// Standalone tests for reasampler::vst::param_slider — no VST3, no REAPER, no framework.
// Same fast assert loop as the sibling pure editor tests (capture_browser / keyboard_strip):
// assert the S12/S15/S16 control-surface layout, toggle-segment split + hit-test, slider
// value<->pixel mapping (round-trip + clamping + endpoints), and point->control routing.
//
// Covers: layoutControls stacking rows top-down with the label column + control column and the
// inter-row gap; an empty list / degenerate panel yielding nothing; toggleSegmentRect splitting
// a toggle into two tiling segments (last absorbs the remainder) + toggleSegmentHitTest;
// sliderTrackRect insetting a half-handle at each end; sliderHandleRect at value 0/0.5/1 and
// out-of-range clamping; valueAtPoint mapping x back to 0..1 (endpoints saturate) as the inverse
// of the handle position; controlAtPoint routing a point to the right control id (toggle whole
// area vs slider track vs knob circle) and MISSING in the label column, a row gap, and
// off-panel. FA4 adds the radial KNOB: computeKnob inscribing the circle in its cell, the
// circular hit-test, the arc angle<->value mapping (min at startDeg, max at endDeg, linear
// midpoint; default = the 6->4 o'clock 300-degree sweep), the needle endpoint on the circle,
// and the vertical-drag delta->value map (up = increase) with clamping at 0/1.

#include "../src/vst/param_slider.h"

#include <cstdio>
#include <vector>

using namespace reasampler::vst;

static int g_fail = 0;
#define CHECK(cond) do { if(!(cond)) { \
    std::printf("FAIL line %d: %s\n", __LINE__, #cond); ++g_fail; } } while(0)

static bool approx(double a, double b) { return (a - b) < 1e-9 && (b - a) < 1e-9; }

// --- layoutControls -----------------------------------------------------------

static void testLayoutStacksRows() {
    const Rect panel{0, 100, 300, 400};
    std::vector<ControlDesc> ctl{
        {1, ControlKind::Toggle},
        {2, ControlKind::Slider},
        {3, ControlKind::Slider},
    };
    const std::vector<ControlRow> rows = layoutControls(panel, ctl);
    CHECK(rows.size() == 3);
    // Row 0 sits at the panel top; each subsequent row is one row-height + gap below.
    CHECK(rows[0].row.top == 100);
    CHECK(rows[0].row.bottom == 100 + kControlRowHeight);
    CHECK(rows[1].row.top == rows[0].row.bottom + kControlRowGap);
    CHECK(rows[2].row.top == rows[1].row.bottom + kControlRowGap);
    // Ids + kinds carried through in order.
    CHECK(rows[0].id == 1 && rows[0].kind == ControlKind::Toggle);
    CHECK(rows[1].id == 2 && rows[1].kind == ControlKind::Slider);
    // Label column then control column, contiguous, spanning the panel width.
    CHECK(rows[0].label.left == panel.left);
    CHECK(rows[0].control.left == rows[0].label.right);
    CHECK(rows[0].control.right == panel.right);
    CHECK(rows[0].label.width() == kControlLabelWidth);
}

static void testLayoutEmptyAndDegenerate() {
    CHECK(layoutControls(Rect{0, 0, 300, 300}, {}).empty());
    std::vector<ControlDesc> ctl{{1, ControlKind::Slider}};
    CHECK(layoutControls(Rect{0, 0, 0, 0}, ctl).empty());
    CHECK(layoutControls(Rect{0, 0, 300, 0}, ctl).empty());
}

static void testLayoutNarrowPanelClampsLabel() {
    // A panel narrower than 2*labelWidth clamps the label column to half so a control column
    // survives.
    const Rect panel{0, 0, 100, 200};
    const std::vector<ControlRow> rows = layoutControls(panel, {{1, ControlKind::Slider}});
    CHECK(rows.size() == 1);
    CHECK(rows[0].label.width() <= panel.width() / 2 + 1);
    CHECK(rows[0].control.width() > 0);
}

