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'''
A Module that creates and modifies a database. In this case, the data is weather information
scraped from a webpage.
'''
import sqlite3
import logging
from dateutil import parser
from scrape_weather import WeatherScraper


class DBOperations:
    """Class for performing operations on a SQLite database"""

    def __init__(self, dbname):
        """
        Constructor for DBOperations class.

        Parameters:
        - dbname: str, the name of the SQLite database file to use
        """
        self.dbname = dbname
        self.logger = logging.getLogger(__name__)

    def initialize_db(self):
        """
        Initialize the SQLite database by creating the weather_data table.

        This method should be called every time the program runs.
        """
        with self.get_cursor() as cursor:
            try:
                cursor.execute('''
                    CREATE TABLE IF NOT EXISTS weather_data (
                        id INTEGER PRIMARY KEY AUTOINCREMENT,
                        sample_date TEXT UNIQUE,
                        location TEXT,
                        min_temp REAL,
                        max_temp REAL,
                        avg_temp REAL
                    )
                ''')
                self.logger.info("Initialized database successfully.")
            except sqlite3.Error as error:
                self.logger.error("An error occurred while creating the table: %s", error)

    def save_data(self, data):
        """
        Save weather data to the SQLite database.

        If the data already exists in the database, it will not be duplicated.

        Parameters:
        - data: dict, the weather data to save to the database. Must have keys for
          sample_date, location, min_temp, max_temp, and avg_temp.
        """
        with self.get_cursor() as cursor:
            try:
                cursor.execute('''
                    INSERT OR IGNORE INTO weather_data
                    (sample_date, location, min_temp, max_temp, avg_temp)
                    VALUES (?, ?, ?, ?, ?)
                ''', (data['sample_date'], data['location'], data['min_temp'], data['max_temp'],
                       data['avg_temp']))
                self.logger.info("Data saved successfully.")
            except sqlite3.Error as error:
                self.logger.error("An error occurred while saving data to the database: %s", error)

    def fetch_data(self, location):
        """
        Fetch weather data from the SQLite database for a specified location.

        Parameters:
        - location: str, the location to fetch weather data for

        Returns:
        - A list of tuples containing the weather data for the specified location,
          where each tuple has the format (sample_date, min_temp, max_temp, avg_temp).
          Returns an empty list if no data is found for the specified location.
        """
        with self.get_cursor() as cursor:
            try:
                cursor.execute('''
                    SELECT sample_date, min_temp, max_temp, avg_temp
                    FROM weather_data
                    WHERE location = ?
                ''', (location,))
                data = cursor.fetchall()
                self.logger.info("Data fetched successfully.")
                return data
            except sqlite3.Error as error:
                self.logger.error("An error occurred while fetching data from the database: %s",
                                  error)
                return []

    def fetch_data_year_to_year(self, first_year, last_year):
        '''
        Fetch weather data from the SQLite database for a specified year range.
        
        Parameters:
        - first_year: int, the first year in the range.
        - end_year: int, the final year in the range.
        
        Returns:
        - A list of data that falls in the range of years specified by the user.'''

        month_data = {1:[], 2:[], 3:[], 4:[], 5:[], 6:[],
                      7:[], 8:[], 9:[], 10:[], 11:[], 12:[]}
        start_year = f'{first_year}-01-01'
        end_year = f'{last_year}-01-01'

        with self.get_cursor() as cursor:
            try:
                for row in cursor.execute('''
                    SELECT sample_date, avg_temp
                    FROM weather_data
                    WHERE sample_date BETWEEN ? AND ?
                    ORDER BY sample_date''',(start_year, end_year)):

                    month = parser.parse(row[0]).month
                    month_data[month].append(row[1])

                self.logger.info("Data fetched successfully.")
                return month_data

            except sqlite3.Error as error:
                self.logger.error("An error occurred while fetching data from the database: %s",
                                  error)
                return []

    def fetch_data_single_month(self, month, year):
        '''
        Fetch weather data from the SQLite database for a specified month and year.
        
        Parameters:
        - month: int, the month to search for.
        - year: int, the year to search for.
        
        Returns:
        - A list of temperatures for the month and year the user searched for'''

        temperatures = {}

        with self.get_cursor() as cursor:
            try:
                for row in cursor.execute('''
                SELECT sample_date, avg_temp
                FROM weather_data
                WHERE sample_date LIKE ?||'-'||'0'||?||'-'||'%'
                ORDER BY sample_date''',(year, month)):
                    temperatures[row[0]] = row[1]
                return temperatures
            except sqlite3.Error as error:
                self.logger.error("An error occurred while fetching data from the database: %s",
                                  error)
                return []



    def purge_data(self):
        """
        Purge all weather data from the SQLite database.
        """
        with self.get_cursor() as cursor:
            try:
                cursor.execute('DELETE FROM weather_data')
                self.logger.info("Data purged successfully.")
            except sqlite3.Error as error:
                self.logger.error("An error occurred while purging data from the database: %s",
                                   error)

    def get_cursor(self):
        """
        Get a cursor to use for database operations.

        Returns:
        - A cursor object for the SQLite database.
        """
        return DBCM(self.dbname)


class DBCM:
    '''
    A class that represents a connection to a database.
    '''
    def __init__(self, dbname):
        self.dbname = dbname
        self.logger = logging.getLogger(__name__)

    def __enter__(self):
        try:
            self.conn = sqlite3.connect(self.dbname)
            self.cursor = self.conn.cursor()
            self.logger.info("Connection to database established successfully.")
            return self.cursor
        except sqlite3.Error as error:
            self.logger.error("An error occurred while connecting to the database: %s", error)
            return None

    def __exit__(self, exc_type, exc_val, exc_tb):
        if exc_type is not None:
            self.conn.rollback()
        else:
            try:
                self.conn.commit()
                self.logger.info("Changes committed successfully.")
            except sqlite3.Error as error:
                self.logger.error("An error occurred while committing changes to the database: %s",
                                  error)
        try:
            self.cursor.close()
            self.conn.close()
            self.logger.info("Connection to database closed successfully.")
        except sqlite3.Error as error:
            self.logger.error("An error occurred while closing the database connection: %s", error)


def main():
    '''
    The main method.
    '''

    # Initialize the database
    data_base = DBOperations("mydatabase.db")
    data_base.initialize_db()

    # Get the weather data
    scraper = WeatherScraper()
    data = scraper.get_data()

    # Process the data and prepare the rows
    rows = []
    for date, temps in data.items():
        row = (
            date,
            "Winnipeg",
            temps["Max"],
            temps["Min"],
            temps["Mean"]
        )
        rows.append(row)

    # Save the data to the database
    with data_base.get_cursor() as cursor:
        try:
            cursor.executemany('''
                INSERT OR IGNORE INTO weather_data
                (sample_date, location, min_temp, max_temp, avg_temp)
                VALUES (?, ?, ?, ?, ?)
            ''', rows)
            data_base.logger.info("Inserted %s rows into the database.", len(rows))
        except sqlite3.Error as error:
            data_base.logger.error("An error occurred while inserting data: %s", error)

if __name__ == '__main__':
    main()