import serial
import time

# Constants
SERIAL_PORT = '/dev/ttyUSB0'
BAUD_RATE = 9600
PREFIX = ""
ATTEMPTS = 3
DELAY = 0.8
KEYSPACE = ["1", "2", "3", "4"]
LENGTH = 4

def get_response_time(serial_port, message):
    """
    Function to send message, wait for response, and measure response time.
    """
    # Flush the input buffer to clear any leftover data
    serial_port.flushInput()

    first_line_received = False

    # Send each character in the message with a delay
    for i, char in enumerate(message):
        time.sleep(DELAY)  # Delay before sending the character
        serial_port.write(char.encode())  # Send one character at a time
        #print(f"sending: {char}")
        if i < len(message)-1:
            #print(f"reading")
            raw_response = serial_port.readline()

    # After sending all characters, we will read until we get the first line (complete response)
    raw_response = b''  # Initialize the response variable

    while True:
        byte = serial_port.read(1)  # Read one byte at a time
        if byte:
            if byte == b'\n' and not first_line_received:
                first_line_received = True  # The first line has been received
                # Do not start timing yet; we need to wait for the next line after the first one
            elif first_line_received:
                # Start measuring response time after the first line is fully received
                start_time = time.time()
                break  # We begin timing here, immediately after the first line has been read

    final_response = serial_port.readline().decode(errors='ignore').strip()
    # Now read the rest of the response and stop when the second newline is encountered
    #final_response = raw_response.decode(errors='ignore').strip()  # Decode the response

    # Measure the time taken for the second line (after the first)
    response_time = time.time() - start_time

    # Debug message to show what was sent, received, and the response time
    print(f"\rSent: {message}, Response: {final_response}, Response Time: {response_time:.4f} seconds", end='', flush=True)

    time.sleep(DELAY)
    return final_response, response_time

def calculate_average_response_time(serial_port, message):
    """
    Calculate average response time over multiple attempts.
    """
    total_time = 0
    response_times = []

    # Try multiple attempts to get the average response time
    for _ in range(ATTEMPTS):
        response, response_time = get_response_time(serial_port, message)
        total_time += response_time
        response_times.append(response_time)
    
    average_time = total_time / ATTEMPTS
    print(f"\r{message} average: {average_time:.4f} seconds                                         ", flush=True)
    return average_time, response_times

def identify_sequence(serial_port):
    """
    Identify the complete sequence of characters by sending test sequences.
    """
    prefix = ""

    # Loop over all positions in the sequence (length 4 in this case)
    for pos in range(LENGTH):
        slowest_avg = float('-inf')  # Initialize with the smallest possible number to track the largest value
        best_digit = None

        # Try each character in the keyspace for this position
        for key in KEYSPACE:
            # Build message for this position
            message = prefix + key + key * (LENGTH - len(prefix) - 1)
            print(f"Testing: {message}", end='', flush=True)

            # Get the average response time for this message
            avg_time, _ = calculate_average_response_time(serial_port, message)

            # Track the slowest (highest average response time)
            if avg_time > slowest_avg:  # Modify comparison to choose the longest time
                slowest_avg = avg_time
                best_digit = key

        # Append the best digit found to the prefix
        prefix += best_digit
        print(f"Best digit for position {pos + 1}: {best_digit} (Average response time: {slowest_avg:.4f} seconds)")

    return prefix

def main():
    # Open the serial port
    with serial.Serial(SERIAL_PORT, BAUD_RATE, timeout=1) as serial_port:
        print(f"Starting sequence identification on port {SERIAL_PORT}...")
        sequence = identify_sequence(serial_port)
        print(f"Identified sequence: {sequence}")

if __name__ == '__main__':
    main()