"""Round 80: scrollbars lose their arrow buttons, and the thumb is a button.

- No arrows: the trough runs the bar's full length and the arrow rects are
  empty, so nothing paints or hit-tests there.
- The thumb gets the buttons' corner radius and emboss, with rims as tall in
  pixels as a button's, however long the thumb.
- The bar's thickness comes from the UI scale through the style, not QSS
  (any QSS rule on a scrollbar part makes Qt draw the arrows itself).
"""
from PyQt6.QtCore import Qt
from PyQt6.QtGui import QColor
from PyQt6.QtWidgets import QPushButton, QScrollBar, QStyle, QStyleOptionSlider

from lintunes import theme
from lintunes.gui.track_table import ClickToJumpScrollStyle

SC = QStyle.SubControl


def _option(bar):
    opt = QStyleOptionSlider()
    bar.initStyleOption(opt)
    return opt


def _bar(qapp, orientation=Qt.Orientation.Vertical):
    bar = QScrollBar(orientation)
    bar.setStyle(ClickToJumpScrollStyle())
    bar.setRange(0, 900)
    bar.setPageStep(100)
    bar.resize(14, 400) if orientation == Qt.Orientation.Vertical \
        else bar.resize(400, 14)
    return bar


def test_no_arrow_buttons(qapp):
    bar = _bar(qapp)
    style, opt = bar.style(), _option(bar)
    cc = QStyle.ComplexControl.CC_ScrollBar
    assert style.subControlRect(cc, opt, SC.SC_ScrollBarAddLine, bar).isEmpty()
    assert style.subControlRect(cc, opt, SC.SC_ScrollBarSubLine, bar).isEmpty()
    assert style.subControlRect(cc, opt, SC.SC_ScrollBarGroove, bar) == opt.rect


def test_thumb_spans_the_full_trough(qapp):
    for orientation in (Qt.Orientation.Vertical, Qt.Orientation.Horizontal):
        bar = _bar(qapp, orientation)
        style, cc = bar.style(), QStyle.ComplexControl.CC_ScrollBar
        bar.setValue(0)
        top = style.subControlRect(cc, _option(bar), SC.SC_ScrollBarSlider, bar)
        bar.setValue(900)
        end = style.subControlRect(cc, _option(bar), SC.SC_ScrollBarSlider, bar)
        if orientation == Qt.Orientation.Vertical:
            assert top.top() == 0 and end.bottom() == 399
            assert top.height() == 40           # 100 / (900 + 100) of 400
        else:
            assert top.left() == 0 and end.right() == 399


def test_tiny_page_keeps_a_grabbable_thumb(qapp):
    bar = _bar(qapp)
    bar.setRange(0, 100000)
    rect = bar.style().subControlRect(QStyle.ComplexControl.CC_ScrollBar,
                                      _option(bar), SC.SC_ScrollBarSlider, bar)
    assert rect.height() == ClickToJumpScrollStyle.extent * 2


def test_thickness_follows_ui_scale(qapp):
    class Prefs(dict):
        def get(self, key, default=None):
            return "large" if key == "ui_scale" else default
    before = ClickToJumpScrollStyle.extent
    try:
        theme.apply_theme(qapp, Prefs())
        assert ClickToJumpScrollStyle.extent == theme.UI_SCALES["large"]["scrollbar"]
        assert "QScrollBar" not in qapp.styleSheet()
    finally:
        ClickToJumpScrollStyle.extent = before


def test_thumb_rims_match_a_real_button(qapp):
    qapp.setStyleSheet(theme.button_emboss_qss(QColor("#d0d0d0")))
    try:
        button = QPushButton("OK")
        height = button.sizeHint().height()
        assert abs(theme.button_rim_px(button.fontMetrics())
                   - theme.EMBOSS_RIM_WIDTH * height) < 1
    finally:
        qapp.setStyleSheet("")


def test_thumb_paints(qapp):
    bar = _bar(qapp)
    bar.setValue(450)
    image = bar.grab().toImage()
    thumb = bar.style().subControlRect(QStyle.ComplexControl.CC_ScrollBar,
                                       _option(bar), SC.SC_ScrollBarSlider, bar)
    trough = image.pixelColor(7, 5)
    middle = image.pixelColor(7, thumb.center().y())
    assert middle != trough