# Introduction to Data Science, Luento-opetus, 2023
# Sergei Panarin


# Data preprocessing

# IMPORTANT THINGS:
# Change the number of input files in the read_data function OR later replace with full data file
# FUNCTION replace owner with symbol is copied from the main branch, DELETE LATER and IMPORT

# Reading the data from source:
# Pandas cannot read from GitLab URLs, so work is done with locally stored datasets.
# Go through partial files containing parts of the whole dataset
# @param  
# @return: full pandas dataframe, containing all the relevant columns from the csv files
def read_data():
    # full_data_df = pd.read_csv("full_data.csv")

    partial_dfs = []

    # range can be changed, reads segments of the full dataset
    for index in range(10):
        datafile="file_segments/game_data_"+str(index+1)+".csv"
        partial_dfs.append(pd.read_csv(datafile))
    
    # Combine partial dataframes into the full version
    full_data_df = pd.concat(partial_dfs)

    return full_data_df

# transform String columns into integer IDs.
# @param: pandas dataframe with the full data
# @return: pandas dataframe with developer, publisher, genres columns encoded with integer IDs
def label_encoding(data):
    to_be_encoded = ["publisher", "developer"]

    # remove everything but the first element in those columns and categorize everything
    for val in to_be_encoded:
        data[val] = data[val].apply(lambda x: str(x).split(",")[0])
        data[val] = data[val].astype('category')


    # select the category columns and apply label encoding
    cat_columns = data.select_dtypes(['category']).columns
    data[cat_columns] = data[cat_columns].apply(lambda x: x.cat.codes)

# Transforms full data dataframe into a dataframe with the following columns:
# - Genre
# - Amount of purchases
# - Interval of time (default chosen as 2 months for now)
# @param: pandas dataframe with the full data, interval integer meaning the number of months
# @return: pandas dataframe with genre, # of purchases, time interval columns

def genre_data_aggregation(data, interval):

    data["genres"] = data["genres"].apply(lambda x: str(x).split(","))

    # preprocess the release date column into the pandas datetime format
    data['release_date'] = pd.to_datetime(data['release_date'], dayfirst=True, format="mixed")
    
    # remove whitespaces
    data['genres'] = data['genres'].map(lambda x: list(map(str.strip, x)))
    data = data[['release_date', 'genres', 'owners']]
    
    agg_data = pd.DataFrame(columns=['genre','dates','populations'])
    # big FOR loop, for now
    
    agg_data = data.explode('genres')
    agg_data = agg_data.groupby("genres")
    #describe()
    agg_data = [group for _, group in agg_data]
    
    for x in agg_data:
        x.dropna(how='any', inplace=True)
        x.sort_values(by=['release_date'], ascending=[True], inplace=True)
        #x = x.groupby( [pd.Grouper(key='release_date', freq=str(interval)+"M"), pd.Grouper('genres')] ).agg({'owners': 'sum'})
    
    
    # remove excessive columns and sort values
    # data = data[['release_date', 'genres', 'owners']].sort_values(['release_date','genres', 'owners'], ascending=[True, True, False])

    dict_data = {}
    # group by the time interval and get sum of the owners
    for i in range(0, len(agg_data)):  
        name = agg_data[i]['genres'].iloc[0]
        agg_data[i] = agg_data[i].groupby(pd.Grouper(key='release_date', freq=str(interval)+"M")).agg({'owners': 'sum'})
        agg_data[i] = agg_data[i].reset_index()
        dict_data[name] = agg_data[i]
        
        
    return dict_data

# Resets Index of the merged dataframe
def clean_index(data):
    return data.reset_index(drop=True)

# Transforms owners column values from str of range of values into the average float value
# @param: pandas dataframe with the full data, interval integer meaning the number of months
# @return: pandas dataframe with owners column modified
def replace_owner_str_with_average_number(data):
    def replace_letters(entry):
        to_remove = {" M": "000000", " k": "000"}

        for char in to_remove.keys():
            entry = entry.replace(char, to_remove[char])

        return entry
        
    data["owners"] = data["owners"].apply(lambda name: replace_letters(name))
    data["owners"] = data["owners"].apply(lambda name: re.findall("\d+",name))
    data["owners"] = data["owners"].apply(lambda name: [int(item) for item in name])
    data["owners"] = data["owners"].apply(lambda name: float(sum(name)/len(name)))
    return data

# Encodes time as numbers for processing
# @param: pandas dataframe with the full data
# @return: pandas dataframe with time modified
def encode_time(df):
    df['release_date']=df['release_date'].map(dt.datetime.toordinal)
    return df

def lin_reg(df):
    
    y = np.asarray(df['owners'])
    X = df[['release_date']]
    #X_train, X_test, y_train, y_test = train_test_split(X,y,train_size=.7,random_state=42)
    
    model = LinearRegression() #create linear regression object
    #model.fit(X_train, y_train) #train model on train data
    model.fit(X, y)
    #model.score(X_train, y_train) #check score
    return model

# Plot the given genre data 
def get_genre_plot(dict_data, genre):
    plt.scatter(dict_data[genre]["release_date"], dict_data[genre]["owners"]) 
    plt.show()
    
def get_data_interval(days):
    base = dt.datetime.now()
    
    final_date = base + dt.timedelta(days=days)

    parts = list(pd.date_range(pd.Timestamp(base), pd.Timestamp(final_date), freq='2M')) 

    dates = [t.toordinal() for t in parts]
    return dates
    
if __name__ == "__main__":

    import pandas as pd
    import numpy as np
    import datetime as dt
    import re
    from sklearn.model_selection import train_test_split
    from sklearn.linear_model import LinearRegression
    import matplotlib.pyplot as plt
    from math import isnan
    
    
    full_data_df = read_data()
    full_data_df = clean_index(full_data_df)

    label_encoding(full_data_df)
    data = replace_owner_str_with_average_number(full_data_df)
    genre_data = genre_data_aggregation(full_data_df, 2)
    
    genre = "Action"
    
    get_genre_plot(genre_data, genre)
    
    # 730 days = 2 years
    dates = np.array(get_data_interval(730))
    dates = dates.reshape(len(dates), 1)
    
    # GET ALL MODELS FOR ALL GENRES
    models = {}
    predictions = {}
    process_data = genre_data
    for x in process_data:  
        genre_data[x] = encode_time(genre_data[x])
        models[x] = lin_reg(genre_data[x])
        
    for genre in models:
        predictions[genre] = models[genre].predict(dates)
        
    # GET POINT OF REFERENCE
    
    
    
    
    
    pass