import numpy as np
import scipy.sparse as sp
import networkx as nx


# Convert sparse matrix to tuple
def sparse_to_tuple(sparse_mx):
    if not sp.isspmatrix_coo(sparse_mx):
        sparse_mx = sparse_mx.tocoo()
    coords = np.vstack((sparse_mx.row, sparse_mx.col)).transpose()
    values = sparse_mx.data
    shape = sparse_mx.shape
    return coords, values, shape


# Get normalized adjacency matrix: A_norm
def preprocess_graph(adj):
    adj = sp.coo_matrix(adj)
    adj_ = adj + sp.eye(adj.shape[0])
    rowsum = np.array(adj_.sum(1))
    degree_mat_inv_sqrt = sp.diags(np.power(rowsum, -0.5).flatten())
    adj_normalized = adj_.dot(degree_mat_inv_sqrt).transpose().dot(degree_mat_inv_sqrt).tocoo()
    return sparse_to_tuple(adj_normalized)


# Prepare feed-dict for Tensorflow session
def construct_feed_dict(adj_normalized, adj, features, placeholders):
    # construct feed dictionary
    feed_dict = dict()
    feed_dict.update({placeholders['features']: features})
    feed_dict.update({placeholders['adj']: adj_normalized})
    feed_dict.update({placeholders['adj_orig']: adj})
    return feed_dict


# Perform train-test split
# Takes in adjacency matrix in sparse format
# Returns: adj_train, train_edges, val_edges, val_edges_false,
# test_edges, test_edges_false
def mask_test_edges(adj, test_frac=.1, val_frac=.05, prevent_disconnect=True, verbose=False):
    # NOTE: Splits are randomized and results might slightly deviate from reported numbers in the paper.

    if verbose == True:
        print('preprocessing...')

    # Remove diagonal elements
    adj = adj - sp.dia_matrix((adj.diagonal()[np.newaxis, :], [0]), shape=adj.shape)
    adj.eliminate_zeros()
    # Check that diag is zero:
    assert np.diag(adj.todense()).sum() == 0

    g = nx.from_scipy_sparse_matrix(adj)
    orig_num_cc = nx.number_connected_components(g)

    adj_triu = sp.triu(adj)  # upper triangular portion of adj matrix
    adj_tuple = sparse_to_tuple(adj_triu)  # (coords, values, shape), edges only 1 way
    edges = adj_tuple[0]  # all edges, listed only once (not 2 ways)
    # edges_all = sparse_to_tuple(adj)[0] # ALL edges (includes both ways)
    num_test = int(np.floor(edges.shape[0] * test_frac))  # controls how large the test set should be
    num_val = int(np.floor(edges.shape[0] * val_frac))  # controls how alrge the validation set should be

    # Store edges in list of ordered tuples (node1, node2) where node1 < node2
    edge_tuples = [(min(edge[0], edge[1]), max(edge[0], edge[1])) for edge in edges]
    all_edge_tuples = set(edge_tuples)
    train_edges = set(edge_tuples)  # initialize train_edges to have all edges
    test_edges = set()
    val_edges = set()

    if verbose == True:
        print('generating test/val sets...')

    # Iterate over shuffled edges, add to train/val sets
    np.random.shuffle(edge_tuples)
    for edge in edge_tuples:
        # print edge
        node1 = edge[0]
        node2 = edge[1]

        # If removing edge would disconnect a connected component, backtrack and move on
        g.remove_edge(node1, node2)
        if prevent_disconnect == True:
            if nx.number_connected_components(g) > orig_num_cc:
                g.add_edge(node1, node2)
                continue

        # Fill test_edges first
        if len(test_edges) < num_test:
            test_edges.add(edge)
            train_edges.remove(edge)

        # Then, fill val_edges
        elif len(val_edges) < num_val:
            val_edges.add(edge)
            train_edges.remove(edge)

