# All imports
# Math
import math
import random
import cv2
import numpy as np
from scipy.stats import pearsonr

from collections import defaultdict

from sklearn.decomposition import LatentDirichletAllocation

# from sklearn.cluster import KMeans

# Torch
import torch
import torchvision.transforms as transforms
from torchvision.datasets import Caltech101
from torchvision.models import resnet50, ResNet50_Weights

import tensorly as tl

import heapq

# OS and env
import json
import os
from os import getenv
from dotenv import load_dotenv
import warnings
from joblib import dump, load

load_dotenv()

# MongoDB
from pymongo import MongoClient

# Visualizing
import matplotlib.pyplot as plt

NUM_LABELS = 101
NUM_IMAGES = 4338

def datasetTransform(image):
    """Transform while loading dataset as scaled tensors of shape (channels, (img_shape))"""
    return transforms.Compose(
        [
            transforms.ToTensor()  # ToTensor by default scales to [0,1] range, the input range for ResNet
        ]
    )(image)

def loadDataset(dataset):
    """Load TorchVision dataset with the defined transform"""
    return dataset(
        root=getenv("DATASET_PATH"),
        download=False,  # True if you wish to download for first time
        transform=datasetTransform,
    )

valid_classification_methods = {
    "m-nn": 1,
    "decision-tree": 2,
    "ppr": 3,
}

def getCollection(db, collection):
    """Load feature descriptor collection from MongoDB"""
    client = MongoClient("mongodb://localhost:27017")
    return client[db][collection]

def euclidean_distance_measure(img_1_fd, img_2_fd):
    img_1_fd_reshaped = img_1_fd.flatten()
    img_2_fd_reshaped = img_2_fd.flatten()

    # Calculate Euclidean distance
    return math.dist(img_1_fd_reshaped, img_2_fd_reshaped)


valid_feature_models = {
    "cm": "cm_fd",
    "hog": "hog_fd",
    "avgpool": "avgpool_fd",
    "layer3": "layer3_fd",
    "fc": "fc_fd",
    "resnet": "resnet_fd",
}

class Node:
    def __init__(self, feature=None, threshold=None, left=None, right=None, value=None):
        self.feature = feature          # Index of feature to split on
        self.threshold = threshold      # Threshold value for the feature
        self.left = left                # Left child node
        self.right = right              # Right child node
        self.value = value              # Class label for leaf node (if applicable)

class DecisionTree:
    def __init__(self, max_depth=None):
        self.max_depth = max_depth      # Maximum depth of the tree
        self.tree = None                # Root node of the tree
    
    def entropy(self, y):
        _, counts = np.unique(y, return_counts=True)
        probabilities = counts / len(y)
        return -np.sum(probabilities * np.log2(probabilities))
    
    def information_gain(self, X, y, feature, threshold):
        left_idxs = X[:, feature] <= threshold
        right_idxs = ~left_idxs
        
        left_y = y[left_idxs]
        right_y = y[right_idxs]
        
        p_left = len(left_y) / len(y)
        p_right = len(right_y) / len(y)
        
        gain = self.entropy(y) - (p_left * self.entropy(left_y) + p_right * self.entropy(right_y))
        return gain
    
    def find_best_split(self, X, y):
        best_gain = 0
        best_feature = None
        best_threshold = None
        
        for feature in range(X.shape[1]):
            thresholds = np.unique(X[:, feature])
            for threshold in thresholds:
                gain = self.information_gain(X, y, feature, threshold)
                if gain > best_gain:
                    best_gain = gain
                    best_feature = feature
                    best_threshold = threshold
        
        return best_feature, best_threshold
    
    def build_tree(self, X, y, depth=0):
        if len(np.unique(y)) == 1 or depth == self.max_depth:
            return Node(value=np.argmax(np.bincount(y)))
        
        best_feature, best_threshold = self.find_best_split(X, y)
        
        if best_feature is None:
            return Node(value=np.argmax(np.bincount(y)))
        
        left_idxs = X[:, best_feature] <= best_threshold
        right_idxs = ~left_idxs
        
        left_subtree = self.build_tree(X[left_idxs], y[left_idxs], depth + 1)
        right_subtree = self.build_tree(X[right_idxs], y[right_idxs], depth + 1)
        
        return Node(feature=best_feature, threshold=best_threshold, left=left_subtree, right=right_subtree)
    
    def fit(self, X, y):
        self.tree = self.build_tree(X, y)
    
    def predict_instance(self, x, node):
        if node.value is not None:
            return node.value
        
        if x[node.feature] <= node.threshold:
            return self.predict_instance(x, node.left)
        else:
            return self.predict_instance(x, node.right)
    
    def predict(self, X):
        predictions = []
        for x in X:
            pred = self.predict_instance(x, self.tree)
            predictions.append(pred)
        return np.array(predictions)

class LSH:
    def __init__(self, data, num_layers, num_hashes):
        self.data = data
        self.num_layers = num_layers
        self.num_hashes = num_hashes
        self.hash_tables = [defaultdict(list) for _ in range(num_layers)]
        self.unique_images_considered = set()
        self.overall_images_considered = set()
        self.create_hash_tables()

