"""Validate headers and content of adjustment file."""
import numpy as np
import pandas as pd

from lib import config
from lib import constants
from lib.utils import aws
from lib.utils import ows
from tasks.adjustment_file_upload import helpers


def validate_format_task(dag_run, **kwargs):
    """Task to validate headers and contents."""
    event = helpers.get_event_from_params(dag_run, **kwargs)
    statement_period_adjustment_file_id = event.target_id
    adjustment_file_details = ows.get_statement_period_adjustment_file_details(
        statement_period_adjustment_file_id
    )

    adjustment_file_location = adjustment_file_details.get('valid_file_location')
    assert adjustment_file_location is not None, 'Missing adjustment file'
    s3_object = aws.split_path(adjustment_file_location)
    bucket = s3_object.bucket
    key = s3_object.key

    account_id = config.S3_ACCOUNT_ID
    file = aws.get_file(account_id, bucket, key)
    df = pd.read_excel(file, engine='openpyxl', na_filter=False)

    if len(df.columns) < (constants.DAG_ADJUSTMENT_FILE_REQUIRED_HEADERS):
        ows.update_adjustment_file(statement_period_adjustment_file_id,
                                   body=dict(
                                       error_type='format_error'
                                   ))
        raise Exception('Missing columns')

    required_headers = df.columns[:constants.DAG_ADJUSTMENT_FILE_REQUIRED_HEADERS]

    if not set(required_headers) == (constants.DAG_ADJUSTMENT_FILE_HEADERS):
        ows.update_adjustment_file(statement_period_adjustment_file_id,
                                   body=dict(
                                       error_type='format_error'
                                   ))
        raise Exception('Mismatched or missing column names')

    df = df.astype(str).replace(r'^\s*$', np.nan, regex=True)
    df = df.dropna(how='all')
    df = df.astype(object).where(pd.notnull(df), None)

    if df.empty:
        ows.update_adjustment_file(statement_period_adjustment_file_id,
                                   body=dict(
                                       error_type='format_error'
                                   ))
        raise Exception('There are no adjustment records in the file')

    if df.shape[0] > constants.DAG_ADJUSTMENT_FILE_MAX_ROWS:
        ows.update_adjustment_file(statement_period_adjustment_file_id,
                                   body=dict(
                                       error_type='row_count_error'
                                   ))
        raise Exception('The file exceeds the maximum number of rows')