scrimshaw (2013-03-02): Modified to work with Kleber tree output

    .. WARNING::

        Internal latex function.

    EXAMPLES::

        sage: from sage.combinat.rigged_configurations.kleber_tree import KleberTree
        sage: KT = KleberTree(['A',3,1], [[3,2],[1,1]])
        sage: latex(KT) # indirect doctest
        \begin{tikzpicture}
        \node[fill=white] (T0) at (0.000, 0.000){$V_{\omega_{1}+2\omega_{3}}$};
        \node (T00) at (0.000, -2.500){$V_{\omega_{3}}$};
        \draw (T0) to node[sloped,above]{\tiny $\alpha_{1} + \alpha_{2} + \alpha_{3}$} (T00);
        \end{tikzpicture}
    """
    draw_point = lambda point: '(%.3f, %.3f)'%(point[0],point[1])
    if not tree_node.children:
        r = ''
        node_name = node_prefix + str(node_id)
        r = "\\node (%s) at %s"%(node_name, draw_point(start))
        if node_label:
            r += "{$%s$};\n"%tree_node._latex_()
        else:
            r += "{};\n"
        rpos[0] = start[0]
        rpos[1] = start[1]
        start[0] += hspace
        return r

    node_name = node_prefix + str(node_id)
    if style_line is None:
        style_line_str = ''
    else:
        style_line_str = "[%s]"%style_line
    if node_label:
        node_place_str = ''
    else:
        node_place_str = ".center"

    nb_children = len(tree_node.children)
    half = nb_children // 2
    children_str = ''
    pos = [start[0],start[1]]
    start[1] += vspace
    lines_str = ''

    # Getting children string
    for i in range(nb_children):
        if i == half and nb_children % 2 == 0:
            pos[0] = start[0]
            start[0] += hspace
        if i == half+1 and nb_children % 2 == 1:
            pos[0] = rpos[0]
        child = tree_node.children[i]
        children_str += _draw_tree(child, node_label=node_label, style_node=style_node, style_point=style_point, style_line=style_line, hspace=hspace, vspace=vspace, start=start, rpos=rpos, node_id=i, node_prefix=node_name, edge_labels=edge_labels, use_vector_notation=use_vector_notation)
        if edge_labels:
            if use_vector_notation:
                edge_str = latex(child.up_root.to_vector())
            else:
                edge_str = latex(child.up_root)
            lines_str += "\\draw%s (%s%s) to node[sloped,above]{\\tiny $%s$} (%s%s%s);\n"%(style_line_str, node_name, node_place_str, edge_str, node_name, i, node_place_str)
        else:
            lines_str += "\\draw%s (%s%s) -- (%s%s%s);\n"%(style_line_str, node_name, node_place_str, node_name, i, node_place_str)

    #drawing root
    if style_node is None:
        style_node = ''
    else:
        style_node = "[%s]"%style_node
    if style_point is None:
        style_point = ''
    else:
        style_point = "[%s]"%style_point
    start[1] -= vspace
    rpos[0] = pos[0]
    rpos[1] = pos[1]
    point_str = ''
    node_str = "\\node%s (%s) at %s"%(style_node, node_name, draw_point(pos))
    if node_label:
        node_str += "{$%s$};\n"%tree_node._latex_()
    else:
        node_str += "{};\n"
        point_str = "\\draw%s (%s) circle;\n"%(style_point, node_name)

    res = node_str
    res += children_str
    res += lines_str
    res += point_str
    return res

#####################
# Kleber tree nodes #
#####################

class KleberTreeNode(Element):
    r"""
    A node in the Kleber tree.

    This class is meant to be used internally by the Kleber tree class and
    should not be created directly by the user.

    For more on the Kleber tree and the nodes, see :class:`KleberTree`.

    The dominating root is the ``up_root`` which is the difference
    between the parent node's weight and this node's weight.

    INPUT:

    - ``parent_obj``    -- The parent object of this element
    - ``node_weight``   -- The weight of this node
    - ``dominant_root`` -- The dominating root
    - ``parent_node``   -- (default:None) The parent node of this node
    """
    def __init__(self, parent_obj, node_weight, dominant_root, parent_node=None):
        r"""
        Initialize the tree node.

        TESTS::

            sage: from sage.combinat.rigged_configurations.kleber_tree import KleberTree
            sage: RS = RootSystem(['A', 2])
            sage: WS = RS.weight_lattice()
            sage: R = RS.root_lattice()
            sage: KT = KleberTree(['A', 2, 1], [[1,1]])
            sage: parent = KT(WS.sum_of_terms([(1,5), (2,2)]), R.zero())
            sage: parent
            Kleber tree node with weight [5, 2] and upwards edge root [0, 0]
            sage: parent.parent_node
            sage: child = KT(WS.sum_of_terms([(1,3), (2,1)]), R.sum_of_terms([(1,1), (2,2)]), parent)
            sage: child
            Kleber tree node with weight [3, 1] and upwards edge root [1, 2]
            sage: child.parent_node
            Kleber tree node with weight [5, 2] and upwards edge root [0, 0]
            sage: TestSuite(parent).run()
        """
        self.parent_node = parent_node
        self.children = []
        self.weight = node_weight
        self.up_root = dominant_root
        Element.__init__(self, parent_obj)

    @lazy_attribute
    def depth(self):
        """
        Return the depth of this node in the tree.

        EXAMPLES::

            sage: from sage.combinat.rigged_configurations.kleber_tree import KleberTree
            sage: RS = RootSystem(['A', 2])
            sage: WS = RS.weight_lattice()
            sage: R = RS.root_lattice()
            sage: KT = KleberTree(['A', 2, 1], [[1,1]])
            sage: n = KT(WS.sum_of_terms([(1,5), (2,2)]), R.zero())
            sage: n.depth
            0
            sage: n2 = KT(WS.sum_of_terms([(1,5), (2,2)]), R.zero(), n)
            sage: n2.depth
            1
        """
        depth = -1 # Offset
        cur = self
        while cur is not None:
            depth += 1
            cur = cur.parent_node

        return depth

    @cached_method
    def multiplicity(self):
        r"""
        Return the multiplicity of ``self``.

        The multiplicity of a node `x` of depth `d` weight `\lambda` in a
        simply-laced Kleber tree is equal to:

        .. MATH::

            \prod_{i > 0} \prod_{a \in \overline{I}}
            \binom{p_i^{(a)} + m_i^{(a)}}{p_i^{(a)}}

        Recall that

        .. MATH::

            m_i^{(a)} = \left( \lambda^{(i-1)} - 2 \lambda^{(i)} +
            \lambda^{(i+1)} \mid \overline{\Lambda}_a \right),

            p_i^{(a)} = \left( \alpha_a \mid \lambda^{(i)} \right)
            - \sum_{j > i} (j - i) L_j^{(a)},

        where `\lambda^{(i)}` is the weight node at depth `i` in the path
        to `x` from the root and we set `\lambda^{(j)} = \lambda` for all
        `j \geq d`.