    def hash_vector(self, vector, seed):
        np.random.seed(seed)
        random_vectors = np.random.randn(self.num_hashes, len(vector))
        return ''.join(['1' if np.dot(random_vectors[i], vector) >= 0 else '0' for i in range(self.num_hashes)])

    def create_hash_tables(self):
        for layer in range(self.num_layers):
            for i, vector in enumerate(self.data):
                hash_code = self.hash_vector(vector, seed=layer)
                self.hash_tables[layer][hash_code].append(i)

    def find_similar(self, external_image, t):
        similar_images = set()
        visited_buckets = set()
        unique_images_considered = set()

        for layer in range(self.num_layers):
            hash_code = self.hash_vector(external_image, seed=layer)
            visited_buckets.add(hash_code)

            # Handling exact matches explicitly
            if hash_code in self.hash_tables[layer]:
                for idx in self.hash_tables[layer][hash_code]:
                    similar_images.add(idx)
                    unique_images_considered.add(idx)

            # Searching in nearby buckets based on Hamming distance
            for key in self.hash_tables[layer]:
                if self.hamming_distance(key, hash_code) <= 1:
                    visited_buckets.add(key)

                    for idx in self.hash_tables[layer][key]:
                        similar_images.add(idx)
                        unique_images_considered.add(idx)

        self.unique_images_considered = unique_images_considered
        self.overall_images_considered = similar_images

        similarities = [
            (idx, self.euclidean_distance(external_image, self.data[idx])) for idx in similar_images
        ]
        similarities.sort(key=lambda x: x[1])

        return [idx for idx, _ in similarities[:t]]

    def hamming_distance(self, code1, code2):
        return sum(c1 != c2 for c1, c2 in zip(code1, code2))

    def euclidean_distance(self, vector1, vector2):
        return np.linalg.norm(vector1 - vector2)

    def get_unique_images_considered_count(self):
        return len(self.unique_images_considered)

    def get_overall_images_considered_count(self):
        return len(self.overall_images_considered)

def extract_latent_semantics_from_feature_model(
    fd_collection,
    k,
    feature_model,
):
    """
    Extract latent semantics for entire collection at once for a given feature_model and dim_reduction_method, and display the imageID-semantic weight pairs

    Leave `top_images` blank to display all imageID-weight pairs
    """


    label_features = np.array([
        np.array(
            calculate_label_representatives(fd_collection, label, feature_model)
        ).flatten()  # get the specific feature model's feature vector
        for label in range(NUM_LABELS)
          # repeat for all images
    ])

    print(
        "Applying {} on the {} space to get {} latent semantics.".format(
            "svd", feature_model, k
        )
    )

    all_latent_semantics = {}

    
    U, S, V_T = svd(label_features, k=k)

    U = [C.real for C in U]
    S = [C.real for C in S]
    V_T = [C.real for C in V_T]

    all_latent_semantics = {
        "image-semantic": U,
        "semantics-core": S,
        "semantic-feature": V_T,
    }

    # for each latent semantic, sort imageID-weight pairs by weights in descending order
    return all_latent_semantics

    
def calculate_label_representatives(fd_collection, label, feature_model):
    """Calculate representative feature vector of a label as the mean of all feature vectors under a feature model"""

    label_fds = [
        np.array(
            img_fds[feature_model]
        ).flatten()  # get the specific feature model's feature vector
        for img_fds in fd_collection.find(
            {"true_label": label, "$mod": [2,0]}
        )  # repeat for all images
    ]

    # Calculate mean across each dimension
    # and build a mean vector out of these means
    label_mean_vector = [sum(col) / len(col) for col in zip(*label_fds)]
    return label_mean_vector

def svd(matrix, k):
    # Step 1: Compute the covariance matrix
    cov_matrix = np.dot(matrix.T, matrix)

    # Step 2: Compute the eigenvalues and eigenvectors of the covariance matrix
    eigenvalues, eigenvectors = np.linalg.eig(cov_matrix)

    # Step 3: Sort the eigenvalues and corresponding eigenvectors
    sort_indices = eigenvalues.argsort()[::-1]
    eigenvalues = eigenvalues[sort_indices]
    eigenvectors = eigenvectors[:, sort_indices]

    # Step 4: Compute the singular values and the left and right singular vectors
    singular_values = np.sqrt(eigenvalues)
    left_singular_vectors = np.dot(matrix, eigenvectors)
    right_singular_vectors = eigenvectors

    # Step 5: Normalize the singular vectors
    for i in range(left_singular_vectors.shape[1]):
        left_singular_vectors[:, i] /= singular_values[i]

    for i in range(right_singular_vectors.shape[1]):
        right_singular_vectors[:, i] /= singular_values[i]

    # Keep only the top k singular values and their corresponding vectors
    singular_values = singular_values[:k]
    left_singular_vectors = left_singular_vectors[:, :k]
    right_singular_vectors = right_singular_vectors[:, :k]

    return left_singular_vectors, np.diag(singular_values), right_singular_vectors.T