import pandas as pd
import sqlite3

database_name = input()
csv_file = input()
table_name = input()
currency_table = input()

def preprocess_vacancies_data(database_name, csv_file_name, table_name, currency_table):
    # Чтение данных о вакансиях из CSV-файла
	df_vacancies = pd.read_csv(csv_file_name)

    # Подключение к базе данных SQLite
	conn = sqlite3.connect(database_name)

    # Чтение данных о курсах валют из таблицы базы данных
	query = f"SELECT * FROM {currency_table}"
	df_currency = pd.read_sql_query(query, conn)

	df_vacancies['salary_from'] = df_vacancies.apply(lambda row: convert_currency(row['salary_from'], row['salary_currency'], df_currency,df_vacancies['published_at']), axis=1)

	df_vacancies['salary_to'] = df_vacancies.apply(lambda row: convert_currency(row['salary_to'], row['salary_currency'], df_currency,df_vacancies['published_at']), axis=1)

	df_vacancies['salary'] = df_vacancies.apply(lambda row: calculate_average_salary(row['salary_from'], row['salary_to']), axis=1)

    # Удаление ненужных столбцов
	df_vacancies = df_vacancies[['name', 'salary', 'area_name', 'published_at']]

    # Запись данных в таблицу базы данных
	df_vacancies.to_sql(table_name, conn, if_exists='replace', index=False)

    # Закрытие соединения с базой данных
	conn.close()

def convert_currency(value, currency, df_currency,year):
	if pd.isnull(value) or pd.isnull(currency):
		return None

    # Получение коэффициента для преобразования валюты
	coefficient = get_currency_coefficient(currency, df_currency,year)

    # Преобразование валюты в рубли
	if coefficient is not None:
		return round(value * coefficient)
	else:
		return None

def get_currency_coefficient(currency, df_currency,year):
	if currency in df_currency.columns:
		return df_currency[currency].iloc[0]
	if currency == 'RUR':
		return 1
	else:
		return None

def calculate_average_salary(salary_from, salary_to):
	if pd.isnull(salary_from) and pd.isnull(salary_to):
		return None
	elif pd.isnull(salary_from):
		return salary_to
	elif pd.isnull(salary_to):
		return salary_from
	else:
		return (salary_from + salary_to) // 2

# Пример использования функции
preprocess_vacancies_data(database_name, csv_file, table_name, currency_table)