        Note that `m_i^{(a)} = 0` for all `i > d`.

        EXAMPLES::

            sage: from sage.combinat.rigged_configurations.kleber_tree import KleberTree
            sage: KT = KleberTree(['A',3,1], [[3,2],[2,1],[1,1],[1,1]])
            sage: for x in KT: x, x.multiplicity()
            (Kleber tree node with weight [2, 1, 2] and upwards edge root [0, 0, 0], 1)
            (Kleber tree node with weight [3, 0, 1] and upwards edge root [0, 1, 1], 1)
            (Kleber tree node with weight [0, 2, 2] and upwards edge root [1, 0, 0], 1)
            (Kleber tree node with weight [1, 0, 3] and upwards edge root [1, 1, 0], 2)
            (Kleber tree node with weight [1, 1, 1] and upwards edge root [1, 1, 1], 4)
            (Kleber tree node with weight [0, 0, 2] and upwards edge root [2, 2, 1], 2)
            (Kleber tree node with weight [2, 0, 0] and upwards edge root [0, 1, 1], 2)
            (Kleber tree node with weight [0, 0, 2] and upwards edge root [1, 1, 0], 1)
            (Kleber tree node with weight [0, 1, 0] and upwards edge root [1, 1, 1], 2)
            (Kleber tree node with weight [0, 1, 0] and upwards edge root [0, 0, 1], 1)

        TESTS:

        We check that :trac:`16057` is fixed::

            sage: RC = RiggedConfigurations(['D',4,1], [[1,3],[3,3],[4,3]])
            sage: sum(x.multiplicity() for x in RC.kleber_tree()) == len(RC.module_generators)
            True
        """
        # The multiplicity corresponding to the root is always 1
        if self.parent_node is None:
            return Integer(1)

        mult = Integer(1)
        I = self.parent()._classical_ct.index_set()
        for a,m in self.up_root:
            p = self.weight[a]
            for r,s in self.parent().B:
                if r == a and s > self.depth:
                    p -= s - self.depth
            mult *= binomial(m + p, m)

        prev_up_root = self.up_root
        cur = self.parent_node
        while cur.parent_node is not None:
            root_diff = cur.up_root - prev_up_root
            for a,m in root_diff:
                p = cur.weight[a]
                for r,s in self.parent().B:
                    if r == a and s > cur.depth:
                        p -= s - cur.depth
                mult *= binomial(m + p, m)
            prev_up_root = cur.up_root
            cur = cur.parent_node

        return mult

    def __hash__(self):
        r"""
        TESTS::

            sage: from sage.combinat.rigged_configurations.kleber_tree import KleberTree
            sage: RS = RootSystem(['A', 2])
            sage: WS = RS.weight_lattice()
            sage: R = RS.root_lattice()
            sage: KT = KleberTree(['A', 2, 1], [[1,1]])
            sage: n = KT(WS.sum_of_terms([(1,5), (2,2)]), R.zero())
            sage: hash(n)
            -603608031356818252 # 64-bit
            -1956156236         # 32-bit
        """
        return hash(self.depth) ^ hash(self.weight)

    def _richcmp_(self, rhs, op):
        r"""
        Check whether two nodes are equal.

        TESTS::

            sage: from sage.combinat.rigged_configurations.kleber_tree import KleberTree
            sage: RS = RootSystem(['A', 2])
            sage: WS = RS.weight_lattice()
            sage: R = RS.root_lattice()
            sage: KT = KleberTree(['A', 2, 1], [[1,1]])
            sage: n = KT(WS.sum_of_terms([(1,5), (2,2)]), R.zero())
            sage: n2 = KT(WS.sum_of_terms([(1,5), (2,2)]), R.zero(), n)
            sage: n2 > n
            True
            sage: n3 = KT(WS.sum_of_terms([(1,5), (2,2)]), R.zero(), n)
            sage: n2 == n3
            True
            sage: n3 = KT(WS.sum_of_terms([(1,5), (2,3)]), R.zero(), n)
            sage: n2 < n3
            True
        """
        lx = self.depth
        rx = rhs.depth
        if lx != rx:
            return richcmp_not_equal(lx, rx, op)

        lx = self.parent_node
        rx = rhs.parent_node
        if lx != rx:
            return richcmp_not_equal(lx, rx, op)

        return richcmp(self.weight, rhs.weight, op)

    def _repr_(self):
        r"""
        Return the string representation of ``self``.

        EXAMPLES::

            sage: from sage.combinat.rigged_configurations.kleber_tree import KleberTree
            sage: RS = RootSystem(['A', 3])
            sage: WS = RS.weight_lattice()
            sage: R = RS.root_lattice()
            sage: KT = KleberTree(['A', 2, 1], [[1,1]])
            sage: node = KT(WS.sum_of_terms([(1,2), (2,1), (3,1)]), R.sum_of_terms([(1,3), (3,3)])); node
            Kleber tree node with weight [2, 1, 1] and upwards edge root [3, 0, 3]

        With virtual nodes::

            sage: from sage.combinat.rigged_configurations.kleber_tree import VirtualKleberTree
            sage: KT = VirtualKleberTree(['A',6,2], [[2,2]])
            sage: KT.root
            Kleber tree node with weight [0, 2, 0, 2, 0] and upwards edge root [0, 0, 0, 0, 0]
        """
        return "Kleber tree node with weight %s and upwards edge root %s"%(
            list(self.weight.to_vector()), list(self.up_root.to_vector()) )

    def _latex_(self):
        r"""
        Return latex representation of ``self``.

