"""Export Request."""

import json

from sales.constants.exceptions import InvalidMessageError

REQUIRED_MESSAGE_FIELDS = [
    'callback_url',
    'destination_s3_bucket',
    'destination_s3_path',
    'sales_file_id',
    'source_table_name']


class ExportRequest():
    """Model export message."""

    def __init__(self, payload):
        """Validate and set message fields."""
        if not payload:
            raise InvalidMessageError('Empty Message Received')
        message = json.loads(payload)
        self.validate(message)
        self.errors = []
        self.destination_s3_bucket = message.get('destination_s3_bucket')
        self.destination_s3_path = message.get('destination_s3_path')
        self.sales_file_id = str(message.get('sales_file_id'))
        self.source_table_name = message.get('source_table_name')
        self.callback_url = message.get('callback_url')
        if not self.callback_url.startswith('/'):
            self.callback_url = '/{}'.format(self.callback_url)

    def validate(self, message):
        """Validate message body."""
        set1 = set(message.keys())
        set2 = set(REQUIRED_MESSAGE_FIELDS)
        diff = set1 ^ set2
        if diff:
            raise InvalidMessageError('Invalid Message Keys. {}'.format(diff))

    def add_error(self, message):
        """Add an error message."""
        self.errors.append(message)

    def get_response_data(self):
        """Format the response payload."""
        return json.dumps({
            'callback_url': self.callback_url,
            'destination_s3_bucket': self.destination_s3_bucket,
            'destination_s3_path': self.destination_s3_path,
            'sales_file_id': self.sales_file_id,
            'source_table_name': self.source_table_name,
            'errors': self.errors,
        })