#!/usr/bin/env python3
"""Class 1 Fax Receiver - for testing with USR sender"""
import termios
import os
import time
import sys

def main():
    if len(sys.argv) < 2:
        print("Usage: class1_receive.py <device>")
        sys.exit(1)
    
    device = sys.argv[1]
    fd = os.open(device, os.O_RDWR | os.O_NOCTTY | os.O_NONBLOCK)
    
    attrs = termios.tcgetattr(fd)
    attrs[4] = termios.B115200
    attrs[5] = termios.B115200
    attrs[2] |= termios.CLOCAL | termios.CREAD
    attrs[3] &= ~termios.ICANON
    attrs[3] &= ~termios.ECHO
    attrs[3] &= ~termios.ECHOE
    attrs[3] &= ~termios.ISIG
    termios.tcsetattr(fd, termios.TCSANOW, attrs)
    termios.tcflush(fd, termios.TCIOFLUSH)
    
    def drain():
        try:
            while True:
                os.read(fd, 4096)
        except BlockingIOError:
            pass
    
    def send_cmd(cmd, wait=0.5):
        drain()
        os.write(fd, cmd.encode() + b"\r")
        time.sleep(wait)
        result = b""
        try:
            while True:
                data = os.read(fd, 4096)
                result += data
        except BlockingIOError:
            pass
        return result.decode(errors="replace")
    
    def wait_for(pattern, timeout=30):
        start = time.time()
        result = b""
        while time.time() - start < timeout:
            try:
                data = os.read(fd, 4096)
                result += data
                decoded = result.decode(errors="replace")
                for p in pattern if isinstance(pattern, list) else [pattern]:
                    if p in decoded:
                        return decoded
            except BlockingIOError:
                time.sleep(0.1)
        return result.decode(errors="replace")
    
    print("[RECV] Initializing Class 1...")
    send_cmd("AT", 0.3)
    send_cmd("AT+FCLASS=1", 0.3)
    
    print("[RECV] Waiting for rings...")
    
    ring_count = 0
    while ring_count < 2:
        try:
            data = os.read(fd, 4096)
            text = data.decode(errors="replace")
            if "RING" in text:
                ring_count += text.count("RING")
                print(f"[RECV] Ring {ring_count}")
        except BlockingIOError:
            time.sleep(0.3)
    
    print("[RECV] Answering...")
    answer_result = send_cmd("ATA", 3)
    print(f"[RECV] ATA result: {answer_result.strip()}")
    
    if "CONNECT" not in answer_result:
        drain()
        os.write(fd, b"ATA\r")
        wait_result = wait_for("CONNECT", 10)
        print(f"[RECV] Wait result: {wait_result.strip()}")
    
    print("[RECV] Connected! Sending CED tone...")
    time.sleep(0.5)
    
    # Send CED tone (2100Hz for 2.6-4 seconds)
    ced_result = send_cmd("AT+FTS=8", 4)  # FTS=8 sends 2100Hz
    print(f"[RECV] CED result: {ced_result.strip()}")
    
    # Wait 75ms then send DIS
    time.sleep(0.1)
    
    print("[RECV] Sending DIS frame...")
    
    # Start HDLC transmit
    os.write(fd, b"AT+FTH=3\r")
    fth_result = wait_for("CONNECT", 5)
    print(f"[RECV] FTH=3: {fth_result.strip()}")
    
    if "CONNECT" in fth_result:
        # DIS frame: preamble+flags+DCS+data+RTC
        # Address: 0xFF (broadcast), Control: 0x80 (DIS from called)
        # DIS data: minimum capabilities
        dis_data = bytes([
            0xFF, 0x13, 0x80,  # Address + Control (DIS from called)
            0x00, 0x50, 0x1F,  # DIS parameters
        ])
        # Add FCS (we'll let modem calculate)
        os.write(fd, dis_data)
        os.write(fd, b"\x00\x00\x00")  # Padding
        time.sleep(0.5)
        
        # Wait for OK
        dis_ok = wait_for("OK", 5)
        print(f"[RECV] DIS sent: {dis_ok.strip()}")
    
    print("[RECV] Waiting for DCS...")
    drain()
    os.write(fd, b"AT+FRH=3\r")
    dcs_result = wait_for("OK", 10)
    print(f"[RECV] DCS received: {len(dcs_result)} bytes")
    
    print("[RECV] Waiting for TCF...")
    drain()
    os.write(fd, b"AT+FRM=96\r")  # Receive at 14400 bps
    tcf_result = wait_for("CONNECT", 5)
    print(f"[RECV] TCF: {tcf_result.strip()}")
    
    # Send CFR
    print("[RECV] Sending CFR...")
    drain()
    os.write(fd, b"AT+FTH=3\r")
    wait_for("CONNECT", 5)
    cfr_data = bytes([0xFF, 0x13, 0x21])  # CFR frame
    os.write(fd, cfr_data)
    os.write(fd, b"\x00\x00\x00")
    time.sleep(0.5)
    wait_for("OK", 5)
    print("[RECV] CFR sent")
    
    print("[RECV] Waiting for page data...")
    # Receive page
    drain()
    os.write(fd, b"AT+FRM=96\r")
    page_result = wait_for("OK", 60)
    print(f"[RECV] Page received!")
    
    # Send MCF
    print("[RECV] Sending MCF...")
    drain()
    os.write(fd, b"AT+FTH=3\r")
    wait_for("CONNECT", 5)
    mcf_data = bytes([0xFF, 0x13, 0x31])  # MCF frame
    os.write(fd, mcf_data)
    os.write(fd, b"\x00\x00\x00")
    time.sleep(0.5)
    wait_for("OK", 5)
    print("[RECV] MCF sent")
    
    # Wait for DCN or hangup
    print("[RECV] Waiting for DCN...")
    drain()
    os.write(fd, b"AT+FRH=3\r")
    dcn_result = wait_for("OK", 10)
    print(f"[RECV] Session ended: {dcn_result[:50]}")
    
    os.close(fd)
    print("[RECV] Done!")

if __name__ == "__main__":
    main()