        TESTS::

            sage: from sage.combinat.rigged_configurations.kleber_tree import KleberTree
            sage: RS = RootSystem(['A', 3])
            sage: WS = RS.weight_lattice()
            sage: R = RS.root_lattice()
            sage: KT = KleberTree(['A', 3, 1], [[3,2], [1,1]])
            sage: node = KT(WS.sum_of_terms([(1,4), (3,1)]), R.zero())
            sage: latex(node)
            V_{4\omega_{1}+\omega_{3}}
            sage: node = KT(WS.zero(), R.zero())
            sage: latex(node)
            V_{0}
            sage: node = KT(WS.sum_of_terms([(1,2)]), R.zero())
            sage: latex(node)
            V_{2\omega_{1}}

        With virtual nodes::

            sage: from sage.combinat.rigged_configurations.kleber_tree import VirtualKleberTree
            sage: KT = VirtualKleberTree(['C',3,1], [[2,2]])
            sage: latex(KT.root)
            [V_{2\omega_{2}+2\omega_{4}}]
            sage: KT = VirtualKleberTree(['A',6,2], [[2,2]])
            sage: latex(KT.root)
            [V_{2\omega_{2}+2\omega_{4}}]
        """
        ret_str = "V_{"
        if self.multiplicity() != 1:
            ret_str = repr(self.multiplicity()) + ret_str
        for pair in self.weight:
            if pair[1] > 1:
                ret_str += repr(pair[1]) + "\omega_{" + repr(pair[0]) + "}+"
            elif pair[1] == 1:
                ret_str += "\omega_{" + repr(pair[0]) + "}+"

        if ret_str[-1] == '{':
            ret_str += "0}"
        else:
            ret_str = ret_str[:-1] + "}"

        ct = self.parent()._cartan_type
        if ct.type() == 'BC' or ct.dual().type() == 'BC':
            return "[" + ret_str + "]"
        elif not ct.is_simply_laced():
            s_factors = self.parent()._folded_ct.scaling_factors()
            gamma = max(s_factors)
            # Subtract 1 for indexing
            if gamma > 1:
                L = [self.parent()._folded_ct.folding_orbit()[a][0] for a in
                     range(1, len(s_factors)) if s_factors[a] == gamma]
            else:
                L = []

            if self.depth % gamma == 0 or all(self.up_root[a] == 0 for a in L):
                return "[" + ret_str + "]"
        return ret_str

#######################
# Kleber tree classes #
#######################

class KleberTree(UniqueRepresentation, Parent):
    r"""
    The tree that is generated by Kleber's algorithm.

    A Kleber tree is a tree of weights generated by Kleber's algorithm
    [Kleber1]_. It is used to generate the set of all admissible rigged
    configurations for the simply-laced affine types `A_n^{(1)}`,
    `D_n^{(1)}`, `E_6^{(1)}`, `E_7^{(1)}`, and `E_8^{(1)}`.

    .. SEEALSO::

        There is a modified version for non-simply-laced affine types at
        :class:`VirtualKleberTree`.

    The nodes correspond to the weights in the positive Weyl chamber obtained
    by subtracting a (non-zero) positive root. The edges are labeled by the
    coefficients of the roots, and `X` is a child of `Y` if `Y` is the root
    else if the edge label of `Y` to its parent `Z` is greater (in every
    component) than the label from `X` to `Y`.

    For a Kleber tree, one needs to specify an affine (simply-laced)
    Cartan type and a sequence of pairs `(r,s)`, where `s` is any positive
    integer and `r` is a node in the Dynkin diagram. Each `(r,s)` can be
    viewed as a rectangle of width `s` and height `r`.

    INPUT:

    - ``cartan_type`` -- an affine simply-laced Cartan type

    - ``B`` -- a list of dimensions of rectangles by `[r, c]`
      where `r` is the number of rows and `c` is the number of columns

    REFERENCES:

    .. [Kleber1] Michael Kleber.
       *Combinatorial structure of finite dimensional representations of
       Yangians: the simply-laced case*.
       Internat. Math. Res. Notices. (1997) no. 4. 187-201.

    .. [Kleber2] Michael Kleber.
       *Finite dimensional representations of quantum affine algebras*.
       Ph.D. dissertation at University of California Berkeley. (1998).
       :arxiv:`math.QA/9809087`.

    EXAMPLES:

    Simply-laced example::

        sage: from sage.combinat.rigged_configurations.kleber_tree import KleberTree
        sage: KT = KleberTree(['A', 3, 1], [[3,2], [1,1]])
        sage: KT.list()
        [Kleber tree node with weight [1, 0, 2] and upwards edge root [0, 0, 0],
         Kleber tree node with weight [0, 0, 1] and upwards edge root [1, 1, 1]]
        sage: KT = KleberTree(['A', 3, 1], [[3,2], [2,1], [1,1], [1,1]])
        sage: KT.cardinality()
        10
        sage: KT = KleberTree(['D', 4, 1], [[2,2]])
        sage: KT.cardinality()
        3
        sage: KT = KleberTree(['D', 4, 1], [[4,5]])
        sage: KT.cardinality()
        1

    From [Kleber2]_::

        sage: KT = KleberTree(['E', 6, 1], [[4, 2]])  # long time (9s on sage.math, 2012)
        sage: KT.cardinality()  # long time
        12

    We check that relabelled types work (:trac:`16876`)::

        sage: ct = CartanType(['A',3,1]).relabel(lambda x: x+2)
        sage: kt = KleberTree(ct, [[3,1],[5,1]])
        sage: list(kt)
        [Kleber tree node with weight [1, 0, 1] and upwards edge root [0, 0, 0],
         Kleber tree node with weight [0, 0, 0] and upwards edge root [1, 1, 1]]
        sage: kt = KleberTree(['A',3,1], [[1,1],[3,1]])
        sage: list(kt)
        [Kleber tree node with weight [1, 0, 1] and upwards edge root [0, 0, 0],
         Kleber tree node with weight [0, 0, 0] and upwards edge root [1, 1, 1]]
    """
    @staticmethod
    def __classcall_private__(cls, cartan_type, B, classical=None):
        """
        Normalize the input arguments to ensure unique representation.

        EXAMPLES::

            sage: from sage.combinat.rigged_configurations.kleber_tree import KleberTree
            sage: KT1 = KleberTree(CartanType(['A',3,1]), [[2,2]])
            sage: KT2 = KleberTree(['A',3,1], [(2,2)])
            sage: KT3 = KleberTree(['A',3,1], ((2,2),))
            sage: KT2 is KT1, KT3 is KT1
            (True, True)
        """
        cartan_type = CartanType(cartan_type)
        if not cartan_type.is_affine():
            raise ValueError("The Cartan type must be affine")

        if not cartan_type.classical().is_simply_laced():
            raise ValueError("use VirtualKleberTree for non-simply-laced types")

        # Standardize B input into a tuple of tuples
        B = tuple([tuple(rs) for rs in B])

        if classical is None:
            classical = cartan_type.classical()
        else:
            classical = CartanType(classical)
        return super(KleberTree, cls).__classcall__(cls, cartan_type, B, classical)

    def __init__(self, cartan_type, B, classical_ct):
        r"""
        Construct a Kleber tree.

        The input ``classical_ct`` is the classical Cartan type to run the
        algorithm on and is only meant to be used internally.

