#!/usr/bin/env python3

import argparse
import sys
import numpy as np
import encoder
import decoder
import channel
import subprocess
import tempfile
import pathlib
import os


def transmit(msg, C):
    """
    Transmitter: encodes the message into real-valued samples using the codebook C.
    """
    return encoder.encode_message(msg, C)


def receive_local(c):
    """
    Sends the samples through the local channel simulation.
    """
    return channel.channel(c)


def receive_server(c, hostname, port):
    """
    Sends the samples to the remote server via client.py and retrieves the output.
    """
    # Write input samples to a temporary file
    with tempfile.NamedTemporaryFile(suffix='.txt', delete=False) as in_f:
        np.savetxt(in_f.name, c)
        in_name = in_f.name
    # Prepare output file
    out_fd, out_name = tempfile.mkstemp(suffix='.txt')
    os.close(out_fd)
    # Invoke client.py
    cmd = [
        sys.executable,
        str(pathlib.Path(__file__).parent / 'client.py'),
        '--input_file', in_name,
        '--output_file', out_name,
        '--srv_hostname', hostname,
        '--srv_port', str(port)
    ]
    try:
        subprocess.run(cmd, check=True)
        Y = np.loadtxt(out_name)
    finally:
        # Clean up temp files
        os.remove(in_name)
        os.remove(out_name)
    return Y


def receive(c, mode, hostname, port):
    """
    Wrapper to choose local or server channel.
    """
    if mode == 'local':
        return receive_local(c)
    elif mode == 'server':
        return receive_server(c, hostname, port)
    else:
        raise ValueError("Mode must be 'local' or 'server'")


def test_performance(msg, num_trials, mode, hostname, port):
    """
    Runs num_trials transmissions of msg through the specified channel and reports accuracy.
    """
    if len(msg) != 40:
        raise ValueError("Message must be exactly 40 characters.")
    # Build codebook for 64 symbols, 40 blocks
    C = encoder.make_codebook(r=5, num_blocks=40)
    successes = 0
    for i in range(num_trials):
        # Transmit
        c = transmit(msg, C)
        # Channel
        Y = receive(c, mode, hostname, port)
        # Decode
        est = decoder.decode_blocks(Y, C)
        if est == msg:
            successes += 1
    pct = successes / num_trials * 100
    # Display results
    print(f"Message: {msg}")
    print(f"Trials: {num_trials}")
    print(f"Mode: {mode}")
    print(f"Correct decodings: {successes}")
    print(f"Accuracy: {pct:.2f}%")


def parse_args():
    parser = argparse.ArgumentParser(description="Test communication system performance.")
    parser.add_argument('--message', '-m', type=str, required=True,
                        help="40-character message to send.")
    parser.add_argument('--trials', '-n', type=int, default=1,
                        help="Number of trials.")
    parser.add_argument('--mode', choices=['local','server'], default='local',
                        help="Channel mode: 'local' or 'server'.")
    parser.add_argument('--hostname', type=str, default='iscsrv72.epfl.ch',
                        help="Server hostname for server mode.")
    parser.add_argument('--port', type=int, default=80,
                        help="Server port for server mode.")
    return parser.parse_args()

if __name__ == '__main__':
    args = parse_args()
    test_performance(args.message, args.trials, args.mode, args.hostname, args.port)