        # Both edge lists full --> break loop
        elif len(test_edges) == num_test and len(val_edges) == num_val:
            break

    if (len(val_edges) < num_val or len(test_edges) < num_test):
        print("WARNING: not enough removable edges to perform full train-test split!")
        print("Num. (test, val) edges requested: (", num_test, ", ", num_val, ")")
        print("Num. (test, val) edges returned: (", len(test_edges), ", ", len(val_edges), ")")

    if prevent_disconnect == True:
        assert nx.number_connected_components(g) == orig_num_cc

    if verbose == True:
        print('creating false test edges...')

    test_edges_false = set()
    while len(test_edges_false) < num_test:
        idx_i = np.random.randint(0, adj.shape[0])
        idx_j = np.random.randint(0, adj.shape[0])
        if idx_i == idx_j:
            continue

        false_edge = (min(idx_i, idx_j), max(idx_i, idx_j))

        # Make sure false_edge not an actual edge, and not a repeat
        if false_edge in all_edge_tuples:
            continue
        if false_edge in test_edges_false:
            continue

        test_edges_false.add(false_edge)

    if verbose == True:
        print('creating false val edges...')

    val_edges_false = set()
    while len(val_edges_false) < num_val:
        idx_i = np.random.randint(0, adj.shape[0])
        idx_j = np.random.randint(0, adj.shape[0])
        if idx_i == idx_j:
            continue

        false_edge = (min(idx_i, idx_j), max(idx_i, idx_j))

        # Make sure false_edge in not an actual edge, not in test_edges_false, not a repeat
        if false_edge in all_edge_tuples or \
                        false_edge in test_edges_false or \
                        false_edge in val_edges_false:
            continue

        val_edges_false.add(false_edge)

    if verbose == True:
        print('creating false train edges...')

    train_edges_false = set()
    while len(train_edges_false) < len(train_edges):
        idx_i = np.random.randint(0, adj.shape[0])
        idx_j = np.random.randint(0, adj.shape[0])
        if idx_i == idx_j:
            continue

        false_edge = (min(idx_i, idx_j), max(idx_i, idx_j))

        # Make sure false_edge in not an actual edge, not in test_edges_false,
        # not in val_edges_false, not a repeat
        if false_edge in all_edge_tuples or \
                        false_edge in test_edges_false or \
                        false_edge in val_edges_false or \
                        false_edge in train_edges_false:
            continue

        train_edges_false.add(false_edge)

    if verbose == True:
        print('final checks for disjointness...')

    # assert: false_edges are actually false (not in all_edge_tuples)
    assert test_edges_false.isdisjoint(all_edge_tuples)
    assert val_edges_false.isdisjoint(all_edge_tuples)
    assert train_edges_false.isdisjoint(all_edge_tuples)

    # assert: test, val, train false edges disjoint
    assert test_edges_false.isdisjoint(val_edges_false)
    assert test_edges_false.isdisjoint(train_edges_false)
    assert val_edges_false.isdisjoint(train_edges_false)

    # assert: test, val, train positive edges disjoint
    assert val_edges.isdisjoint(train_edges)
    assert test_edges.isdisjoint(train_edges)
    assert val_edges.isdisjoint(test_edges)

    if verbose == True:
        print('creating adj_train...')

    # Re-build adj matrix using remaining graph
    adj_train = nx.adjacency_matrix(g)

    # Convert edge-lists to numpy arrays
    train_edges = np.array([list(edge_tuple) for edge_tuple in train_edges])
    train_edges_false = np.array([list(edge_tuple) for edge_tuple in train_edges_false])
    val_edges = np.array([list(edge_tuple) for edge_tuple in val_edges])
    val_edges_false = np.array([list(edge_tuple) for edge_tuple in val_edges_false])
    test_edges = np.array([list(edge_tuple) for edge_tuple in test_edges])
    test_edges_false = np.array([list(edge_tuple) for edge_tuple in test_edges_false])

    if verbose == True:
        print('Done with train-test split!')
        print('')

    # NOTE: these edge lists only contain single direction of edge!
    return adj_train, train_edges, train_edges_false, \
           val_edges, val_edges_false, test_edges, test_edges_false


# Perform train-test split
# Takes in adjacency matrix in sparse format (from a directed graph)
# Returns: adj_train, train_edges, val_edges, val_edges_false,
# test_edges, test_edges_false
def mask_test_edges_directed(adj, test_frac=.1, val_frac=.05,
                             prevent_disconnect=True, verbose=False, false_edge_sampling='iterative'):
    if verbose == True:
        print('preprocessing...')