        EXAMPLES::

            sage: from sage.combinat.rigged_configurations.kleber_tree import KleberTree
            sage: KT = KleberTree(['D', 3, 1], [[1,1], [1,1]]); KT
            Kleber tree of Cartan type ['D', 3, 1] and B = ((1, 1), (1, 1))
            sage: TestSuite(KT).run(skip="_test_elements")
        """
        Parent.__init__(self, category=FiniteEnumeratedSets())

        self._cartan_type = cartan_type
        self.B = B
        self._classical_ct = classical_ct
        self._build_tree()
        self._latex_options = dict(edge_labels=True, use_vector_notation=False,
                                  hspace=2.5, vspace=min(-2.5, -0.75*self._classical_ct.rank()))

    def latex_options(self, **options):
        """
        Return the current latex options if no arguments are passed, otherwise
        set the corresponding latex option.

        OPTIONS:

        - ``hspace`` -- (default: `2.5`) the horizontal spacing of the
          tree nodes
        - ``vspace`` -- (default: ``x``) the vertical spacing of the tree
          nodes, here ``x`` is the minimum of `-2.5` or `-.75n` where `n` is
          the rank of the classical type
        - ``edge_labels`` -- (default: ``True``) display edge labels
        - ``use_vector_notation`` -- (default: ``False``) display edge labels
          using vector notation instead of a linear combination

        EXAMPLES::

            sage: from sage.combinat.rigged_configurations.kleber_tree import KleberTree
            sage: KT = KleberTree(['D', 3, 1], [[2,1], [2,1]])
            sage: KT.latex_options(vspace=-4, use_vector_notation=True)
            sage: sorted(KT.latex_options().items())
            [('edge_labels', True), ('hspace', 2.5), ('use_vector_notation', True), ('vspace', -4)]
        """
        if not options:
            from copy import copy
            return copy(self._latex_options)
        for k in options:
            self._latex_options[k] = options[k]

    def _latex_(self):
        r"""
        Return a latex representation of this Kleber tree.

        .. SEEALSO::

            :meth:`latex_options()`

        EXAMPLES::

            sage: from sage.combinat.rigged_configurations.kleber_tree import KleberTree
            sage: KT = KleberTree(['D', 3, 1], [[2,1], [2,1]])
            sage: KT._latex_()
            '\\begin{tikzpicture}...\\end{tikzpicture}'
        """
        from sage.graphs.graph_latex import setup_latex_preamble
        setup_latex_preamble()

        return "\\begin{tikzpicture}\n" + \
               _draw_tree(self.root, **self._latex_options) \
               + "\\end{tikzpicture}"

    def _build_tree(self):
        """
        Build the Kleber tree.

        TESTS:

        This is called from the constructor::

            sage: from sage.combinat.rigged_configurations.kleber_tree import KleberTree
            sage: KT = KleberTree(['A',3,1], [[2,2]]) # indirect doctest
        """
        P = self._classical_ct.root_system().weight_lattice()
        # Create an empty node at first step
        self.root = KleberTreeNode(self, P.zero(),
                                   self._classical_ct.root_system().root_lattice().zero())
        full_list = [self.root] # The list of tree nodes

        n = self._classical_ct.rank()

        # Convert the B values into an L matrix
        L = []
        I = self._classical_ct.index_set()
        for i in range(n):
            L.append([0])

        for r,s in self.B:
            while len(L[0]) < s: # Add more columns if needed
                for row in L:
                    row.append(0)
            L[I.index(r)][s - 1] += 1 # The -1 is for indexing

        # Perform a special case of the algorithm for the root node
        weight_basis = P.basis()
        for a in range(n):
            self.root.weight += sum(L[a]) * weight_basis[I[a]]
        new_children = []
        for new_child in self._children_iter(self.root):
            if not self._prune(new_child, 1):
                new_children.append(new_child)
                self.root.children.append(new_child)
                full_list.append(new_child)

        depth = 1
        growth = True

        # self._has_normaliz is set by _children_iter
        if self._classical_ct.rank() >= 7 or self._has_normaliz:
            child_itr = self._children_iter
        else:
            child_itr = self._children_iter_vector

        while growth:
            growth = False
            depth += 1
            leaves = new_children
            new_children = []

            if depth <= len(L[0]):
                for x in full_list:
                    growth = True
                    for a in range(n):
                        for i in range(depth - 1, len(L[a])): # Subtract 1 for indexing
                            x.weight += L[a][i] * weight_basis[I[a]]

                    if x in leaves:
                        for new_child in child_itr(x):
                            if not self._prune(new_child, depth):
                                new_children.append(new_child)
            else:
                for x in leaves:
                    for new_child in child_itr(x):
                        if not self._prune(new_child, depth):
                            new_children.append(new_child)

            # Connect the new children into the tree
            if new_children:
                growth = True
                for new_child in new_children:
                    new_child.parent_node.children.append(new_child)
                    full_list.append(new_child)

        self._set = full_list

    def _children_iter(self, node):
        r"""
        Iterate over the children of ``node``.

        Helper iterator to iterate over all children, by generating and/or
        computing them, of the Kleber tree node.

        We compute the children by computing integral points (expressed as
        simple roots) in the polytope given by the intersection of the
        negative root cone and shifted positive weight cone. More precisely,
        we rewrite the condition `\lambda - \mu \in Q^+`, for `\mu \in  P^+`,
        as `\lambda - Q^+ = \mu \in P^+`.

        INPUT:

        - ``node`` -- the current node in the tree whose children we want
          to generate

        TESTS::

            sage: from sage.combinat.rigged_configurations.kleber_tree import KleberTree
            sage: KT = KleberTree(['D', 3, 1], [[1,1], [1,1]])
            sage: for x in KT: x # indirect doctest
            Kleber tree node with weight [2, 0, 0] and upwards edge root [0, 0, 0]
            Kleber tree node with weight [0, 1, 1] and upwards edge root [1, 0, 0]
            Kleber tree node with weight [0, 0, 0] and upwards edge root [2, 1, 1]

            sage: KT = KleberTree(['D', 4, 1], [[2,2]])
            sage: KT[1]
            Kleber tree node with weight [0, 1, 0, 0] and upwards edge root [1, 2, 1, 1]
            sage: for x in KT: x
            Kleber tree node with weight [0, 2, 0, 0] and upwards edge root [0, 0, 0, 0]
            Kleber tree node with weight [0, 1, 0, 0] and upwards edge root [1, 2, 1, 1]
            Kleber tree node with weight [0, 0, 0, 0] and upwards edge root [1, 2, 1, 1]
            sage: for x in KT._children_iter(KT[1]): x
            Kleber tree node with weight [0, 0, 0, 0] and upwards edge root [1, 2, 1, 1]
        """
        n = self._classical_ct.rank()
        I = self._classical_ct.index_set()
        Q = self._classical_ct.root_system().root_lattice()
        P = self._classical_ct.root_system().weight_lattice()

