"""Lambda function which processes a file uploaded on S3 by Looker.

Then it uploads processed file on the GfK's FTP server.
Basically it removes leading zeros from the first column, and wraps it with
double quotes.
"""


import csv
import datetime
import os
import tempfile
from urllib.parse import unquote_plus

import boto3
import config
import pysftp
import sentry_sdk
from config import FTP_CREDENTIALS
from config import get_
from sentry_sdk import capture_exception
from sentry_sdk.integrations.aws_lambda import AwsLambdaIntegration


FILENAME_TO_UPLOAD = 'Releases_Deliverable_to_GfK.txt'


def _send_sns():
    """Email data-squad@theorchard.com."""
    try:
        client = boto3.client('sns', region_name='us-east-1')
        client.publish(
            TopicArn='arn:aws:sns:us-east-1:437795906767'
                     ':prod-swf-feed-ingestion',
            Message='Releases were successfuly delivered to Gfk '
                    'via https://theorchard.looker.com/looks/13413 and '
                    'https://github.com/theorchard/lambda-looker',
            Subject='{} GfK delivery'.format(
                datetime.date.today().strftime('%Y-%m-%d')))
    except Exception as e:
        print(str(e))  # TODO: remove after successful message delivery


def _upload_to_ftp(tmpfile):
    """Upload a file to IN directory on the GfK's FTP server."""
    cnopts = pysftp.CnOpts()
    cnopts.hostkeys = None
    with pysftp.Connection(FTP_CREDENTIALS['host'],
                           username=get_('GFK_FTP_USERNAME'),
                           password=get_('GFK_FTP_PASSWORD'),
                           cnopts=cnopts) as sftp:
        sftp.put(tmpfile.name, '{}/{}'.format(
            FTP_CREDENTIALS['remote_ftp_dir'], FILENAME_TO_UPLOAD))
        sftp.close()
    _send_sns()


def handler(event, context):
    """Get a file from S3, process it, and upload to FTP."""
    if get_('SENTRY_DSN'):
        sentry_sdk.init(
            dsn=get_('SENTRY_DSN'),
            environment=config.ENVIRONMENT,
            integrations=[AwsLambdaIntegration(timeout_warning=True)],
        )  # save tests from failing on init step

    s3 = boto3.resource('s3')
    bucket = s3.Bucket(event['detail']['bucket']['name'])

    # get full filename of a file, uploaded by Looker to S3
    filename = unquote_plus(event['detail']['object']['key'])
    # download file
    local_path = '/tmp/{}'.format(os.path.basename(filename))
    bucket.download_file(filename, local_path)

    with open(local_path) as csvfile:
        reader = csv.reader(csvfile)
        with tempfile.NamedTemporaryFile(mode='w+t') as tmpfile:
            for index, row in enumerate(reader):
                if index == 0:  # write header
                    tmpfile.write('\t'.join([row[0], row[1]]) + '\n')
                else:  # write rows
                    tmpfile.write(
                        '\t'.join(
                            ['"' + row[0].lstrip('0') + '"', row[1]]) + '\n')
            tmpfile.flush()
            try:
                _upload_to_ftp(tmpfile)
            except Exception as e:
                capture_exception(e)
                raise e