    # Remove diagonal elements
    adj = adj - sp.dia_matrix((adj.diagonal()[np.newaxis, :], [0]), shape=adj.shape)
    adj.eliminate_zeros()
    # Check that diag is zero:
    assert np.diag(adj.todense()).sum() == 0

    # Convert to networkx graph to calc num. weakly connected components
    g = nx.from_scipy_sparse_matrix(adj, create_using=nx.DiGraph())
    orig_num_wcc = nx.number_weakly_connected_components(g)

    adj_tuple = sparse_to_tuple(adj)  # (coords, values, shape)
    edges = adj_tuple[0]  # List of ALL edges (either direction)
    edge_pairs = [(edge[0], edge[1]) for edge in edges]  # store edges as list of tuples (from_node, to_node)

    num_test = int(np.floor(edges.shape[0] * test_frac))  # controls how large the test set should be
    num_val = int(np.floor(edges.shape[0] * val_frac))  # controls how alrge the validation set should be
    num_train = len(edge_pairs) - num_test - num_val  # num train edges

    all_edge_set = set(edge_pairs)
    train_edges = set(edge_pairs)  # init train_edges to have all edges
    test_edges = set()  # init test_edges as empty set
    val_edges = set()  # init val edges as empty set

    ### ---------- TRUE EDGES ---------- ###
    # Shuffle and iterate over all edges
    np.random.shuffle(edge_pairs)

    # get initial bridge edges
    bridge_edges = set(nx.bridges(nx.to_undirected(g)))

    if verbose:
        print('creating true edges...')

    for ind, edge in enumerate(edge_pairs):
        node1, node2 = edge[0], edge[1]

        # Recalculate bridges every ____ iterations to relatively recent
        if ind % 10000 == 0:
            bridge_edges = set(nx.bridges(nx.to_undirected(g)))

            # Don't sample bridge edges to increase likelihood of staying connected
        if (node1, node2) in bridge_edges or (node2, node1) in bridge_edges:
            continue

        # If removing edge would disconnect the graph, backtrack and move on
        g.remove_edge(node1, node2)
        if prevent_disconnect == True:
            if not nx.is_weakly_connected(g):
                g.add_edge(node1, node2)
                continue

        # Fill test_edges first
        if len(test_edges) < num_test:
            test_edges.add(edge)
            train_edges.remove(edge)
            if len(test_edges) % 10000 == 0 and verbose == True:
                print('Current num test edges: ', len(test_edges))

        # Then, fill val_edges
        elif len(val_edges) < num_val:
            val_edges.add(edge)
            train_edges.remove(edge)
            if len(val_edges) % 10000 == 0 and verbose == True:
                print('Current num val edges: ', len(val_edges))

        # Both edge lists full --> break loop
        elif len(test_edges) == num_test and len(val_edges) == num_val:
            break

    # Check that enough test/val edges were found
    if (len(val_edges) < num_val or len(test_edges) < num_test):
        print("WARNING: not enough removable edges to perform full train-test split!")
        print("Num. (test, val) edges requested: (", num_test, ", ", num_val, ")")
        print("Num. (test, val) edges returned: (", len(test_edges), ", ", len(val_edges), ")")

    # Print stats for largest remaining WCC
    print('Num WCC: ', nx.number_weakly_connected_components(g))
    largest_wcc_set = max(nx.weakly_connected_components(g), key=len)
    largest_wcc = g.subgraph(largest_wcc_set)
    print('Largest WCC num nodes: ', largest_wcc.number_of_nodes())
    print('Largest WCC num edges: ', largest_wcc.number_of_edges())

    if prevent_disconnect == True:
        assert nx.number_weakly_connected_components(g) == orig_num_cc

