"""
NOTEs:

- This file is note meant to be run, it's just a collection of functions that are used in the other files. It's just a way to keep the code clean and organized.

- Why do I use os.path.join and not the "/"? Because it's more portable, it works on every OS, while "/" works only on Linux and Mac. In windows you would have to change all the "/" with "\". With os.path.join you don't have to worry about it and, as always, f*** Microsoft.
"""

from multiprocessing import Pool
import itertools
import os
import random
import wget
import zipfile
import pandas as pd
import tqdm as tqdm
import networkx as nx
from typing import Literal
from itertools import combinations
import plotly.graph_objects as go
from collections import Counter
import numpy as np
import gdown
from networkx.utils import py_random_state

# ------------------------------------------------------------------------#

def download_datasets():

    urls = [
        ["https://snap.stanford.edu/data/loc-brightkite_edges.txt.gz", "https://snap.stanford.edu/data/loc-brightkite_totalCheckins.txt.gz"],
        ["https://snap.stanford.edu/data/loc-gowalla_edges.txt.gz", "https://snap.stanford.edu/data/loc-gowalla_totalCheckins.txt.gz"],
        ["https://drive.google.com/file/d/1PNk3zY8NjLcDiAbzjABzY5FiPAFHq6T8/view?usp=sharing"]
    ]

    folders = ["brightkite", "gowalla", "foursquare"]

    if not os.path.exists("data"):
        os.mkdir("data")

    for folder in folders:
        if not os.path.exists(os.path.join("data", folder)):
            os.mkdir(os.path.join("data", folder))

    # Download every url in their respective folder. For the last one, we have to use gdown, because it's a google drive link. If the file is already downloaded, skip the download

    for i in range(len(urls)):
        for url in urls[i]:
            if not os.path.exists(os.path.join("data", folders[i], url.split("/")[-1])):
                if i == 2:
                    output = os.path.join("data", folders[i], "something.zip")
                    gdown.download(url, output, quiet=False, fuzzy=True)
                else:
                    wget.download(url, os.path.join("data", folders[i]))

    # unzip all the files in the 3 folders. Then remove the .gz or .zip files

    for folder in folders:
        for file in os.listdir(os.path.join("data", folder)):
            print(folder, file)
            if file.endswith(".gz"):
                os.system("gunzip {}".format(os.path.join("data", folder, file)))
            elif file.endswith(".zip"):
                os.system("unzip {}".format(os.path.join("data", folder, file)))
                os.remove(os.path.join("data", folder, file))

    # take all the .txt files from data/foursquare/dataset_WWW2019 and move them to data/foursquare

    for file in os.listdir(os.path.join("data", "foursquare", "dataset_WWW2019")):
        if file.endswith(".txt"):
            os.rename(os.path.join("data", "foursquare", "dataset_WWW2019", file), os.path.join("data", "foursquare", file))

    # remove the dataset_WWW2019 folder, note that is not empty
    # os.rmdir(os.path.join("data", "foursquare", "dataset_WWW2019"))

    for file in ["dataset_WWW_friendship_old.txt", "dataset_WWW_readme.txt", "raw_Checkins_anonymized.txt", "raw_POIs.txt"]:
        os.remove(os.path.join("data", "foursquare", file))

    # Now we want to clean our data and rename the files.

    for file in os.listdir(os.path.join("data", "brightkite")):
        if file.endswith("_edges.txt"):
            os.rename(os.path.join("data", "brightkite", file), os.path.join("data", "brightkite", "brightkite_friends_edges.txt"))

    for file in os.listdir(os.path.join("data", "gowalla")):
        if file.endswith("_edges.txt"):
            os.rename(os.path.join("data", "gowalla", file), os.path.join("data", "gowalla", "gowalla_friends_edges.txt"))

    for file in os.listdir(os.path.join("data", "foursquare")):
        if file.endswith("dataset_WWW_friendship_new.txt"):
            os.rename(os.path.join("data", "foursquare", file), os.path.join("data", "foursquare", "foursquare_friends_edges.txt"))

    # Now we from the _totalCheckins.txt files we want to keep only the first and last column, which are the user ID and the venue ID. We also want to remove the header of the file.