        # Construct the polytope by inequalities
        from sage.geometry.polyhedron.constructor import Polyhedron
        # Construct the shifted weight cone
        root_weight = node.weight.to_vector()
        ieqs = [[root_weight[i]] + list(col)
                for i,col in enumerate(self._classical_ct.cartan_matrix())]
        # Construct the negative weight cone
        for i in range(n):
            v = [0] * (n+1)
            v[i+1] = -1
            ieqs.append(v)
        ieqs.append([-1]*(n+1)) # For avoiding the origin
        # Construct the bounds for the non-root nodes
        if node != self.root:
            for i,c in enumerate(node.up_root.to_vector()):
                v = [0] * (n+1)
                v[0] = c
                v[i+1] = 1
                ieqs.append(v)

        try:
            poly = Polyhedron(ieqs=ieqs, backend='normaliz')
            self._has_normaliz = True
        except ImportError:
            poly = Polyhedron(ieqs=ieqs)
            self._has_normaliz = False

        # Build the nodes from the polytope
        # Sort for a consistent ordering (it is typically a small list)
        for pt in sorted(poly.integral_points(), reverse=True):
            up_root = Q._from_dict({I[i]: -val for i,val in enumerate(pt) if val != 0},
                                   remove_zeros=False)
            wt = node.weight + sum(val * P.simple_root(I[i]) for i,val in enumerate(pt))
            yield KleberTreeNode(self, wt, up_root, node)

    def _children_iter_vector(self, node):
        r"""
        Iterate over the children of ``node``.

        Helper iterator to iterate over all children, by generating and/or
        computing them, of the Kleber tree node. This implementation
        iterates over all possible uproot vectors.

        .. SEEALSO::

            :meth:`_children_iter`

        INPUT:

        - ``node`` -- the current node in the tree whose children we want
          to generate

        TESTS::

            sage: from sage.combinat.rigged_configurations.kleber_tree import KleberTree
            sage: KT = KleberTree(['D', 4, 1], [[2,2]])
            sage: KT[1]
            Kleber tree node with weight [0, 1, 0, 0] and upwards edge root [1, 2, 1, 1]
            sage: for x in KT._children_iter(KT[1]): x
            Kleber tree node with weight [0, 0, 0, 0] and upwards edge root [1, 2, 1, 1]
        """
        Q = self._classical_ct.root_system().root_lattice()
        P = self._classical_ct.root_system().weight_lattice()
        I = self._classical_ct.index_set()
        wt = node.weight.to_vector()
        # Everything is dense at this point; moreover, ranks are relatively small
        CM = self._classical_ct.cartan_matrix().dense_matrix()
        F = FreeModule(ZZ, self._classical_ct.rank())

        L = [range(val + 1) for val in node.up_root.to_vector()]

        it = itertools.product(*L)
        next(it)  # First element is the zero element
        for root in it:
            # Convert the list to the weight lattice
            converted_root = CM * F(root)

            if all(wt[i] >= val for i,val in enumerate(converted_root)):
                wd = {I[i]: wt[i] - val for i, val in enumerate(converted_root)}
                rd = {I[i]: val for i, val in enumerate(root)}
                yield KleberTreeNode(self, P._from_dict(wd), Q._from_dict(rd), node)

    def _prune(self, new_child, depth):
        r"""
        Return ``True`` if we are to prune the tree at ``new_child``.

        This always returns ``False`` since we do not do any pruning.

        EXAMPLES::

            sage: from sage.combinat.rigged_configurations.kleber_tree import KleberTree
            sage: KT = KleberTree(['A', 2, 1], [[1,1]])
            sage: KT._prune(KT.root, 0)
            False
        """
        return False

    def breadth_first_iter(self):
        r"""
        Iterate over all nodes in the tree following a breadth-first traversal.

        EXAMPLES::

            sage: from sage.combinat.rigged_configurations.kleber_tree import KleberTree
            sage: KT = KleberTree(['A', 3, 1], [[2, 2], [2, 3]])
            sage: for x in KT.breadth_first_iter(): x
            Kleber tree node with weight [0, 5, 0] and upwards edge root [0, 0, 0]
            Kleber tree node with weight [1, 3, 1] and upwards edge root [0, 1, 0]
            Kleber tree node with weight [0, 3, 0] and upwards edge root [1, 2, 1]
            Kleber tree node with weight [2, 1, 2] and upwards edge root [0, 1, 0]
            Kleber tree node with weight [1, 1, 1] and upwards edge root [0, 1, 0]
            Kleber tree node with weight [0, 1, 0] and upwards edge root [1, 2, 1]
        """
        cur = []
        next = [self.root]
        while len(next) > 0:
            cur = next
            next = []
            for node in cur:
                yield node
                next.extend(node.children)

    def depth_first_iter(self):
        r"""
        Iterate (recursively) over the nodes in the tree following a
        depth-first traversal.

        EXAMPLES::

            sage: from sage.combinat.rigged_configurations.kleber_tree import KleberTree
            sage: KT = KleberTree(['A', 3, 1], [[2, 2], [2, 3]])
            sage: for x in KT.depth_first_iter(): x
            Kleber tree node with weight [0, 5, 0] and upwards edge root [0, 0, 0]
            Kleber tree node with weight [1, 3, 1] and upwards edge root [0, 1, 0]
            Kleber tree node with weight [2, 1, 2] and upwards edge root [0, 1, 0]
            Kleber tree node with weight [0, 3, 0] and upwards edge root [1, 2, 1]
            Kleber tree node with weight [1, 1, 1] and upwards edge root [0, 1, 0]
            Kleber tree node with weight [0, 1, 0] and upwards edge root [1, 2, 1]
        """
        return self._depth_first_iter(None)

    def _depth_first_iter(self, cur):
        r"""
        Helper recursive function used in depth-first iteration.

        EXAMPLES::

            sage: from sage.combinat.rigged_configurations.kleber_tree import KleberTree
            sage: KT = KleberTree(['A', 3, 1], [[2, 2], [2, 3]])
            sage: for x in KT._depth_first_iter(None): x
            Kleber tree node with weight [0, 5, 0] and upwards edge root [0, 0, 0]
            Kleber tree node with weight [1, 3, 1] and upwards edge root [0, 1, 0]
            Kleber tree node with weight [2, 1, 2] and upwards edge root [0, 1, 0]
            Kleber tree node with weight [0, 3, 0] and upwards edge root [1, 2, 1]
            Kleber tree node with weight [1, 1, 1] and upwards edge root [0, 1, 0]
            Kleber tree node with weight [0, 1, 0] and upwards edge root [1, 2, 1]
        """
        if cur is None:
            cur = self.root

        yield cur

        for child in cur.children:
            for x in self._depth_first_iter(child):
                yield x

    __iter__ = breadth_first_iter

    def _repr_(self):
        """
        Return a text representation of this Kleber tree.

