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"""PySide6 Charts example: Simple memory usage viewer"""

import os
import sys
from PySide6.QtCore import QProcess
from PySide6.QtWidgets import QApplication, QMainWindow
from PySide6.QtCharts import QChart, QChartView, QPieSeries


def run_process(command, arguments):
    process = QProcess()
    process.start(command, arguments)
    process.waitForFinished()
    std_output = process.readAllStandardOutput().data().decode('utf-8')
    return std_output.split('\n')

def get_memory_usage():
    result = []
    if sys.platform == 'win32':
        # Windows: Obtain memory usage in KB from 'tasklist'
        for line in run_process('tasklist', [])[3:]:
            if len(line) >= 74:
                command = line[0:23].strip()
                if command.endswith('.exe'):
                    command = command[0:len(command) - 4]
                memory_usage = float(line[64:74].strip().replace(',', '').replace('.', ''))
                legend = ''
                if memory_usage > 10240:
                    mb = memory_usage / 1024
                    legend = f'{command} {mb}M'
                else:
                    legend = f'{command} {memory_usage}K'
                result.append([legend, memory_usage])
    else:
        # Unix: Obtain memory usage percentage from 'ps'
        ps_options = ['-e', 'v']
        memory_column = 8
        command_column = 9
        if sys.platform == 'darwin':
            ps_options = ['-e', '-v']
            memory_column = 11
            command_column = 12
        for line in run_process('ps', ps_options):
            tokens = line.split(None)
            if len(tokens) > command_column and "PID" not in tokens: # Percentage and command
                command = tokens[command_column]
                if not command.startswith('['):
                    command = os.path.basename(command)
                    memory_usage = round(float(tokens[memory_column].replace(',', '.')))
                    legend = f'{command} {memory_usage}%'
                    result.append([legend, memory_usage])

    result.sort(key = lambda x: x[1], reverse=True)
    return result

class MainWindow(QMainWindow):

    def __init__(self):
        super().__init__()

        self.setWindowTitle('Memory Usage')

        memory_usage = get_memory_usage()
        if len(memory_usage) > 5:
            memory_usage = memory_usage[0:4]

        self.series = QPieSeries()
        for item in memory_usage:
            self.series.append(item[0], item[1])

        slice = self.series.slices()[0]
        slice.setExploded()
        slice.setLabelVisible()
        self.chart = QChart()
        self.chart.addSeries(self.series)
        self._chart_view = QChartView(self.chart)
        self.setCentralWidget(self._chart_view)

if __name__ == '__main__':
    app = QApplication(sys.argv)
    main_win = MainWindow()
    available_geometry = main_win.screen().availableGeometry()
    size = available_geometry.height() * 3 / 4
    main_win.resize(size, size)
    main_win.show()
    sys.exit(app.exec_())