    for file in os.listdir(os.path.join("data", "brightkite")):
        if file.endswith("_totalCheckins.txt"):
            df = pd.read_csv(os.path.join("data", "brightkite", file), sep="\t", header=None, names=["user_id", "check-in time", "latitude", "longitude", "venue_id"])
            df["check-in time"] = pd.to_datetime(df["check-in time"])
            df = df[df["check-in time"].dt.year == 2010]
            df = df.drop(["check-in time", "latitude", "longitude"], axis=1)
            df.to_csv(os.path.join("data", "brightkite", "brightkite_checkins.txt"), sep="\t", header=False, index=False, errors="ignore", encoding="utf-8")
            os.remove(os.path.join("data", "brightkite", file))

    for file in os.listdir(os.path.join("data", "gowalla")):
        if file.endswith("_totalCheckins.txt"):
            df = pd.read_csv(os.path.join("data", "gowalla", file), sep="\t", header=None, names=["user_id", "check-in time", "latitude", "longitude", "venue_id"])
            df["check-in time"] = pd.to_datetime(df["check-in time"])
            df = df[df["check-in time"].dt.year == 2010]
            df = df.drop(["check-in time", "latitude", "longitude"], axis=1)
            df.to_csv(os.path.join("data", "gowalla", "gowalla_checkins.txt"), sep="\t", header=False, index=False, errors="ignore", encoding="utf-8")
            os.remove(os.path.join("data", "gowalla", file))

    for file in os.listdir(os.path.join("data", "foursquare")):
        if file.endswith("dataset_WWW_Checkins_anonymized.txt"):
            df = pd.read_csv(os.path.join("data", "foursquare", file), sep="\t", header=None)
            df = df[[0, 1]]
            df.to_csv(os.path.join("data", "foursquare", "foursquare_checkins.txt"), sep="\t", header=False, index=False, errors="ignore", encoding="utf-8")
            os.remove(os.path.join("data", "foursquare", file))

# ------------------------------------------------------------------------#

def create_graph_from_checkins(dataset: Literal['brightkite', 'gowalla', 'foursquareEU', 'foursquareIT'], create_file = True) -> nx.Graph:

    """
    Create a graph from the checkins of the dataset. The graph is undirected and the nodes are the users and the edges are the checkins in common.

    Parameters
    ----------
    `dataset` : Literal['brightkite', 'gowalla', 'foursquareEU', 'foursquareIT']
        The dataset to use.
    `create_file` : bool, optional
        If True, the graph is saved in a file, by default True

    Returns
    -------
    `G` : networkx.Graph

    Raises
    ------
    ValueError
        If the dataset is not valid.

    """

    if dataset not in ['brightkite', 'gowalla', 'foursquareEU', 'foursquareIT']:
        raise ValueError("Dataset not valid. Please choose between brightkite, gowalla, foursquareEU, foursquareUS, foursquareIT")

    if dataset in ['brightkite', 'gowalla']:
        file = os.path.join("data", dataset, dataset + "_checkins.txt")

        print("\nCreating the graph for the dataset {}...".format(dataset))

        df = pd.read_csv(file, sep="\t", header=None, names=["user_id", "venue_id"])

        G = nx.Graph()
        venues_users = df.groupby("venue_id")["user_id"].apply(set)

        for users in tqdm.tqdm(venues_users):
            for user1, user2 in combinations(users, 2):
                G.add_edge(user1, user2)

        # path to the file where we want to save the graph
        edges_path = os.path.join("data", dataset , dataset + "_checkins_edges.tsv")

        print("Done! The graph has {} edges".format(G.number_of_edges()), " and {} nodes".format(G.number_of_nodes()))

        # delete from memory the dataframe
        del df

        if create_file:
            # save the graph in a file
            nx.write_edgelist(G, edges_path, data=True, delimiter="\t", encoding="utf-8")

        return G

    else:
        # path to the checkins file and the POIS file
        path_checkins = os.path.join("data", "foursquare", "foursquare_checkins.txt")
        path_POIS = os.path.join("data", "foursquare", "raw_POIs.txt")

        # dataframe with the checkins, we need only the user_id and the venue_id
        df_all = pd.read_csv(path_checkins, sep="\t", header=None, names=['user_id', 'venue_id', 'time', 'offset'])
        df_all = df_all[['user_id', 'venue_id']]