        EXAMPLES::

            sage: from sage.combinat.rigged_configurations.kleber_tree import KleberTree
            sage: KleberTree(['D', 4, 1], [[2, 2]]) # indirect doctest
            Kleber tree of Cartan type ['D', 4, 1] and B = ((2, 2),)
        """
        return "Kleber tree of Cartan type %s and B = %s"%(repr(self._cartan_type), self.B)

    def cartan_type(self):
        r"""
        Return the Cartan type of this Kleber tree.

        EXAMPLES::

            sage: from sage.combinat.rigged_configurations.kleber_tree import KleberTree
            sage: KT = KleberTree(['A', 3, 1], [[1,1]])
            sage: KT.cartan_type()
            ['A', 3, 1]
        """
        return self._cartan_type

    def digraph(self):
        r"""
        Return a DiGraph representation of this Kleber tree.

        EXAMPLES::

            sage: from sage.combinat.rigged_configurations.kleber_tree import KleberTree
            sage: KT = KleberTree(['D', 4, 1], [[2, 2]])
            sage: KT.digraph()  # optional - dot2tex graphviz
            Digraph on 3 vertices
        """
        d = {}
        for x in self.breadth_first_iter():
            d[x] = {}
            if x.parent_node is None:
                continue
            d[x][x.parent_node] = tuple(x.up_root.to_vector())
        G = DiGraph(d)

        if have_dot2tex():
            G.set_latex_options(format="dot2tex", edge_labels=True)
        return G

    def plot(self, **options):
        """
        Return the plot of self as a directed graph.

        EXAMPLES::

            sage: from sage.combinat.rigged_configurations.kleber_tree import KleberTree
            sage: KT = KleberTree(['D', 4, 1], [[2, 2]])
            sage: print(KT.plot())  # optional - dot2tex graphviz
            Graphics object consisting of 8 graphics primitives
        """
        return self.digraph().plot(edge_labels=True, vertex_size=0, **options)

    def _element_constructor_(self, node_weight, dominant_root, parent_node=None):
        """
        Construct a Kleber tree node.

        EXAMPLES::

            sage: from sage.combinat.rigged_configurations.kleber_tree import KleberTree
            sage: RS = RootSystem(['A', 2])
            sage: WS = RS.weight_lattice()
            sage: R = RS.root_lattice()
            sage: KT = KleberTree(['A', 2, 1], [[1,1]])
            sage: root = KT(WS.sum_of_terms([(1,5), (2,2)]), R.zero()); root # indirect doctest
            Kleber tree node with weight [5, 2] and upwards edge root [0, 0]
            sage: child = KT(WS.sum_of_terms([(1,5), (2,1)]), R.zero(), root); child # indirect doctest
            Kleber tree node with weight [5, 1] and upwards edge root [0, 0]
            sage: child.parent_node
            Kleber tree node with weight [5, 2] and upwards edge root [0, 0]
        """
        return self.element_class(self, node_weight, dominant_root, parent_node)

    Element = KleberTreeNode

class VirtualKleberTree(KleberTree):
    """
    A virtual Kleber tree.

    We can use a modified version of the Kleber algorithm called the virtual
    Kleber algorithm [OSS03]_ to compute all admissible rigged configurations
    for non-simply-laced types. This uses the following embeddings
    into the simply-laced types:

    .. MATH::

        C_n^{(1)}, A_{2n}^{(2)}, A_{2n}^{(2)\dagger}, D_{n+1}^{(2)}
        \hookrightarrow A_{2n-1}^{(1)}

        A_{2n-1}^{(2)}, B_n^{(1)} \hookrightarrow D_{n+1}^{(1)}

        E_6^{(2)}, F_4^{(1)} \hookrightarrow E_6^{(1)}

        D_4^{(3)}, G_2^{(1)} \hookrightarrow D_4^{(1)}

    One then selects the subset of admissible nodes which are translates of
    the virtual requirements. In the graph, the selected nodes are indicated
    by brackets `[]`.

    .. NOTE::

        Because these are virtual nodes, all information is given
        in the corresponding simply-laced type.

    .. SEEALSO::

        For more on the Kleber algorithm, see :class:`KleberTree`.

    REFERENCES:

    .. [OSS03] Masato Okado, Anne Schilling, and Mark Shimozono.
       *Virtual crystals and Klebers algorithm*. Commun. Math. Phys. **238**
       (2003). 187-209. :arxiv:`math.QA/0209082`.

    INPUT:

    - ``cartan_type`` -- an affine non-simply-laced Cartan type

    - ``B`` -- a list of dimensions of rectangles by `[r, c]`
      where `r` is the number of rows and `c` is the number of columns

    EXAMPLES::

        sage: from sage.combinat.rigged_configurations.kleber_tree import VirtualKleberTree
        sage: KT = VirtualKleberTree(['C', 4, 1], [[2,2]])
        sage: KT.cardinality()
        3
        sage: KT.base_tree().cardinality()
        6
        sage: KT = VirtualKleberTree(['C', 4, 1], [[4,5]])
        sage: KT.cardinality()
        1
        sage: KT = VirtualKleberTree(['D', 5, 2], [[2,1], [1,1]])
        sage: KT.cardinality()
        8
        sage: KT = VirtualKleberTree(CartanType(['A', 4, 2]).dual(), [[1,1], [2,2]])
        sage: KT.cardinality()
        15
    """
    @staticmethod
    def __classcall_private__(cls, cartan_type, B):
        """
        Normalize the input arguments to ensure unique representation.

        EXAMPLES::

            sage: from sage.combinat.rigged_configurations.kleber_tree import VirtualKleberTree
            sage: KT1 = VirtualKleberTree(CartanType(['C',3,1]).as_folding(), [[2,2]])
            sage: KT2 = VirtualKleberTree(CartanType(['C',3,1]), [(2,2)])
            sage: KT3 = VirtualKleberTree(['C',3,1], ((2,2),))
            sage: KT2 is KT1, KT3 is KT1
            (True, True)
        """
        cartan_type = CartanType(cartan_type)
        # Standardize B input into a tuple of tuples
        B = tuple(map(tuple, B))
        if cartan_type.type() == 'BC' or cartan_type.dual().type() == 'BC':
            # Types A_{2n}^{(2)} and its dual
            return KleberTreeTypeA2Even(cartan_type, B)
        if cartan_type.classical().is_simply_laced():
            raise ValueError("use KleberTree for simply-laced types")
        return super(VirtualKleberTree, cls).__classcall__(cls, cartan_type, B)

    def __init__(self, cartan_type, B):
        """
        Initialize ``self``.

