Use the REST_server.py and REST_Client.py to implement a Loan Calculator in Python. A loan resource represents a standard loan using four parameters:

- Initial balance of the loan

- Annual interest rate on the loan

- Number of months in the term of the loan

- Monthly payment of the loan

?It is assumed that the loan will be paid off exactly after the given number of months.

?We will use the following version of a loan:

- At the end of each month during the term of the loan the amount of interest accrued during that month is computed

?This is the balance times the annual interest rate divided by 12

- The accrued interest is added to the balance of the loan

- The monthly payment is subtracted from the balance

-The balance remaining is carried forward to the next month until the end of the loan

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REST SERVER.PY

import re from http.server import HTTPServer, BaseHTTPRequestHandler import logging from json import loads, dumps from tickets import create_ticket from db_util.db_help import get_loan_for_loan_id, get_owner_id_for_ticket

class RestHandler(BaseHTTPRequestHandler):

def get_data(self): if 'content-length' in self.headers: data=self.rfile.read(int(self.headers['content-length'])) logging.info('data is '+data.decode()) return loads(data) else: logging.debug('no content lenght') return {}

def send_data(self, rtdata): # take rtdata, and create and send a response self.send_response(200) self.send_header('content-type', "application/json") rt=dumps(rtdata).encode() self.send_header('content-length', len(rt)) self.end_headers() self.wfile.write(rt)

def send_error_message(self, message, status_code=412): self.send_response(status_code) self.send_header('content-type', "application/json") rt = dumps({'error': message}).encode() self.send_header('content-length', len(rt)) self.end_headers() self.wfile.write(rt)

def do_GET(self): if re.fullmatch("/loan/(\\d+)", self.path): data=self.get_data() if 'ticket' in data: ticket=data['ticket'] # data={'ticket': 'o1u4hfjasdfkah3iurhf'} # data['ticket']=>'o1u4hfjasdfkah3iurhf' else: ticket=None if ticket: # parse the path to obtain loan_id match=re.fullmatch("/loan/(\\d+)", self.path) loan_id=int(match.group(1)) # client request= "GET /loan/1" # match=/loan/1 # group(1)=1 # client request= "GET /loan/4" # group(2)=4

# send query to the DB to obtain loan information where # loan_id=1 the_loan=get_loan_for_loan_id(loan_id) if the_loan: # check the_loan and the ticket have the same owner oid=get_owner_id_for_ticket(ticket) if oid==the_loan['owner']: # send the_loan back to the client self.send_data({'loan':the_loan}) else: self.send_error_message("no permission to access to the loan info.") else: self.send_error_message("no loan data found") else: self.send_error_message("ticket required for operation")

def do_POST(self): # implementing "Request a ticket" operation. # POST, /owner/ticket # 1. How to get the path from the request object. print(self.path) # 2. check that the path satisfies the pattern if re.fullmatch("/owner/ticket", self.path): # 3. get the owner name from the request body data=self.get_data() #{'owner_name': 'Alice'} owner_name=data.get('owner_name') #owner_name=data['owner_name'] print(owner_name) if owner_name: # 4. check the validity of the owner name # create a ticket ticket=create_ticket(owner_name) if ticket: # create a response: intial line, headers, and body # send the response back to the client self.send_data({'ticket':ticket}) else: # the name of owner was invalid self.send_error_message("invalid owner name:"+str(owner_name)) else: self.send_error_message("didn't receive a valid owner name:" + str(owner_name)) pass elif re.fullmatch("/owner",self.path): pass elif re.fullmatch("/loan", self.path): pass else: self.send_error_message("invalid path:" + str(self.path))

#create_owner #create_loan

def do_PUT(self): pass def do_DELETE(self): pass

if __name__=="__main__": server=HTTPServer(('',8080), RestHandler) server.serve_forever()

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REST_CLIENT.PY

import requests

data={'owner_name':'Alice'}

response=requests.post("http://localhost:8080/owner/ticket", json=data)

response_dic=response.json()

print(response_dic) print(response_dic.get('ticket')) print(response_dic['ticket'])

if 'ticket' in response_dic: ticket=response_dic['ticket'] print(ticket) #data2={'ticket':ticket} response2=requests.get("http://localhost:8080/loan/1", json=response_dic) print(response2) print(response2.text)