// --- toggle -------------------------------------------------------------------

static void testToggleSegmentsTile() {
    const Rect control{100, 0, 300, 22};  // width 200
    const Rect s0 = toggleSegmentRect(control, 0);
    const Rect s1 = toggleSegmentRect(control, 1);
    CHECK(s0.left == 100 && s0.right == 200);
    CHECK(s1.left == 200 && s1.right == 300);  // last absorbs remainder -> reaches control.right
    // Out of range.
    CHECK(toggleSegmentRect(control, 2).width() == 0);
    CHECK(toggleSegmentRect(control, -1).width() == 0);
}

static void testToggleSegmentRemainderInLast() {
    const Rect control{0, 0, 201, 22};  // odd width -> seg0 = 100, seg1 = 101 (absorbs remainder)
    CHECK(toggleSegmentRect(control, 0).width() == 100);
    CHECK(toggleSegmentRect(control, 1).right == 201);
}

static void testToggleHitTest() {
    const Rect control{100, 0, 300, 22};
    CHECK(toggleSegmentHitTest(control, 150, 10) == 0);
    CHECK(toggleSegmentHitTest(control, 250, 10) == 1);
    CHECK(toggleSegmentHitTest(control, 50, 10) == -1);   // left of control
    CHECK(toggleSegmentHitTest(control, 150, 40) == -1);  // below control
}

// --- slider -------------------------------------------------------------------

static void testSliderTrackInsetsHalfHandle() {
    const Rect control{100, 0, 300, 22};
    const Rect track = sliderTrackRect(control);
    CHECK(track.left == control.left + kSliderHandleWidth / 2);
    CHECK(track.right == control.right - kSliderHandleWidth / 2);
    // A control too narrow for a handle yields an empty track.
    CHECK(sliderTrackRect(Rect{0, 0, kSliderHandleWidth - 1, 22}).width() == 0);
}

static void testSliderHandleAtEndpointsAndMid() {
    const Rect control{100, 0, 300, 22};
    const Rect track = sliderTrackRect(control);
    const int half = kSliderHandleWidth / 2;
    // Value 0 -> handle centered at track.left.
    const Rect h0 = sliderHandleRect(control, 0.0);
    CHECK(h0.left + half == track.left);
    // Value 1 -> handle centered at track.right.
    const Rect h1 = sliderHandleRect(control, 1.0);
    CHECK(h1.left + half == track.right);
    // Value 0.5 -> centered at the track middle.
    const Rect hm = sliderHandleRect(control, 0.5);
    CHECK(hm.left + half == track.left + track.width() / 2);
}

static void testSliderHandleClampsOutOfRange() {
    const Rect control{0, 0, 200, 22};
    CHECK(sliderHandleRect(control, -0.5).left == sliderHandleRect(control, 0.0).left);
    CHECK(sliderHandleRect(control, 5.0).left == sliderHandleRect(control, 1.0).left);
}

static void testValueAtPointEndpointsSaturate() {
    const Rect control{100, 0, 300, 22};
    const Rect track = sliderTrackRect(control);
    CHECK(approx(valueAtPoint(control, track.left - 20), 0.0));
    CHECK(approx(valueAtPoint(control, track.left), 0.0));
    CHECK(approx(valueAtPoint(control, track.right + 20), 1.0));
    CHECK(approx(valueAtPoint(control, track.right), 1.0));
}

static void testValueAtPointIsHandleInverse() {
    // Round-trip: a value -> handle center -> valueAtPoint recovers (within one pixel quantum).
    const Rect control{50, 0, 450, 22};  // wide track for pixel resolution
    const Rect track = sliderTrackRect(control);
    for (double v : {0.1, 0.25, 0.5, 0.75, 0.9}) {
        const Rect h = sliderHandleRect(control, v);
        const int centerX = h.left + kSliderHandleWidth / 2;
        const double back = valueAtPoint(control, centerX);
        CHECK(back >= v - 0.01 && back <= v + 0.01);
        CHECK(centerX >= track.left && centerX <= track.right);
    }
}

static void testValueAtPointDegenerateTrack() {
    CHECK(approx(valueAtPoint(Rect{0, 0, kSliderHandleWidth - 1, 22}, 5), 0.0));
}

