import math

from PyQt6.QtWidgets import QScrollBar
from PyQt6.QtCore import pyqtSignal
import logging

log = logging.getLogger("scaledScrollBar")


class ScaledScrollBar(QScrollBar):
    is_huge = False

    valueChanged = pyqtSignal(str)
    """Signal emitted when the scroll bar value changes. 
        **Note**: The value is a string and must be parsed into an int. 
        QT's signal api only supports 32bit integers. Ints larger 
        than 2**32-1 will overflow. Probably because there is some C/C++
        code involved. We work around this by converting the python int 
        into a string."""

    def __init__(self):
        super(ScaledScrollBar, self).__init__()
        self.real_maximum = self.maximum()
        super().valueChanged.connect(self._valueChanged)

    def setValue(self, value: int) -> None:
        if self.is_huge:
            real_position = value / self.real_maximum
            super().setValue(self.maximum() * real_position)
        else:
            super().setValue(value)

    def setMaximum(self, maximum: int) -> None:
        if maximum > 2 ** 31:
            new_maximum = 1000 * math.log2(maximum)
            super().setMaximum(new_maximum)
            self.real_maximum = maximum

            if not self.is_huge:
                old_position = self.value() / self.maximum()
                self.setValue(new_maximum * old_position)

            self.is_huge = True
        else:
            self.is_huge = False
            super().setMaximum(maximum)

    def _valueChanged(self, value: int):
        if self.is_huge:
            real_value = (value / self.maximum()) * self.real_maximum
            # print("scaled value changed: %d -> %d (%f)" % (value, real_value, value / self.maximum()))
            self.valueChanged.emit(str(int(real_value)))
        else:
            self.valueChanged.emit(str(int(value)))