import panel as pn
import pandas as pd
from collections import defaultdict
pn.extension()


data = {
    "world": ["Earth", "Earth", "Earth", "Earth", "Earth", "Earth"],
    "continent": ["Europe", "Europe", "Asia", "Asia", "North America", "North America"],
    "country": ["France", "France", "Japan", "Japan", "USA", "USA"],
    "manufacturer": ["Fiat", "Peugeot", "Toyota", "Nissan", "Ford", "Ford"],
    "model": ["500", "208", "Corolla", "Sentra", "Mustang", "Mustang"],
}
df = pd.DataFrame(data)

cols = list(df.columns)
grouped = df.groupby(cols[:-1])
nested = grouped[cols[-1]].apply(lambda x: x.tolist()).to_dict()
create_nested_defaultdict = lambda depth: defaultdict(
    lambda: create_nested_defaultdict(depth - 1)
)
nested_data = create_nested_defaultdict(len(cols) - 1)
for keys, values in nested.items():
    if isinstance(keys, str):
        keys = (keys,)
    current_dict = nested_data
    for i, key in enumerate(keys):
        if i != len(keys) - 1:
            current_dict = current_dict[key]
        else:
            current_dict[key] = values
pn.widgets.NestedSelect(options=nested_data)

import pandas as pd
from collections import OrderedDict
from pandas.core.indexes.multi import MultiIndex

def multiindex2dict(p: pd.MultiIndex|dict) -> dict:
    """
    Converts a pandas Multiindex to a nested dict
    :parm p: As this is a recursive function, initially p is a pd.MultiIndex, but after the first iteration it takes
    the internal_dict value, so it becomes to a dictionary
    """
    internal_dict = {}
    end = False
    for x in p:
        # Since multi-indexes have a descending hierarchical structure, it is convenient to start from the last
        # element of each tuple. That is, we start by generating the lower level to the upper one. See the example
        if isinstance(p, pd.MultiIndex):
            # This checks if the tuple x without the last element has len = 1. If so, the unique value of the
            # remaining tuple works as key in the new dict, otherwise the remaining tuple is used. Only for 2 levels
            # pd.MultiIndex
            if len(x[:-1]) == 1:
                t = x[:-1][0]
                end = True
            else:
                t = x[:-1]
            if t not in internal_dict:
                internal_dict[t] = [x[-1]]
            else:
                internal_dict[t].append(x[-1])
        elif isinstance(x, tuple):
            # This checks if the tuple x without the last element has len = 1. If so, the unique value of the
            # remaining tuple works as key in the new dict, otherwise the remaining tuple is used
            if len(x[:-1]) == 1:
                t = x[:-1][0]
                end = True
            else:
                t = x[:-1]
            if t not in internal_dict:
                internal_dict[t] = {x[-1]: p[x]}
            else:
                internal_dict[t][x[-1]] = p[x]
    
    # Uncomment this line to know how the dictionary is generated starting from the lowest level
    # print(internal_dict)
    if end:
        return internal_dict
    return multiindex2dict(internal_dict)