"""Import statements."""

import os

from accounting import config
from accounting.adapters.log import getlogger
from accounting.data import get_db_adapter
from accounting.data import read_statement_file

SELECT_SQL = (
    'SELECT '
    'COUNT(*) as count '
    'FROM `dig_sales` '
    'WHERE `period_id` = {:d}')

INSERT_SQL = (
    'INSERT INTO `dig_sales` '
    '(`statement_id`, `dms_customer_id`, `actual_statement_no`, `paid`, '
    '`year`, `quarter`, `month`, `check_detail_id`, `period_id`, '
    ' `activity_rate`, `original_currency_id`) '
    'VALUES {}')

VALUE_SQL = (
    '({statement_id}, {dms_customer_id}, "{actual_statement_no}", "{paid}", '
    '{year}, {quarter}, {month}, "{check_detail_id}", {period_id}, '
    '{activity_rate}, {original_currency_id})')

ALREADY_EXISTS_TEXT = (
    'Exchange rates already exist for period {:d}. '
    'Canceling import.')

MISMATCH_TEXT = (
    'Import period id does not match current period id. '
    'Given {:d}, expecting {:d}. '
    'Canceling import.')

IMPORT_TEXT = 'Importing currency exchange rates for period {:d}'


def import_statements():
    """Import currency exchange rates.

    Performs checks that the given period id does not already exist in the db.
    Checks that the imported period_id matches the current period_id.

    Raises:
        Exception: Statements already exist for the current period.

    """
    logger = getlogger()
    if check_statements_exist_for_period():
        raise Exception(ALREADY_EXISTS_TEXT.format(config.PERIOD_ID))
    load_statements()
    logger.info(IMPORT_TEXT.format(config.PERIOD_ID))


def check_statements_exist_for_period():
    """Check if currency exchange rates exist for the given period.

    Returns:
        bool: if rows exist for the given period.

    """
    db_adapter = get_db_adapter()
    row = db_adapter.fetch_rows(SELECT_SQL.format(config.PERIOD_ID))
    return row[0][0] > 0


def load_statements():
    """Build insert sql for exchange rates.

    Returns:
        str: Insert SQL for exchange rates.

    """
    # db_adapter = get_db_adapter()
    for statement in read_statement_file(os.environ.get('STATEMENTS_FILE')):
        adapter = get_db_adapter()
        values = VALUE_SQL.format(**statement)
        adapter.execute(INSERT_SQL.format(values))