// --- knob (FA4) -----------------------------------------------------------------

static bool near(double a, double b, double tol) { return (a - b) < tol && (b - a) < tol; }

static void testKnobGeometryInscribesCell() {
    // A 44x44 cell at (100,0): center (122,22), radius 22.
    const KnobGeometry g = computeKnob(Rect{100, 0, 144, 44});
    CHECK(approx(g.centerX, 122.0));
    CHECK(approx(g.centerY, 22.0));
    CHECK(approx(g.radius, 22.0));
    // A wide cell inscribes on the smaller (vertical) dimension.
    const KnobGeometry w = computeKnob(Rect{0, 0, 200, 22});
    CHECK(approx(w.radius, 11.0));
    CHECK(approx(w.centerX, 100.0));
    // Degenerate cells yield radius 0.
    CHECK(computeKnob(Rect{0, 0, 0, 22}).radius == 0.0);
    CHECK(computeKnob(Rect{0, 0, 22, 0}).radius == 0.0);
}

static void testKnobHitTestCircle() {
    const KnobGeometry g = computeKnob(Rect{100, 0, 144, 44});  // center (122,22), r 22
    CHECK(knobHitTest(g, 122, 22));       // center
    CHECK(knobHitTest(g, 122 + 22, 22));  // on the circle boundary (inclusive)
    CHECK(!knobHitTest(g, 122 + 22, 44)); // cell corner: inside the rect, outside the circle
    CHECK(!knobHitTest(g, 122, 45));      // just below the circle
    CHECK(!knobHitTest(KnobGeometry{}, 0, 0));  // degenerate knob hits nothing
}

static void testKnobDefaultArcIsSixToFourOClock() {
    const KnobArc arc;  // default: 180 (6 o'clock) clockwise to 120 (4 o'clock)
    CHECK(approx(knobSweepDeg(arc), 300.0));
    CHECK(approx(knobValueAngleDeg(arc, 0.0), kKnobArcStartDeg));  // min at 6 o'clock
    CHECK(approx(knobValueAngleDeg(arc, 1.0), kKnobArcEndDeg));    // max at 4 o'clock
    // Midpoint: halfway around the clockwise sweep -> 180 + 150 = 330.
    CHECK(approx(knobValueAngleDeg(arc, 0.5), 330.0));
    // Out-of-range values clamp to the arc ends.
    CHECK(approx(knobValueAngleDeg(arc, -0.5), kKnobArcStartDeg));
    CHECK(approx(knobValueAngleDeg(arc, 1.5), kKnobArcEndDeg));
}

static void testKnobArcIsParameterized() {
    // A custom non-wrapping arc: 3 o'clock down to 9 o'clock through 6.
    const KnobArc arc{90.0, 270.0};
    CHECK(approx(knobSweepDeg(arc), 180.0));
    CHECK(approx(knobValueAngleDeg(arc, 0.0), 90.0));
    CHECK(approx(knobValueAngleDeg(arc, 0.5), 180.0));
    CHECK(approx(knobValueAngleDeg(arc, 1.0), 270.0));
    // Equal start/end means a full-circle sweep (end at-or-behind start wraps +360).
    CHECK(approx(knobSweepDeg(KnobArc{0.0, 0.0}), 360.0));
}

static void testKnobNeedlePointOnCircle() {
    const KnobGeometry g = computeKnob(Rect{100, 0, 144, 44});  // center (122,22), r 22
    // Default arc, value 0 -> 6 o'clock -> straight DOWN from the center (screen +y).
    const KnobPoint p6 = knobNeedlePoint(g, KnobArc{}, 0.0);
    CHECK(near(p6.x, 122.0, 1e-6) && near(p6.y, 44.0, 1e-6));
    // A 12 o'clock needle points straight UP; 3 o'clock points RIGHT.
    const KnobPoint p12 = knobNeedlePoint(g, KnobArc{0.0, 180.0}, 0.0);
    CHECK(near(p12.x, 122.0, 1e-6) && near(p12.y, 0.0, 1e-6));
    const KnobPoint p3 = knobNeedlePoint(g, KnobArc{0.0, 180.0}, 0.5);
    CHECK(near(p3.x, 144.0, 1e-6) && near(p3.y, 22.0, 1e-6));
    // Every needle endpoint sits ON the circle.
    for (double v : {0.0, 0.25, 0.5, 0.75, 1.0}) {
        const KnobPoint p = knobNeedlePoint(g, KnobArc{}, v);
        const double dx = p.x - g.centerX, dy = p.y - g.centerY;
        CHECK(near(dx * dx + dy * dy, g.radius * g.radius, 1e-6));
    }
}

