#!/usr/bin/env python3

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

# Global paths for debugging
INPUT_FILE = None
OUTPUT_FILE = None

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. If INPUT_FILE and/or
    OUTPUT_FILE are set, uses those filenames (and preserves them); otherwise uses temporary files.
    '''
    global INPUT_FILE, OUTPUT_FILE
    # Determine input file path
    if INPUT_FILE:
        in_name = INPUT_FILE
        np.savetxt(in_name, c)
        delete_in = False
    else:
        with tempfile.NamedTemporaryFile(suffix='.txt', delete=False) as in_f:
            np.savetxt(in_f.name, c)
            in_name = in_f.name
        delete_in = True
    # Determine output file path
    if OUTPUT_FILE:
        out_name = OUTPUT_FILE
        delete_out = False
    else:
        out_fd, out_name = tempfile.mkstemp(suffix='.txt')
        os.close(out_fd)
        delete_out = True
    # 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:
        if delete_in and os.path.exists(in_name):
            os.remove(in_name)
        if delete_out and os.path.exists(out_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=200,
                        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.')
    parser.add_argument('--input_file', '-i', type=str, default=None,
                        help='Path to write server input samples (input.txt).')
    parser.add_argument('--output_file', '-o', type=str, default=None,
                        help='Path to write server output samples (output.txt).')
    return parser.parse_args()

if __name__ == '__main__':
    args = parse_args()
    # Set global paths
    INPUT_FILE = args.input_file
    OUTPUT_FILE = args.output_file
    test_performance(args.message, args.trials, args.mode, args.hostname, args.port)