import psutil
from datetime import datetime
import pandas as pd
import time
import os


sort_by = "memory_usage"
columns = [
    "name",
    "cpu_usage",
    "memory_usage",
    "read_bytes",
    "write_bytes",
    "status",
    "create_time",
    "nice",
    "n_threads",
    "cores",
    "username",
]
name_filter = ["pwrplay.exe", "httpd.exe", "impadmin.exe", "trnsfrmr.exe"]


def get_size(bytes):
    """Returns size of bytes in a nice format"""
    for unit in ["", "K", "M", "G", "T", "P"]:
        if bytes < 1024:
            return f"{bytes:.2f}{unit}B"
        bytes /= 1024


def get_processes_info(name_filter):
    processes = []
    for process in psutil.process_iter():
        with process.oneshot():
            pid = process.pid
            if pid == 0:
                continue
            name = process.name().lower()
            if name not in name_filter:
                continue
            try:
                create_time = datetime.fromtimestamp(process.create_time())
            except OSError:
                create_time = datetime.fromtimestamp(psutil.boot_time())
            try:
                cores = len(process.cpu_affinity())
            except psutil.AccessDenied:
                cores = 0
            cpu_usage = process.cpu_percent()
            status = process.status()
            try:
                nice = int(process.nice())
            except psutil.AccessDenied:
                nice = 0
            try:
                memory_usage = process.memory_full_info().uss
            except psutil.AccessDenied:
                memory_usage = 0
            io_counters = process.io_counters()
            read_bytes = io_counters.read_bytes
            write_bytes = io_counters.write_bytes
            n_threads = process.num_threads()
            try:
                username = process.username()
            except psutil.AccessDenied:
                username = "N/A"

        processes.append(
            {
                "pid": pid,
                "name": name,
                "create_time": create_time,
                "cores": cores,
                "cpu_usage": cpu_usage,
                "status": status,
                "nice": nice,
                "memory_usage": memory_usage,
                "read_bytes": read_bytes,
                "write_bytes": write_bytes,
                "n_threads": n_threads,
                "username": username,
            }
        )

    return processes


def construct_dataframe(processes):
    df = pd.DataFrame(processes)
    df.set_index("pid", inplace=True)
    df.sort_values(sort_by, inplace=True)
    # pretty printing bytes
    df["memory_usage"] = df["memory_usage"].apply(get_size)
    df["write_bytes"] = df["write_bytes"].apply(get_size)
    df["read_bytes"] = df["read_bytes"].apply(get_size)
    # convert to proper date format
    df["create_time"] = df["create_time"].apply(datetime.strftime, args=("%Y-%m-%d %H:%M:%S",))
    # reorder and define used columns
    df = df[columns]
    return df


def main():
    while True:
        processes = get_processes_info(name_filter)
        if len(processes) > 0:
            df = construct_dataframe(processes)
            os.system("cls") if "nt" in os.name else os.system("clear")
            print(df.to_string())
        else:
            print("No active processes.")
        time.sleep(10)


if __name__ == "__main__":
    main()