    # Fraction of edges with both endpoints in largest WCC
    def frac_edges_in_wcc(edge_set):
        num_wcc_contained_edges = 0.0
        num_total_edges = 0.0
        for edge in edge_set:
            num_total_edges += 1
            if edge[0] in largest_wcc_set and edge[1] in largest_wcc_set:
                num_wcc_contained_edges += 1
        frac_in_wcc = num_wcc_contained_edges / num_total_edges
        return frac_in_wcc

    # Check what percentage of edges have both endpoints in largest WCC
    print('Fraction of train edges with both endpoints in L-WCC: ', frac_edges_in_wcc(train_edges))
    print('Fraction of test edges with both endpoints in L-WCC: ', frac_edges_in_wcc(test_edges))
    print('Fraction of val edges with both endpoints in L-WCC: ', frac_edges_in_wcc(val_edges))

    # Ignore edges with endpoint not in largest WCC
    print('Removing edges with either endpoint not in L-WCC from train-test split...')
    train_edges = {edge for edge in train_edges if edge[0] in largest_wcc_set and edge[1] in largest_wcc_set}
    test_edges = {edge for edge in test_edges if edge[0] in largest_wcc_set and edge[1] in largest_wcc_set}
    val_edges = {edge for edge in val_edges if edge[0] in largest_wcc_set and edge[1] in largest_wcc_set}

    ### ---------- FALSE EDGES ---------- ###

    # Initialize empty sets
    train_edges_false = set()
    test_edges_false = set()
    val_edges_false = set()


    # Generate candidate false edges (from g-complement) and iterate through them
    if false_edge_sampling == 'iterative':
        if verbose == True:
            print('preparing complement adjacency matrix...')

        # Sample false edges from G-complement, instead of randomly generating edges
        # g_complement = nx.complement(g)
        adj_complement = 1 - adj.toarray()  # flip 0's, 1's in adjacency matrix
        np.fill_diagonal(adj_complement, val=0)  # set diagonals to 0

        # 2 numpy arrays indicating x, y coords in adj_complement
        # WARNING: This line can use up a lot of RAM depending on 'adj' size
        idx1, idx2 = np.where(adj_complement == 1)

        edges_false = np.stack((idx1, idx2), axis=-1)  # stack arrays into coord pairs.
        edge_pairs_false = [(edge[0], edge[1]) for false_edge in edges_false]

        # Shuffle and iterate over false edges
        np.random.shuffle(edge_pairs_false)
        if verbose == True:
            print('adding candidate false edges to false edge sets...')
        for false_edge in edge_pairs_false:
            # Fill train_edges_false first
            if len(train_edges_false) < len(train_edges):
                train_edges_false.add(false_edge)
                if len(train_edges_false) % 100000 == 0 and verbose == True:
                    print('Current num false train edges: ', len(train_edges_false))

            # Fill test_edges_false next
            elif len(test_edges_false) < len(test_edges):
                test_edges_false.add(false_edge)
                if len(test_edges_false) % 100000 == 0 and verbose == True:
                    print('Current num false test edges: ', len(test_edges_false))

            # Fill val_edges_false last
            elif len(val_edges_false) < len(val_edges):
                val_edges_false.add(false_edge)
                if len(val_edges_false) % 100000 == 0 and verbose == True:
                    print('Current num false val edges: ', len(val_edges_false))

            # All sets filled --> break
            elif len(train_edges_false) == len(train_edges) and \
                            len(test_edges_false) == len(test_edges) and \
                            len(val_edges_false) == len(val_edges):
                break

    # Randomly generate false edges (idx_i, idx_j) 1 at a time to save memory
    elif false_edge_sampling == 'random':
        if verbose == True:
            print('creating false test edges...')