        EXAMPLES::

            sage: from sage.combinat.rigged_configurations.kleber_tree import VirtualKleberTree
            sage: KT = VirtualKleberTree(['C',4,1], [[2,2]])
            sage: TestSuite(KT).run(skip="_test_elements")
        """
        self._folded_ct = cartan_type.as_folding()
        virtual_dims = []
        self.base_dims = B
        sigma = self._folded_ct.folding_orbit()
        gamma = self._folded_ct.scaling_factors()
        classical_ct = self._folded_ct.folding_of().classical()
        for r,s in B:
            for i in sigma[r]:
                virtual_dims.append([i, s * gamma[r]])

        KleberTree.__init__(self, cartan_type, virtual_dims, classical_ct)

    def _repr_(self):
        """
        Return a text representation of this Kleber tree.

        EXAMPLES::

            sage: from sage.combinat.rigged_configurations.kleber_tree import VirtualKleberTree
            sage: VirtualKleberTree(['C', 4, 1], [[2, 2]])
            Virtual Kleber tree of Cartan type ['C', 4, 1] and B = ((2, 2),)
        """
        return "Virtual Kleber tree of Cartan type %s and B = %s"%(repr(self._cartan_type), self.base_dims)

    def _prune(self, new_child, depth):
        r"""
        Return ``True`` if we are to prune the tree at ``new_child``.

        Suppose `\lambda` is the weight of the child we want to add at depth
        `\ell`. We prune ``new_child`` if either of the following conditions
        are not satisfied:

        1. `(\lambda \mid \alpha_a) = (\lambda \mid \alpha_b)` if `a` and `b`
           are in the same `\sigma`-orbit.
        2. If `\ell - 1 \notin \gamma_a \ZZ`, then the `a`-th component of
           ``up_root`` of ``new_child`` must equal the `a`-th component of
           ``up_root`` of its ``parent_node``. Note that from condition 1,
           we only need to check one such `a` from each `\sigma`-orbit.

        These conditions are equivalent to Definition 4.1 in [OSS03]_.

        EXAMPLES::

            sage: from sage.combinat.rigged_configurations.kleber_tree import VirtualKleberTree
            sage: RS = RootSystem(['A', 3])
            sage: WS = RS.weight_lattice()
            sage: R = RS.root_lattice()
            sage: KT = VirtualKleberTree(['C',2,1], [[1,2],[1,1],[2,1]])
            sage: x = KT(WS.sum_of_terms([(1,1), (2,1), (3,3)]), R.sum_of_terms([(1,2),(2,2),(3,1)]), KT.root)
            sage: KT._prune(x, 1)
            True
        """
        sigma = self._folded_ct._orbit
        for orbit in sigma[1:]:
            start = new_child.weight[orbit[0]]
            for i in orbit[1:]:
                if new_child.weight[i] != start:
                    return True
        gamma = self._folded_ct.scaling_factors()
        for a in range(1, len(gamma)):
            if (depth - 1) % gamma[a] != 0 and new_child.up_root[sigma[a][0]] \
              != new_child.parent_node.up_root[sigma[a][0]]:
                return True
        return False

    def breadth_first_iter(self, all_nodes=False):
        r"""
        Iterate over all nodes in the tree following a breadth-first traversal.

        INPUT:

        - ``all_nodes`` -- (default: ``False``) if ``True``, output all
          nodes in the tree

        EXAMPLES::

            sage: from sage.combinat.rigged_configurations.kleber_tree import VirtualKleberTree
            sage: KT = VirtualKleberTree(['C', 2, 1], [[1,1], [2,1]])
            sage: for x in KT.breadth_first_iter(): x
            Kleber tree node with weight [1, 2, 1] and upwards edge root [0, 0, 0]
            Kleber tree node with weight [1, 0, 1] and upwards edge root [0, 1, 0]
            sage: for x in KT.breadth_first_iter(True): x
            Kleber tree node with weight [1, 2, 1] and upwards edge root [0, 0, 0]
            Kleber tree node with weight [0, 2, 0] and upwards edge root [1, 1, 1]
            Kleber tree node with weight [1, 0, 1] and upwards edge root [0, 1, 0]
        """
        s_factors = self._folded_ct.scaling_factors()
        gamma = max(s_factors)
        # Subtract 1 for indexing
        if gamma > 1:
            sigma = self._folded_ct.folding_orbit()
            L = [sigma[a][0] for a in range(1, len(s_factors))
                 if s_factors[a] == gamma]
        else:
            L = []

        for x in KleberTree.breadth_first_iter(self):
            if all_nodes or (x.depth) % gamma == 0 or all(x.up_root[a] == 0 for a in L):
                yield x

    def depth_first_iter(self, all_nodes=False):
        r"""
        Iterate (recursively) over the nodes in the tree following a
        depth-first traversal.

        INPUT:

        - ``all_nodes`` -- (default: ``False``) if ``True``, output all
          nodes in the tree

        EXAMPLES::

            sage: from sage.combinat.rigged_configurations.kleber_tree import VirtualKleberTree
            sage: KT = VirtualKleberTree(['C', 2, 1], [[1,1], [2,1]])
            sage: for x in KT.depth_first_iter(): x
            Kleber tree node with weight [1, 2, 1] and upwards edge root [0, 0, 0]
            Kleber tree node with weight [1, 0, 1] and upwards edge root [0, 1, 0]
            sage: for x in KT.depth_first_iter(True): x
            Kleber tree node with weight [1, 2, 1] and upwards edge root [0, 0, 0]
            Kleber tree node with weight [0, 2, 0] and upwards edge root [1, 1, 1]
            Kleber tree node with weight [1, 0, 1] and upwards edge root [0, 1, 0]
        """
        s_factors = self._folded_ct.scaling_factors()
        gamma = max(s_factors)
        # Subtract 1 for indexing
        if gamma > 1:
            sigma = self._folded_ct.folding_orbit()
            L = [sigma[a][0] for a in range(1, len(s_factors))
                 if s_factors[a] == gamma]
        else:
            L = []

        for x in self._depth_first_iter(None):
            if all_nodes or (x.depth) % gamma == 0 or all(x.up_root[a] == 0 for a in L):
                yield x

    __iter__ = breadth_first_iter

    def base_tree(self):
        """
        Return the underlying virtual Kleber tree associated to ``self``.

        EXAMPLES::

            sage: from sage.combinat.rigged_configurations.kleber_tree import VirtualKleberTree
            sage: KT = VirtualKleberTree(['C', 4, 1], [[2,2]])
            sage: KT.base_tree()
            Kleber tree of Cartan type ['A', 7, 1] and B = ((2, 2), (6, 2))
        """
        return KleberTree(self._folded_ct.folding_of(), self.B)

class KleberTreeTypeA2Even(VirtualKleberTree):
    r"""
    Kleber tree for types `A_{2n}^{(2)}` and `A_{2n}^{(2)\dagger}`.

