import json
import hashlib
import hmac
from backend import handle_data
from settings import *

def app(environ, start_response):
	try:
		data: dict = get_data(environ.copy())
	except Exception as e:
		start_response('400', [
			('Content-Type', 'text/plain')
		])
		return iter([str(e).encode()])

	try:
		logging: str = handle_data(data)
	except Exception as e:
		start_response('500', [
			('Content-Type', 'text/plain')
		])
		return iter([str(e).encode()])

	start_response('200 OK', [
		('Content-Type', 'text/plain')
	])

	return iter([logging.encode()])

def get_data(environ):
	if environ['REQUEST_METHOD'] == 'POST':
		if 'application/json' != environ.get('CONTENT_TYPE'):
			raise Exception('Error: Content-Type is not application/json: ' + environ.get('CONTENT_TYPE'))

		try:
			request_body_size = int(environ.get('CONTENT_LENGTH', 0))
		except (ValueError):
			request_body_size = 0

		if 0 == request_body_size:
			raise Exception('Error: Content-Length is 0')

		request_body = environ.get('wsgi.input').read(request_body_size)

		signature = environ.get('HTTP_X_GITEA_SIGNATURE')

		if not signature:
			raise Exception('Error: Missing signature')

		signature_actual = hmac.new(SECRET_KEY.encode(), request_body, hashlib.sha256).hexdigest()

		if signature_actual != signature:
			raise Exception('Error: Signature could not be validated')

		try:
			data = json.loads(request_body)
		except json.decoder.JSONDecodeError as e:
			raise Exception('Error: Could not parse the JSON body: %s' % e)

		return data
	else:
		raise Exception('Error: Request is not POST: ' + environ.get('REQUEST_METHOD'))