from socket import $*$

from struct import pack, unpack

import os$,$ time, sys$,$ logging$,$ hashlib, math

$"""$

Protocol Description

$1.$ Client initiates connection with the server

$2.$ Client sends a request to the server to transfer a file. This request includes

$*$ the name of the file

$*$ the size of the file

$*$ the chunk size to be used during transfer

$*$ the checksum length used to validate the file chunks

$3.$ Server responds with an ACK indicating it is ready to receive the file. The ACK uses the following format

$*$ ACK type

$*$ the next expected chunk number. This should be zero here as the server needs the first chunk

$4.$ The client begins sending chunks of the file to the server. Chunks use the following format

$*$ the chunk number

$*$ the current file chunk

$*$ a checksum of the other data in this chunk

$5.$ The server receives chunks and sends an ACK message. The ACK uses the following format:

$*$ ACK type

$*$ the next expected chunk number. Note: if the packet is received successfully, this is the next packet number. If the packet was NOT received successfully $($i$.$e$.$ the checksum didn't validate$)$ then this should be the previously expected chunk number

$6.$ This continues until the entire file has been received and the server saves the file and sends a final ACK to the client. The client can then either send another file, or close the connection and quit.

$"""$

class FileTransferClient:

def $\_\_$init$\_\_($self$,$ host, port, chunk$\_$size$=32768,$ hash$\_$length$=8)$:

$"""$

Initializes the FileTransferClient.

This constructor sets up the logging configuration for the client and stores and provided parameters.

Parameters:

host $($string$)$: the hostname or IP address to connect to

port $($int$)$: The port number to connect TODO $-$

chunk$\_$size $($int$)$: the number of bytes in each chunk to use when transmitting the file

hash$\_$length $($int$)$: the length of the hash in bytes

Note:

The logger setup provided should not be modified and is used for outputting

status and debugging messages.

$"""$

# Do not modify this logger code. You can continue to use print$()$ commands for your code.

# The logger is in place to ensure that you receive proper output and debugging messages from the tester

self.logger $=$ logging$.$getLogger$("$CLIENT$")$

self.handler $=$ logging$.$StreamHandler$($sys$.$stdout$)$

formatter $=$ logging$.$Formatter$("\%($asctime$)$s $-\%($levelname$)$s $-\%($message$)$s$")$

self.handler.setFormatter$($formatter$)$

self.logger$.$addHandler$($self$.$handler$)$

self.logger$.$propagate $=$ False

self.logger$.$info$("$Initializing client..."$)$

# End of logger code

self.host $=$ host

self.port $=$ port

self.chunk$\_$size $=$ chunk$\_$size

self.hash$\_$length $=$ hash$\_$length

self.client$\_$socket $=$ None

def start$($self$)$:

$"""$

Initiates a connection to the server and marks the client as running. This function

does not attempt to send or receive any messages to or from the server.

This method is responsible for establishing a socket connection to the specified

server using the host and port attributes set during the client's initialization.

It creates a TCP socket object and attempts to connect to the server. It logs

the connection attempt and reports any errors encountered during the process.

Returns:

True or False depending on whether the connection was successful.

Exceptions:

$-$ OSError: Raised if the socket encounters a problem $($e$.$g$.,$ network

issue, invalid host$/$port$).$

Usage Example:

client $=$ FileTransferClient$($host$=\text{'}192\mathrm{.}168\mathrm{.}1\mathrm{.}10\text{'},$ port$=12345,$ hash$\_$length$=8)$

if client.start$()$:

$...$ do something $...$

Note:

$-$ It is important to call this method before attempting to send or receive

messages using the client.

$-$ Ensure that the server is up and running at the specified host and port

before calling this method.

$"""$

# TODO: Implement the functionality described in this function's docstring

pass

def read$\_$file$($self$,$ filepath$)$:

$"""$

Reads the contents of a file and returns the data as a byte object.

This is a helper function. You do not need to modify it$.$ You can use it in the send$\_$file

method to read the contents of a file and return the data as a byte object.

$"""$

with open$($filepath$,"$rb$")$ as file:

data $=$ file.read$()$

return data

def send$\_$file$($self$,$ filepath$)$:

$"""$

Sends a file to the server using the established connection.

File Transfer Protocol:

$1.$ Send a file transfer request to the server. Generate this request using the

pack$\_$transfer$\_$request$\_$message function

$2.$ Receive