import json
import requests
import logging
import base64
import psycopg2
import os
import sys

logger = logging.getLogger()
logger.setLevel(logging.INFO)

def get_db_creds():
  db_name = os.environ['DB_NAME']
  db_password = os.environ['DB_PASSWORD']
  db_user = os.environ['DB_USER']
  rds_endpoint = os.environ['RDS_ENDPOINT']
  return (db_name, db_password, db_user, rds_endpoint)

def connect_to_rds():
  try:
    db_name, db_password, db_user, rds_endpoint = get_db_creds()
    conn = psycopg2.connect(dbname=db_name, user=db_user, host=rds_endpoint, password=db_password)
    return (conn, conn.cursor())
  except Exception as e:
    logger.error("Lambda: ERROR Unable to connect to RDS")
    sys.exit()

def unpack_record(record):
  """Kinesis data is base64 encoded - unpack the payload"""
  payload = base64.b64decode(record["kinesis"]["data"])
  json_record = json.loads(payload)
  return json_record

# this event is a blob of JSON from Kinesis
# let's assume we know the error will be id (from a DB maybe? or the user? who knows)
# as well as the page the event was triggered on in the app (path), a status and a created time
# something like:
# {
#  "id": "1",
#  "path": "/login",
#  "status": "500",
#  "event_created_at": "2018-07-20T13:28:59.529Z"
# }
def error_sink(event, context):
  logger.info("Lambda: Executing...")
  records = event['Records']
  conn, cur = connect_to_rds()
  json_records = tuple(map(unpack_record, records))
  try: # NB - executemany isn't necessarily quicker, it's just terser in this example. See the docs for more...
    cur.executemany("""INSERT INTO errorevents(id,path,status,event_created_at) VALUES (%(id)s, %(path)s, %(status)s, %(event_created_at)s)""", json_records)
    conn.commit()
    logger.info("Lambda: " + str(json_records.__len__()) + " records processed")
  except Exception as e:
    logger.error("Lambda: EXCEPTION in error_sink: " + str(e))
  finally:
    cur.close()