import pandas as pd
import numpy as np
import itertools
from scipy.stats import entropy


def compute_features(filtered_data, apps_type, requested_features, apps_features, time_segment):        
    # There is the rare occasion that filtered_data is empty (found in testing)
    if "timeoffirstuse" in requested_features:
        time_first_event = filtered_data.sort_values(by="timestamp", ascending=True).drop_duplicates(subset="local_segment", keep="first").set_index("local_segment")
        if time_first_event.empty:
            apps_features["timeoffirstuse" + apps_type] = np.nan
        else:
            apps_features["timeoffirstuse" + apps_type] = time_first_event["local_hour"] * 60 + time_first_event["local_minute"]
    if "timeoflastuse" in requested_features:
        time_last_event = filtered_data.sort_values(by="timestamp", ascending=False).drop_duplicates(subset="local_segment", keep="first").set_index("local_segment")
        if time_last_event.empty:
            apps_features["timeoflastuse" + apps_type] = np.nan
        else:
            apps_features["timeoflastuse" + apps_type] = time_last_event["local_hour"] * 60 + time_last_event["local_minute"]
    if "frequencyentropy" in requested_features:
        apps_with_count = filtered_data.groupby(["local_segment","application_name"]).count().sort_values(by="timestamp", ascending=False).reset_index()
        if (len(apps_with_count.index) < 2 ):
            apps_features["frequencyentropy" + apps_type] = np.nan
        else:    
            apps_features["frequencyentropy" + apps_type] = apps_with_count.groupby("local_segment")["timestamp"].agg(entropy)
    if "count" in requested_features:
        apps_features["count" + apps_type] = filtered_data.groupby(["local_segment"]).count()["timestamp"]
        apps_features.fillna(value={"count" + apps_type: 0}, inplace=True)
    return apps_features


def rapids_features(sensor_data_files, time_segment, provider, filter_data_by_segment, *args, **kwargs):
    
    apps_data = pd.read_csv(sensor_data_files["sensor_data"])

    requested_features = provider["FEATURES"]
    excluded_categories = provider["EXCLUDED_CATEGORIES"]
    excluded_apps = provider["EXCLUDED_APPS"]
    multiple_categories_with_genres = provider["MULTIPLE_CATEGORIES"]
    single_categories = provider["SINGLE_CATEGORIES"]
    multiple_categories = provider["MULTIPLE_CATEGORIES"]
    single_apps = provider["SINGLE_APPS"]

    single_categories = list(set(single_categories) - set(excluded_categories))
    multiple_categories = list(multiple_categories_with_genres.keys() - set(excluded_categories))
    single_apps = list(set(single_apps) - set(excluded_apps))

    # exclude categories in the excluded_categories list
    if "system_apps" in excluded_categories:
        apps_data = apps_data[apps_data["is_system_app"] == 0]
    apps_data = apps_data[~apps_data["genre"].isin(excluded_categories)]
    # exclude apps in the excluded_apps list
    apps_data = apps_data[~apps_data["package_name"].isin(excluded_apps)]
    
    apps_features = pd.DataFrame(columns=["local_segment"] + ["".join(feature) for feature in itertools.product(requested_features, single_categories + multiple_categories + single_apps)])
    if not apps_data.empty:
        # deep copy the apps_data for the top1global computation
        apps_data_global = apps_data.copy()
        
        apps_data = filter_data_by_segment(apps_data, time_segment)
        
        if not apps_data.empty:
            apps_features = pd.DataFrame()
            # single category
            single_categories.sort()
            for sc in single_categories:
                if sc == "all":
                    apps_features = compute_features(apps_data, "all", requested_features, apps_features, time_segment)
                else:
                    filtered_data = apps_data[apps_data["genre"].isin([sc])]
                    apps_features = compute_features(filtered_data, sc, requested_features, apps_features, time_segment)
            # multiple category
            for mc in multiple_categories:
                filtered_data = apps_data[apps_data["genre"].isin(multiple_categories_with_genres[mc])]
                apps_features = compute_features(filtered_data, mc, requested_features, apps_features, time_segment)
            # single apps
            for app in single_apps:
                col_name = app
                if app == "top1global":
                    # get the most used app
                    apps_with_count = apps_data_global.groupby(["package_name"]).count().sort_values(by="timestamp", ascending=False).reset_index()
                    app = apps_with_count.iloc[0]["package_name"]
                    col_name = "top1global"
                filtered_data = apps_data[apps_data["package_name"].isin([app])]
                apps_features = compute_features(filtered_data, col_name, requested_features, apps_features, time_segment)
 
            apps_features = apps_features.reset_index()
    
    return apps_features