        # dataframe with the POIS, we need only the venue_id and the country code
        df_POIS = pd.read_csv(path_POIS, sep='\t', header=None, names=['venue_id', 'lat', 'lon', 'category', 'country code'])
        df_POIS = df_POIS[['venue_id', 'country code']]

        if dataset == "foursquareIT":
            venues_array = df_POIS[df_POIS['country code'] == 'IT']['venue_id'].values

        elif dataset == "foursquareEU":
            # list of the countries in the EU
            EU_countries = ['AT', 'BE', 'BG', 'CY', 'CZ', 'DE', 'DK', 'EE', 'ES', 'FI', 'FR', 'GR', 'HR', 'HU', 'IE', 'IT', 'LT', 'LU', 'LV', 'MT', 'NL', 'PL', 'PT', 'RO', 'SE', 'SI', 'SK']

            venues_array = df_POIS[df_POIS['country code'].isin(EU_countries)]['venue_id'].values

        print("\nCreating the graph for the dataset {}...".format(dataset))

        # we create a dataframe with the checkins in the corresponding country
        df_country = df_all[df_all['venue_id'].isin(venues_array)]

        G = nx.Graph()
        venues_users = df_country.groupby("venue_id")["user_id"].apply(set)

        for users in tqdm.tqdm(venues_users):
            for user1, user2 in combinations(users, 2):
                G.add_edge(user1, user2)

        # path to the file where we want to save the graph
        edges_path = os.path.join("data", "foursquare", dataset + "_checkins_edges.tsv")

        print("Done! The graph has {} edges".format(G.number_of_edges()), " and {} nodes".format(G.number_of_nodes()))

        # delete from memory the dataframes
        del df_all, df_POIS, df_country

        if create_file:
            # save the graph in a file
            nx.write_edgelist(G, edges_path, data=True, delimiter="\t", encoding="utf-8")

        return G

# ------------------------------------------------------------------------#

def create_friendships_graph(dataset: Literal['brightkite', 'gowalla', 'foursquareEU', 'foursquareIT']) -> nx.Graph:

    """
    Create the graph of friendships for the dataset brightkite, gowalla or foursquare.
    The graph is saved in a file.

    Parameters
    ----------
    `dataset` : str
        The dataset for which we want to create the graph of friendships.

    Returns
    -------
    `G` : networkx.Graph
        The graph of friendships.

    Notes
    -----
    Since we are taking sub-samples of each check-ins dataset, we are also taking sub-samples of the friendship graph. A user is included in the friendship graph if he has at least one check-in in the sub-sample.
    """

    if dataset not in ["brightkite", "gowalla", "foursquareEU", "foursquareIT"]:
        raise ValueError("The dataset must be brightkite, gowalla or foursquare")

    if dataset in ["foursquareEU", "foursquareIT"]:
        file = os.path.join("data", "foursquare", "foursquare_friends_edges.txt")

        # dataframe with the edges of the graph (friends)
        df_friends_all = pd.read_csv(file, sep="\t", header=None, names=["node1", "node2"])

        # set of the unique users in the graph (friends)
        unique_friends = set(df_friends_all["node1"].unique()).union(set(df_friends_all["node2"].unique()))

        # dataframe with the edges of the graph (checkins)
        df_checkins = pd.read_csv(os.path.join("data", "foursquare", dataset + "_checkins_edges.tsv"), sep="\t", header=None, names=["node1", "node2"])
        unique_checkins = set(df_checkins["node1"].unique()).union(set(df_checkins["node2"].unique()))

        # take the intersection of the two sets
        unique_users = unique_friends.intersection(unique_checkins)

        # create a dataframe with the edges of the graph
        df = df_friends_all[df_friends_all["node1"].isin(unique_users) & df_friends_all["node2"].isin(unique_users)]

        # create a tsv file with the edges of the graph that ends with _filtered.tsv
        df.to_csv(os.path.join("data", "foursquare", dataset + "_friends_edges_filtered.tsv"), sep="\t", header=False, index=False)

