import pprint
import pandas as panda
import statistics


class DataManager:

    def __init__(self):
        pass

    def data_loader(self):
        self.add_first_line('iris.data', 'SepalLengthCm,SepalWidthCm,PetalLengthCm,PetalWidthCm,Class')
        dataset = panda.read_csv('iris.data')
        separated_data = {data_column: dataset[data_column].tolist() for data_column in dataset.columns}
        self.rm_first_line('iris.data')
        return separated_data

    def add_first_line(self, filename, line):
        with open(filename, 'r+') as f_handler:
            content = f_handler.read()
            f_handler.seek(0, 0)
            f_handler.write(line.rstrip('\r\n') + '\n' + content)

    def rm_first_line(self, filename):
        with open(filename, 'r') as fin:
            data = fin.read().splitlines(True)
        with open(filename, 'w') as fout:
            fout.writelines(data[1:])

    def prepare_context(self):
        data = self.data_loader()
        context = {}
        for column_name, values in data.items():
            column_context = {}
            try:
                if type(values[0]) is str:
                    mode_value = statistics.mode(values)

                    column_context['mode_value'] = mode_value
                    column_context['freq_mode_value'] = values.count(mode_value)
                else:
                    mean_value = statistics.mean(values)

                    column_context['mean_value'] = mean_value
                    column_context['median_value'] = statistics.median(values)
                    column_context['min_value'] = min(values)
                    column_context['max_value'] = max(values)
                    column_context['variance_value'] = statistics.pvariance(values, mean_value)
            except statistics.StatisticsError as message:
                column_context['error'] = message
            finally:
                context[column_name] = column_context
        return context


def main():
    data_manager = DataManager()
    pprint.pprint(data_manager.prepare_context(), width=1)


if __name__ == '__main__':
    main()