static void testKnobDragUpIncreases() {
    // Up (negative dy) increases, down decreases, scaled by the drag range.
    CHECK(approx(knobDragValue(0.5, -32, 128), 0.75));
    CHECK(approx(knobDragValue(0.5, +32, 128), 0.25));
    // A full-range upward drag from 0 lands exactly at 1.
    CHECK(approx(knobDragValue(0.0, -128, 128), 1.0));
    // Default sensitivity applies when the range is omitted.
    CHECK(approx(knobDragValue(0.0, -kKnobDragRangePixels), 1.0));
}

static void testKnobDragClamps() {
    CHECK(approx(knobDragValue(0.9, -64, 128), 1.0));  // over-drag up clamps at 1
    CHECK(approx(knobDragValue(0.1, +64, 128), 0.0));  // over-drag down clamps at 0
    // The start value itself is clamped before the delta applies.
    CHECK(approx(knobDragValue(1.5, 0, 128), 1.0));
    CHECK(approx(knobDragValue(-0.5, 0, 128), 0.0));
    // A degenerate drag range yields the clamped start value.
    CHECK(approx(knobDragValue(0.7, -50, 0), 0.7));
}

// --- controlAtPoint routing ---------------------------------------------------

static void testControlAtPointRoutes() {
    const Rect panel{0, 0, 300, 400};
    std::vector<ControlDesc> ctl{
        {10, ControlKind::Toggle},
        {20, ControlKind::Slider},
    };
    ctl.push_back({30, ControlKind::Knob});
    const std::vector<ControlRow> rows = layoutControls(panel, ctl);
    // A point in the toggle's control area routes to the toggle id.
    const Rect tctl = rows[0].control;
    CHECK(controlAtPoint(rows, (tctl.left + tctl.right) / 2, (tctl.top + tctl.bottom) / 2) == 10);
    // A point on the slider's track routes to the slider id.
    const Rect strack = sliderTrackRect(rows[1].control);
    CHECK(controlAtPoint(rows, (strack.left + strack.right) / 2,
                         (strack.top + strack.bottom) / 2) == 20);
    // A point at the knob's center routes to the knob id; the control-rect corner (outside
    // the circle) is a miss.
    const KnobGeometry kg = computeKnob(rows[2].control);
    CHECK(controlAtPoint(rows, static_cast<int>(kg.centerX), static_cast<int>(kg.centerY)) == 30);
    CHECK(controlAtPoint(rows, rows[2].control.left + 1, rows[2].control.top + 1) == -1);
}

static void testControlAtPointMisses() {
    const Rect panel{0, 0, 300, 400};
    const std::vector<ControlRow> rows =
        layoutControls(panel, {{10, ControlKind::Toggle}, {20, ControlKind::Slider}});
    // The label column is not interactive.
    CHECK(controlAtPoint(rows, rows[0].label.left + 2, rows[0].label.top + 4) == -1);
    // The gap between rows is a miss.
    const int gapY = rows[0].row.bottom + kControlRowGap / 2;
    CHECK(controlAtPoint(rows, 200, gapY) == -1);
    // Off-panel below.
    CHECK(controlAtPoint(rows, 200, 5000) == -1);
}

int main() {
    testLayoutStacksRows();
    testLayoutEmptyAndDegenerate();
    testLayoutNarrowPanelClampsLabel();
    testToggleSegmentsTile();
    testToggleSegmentRemainderInLast();
    testToggleHitTest();
    testSliderTrackInsetsHalfHandle();
    testSliderHandleAtEndpointsAndMid();
    testSliderHandleClampsOutOfRange();
    testValueAtPointEndpointsSaturate();
    testValueAtPointIsHandleInverse();
    testValueAtPointDegenerateTrack();
    testKnobGeometryInscribesCell();
    testKnobHitTestCircle();
    testKnobDefaultArcIsSixToFourOClock();
    testKnobArcIsParameterized();
    testKnobNeedlePointOnCircle();
    testKnobDragUpIncreases();
    testKnobDragClamps();
    testControlAtPointRoutes();
    testControlAtPointMisses();

    if (g_fail == 0) std::printf("param_slider: all tests passed\n");
    return g_fail != 0;
}