        # FALSE TEST EDGES
        while len(test_edges_false) < len(test_edges):
            idx_i = np.random.randint(0, adj.shape[0])
            idx_j = np.random.randint(0, adj.shape[0])
            if idx_i == idx_j:  # no self-loops
                continue

            # Ensure both endpoints are in largest WCC
            if idx_i not in largest_wcc_set or idx_j not in largest_wcc_set:
                continue

            false_edge = (idx_i, idx_j)

            # Make sure false_edge not an actual edge, and not a repeat
            if false_edge in all_edge_set:
                continue
            if false_edge in test_edges_false:
                continue

            test_edges_false.add(false_edge)

            if len(test_edges_false) % 100000 == 0 and verbose == True:
                print('Current num false test edges: ', len(test_edges_false))

        # FALSE VAL EDGES
        if verbose == True:
            print('creating false val edges...')

        while len(val_edges_false) < len(val_edges):
            idx_i = np.random.randint(0, adj.shape[0])
            idx_j = np.random.randint(0, adj.shape[0])
            if idx_i == idx_j:
                continue

            false_edge = (idx_i, idx_j)

            # Make sure false_edge in not an actual edge, not in test_edges_false, not a repeat
            if false_edge in all_edge_set or \
                            false_edge in test_edges_false or \
                            false_edge in val_edges_false:
                continue

            val_edges_false.add(false_edge)

            if len(val_edges_false) % 100000 == 0 and verbose == True:
                print('Current num false val edges: ', len(val_edges_false))

        # FALSE TRAIN EDGES
        if verbose == True:
            print('creating false train edges...')

        while len(train_edges_false) < len(train_edges):
            idx_i = np.random.randint(0, adj.shape[0])
            idx_j = np.random.randint(0, adj.shape[0])
            if idx_i == idx_j:
                continue

            false_edge = (idx_i, idx_j)

            # Make sure false_edge in not an actual edge, not in test_edges_false,
            # not in val_edges_false, not a repeat
            if false_edge in all_edge_set or \
                            false_edge in test_edges_false or \
                            false_edge in val_edges_false or \
                            false_edge in train_edges_false:
                continue

            train_edges_false.add(false_edge)

            if len(train_edges_false) % 100000 == 0 and verbose == True:
                print('Current num false train edges: ', len(train_edges_false))

    ### ---------- FINAL DISJOINTNESS CHECKS ---------- ###
    if verbose == True:
        print('final checks for disjointness...')

    # assert: false_edges are actually false (not in all_edge_tuples)
    assert test_edges_false.isdisjoint(all_edge_set)
    assert val_edges_false.isdisjoint(all_edge_set)
    assert train_edges_false.isdisjoint(all_edge_set)

    # assert: test, val, train false edges disjoint
    assert test_edges_false.isdisjoint(val_edges_false)
    assert test_edges_false.isdisjoint(train_edges_false)
    assert val_edges_false.isdisjoint(train_edges_false)

    # assert: test, val, train positive edges disjoint
    assert val_edges.isdisjoint(train_edges)
    assert test_edges.isdisjoint(train_edges)
    assert val_edges.isdisjoint(test_edges)

    if verbose == True:
        print('creating adj_train...')

    # Re-build adj matrix using remaining graph
    adj_train = nx.adjacency_matrix(g)

    # Convert edge-lists to numpy arrays
    train_edges = np.array([list(edge_tuple) for edge_tuple in train_edges])
    train_edges_false = np.array([list(edge_tuple) for edge_tuple in train_edges_false])
    val_edges = np.array([list(edge_tuple) for edge_tuple in val_edges])
    val_edges_false = np.array([list(edge_tuple) for edge_tuple in val_edges_false])
    test_edges = np.array([list(edge_tuple) for edge_tuple in test_edges])
    test_edges_false = np.array([list(edge_tuple) for edge_tuple in test_edges_false])

    if verbose == True:
        print('Done with train-test split!')
        print('Num train edges (true, false): (', train_edges.shape[0], ', ', train_edges_false.shape[0], ')')
        print('Num test edges (true, false): (', test_edges.shape[0], ', ', test_edges_false.shape[0], ')')
        print('Num val edges (true, false): (', val_edges.shape[0], ', ', val_edges_false.shape[0], ')')
        print('')

    # Return final edge lists (edges can go either direction!)
    return adj_train, train_edges, train_edges_false, \
           val_edges, val_edges_false, test_edges, test_edges_false