import socket
import time
import random
from datetime import datetime
import threading

HOST = "127.0.0.1"
PORT = 12345

VT = b'\x0b'
FS_CR = b'\x1c\x0d'

def generate_hl7_message(patient_id, device_id):
    hr = random.randint(70, 95)
    spo2 = random.randint(96, 99)
    sys = random.randint(115, 125)
    dia = random.randint(75, 83)
    map_bp = int(dia + (sys - dia) / 3)
    resp = random.randint(14, 18)
    temp = round(random.uniform(36.5, 37.1), 1)

    now_str = datetime.now().strftime("%Y%m%d%H%M%S")

    msh = f"MSH|^~\\&|{device_id}|MOCK_FACILITY|RECEIVING_APP|RECEIVING_FACILITY|{now_str}||ORU^R01|MSG{now_str}|P|2.3.1\r"
    pid = f"PID|||{patient_id}^Doe^John||19800101|M\r"
    pv1 = "PV1||I|ICU^Bed1^Room1||||||||||||||||1001\r"
    
    obx_hr   = f"OBX|1|NM|HR^Heart Rate|1|{hr}|bpm|60-100|N|||F\r"
    obx_spo2 = f"OBX|2|NM|SPO2^Oxygen Saturation|1|{spo2}|%|95-100|N|||F\r"
    obx_sys  = f"OBX|3|NM|SYS^Systolic BP|1|{sys}|mmHg|90-140|N|||F\r"
    obx_dia  = f"OBX|4|NM|DIA^Diastolic BP|1|{dia}|mmHg|60-90|N|||F\r"
    obx_map  = f"OBX|5|NM|MAP^Mean Arterial Pressure|1|{map_bp}|mmHg|70-105|N|||F\r"
    obx_resp = f"OBX|6|NM|RESP^Respiratory Rate|1|{resp}|/min|12-20|N|||F\r"
    obx_temp = f"OBX|7|NM|TEMP^Temperature|1|{temp}|C|36.1-37.2|N|||F"

    hl7_msg = msh + pid + pv1 + obx_hr + obx_spo2 + obx_sys + obx_dia + obx_map + obx_resp + obx_temp
    return hl7_msg

def run_monitor(patient_id, device_id, interval):
    print(f"Starting simulated {device_id}...")
    while True:
        try:
            s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
            s.connect((HOST, PORT))
            print(f"[{device_id}] Connected to server")
            while True:
                hl7_msg = generate_hl7_message(patient_id, device_id)
                framed_msg = VT + hl7_msg.encode('utf-8') + FS_CR
                s.sendall(framed_msg)
                try:
                    s.settimeout(1.0)
                    response = s.recv(4096)
                except socket.timeout:
                    pass
                time.sleep(interval)
        except Exception as e:
            print(f"[{device_id}] Error: {e}. Reconnecting in 3 seconds...")
            time.sleep(3)

def main():
    t1 = threading.Thread(target=run_monitor, args=("PAT-1001", "CMS7000PLUS_127.0.0.1", 3), daemon=True)
    t2 = threading.Thread(target=run_monitor, args=("PAT-8500", "CMS8500_127.0.0.1", 4), daemon=True)
    t1.start()
    t2.start()
    
    try:
        while True:
            time.sleep(1)
    except KeyboardInterrupt:
        print("Stopping simulators.")

if __name__ == "__main__":
    main()