        # create the graph
        G = nx.from_pandas_edgelist(df, "node1", "node2", create_using=nx.Graph())
        del df_friends_all, df_checkins, df

        return G

    elif dataset in ["brightkite", "gowalla"]:
        file = os.path.join("data", dataset, dataset + "_friends_edges.txt")

        df_friends_all = pd.read_csv(file, sep="\t", header=None, names=["node1", "node2"])
        unique_friends = set(df_friends_all["node1"].unique()).union(set(df_friends_all["node2"].unique()))

        df_checkins = pd.read_csv(os.path.join("data", dataset, dataset + "_checkins_edges.tsv"), sep="\t", header=None, names=["node1", "node2"])
        unique_checkins = set(df_checkins["node1"].unique()).union(set(df_checkins["node2"].unique()))

        unique_users = unique_friends.intersection(unique_checkins)

        df = df_friends_all[df_friends_all["node1"].isin(unique_users) & df_friends_all["node2"].isin(unique_users)]

        df.to_csv(os.path.join("data", dataset, dataset + "_friends_edges_filtered.tsv"), sep="\t", header=False, index=False)

        G = nx.from_pandas_edgelist(df, "node1", "node2", create_using=nx.Graph())
        del df_friends_all, df_checkins, df

        return G

# ------------------------------------------------------------------------#

def degree_distribution(G: nx.Graph, log: bool = True, save: bool = False) -> None:

        """
        This function takes in input a networkx graph object and plots the degree distribution of the graph.

        Parameters
        ----------
        `G` : networkx graph object
            The graph object

        `log` : bool, optional
            If True, the plot will be in log-log scale, by default True

        `save` : bool, optional
            If True, the plot will be saved in the folder "plots", by default False

        Returns
        -------
        None

        Notes
        -----
        Due to the characteristics of datasets, not using a log log scale will lead to a un-useful plot. Even if using a log scales alters the power-law distribution, it is still clearly visible and distinguishable from a poisson distribution (witch is what we are interested in in this case)

        """

        degrees = [G.degree(n) for n in G.nodes()]
        degreeCount = Counter(degrees)

        fig = go.Figure()
        fig.add_trace(go.Bar(x=list(degreeCount.keys()), y=list(degreeCount.values()), name='Degree Distribution'))

        if log:
            fig.update_layout(
                title='Degree Distribution (log-log scale) of {}' .format(G.name),
                xaxis_title='Degree',
                yaxis_title='Number of Nodes',
                xaxis_type='log',
                yaxis_type='log',
                width=800,
                height=600,
                template='plotly_white'
            )

        else:
            fig.update_layout(
                title='Degree Distribution of {}' .format(G.name),
                xaxis_title='Degree',
                yaxis_title='Number of Nodes',
                width=800,
                height=600,
                template='plotly_white'
            )

        fig.show()

        if save:
            fig.write_image("plots/degree_distribution_{}.png".format(G.name))

# ------------------------------------------------------------------------#

def chunks(l, n):
    """
    Auxiliary function to divide a list of nodes `l` in `n` chunks

    Parameters
    ----------
    `l` : list
        List of nodes

    `n` : int
        Number of chunks

    """

    l_c = iter(l)
    while 1:
        x = tuple(itertools.islice(l_c, n))
        if not x:
            return
        yield x

# ------------------------------------------------------------------------#

def betweenness_centrality_parallel(G, processes=None, k =None) -> dict:
    """
    Compute the betweenness centrality for nodes in a graph using multiprocessing.

    Parameters
    ----------
    G : graph
        A networkx graph

    processes : int, optional
        The number of processes to use for computation.
        If `None`, then it sets processes = 1

    k : int, optional
        Percent of nodes to sample. If `None`, then all nodes are used.

    seed : int, optional
        Seed for random number generator (default=None).

    Returns
    -------
    dict

    Notes
    -----
    Do not use more then 6 process for big graphs, otherwise the memory will be full. Do it only if you have more at least 32 GB of RAM. For small graphs, you can use more processes.

