import boto3
import os
import requests

from base64 import b64decode
from botocore.exceptions import ClientError

dynamodb = boto3.resource('dynamodb', region_name='us-west-2')

ENCRYPTED = os.environ['RECAPTCHA_SECRET']
# Decrypt code should run once and variables stored outside of the function
# handler so that these are decrypted once per container
RECAPTCHA_SECRET = boto3.client('kms').decrypt(CiphertextBlob=b64decode(ENCRYPTED))['Plaintext']

def lambda_handler(event, context):
    table = dynamodb.Table('urlshorten')

    if 'from' in event and 'to' in event:
        captcha_data = {
            'secret': RECAPTCHA_SECRET,
            'response': event['g-recaptcha-response'],
            'remoteip': event['remoteip']
        }

        verify = requests.get('https://www.google.com/recaptcha/api/siteverify',
                              params=captcha_data)
        if not (verify.status_code == 200 and verify.json()['success']):
            return {
                'status': 'error',
                'error': verify.json()
            }

        ssl = event['to'][:5].lower() == 'https'

        url = ('https://' if ssl else 'http://') + event['to'].split('://')[-1]

        try:
            table.put_item(
                Item={
                    'key': event['from'],
                    'value': url
                },
                ConditionExpression='attribute_not_exists(#key)',
                ExpressionAttributeNames={
                    '#key': 'key'
                }
            )
        except ClientError as e:
            return {
                'status': 'error',
                'error': e.response['Error']
            }
        except KeyError:
            return {
                'status': 'error',
                'error': 'Invalid Request',
                'location': '/'
            }
        else:
            return {
                'status': 'ok'
            }

    try:
        response = table.get_item(Key={ 'key': event['shortUrl'] })
        location = response['Item']['value']
    except ClientError as e:
        return e.response['Error']
    except KeyError:
        return {
            'location': '/'
        }
    else:
        return {
            'location': response['Item']['value']
        }