"""Small activity spinner: a rotating accent-coloured arc. Runs only while visible."""
from PySide6.QtCore import QEvent, QRectF, QTimer, Qt
from PySide6.QtGui import QColor, QPainter, QPalette, QPen
from PySide6.QtWidgets import QWidget

from . import icons

STEP_MS = 16
STEP_DEG = 9


def paint_arc(p, rect, angle, color=icons.ACCENT):
    """Draw the spinner (faint ring + 100 degree arc) into rect; used by Spinner and the waveform overlay."""
    w = max(1.5, rect.width() / 8)
    r = rect.adjusted(w / 2, w / 2, -w / 2, -w / 2)
    p.save()
    p.setRenderHint(QPainter.RenderHint.Antialiasing)
    ring = QColor(color)
    ring.setAlpha(45)
    p.setPen(QPen(ring, w))
    p.drawEllipse(r)
    pen = QPen(QColor(color), w)
    pen.setCapStyle(Qt.PenCapStyle.RoundCap)
    p.setPen(pen)
    p.drawArc(r, int(-angle * 16), 100 * 16)
    p.restore()


class Spinner(QWidget):
    def __init__(self, size=16, parent=None):
        super().__init__(parent)
        self.setFixedSize(size, size)
        self.angle = 0
        self.timer = QTimer(self)
        self.timer.setInterval(STEP_MS)
        self.timer.timeout.connect(self._step)
        self.hide()

    def _step(self):
        self.angle = (self.angle + STEP_DEG) % 360
        self.update()

    def showEvent(self, e):
        self.timer.start()
        super().showEvent(e)

    def hideEvent(self, e):
        self.timer.stop()
        super().hideEvent(e)

    def paintEvent(self, _):
        p = QPainter(self)
        paint_arc(p, QRectF(self.rect()), self.angle)


class BusyOverlay(QWidget):
    """A list being (re)loaded: a light veil over the widget with the spinner and a message in its centre, the
    same arc as the waveform's loading state. Covers the target and follows its size; blocks clicks while on."""

    def __init__(self, target):
        super().__init__(target)
        self.target = target
        self.message = ""
        self.angle = 0
        self.timer = QTimer(self)
        self.timer.setInterval(STEP_MS)
        self.timer.timeout.connect(self._step)
        target.installEventFilter(self)
        self.hide()

    def start(self, message):
        self.message = message
        self.setGeometry(self.target.rect())
        self.raise_()
        self.show()
        self.timer.start()
        self.update()

    def stop(self):
        self.timer.stop()
        self.hide()

    @property
    def busy(self):
        return not self.isHidden()          # on, whether or not the window is on screen yet

    def _step(self):
        self.angle = (self.angle + STEP_DEG) % 360
        if self.isVisible():
            self.update()

    def eventFilter(self, obj, e):
        if obj is self.target and e.type() == QEvent.Type.Resize:
            self.setGeometry(self.target.rect())
        return False

    def paintEvent(self, _):
        p = QPainter(self)
        p.setRenderHint(QPainter.RenderHint.Antialiasing)
        pal = self.palette()
        veil = QColor(pal.color(QPalette.ColorRole.Base))
        veil.setAlpha(210)
        p.fillRect(self.rect(), veil)
        fm = p.fontMetrics()
        d, gap, pad = 20, 12, 16
        tw = fm.horizontalAdvance(self.message)
        w, h = pad + d + gap + tw + pad, max(d, fm.height()) + 2 * pad - 8
        box = QRectF((self.width() - w) / 2, (self.height() - h) / 2, w, h)
        border = QColor(pal.color(QPalette.ColorRole.Text))
        border.setAlpha(40)
        p.setPen(QPen(border, 1))
        p.setBrush(pal.color(QPalette.ColorRole.Window))
        p.drawRoundedRect(box, 8, 8)
        y = box.center().y()
        paint_arc(p, QRectF(box.left() + pad, y - d / 2, d, d), self.angle)
        p.setPen(pal.color(QPalette.ColorRole.Text))
        p.drawText(QRectF(box.left() + pad + d + gap, y - fm.height() / 2, tw + 2, fm.height()),
                   Qt.AlignmentFlag.AlignVCenter | Qt.AlignmentFlag.AlignLeft, self.message)