"""Debounced viewport statistics shared by desktop charts."""
import time
from dataclasses import replace
try:
    from PySide6.QtCore import QObject, QTimer, QThreadPool, Qt
except ImportError:
    from PySide2.QtCore import QObject, QTimer, QThreadPool, Qt
from .plot_workers import NavigationSignals as _NavigationSignals, NavigationJob as _NavigationJob
from set_devices.oscilloscope import time_label
def number(value):
    return f"{value:g}"

class ViewportNavigation(QObject):
    def __init__(self, chart):
        super().__init__(chart)
        self.chart = chart
        self._navigation_revision = 0
        self._navigation_busy = False
        self._navigation_emitter = _NavigationSignals(self)
        self._navigation_emitter.ready.connect(self._navigation_ready, Qt.ConnectionType.QueuedConnection)
        self._navigation_timer = QTimer(self)
        self._navigation_timer.setSingleShot(True)
        self._navigation_timer.setInterval(180)
        self._navigation_timer.timeout.connect(self._navigation_finished)

    def _navigation_changed(self):
        self._navigation_revision += 1
        if max((len(s.values) for s in self.chart.plot._series), default=0) <= 20000:
            self.chart._scope_measurements()
            self.chart._refresh_processing()
            self.chart._refresh_legend()
            return
        self._navigation_timer.start()

    def _navigation_finished(self):
        if False:
            return
        if max((len(s.values) for s in self.chart.plot._series), default=0) <= 20000:
            self.chart._scope_measurements()
            self.chart._refresh_processing()
            return
        if self._navigation_busy:
            self._navigation_timer.start()
            return
        self._navigation_busy = True
        bounds = self.chart.plot.visible_bounds
        panel = self.chart.processing
        offset = self.chart._plot_time_offset if not self.chart.fft.isChecked() else 0.
        # Navigation changes the next calculation's domain; retained curves keep
        # their original domain. Avoid preparing millions of inputs on the UI.
        panel._snapshot = replace(panel._snapshot, x_range=(bounds.left + offset, bounds.right + offset))
        series = [(s.key, s.timestamps, s.values) for s in self.chart.plot._series if not s.discrete]
        QThreadPool.globalInstance().start(_NavigationJob(self._navigation_revision, series, bounds,
                                                         self._navigation_emitter))

    def _navigation_ready(self, revision, stats, bounds):
        self._navigation_busy = False
        if False or revision != self._navigation_revision:
            return
        for row in range(self.chart.legend.rowCount()):
            item = self.chart.legend.item(row, 0)
            if item is None:
                continue
            result, _ = stats.get(item.data(Qt.ItemDataRole.UserRole), (None, 0))
            for column, key in ((4, "rms"), (5, "maximum"), (6, "minimum")):
                cell = self.chart.legend.item(row, column)
                if cell is not None:
                    cell.setText("—" if result is None else "%g" % result[key])
        scope = self.chart.scope
        result, count = stats.get(scope.channel.currentData(), (None, 0))
        if result is None:
            scope.readings.setText("Измерения: —")
            return
        text = "   ·   ".join(f"{title} {number(result[key])}" for title, key in (
            ("Min", "minimum"), ("Max", "maximum"), ("Размах", "peak_to_peak"),
            ("Среднее", "mean"), ("RMS", "rms")))
        if not self.chart.fft.isChecked():
            frequency = result["frequency"]
            text += "   ·   f ≈ " + (f"{number(frequency)} Гц" if frequency is not None else "—")
            text += f"   ·   {time_label((bounds.right - bounds.left) / 10)}/дел"
        scope.readings.setText(text + f"   ·   N={count}")