lambda_function.py

import json
import re
import logging
from urllib.parse import unquote

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

def lambda_handler(event, context):
  logger.info(json.dumps(event))
  req = parse(event['body'])
  
  return {
    "statusCode": 200,
    "body": switch[req['command']](req['text'])
  }

def parse(body):
  return dict(map(to_key_value, body.split('&')))

def to_key_value(s):
  return list(map(lambda pair: unquote(pair).replace('+', ' '), s.split('=', 1)))

switch = {
  '/f2c': lambda text: convert_with(text, f2c_string),
  '/c2f': lambda text: convert_with(text, c2f_string)
}
def convert_with(text, converter):
  words = list(filter(bool, re.compile("\s+").split(text)))
  return "\r\n".join(list(map(converter, words)))

f2c_string = lambda f: convert(f, fahrenheit_to_celcius)
c2f_string = lambda c: convert(c, celcius_to_fahrenheit)

def convert(w, f):
  try:
    return str(f(int(w)))
  except Exception as e:
    return "---"

fahrenheit_to_celcius = lambda f: (f - 32) * 5 / 9
celcius_to_fahrenheit = lambda c: c * 9 / 5 + 32