import sys
from PySide6.QtWidgets import (
    QApplication, QMainWindow, QWidget,
    QPushButton, QGridLayout, QStackedWidget
)
from PySide6.QtCore import Qt


class HomeScreen(QWidget):
    def __init__(self, stack):
        super().__init__()
        layout = QGridLayout()

        btn_media = QPushButton("MEDIA")
        btn_radio = QPushButton("RADIO")
        btn_bt = QPushButton("BLUETOOTH")
        btn_settings = QPushButton("SETTINGS")

        for btn in (btn_media, btn_radio, btn_bt, btn_settings):
            btn.setMinimumSize(300, 180)

        btn_media.clicked.connect(lambda: stack.setCurrentIndex(1))
        btn_radio.clicked.connect(lambda: stack.setCurrentIndex(2))
        btn_settings.clicked.connect(lambda: stack.setCurrentIndex(3))

        layout.addWidget(btn_media, 0, 0)
        layout.addWidget(btn_radio, 0, 1)
        layout.addWidget(btn_bt, 1, 0)
        layout.addWidget(btn_settings, 1, 1)

        self.setLayout(layout)


class StubScreen(QWidget):
    def __init__(self, name, stack):
        super().__init__()
        layout = QGridLayout()
        btn_back = QPushButton("← BACK")
        btn_back.setMinimumSize(200, 100)
        btn_back.clicked.connect(lambda: stack.setCurrentIndex(0))
        layout.addWidget(btn_back, 0, 0, alignment=Qt.AlignLeft)
        self.setLayout(layout)


class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()
        self.setWindowTitle("Car UI")
        self.showFullScreen()

        self.stack = QStackedWidget()

        self.stack.addWidget(HomeScreen(self.stack))       # 0
        self.stack.addWidget(StubScreen("Media", self.stack))     # 1
        self.stack.addWidget(StubScreen("Radio", self.stack))     # 2
        self.stack.addWidget(StubScreen("Settings", self.stack))  # 3

        self.setCentralWidget(self.stack)


app = QApplication(sys.argv)
app.setStyleSheet(open("styles/style.qss").read())
window = MainWindow()
window.show()
sys.exit(app.exec())