#!/usr/bin/env python3
"""Simple RTP test sender for validating rtp_receiver_tester."""

import socket
import struct
import sys
import time
import argparse


def create_rtp_packet(sequence: int, timestamp: int, payload_type: int, payload: bytes) -> bytes:
    """Create an RTP packet (RFC3550)."""
    # RTP header format:
    # Byte 0: V(2) P(1) X(1) CC(4)
    # Byte 1: M(1) PT(7)
    # Bytes 2-3: Sequence
    # Bytes 4-7: Timestamp
    # Bytes 8-11: SSRC
    version = 2
    padding = 0
    extension = 0
    csrc_count = 0
    marker = 0
    
    byte0 = (version << 6) | (padding << 5) | (extension << 4) | csrc_count
    byte1 = (marker << 7) | payload_type
    
    ssrc = 0x12345678
    
    header = struct.pack('!BBHII', byte0, byte1, sequence, timestamp, ssrc)
    return header + payload


def send_rtp_packets(target_host: str, target_port: int, payload_type: int, 
                     packet_count: int, interval_ms: float):
    """Send RTP packets to target."""
    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    
    try:
        for i in range(packet_count):
            # Create dummy payload (could be NAL unit for video)
            payload = bytes([0x00, 0x00, 0x00, 0x01, 0x09, 0x10])  # Simple dummy data
            
            packet = create_rtp_packet(
                sequence=i % 65536,
                timestamp=i * 3000,  # 3000 ticks per packet (90kHz / 30fps)
                payload_type=payload_type,
                payload=payload
            )
            
            sock.sendto(packet, (target_host, target_port))
            
            if interval_ms > 0:
                time.sleep(interval_ms / 1000.0)
                
        print(f"Sent {packet_count} RTP packets with PT={payload_type}")
        
    finally:
        sock.close()


def main():
    parser = argparse.ArgumentParser(description='Send test RTP packets')
    parser.add_argument('--host', default='127.0.0.1', help='Target host')
    parser.add_argument('--port', type=int, default=5004, help='Target port')
    parser.add_argument('--pt', type=int, default=96, help='Payload type')
    parser.add_argument('--count', type=int, default=20, help='Number of packets')
    parser.add_argument('--interval-ms', type=float, default=50, help='Interval between packets')
    
    args = parser.parse_args()
    
    send_rtp_packets(
        args.host, 
        args.port, 
        args.pt, 
        args.count, 
        args.interval_ms
    )


if __name__ == '__main__':
    main()