import socket
import sys
import os
import time

def start_client(ip, port, path):
    if not os.path.exists(path): return
    
    client_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    addr = (ip, port)
    (filename, filesize) = os.path.basename(path), os.path.getsize(path)

    try:
        print(f"\033[46m[客户端]\033[0m {ip}:{port}，建立连接")
        while True:
            try:
                client_socket.sendto(b"SYN", addr)
                if client_socket.recv(1024) == b"SYN-ACK": break
            except socket.timeout: continue

        print(f"\033[46m[客户端]\033[0m 发送元数据：{filename}（{filesize} 字节）")
        while True:
            try:
                client_socket.sendto(f"META|{filename}|{filesize}".encode(), addr)
                if client_socket.recv(1024) == b"META-ACK": break
            except socket.timeout: continue

        print("\033[46m[客户端]\033[0m 传输数据……")
        with open(path, 'rb') as f:
            while True:
                chunk = f.read(1400)
                if not chunk: break
                client_socket.sendto(chunk, addr)
                time.sleep(0.001) # 简单的流控制

        print("\033[46m[客户端]\033[0m 释放连接")
        for _ in range(3):
            try:
                client_socket.sendto(b"FIN", addr)
                if client_socket.recv(1024) == b"FIN-ACK": break
            except socket.timeout: continue
        print("\033[46m[客户端]\033[0m 连接关闭")

    except KeyboardInterrupt: pass
    finally: client_socket.close()

if __name__ == "__main__":
    if len(sys.argv) < 3:
        print("【用法】python3 file_sender.py <IP>:<端口> <文件路径>")
        sys.exit(1)

    try:
        (ip, port) = sys.argv[1].split(':')
        start_client(ip, int(port), sys.argv[2])
    except ValueError:
        print("【错误】地址格式应为 IP:端口")