    Note that here for `A_{2n}^{(2)}` we use `\tilde{\gamma}_a` in place of
    `\gamma_a` in constructing the virtual Kleber tree, and so we end up
    selecting all nodes since `\tilde{\gamma}_a = 1` for all `a \in
    \overline{I}`. For type `A_{2n}^{(2)\dagger}`, we have `\gamma_a = 1`
    for all `a \in \overline{I}`.

    .. SEEALSO::

        :class:`VirtualKleberTree`
    """
    @staticmethod
    def __classcall_private__(cls, cartan_type, B):
        """
        Normalize the input arguments to ensure unique representation.

        EXAMPLES::

            sage: from sage.combinat.rigged_configurations.kleber_tree import VirtualKleberTree
            sage: KT1 = VirtualKleberTree(CartanType(['A',6,2]), [[2,2]])
            sage: KT2 = VirtualKleberTree(['A',6,2], [(2,2)])
            sage: KT3 = VirtualKleberTree(['A',6,2], ((2,2),))
            sage: KT2 is KT1, KT3 is KT1
            (True, True)
        """
        cartan_type = CartanType(cartan_type)
        # Standardize B input into a tuple of tuples
        B = tuple(map(tuple, B))
        return super(KleberTreeTypeA2Even, cls).__classcall__(cls, cartan_type, B)

    def __init__(self, cartan_type, B):
        """
        Initialize ``self``.

        EXAMPLES::

            sage: from sage.combinat.rigged_configurations.kleber_tree import VirtualKleberTree
            sage: KT = VirtualKleberTree(['A',6,2], [[2,2]]); KT
            Virtual Kleber tree of Cartan type ['BC', 3, 2] and B = ((2, 2),)
            sage: TestSuite(KT).run(skip="_test_elements")
        """
        self._folded_ct = cartan_type.as_folding()
        virtual_dims = []
        n = cartan_type.classical().rank()
        self.base_dims = B
        sigma = self._folded_ct.folding_orbit()
        classical_ct = self._folded_ct.folding_of().classical()
        for r,s in B:
            if r == n:
                virtual_dims.extend([[n, s], [n, s]])
            else:
                for i in sigma[r]:
                    virtual_dims.append([i, s])

        KleberTree.__init__(self, cartan_type, virtual_dims, classical_ct)

    def __iter__(self):
        """
        Iterate over all of the nodes.

        EXAMPLES::

            sage: from sage.combinat.rigged_configurations.kleber_tree import VirtualKleberTree
            sage: KT = VirtualKleberTree(['A',6,2], [[2,2]])
            sage: L = [x for x in KT]
            sage: len(L) == KT.cardinality()
            True
        """
        return KleberTree.__iter__(self)

    def _prune(self, new_child, depth):
        r"""
        Return ``True`` if we are to prune the tree at ``new_child``.

        Suppose `\lambda` is the weight of the child we want to add at
        depth `\ell`. We prune ``new_child`` if `(\lambda \mid \alpha_a)
        \neq (\lambda \mid \alpha_b)` if `a` and `b` are in the same
        `\sigma`-orbit.

        These conditions are equivalent to Definition 4.1 in [OSS03]_ by using
        `\tilde{\gamma}`, and since `\tilde{\gamma}_a = 1` for all `a`, the
        second condition becomes vacuous.

        EXAMPLES::

            sage: from sage.combinat.rigged_configurations.kleber_tree import VirtualKleberTree
            sage: RS = RootSystem(['A', 5])
            sage: WS = RS.weight_lattice()
            sage: R = RS.root_lattice()
            sage: KT = VirtualKleberTree(['A',6,2], [[2,2]])
            sage: x = KT(WS.sum_of_terms([(2,1), (4,1)]), R.sum_of_terms([(1,1),(2,2),(3,2),(4,2),(5,1)]), KT.root)
            sage: KT._prune(x, 1)
            False
        """
        sigma = self._folded_ct._orbit
        for orbit in sigma[1:]:
            start = new_child.weight[orbit[0]]
            for i in orbit[1:]:
                if new_child.weight[i] != start:
                    return True
        return False

    def breadth_first_iter(self, all_nodes=False):
        r"""
        Iterate over all nodes in the tree following a breadth-first traversal.

        INPUT:

        - ``all_nodes`` -- (default: ``False``) if ``True``, output all
          nodes in the tree

        EXAMPLES::

            sage: from sage.combinat.rigged_configurations.kleber_tree import VirtualKleberTree
            sage: KT = VirtualKleberTree(['A', 4, 2], [[2,1]])
            sage: for x in KT.breadth_first_iter(): x
            Kleber tree node with weight [0, 2, 0] and upwards edge root [0, 0, 0]
            Kleber tree node with weight [1, 0, 1] and upwards edge root [0, 1, 0]
            Kleber tree node with weight [0, 0, 0] and upwards edge root [1, 2, 1]
            sage: for x in KT.breadth_first_iter(True): x
            Kleber tree node with weight [0, 2, 0] and upwards edge root [0, 0, 0]
            Kleber tree node with weight [1, 0, 1] and upwards edge root [0, 1, 0]
            Kleber tree node with weight [0, 0, 0] and upwards edge root [1, 2, 1]
        """
        return KleberTree.breadth_first_iter(self)

    def depth_first_iter(self, all_nodes=False):
        r"""
        Iterate (recursively) over the nodes in the tree following a
        depth-first traversal.

        INPUT:

        - ``all_nodes`` -- (default: ``False``) if ``True``, output all
          nodes in the tree

        EXAMPLES::

            sage: from sage.combinat.rigged_configurations.kleber_tree import VirtualKleberTree
            sage: KT = VirtualKleberTree(['A', 4, 2], [[2,1]])
            sage: for x in KT.depth_first_iter(): x
            Kleber tree node with weight [0, 2, 0] and upwards edge root [0, 0, 0]
            Kleber tree node with weight [1, 0, 1] and upwards edge root [0, 1, 0]
            Kleber tree node with weight [0, 0, 0] and upwards edge root [1, 2, 1]
            sage: for x in KT.depth_first_iter(True): x
            Kleber tree node with weight [0, 2, 0] and upwards edge root [0, 0, 0]
            Kleber tree node with weight [1, 0, 1] and upwards edge root [0, 1, 0]
            Kleber tree node with weight [0, 0, 0] and upwards edge root [1, 2, 1]
        """
        return KleberTree.depth_first_iter(self)

