from __future__ import absolute_import
import numpy as np
import dgl
import os
import random

from dgl.data.utils import download, extract_archive, get_download_dir


class TUDataset(object):
    """
    TUDataset contains lots of graph kernel datasets for graph classification.
    Use provided node feature by default. If no feature provided, use one-hot node label instead.
    If neither labels provided, use constant for node feature.

    :param name: Dataset Name, such as `ENZYMES`, `DD`, `COLLAB`
    :param use_pandas: Default: False.
        Numpy's file read function has performance issue when file is large,
        using pandas can be faster.
    :param hidden_size: Default 10. Some dataset doesn't contain features.
        Use constant node features initialization instead, with hidden size as `hidden_size`.

    """

    _url = r"https://ls11-www.cs.tu-dortmund.de/people/morris/graphkerneldatasets/{}.zip"

    def __init__(self, name, use_pandas=False,
                 hidden_size=10, max_allow_node=None):

        self.name = name
        self.hidden_size = hidden_size
        self.extract_dir = self._download()
        self.data_mode = None
        self.max_allow_node = max_allow_node

        if use_pandas:
            import pandas as pd
            DS_edge_list = self._idx_from_zero(
                pd.read_csv(self._file_path("A"), delimiter=",", dtype=int, header=None).values)
        else:
            DS_edge_list = self._idx_from_zero(
                np.genfromtxt(self._file_path("A"), delimiter=",", dtype=int))

        DS_indicator = self._idx_from_zero(
            np.genfromtxt(self._file_path("graph_indicator"), dtype=int))
        DS_graph_labels = self._idx_from_zero(
            np.genfromtxt(self._file_path("graph_labels"), dtype=int))

        g = dgl.DGLGraph()
        g.add_nodes(int(DS_edge_list.max()) + 1)
        g.add_edges(DS_edge_list[:, 0], DS_edge_list[:, 1])

        node_idx_list = []
        self.max_num_node = 0
        for idx in range(np.max(DS_indicator) + 1):
            node_idx = np.where(DS_indicator == idx)
            node_idx_list.append(node_idx[0])
            if len(node_idx[0]) > self.max_num_node:
                self.max_num_node = len(node_idx[0])

        self.graph_lists = g.subgraphs(node_idx_list)
        self.num_labels = max(DS_graph_labels) + 1
        self.graph_labels = DS_graph_labels

        try:
            DS_node_labels = self._idx_from_zero(
                np.loadtxt(self._file_path("node_labels"), dtype=int))
            g.ndata['node_label'] = DS_node_labels
            one_hot_node_labels = self._to_onehot(DS_node_labels)
            for idxs, g in zip(node_idx_list, self.graph_lists):
                g.ndata['feat'] = one_hot_node_labels[idxs, :]
            self.data_mode = "node_label"
        except IOError:
            print("No Node Label Data")

        try:
            DS_node_attr = np.loadtxt(
                self._file_path("node_attributes"), delimiter=",")
            for idxs, g in zip(node_idx_list, self.graph_lists):
                g.ndata['feat'] = DS_node_attr[idxs, :]
            self.data_mode = "node_attr"
        except IOError:
            print("No Node Attribute Data")

        if 'feat' not in g.ndata.keys():
            for idxs, g in zip(node_idx_list, self.graph_lists):
                g.ndata['feat'] = np.ones((g.number_of_nodes(), hidden_size))
            self.data_mode = "constant"
            print(
                "Use Constant one as Feature with hidden size {}".format(hidden_size))

        # remove graphs that are too large by user given standard
        # optional pre-processing steop in conformity with Rex Ying's original
        # DiffPool implementation
        if self.max_allow_node:
            preserve_idx = []
            print("original dataset length : ", len(self.graph_lists))
            for (i, g) in enumerate(self.graph_lists):
                if g.number_of_nodes() <= self.max_allow_node:
                    preserve_idx.append(i)
            self.graph_lists = [self.graph_lists[i] for i in preserve_idx]
            print(
                "after pruning graphs that are too big : ", len(
                    self.graph_lists))
            self.graph_labels = [self.graph_labels[i] for i in preserve_idx]
            self.max_num_node = self.max_allow_node

    def __getitem__(self, idx):
        """Get the i^th sample.
        Paramters
        ---------
        idx : int
            The sample index.
        Returns
        -------
        (dgl.DGLGraph, int)
            DGLGraph with node feature stored in `feat` field and node label in `node_label` if available.
            And its label.
        """
        g = self.graph_lists[idx]
        return g, self.graph_labels[idx]

    def __len__(self):
        return len(self.graph_lists)

    def _download(self):
        download_dir = get_download_dir()
        zip_file_path = os.path.join(
            download_dir,
            "tu_{}.zip".format(
                self.name))
        download(self._url.format(self.name), path=zip_file_path)
        extract_dir = os.path.join(download_dir, "tu_{}".format(self.name))
        extract_archive(zip_file_path, extract_dir)
        return extract_dir

    def _file_path(self, category):
        return os.path.join(self.extract_dir, self.name,
                            "{}_{}.txt".format(self.name, category))

    @staticmethod
    def _idx_from_zero(idx_tensor):
        return idx_tensor - np.min(idx_tensor)

    @staticmethod
    def _to_onehot(label_tensor):
        label_num = label_tensor.shape[0]
        assert np.min(label_tensor) == 0
        one_hot_tensor = np.zeros((label_num, np.max(label_tensor) + 1))
        one_hot_tensor[np.arange(label_num), label_tensor] = 1
        return one_hot_tensor

    def statistics(self):
        return self.graph_lists[0].ndata['feat'].shape[1],\
            self.num_labels,\
            self.max_num_node