    """

    # if process is None or 1, run the standard algorithm with one process
    if processes is None or processes == 1:
        print("\tRunning the networkx approximated algorithm with just one process")
        G_copy = G.copy()
        sample = int((k)*G_copy.number_of_nodes())
        print("\tNumber of nodes after removing {} % of nodes: {}" .format((k)*100, G_copy.number_of_nodes()))
        return np.mean(nx.betweenness_centrality(G, k=sample, seed=42).values())

    if processes > os.cpu_count():
        raise ValueError("The number of processes must be less than the number of cores in the system.")

    if k is not None:
        if (k < 0 or k > 1):
            raise ValueError("k must be between 0 and 1.")
        else:
            G_copy = G.copy()
            G_copy.remove_nodes_from(random.sample(G_copy.nodes(), int((k)*G_copy.number_of_nodes())))
            print("\tNumber of nodes after removing {}% of nodes: {}" .format((k)*100, G_copy.number_of_nodes()))
            print("\tNumber of edges after removing {}% of nodes: {}" .format((k)*100, G_copy.number_of_edges()))

    p = Pool(processes=processes)
    node_divisor = len(p._pool) * 4
    node_chunks = list(chunks(G_copy.nodes(), G_copy.order() // node_divisor))
    num_chunks = len(node_chunks)
    bt_sc = p.starmap(
        nx.betweenness_centrality_subset,
        zip(
            [G_copy] * num_chunks, # this returns a list of Gs
            node_chunks,
            [list(G_copy)] * num_chunks, # this returns a list of lists of nodes
            [True] * num_chunks,
            [None] * num_chunks,
        ),
    )

    # Reduce the partial solutions
    bt_c = bt_sc[0]
    for bt in bt_sc[1:]:
        for n in bt:
            bt_c[n] += bt[n]

    return bt_c

# ------------------------------------------------------------------------#

def average_shortest_path(G: nx.Graph, k=None) -> float:

        """
        This function takes in input a networkx graph and returns the average shortest path length of the graph. This works also for disconnected graphs.

        Parameters
        ----------
        `G` : networkx graph
            The graph to compute the average shortest path length of.
        `k` : int
            percentage of nodes to remove from the graph. If k is None, the average shortest path length of each connected component is computed using all the nodes of the connected component.

        Returns
        -------
        float
            The average shortest path length of the graph.

        Raises
        ------
        ValueError
            If k is not between 0 and 1
        """

        if k is not None and (k < 0 or k > 1):
            raise ValueError("k must be between 0 and 1")
        elif k is None:
            connected_components = list(nx.connected_components(G))
        else:
            G_copy = G.copy()
            # remove the k% of nodes from G
            G_copy.remove_nodes_from(random.sample(G_copy.nodes(), int((k)*G_copy.number_of_nodes())))
            print("\tNumber of nodes after removing {}% of nodes: {}" .format((k)*100, G_copy.number_of_nodes()))
            print("\tNumber of edges after removing {}% of nodes: {}" .format((k)*100, G_copy.number_of_edges()))

        tmp = 0
        connected_components = list(nx.connected_components(G_copy))
        # remove all the connected components with less than 10 nodes
        connected_components = [c for c in connected_components if len(c) > 10]

        print("\tNumber of connected components with more then 10 nodes: {}" .format(len(connected_components)), "\r")
        for C in (G_copy.subgraph(c).copy() for c in connected_components):
            print("\tComputing average shortest path length of connected component with {} nodes and {} edges" .format(C.number_of_nodes(), C.number_of_edges()), "\r", end="")
            tmp += nx.average_shortest_path_length(C)

        return np.mean(tmp)

# ------------------------------------------------------------------------#

def average_clustering_coefficient(G: nx.Graph, k=None) -> float:

            """
            This function takes in input a networkx graph and returns the average clustering coefficient of the graph. This works also for disconnected graphs.

            Parameters
            ----------
            G : networkx graph
                The graph to compute the average clustering coefficient of.
            k : int
                percentage of nodes to remove from the graph. If k is None, the average clustering coefficient of each connected component is computed using all the nodes of the connected component.

            Returns
            -------
            float
                The average clustering coefficient of the graph.

            Raises
            ------
            ValueError
                If k is not between 0 and 1
            """

            if k is not None and (k < 0 or k > 1):
                raise ValueError("k must be between 0 and 1")

            elif k is None:
                return nx.average_clustering(G)

            else:
                G_copy = G.copy()
                G_copy.remove_nodes_from(random.sample(list(G_copy.nodes()), int((k)*G_copy.number_of_nodes())))
                print("\tNumber of nodes after removing {}% of nodes: {}" .format((k)*100, G_copy.number_of_nodes()))
                return nx.average_clustering(G_copy)