import librosa.feature
import pandas as pd
import numpy as np
from pathlib import Path
from os import chdir
import os
import csv
from tensorflow import keras
from sklearn.model_selection import train_test_split
from sklearn.preprocessing import LabelEncoder, StandardScaler
from keras import models
from keras import layers
import matplotlib.pyplot as plt
from sklearn.metrics import classification_report
import constants


def create_csv_header():
    header = 'filename '
    for i in range(constants.MFCC_FEATURE_START, constants.MFCC_FEATURE_END):
        header += f' mfcc{i}'
    header += ' label'
    header = header.split()
    file = open(constants.FEATURES_CSV_NAME, 'w', newline='')
    with file:
        writer = csv.writer(file)
        writer.writerow(header)


def extract_features(trainingDataDir, trainingDataSubDirs):
    create_csv_header()
    # Looping over every file inside the subdirectories for feature extraction
    for trainingDataSubDir in trainingDataSubDirs:
        for fileName in os.listdir(trainingDataDir/f'{trainingDataSubDir}'):
            if fileName.endswith(".wav"):
                audioFile = trainingDataDir/f'{trainingDataSubDir}/{fileName}'
                print("Extracting Features from Directory "+trainingDataSubDir+" and file "+audioFile.name)
                y, sr = librosa.load(audioFile, mono=True)
                mfcc = librosa.feature.mfcc(y=y, sr=sr, n_mfcc=(constants.MFCC_FEATURE_END - constants.MFCC_FEATURE_START))
                to_append = f'{audioFile.name}'
                for g in mfcc:
                    to_append += f' {np.mean(g)}'
                if trainingDataSubDir == constants.CAR:
                    to_append += f' {constants.LIGHT_WEIGHT}'
                elif trainingDataSubDir == constants.BUS:
                    to_append += f' {constants.MEDIUM_WEIGHT}'
                elif trainingDataSubDir == constants.TRUCK:
                    to_append += f' {constants.HEAVY_WEIGHT}'
                elif trainingDataSubDir == constants.MOTORCYCLE:
                    to_append += f' {constants.TWO_WHEELED}'
                elif trainingDataSubDir == constants.TRAM:
                    to_append += f' {constants.RAIL_BOUND}'

                file = open(constants.FEATURES_CSV_NAME, 'a', newline='')
                with file:
                    writer = csv.writer(file)
                    writer.writerow(to_append.split())


def preprocessing_csv_data():
    print("Reading Features... ")
    data = pd.read_csv(constants.FEATURES_CSV_NAME)
    data.head()
    # Dropping unnecessary columns (Column Filename is dropped)
    data = data.drop(['filename'], axis=1)
    data.head()
    return data


def encode_labels(data):
    # Extracting classes/label column as y from csv and converting string labels to numbers using LabelEncoder
    audio_list = data.iloc[:, -1]
    encoder = LabelEncoder()
    target_labels = encoder.fit_transform(audio_list)
    return target_labels, encoder


def normalize_data(data):
    # normalizing - Extracting Remaining Columns as X and normalizing them to a common scale
    scaler = StandardScaler()
    X = scaler.fit_transform(np.array(data.iloc[:, :-1], dtype=float))
    return X


def train_test_data_split(X, y):
    # splitting of dataset into train and test dataset
    X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.20)
    return X_train, X_test, y_train, y_test


def create_and_compile_model():
    print("Creating a Model")
    # creating a model
    model = models.Sequential()
    model.add(layers.Dense(constants.HIDDEN_LAYER_1_DIMENSIONS, activation=constants.ACTIVATION_RELU, input_shape=(X.shape[1],)))
    model.add(layers.Dense(constants.HIDDEN_LAYER_2_DIMENSIONS, activation=constants.ACTIVATION_RELU))
    model.add(layers.Dense(constants.HIDDEN_LAYER_3_DIMENSIONS, activation=constants.ACTIVATION_RELU))
    model.add(layers.Dense(constants.OUTPUT_LAYER_DIMENSIONS, activation=constants.ACTIVATION_SOFTMAX))

    print("Compiling a Model")
    model.compile(optimizer= constants.OPTIMIZER_ADAM, loss= constants.LOSS_FUNCTION_SPARSE, metrics=[constants.ACCURACY_METRICS])
    return model


def train_and_save_model(model, X_train, y_train, X_test, y_test):
    logdir = constants.LOG_DIR_PATH
    tensorboard_callback = keras.callbacks.TensorBoard(log_dir=logdir)
    print("Start Training...")
    history = model.fit(X_train, y_train, epochs=35, validation_data=(X_test, y_test), callbacks=[tensorboard_callback])
    # Saving the trained model to avoid re-training
    model.save(constants.TRAINED_MODEL)
    return history


def predict(X_test, y_test):
    print("Predictions.....")
    predictions = np.argmax(model.predict(X_test), axis=-1)
    target_names = [constants.LIGHT_WEIGHT, constants.MEDIUM_WEIGHT, constants.HEAVY_WEIGHT,constants.TWO_WHEELED, constants.RAIL_BOUND]
    print(classification_report(y_test, predictions, target_names=target_names))


def plot_model_accuracy(history):
    # Plot graph Model Accuracy
    plt.plot(history.history['accuracy'])
    plt.plot(history.history['val_accuracy'])
    plt.title('Model Accuracy')
    plt.ylabel('Accuracy')
    plt.xlabel('Epoch')
    plt.legend(['Train', 'Test'], loc='upper left')
    plt.show()


def plot_model_loss(history):
    # Plot graph Model Loss
    plt.plot(history.history['loss'])
    plt.plot(history.history['val_loss'])
    plt.title('Model loss')
    plt.ylabel('Loss')
    plt.xlabel('Epoch')
    plt.legend(['Train', 'Test'], loc='upper right')
    plt.show()


# Changing Directory to Training Dataset Folder
chdir(constants.TRAINING_DATA_DIRECTORY_NAME)
trainingDataDir = Path.cwd()
trainingDataSubDirs = os.listdir(trainingDataDir)

extract_features(trainingDataDir, trainingDataSubDirs)
data = preprocessing_csv_data()
target_labels, encoder = encode_labels(data)
X = normalize_data(data)
X_train, X_test, y_train, y_test = train_test_data_split(X, target_labels)
model = create_and_compile_model()
history = train_and_save_model(model, X_train, y_train, X_test, y_test)
predict(X_test, y_test)
plot_model_accuracy(history)
plot_model_loss(history)