// Standalone tests for reasampler::instrument::ui::master_meter — no VST3, no REAPER, no
// framework. Assert:
//
//  * column interior — the 22/4/36 decomposition, the mono bar taking the whole field, the
//    two stereo bars at 17 px and kMeterBarGap apart, all inside the column.
//  * bar count — the SAME LaneSplit waveformSurface folds, over channel mode x source
//    channel count, so it can never become a second rule.
//  * the dB axis — top/floor land on the field's edges, it is monotone, and it clamps.
//  * ballistics — instantaneous rise, 20 dB/s fall, the 1.5 s hold and its release; the
//    audio thread's clip latch surviving a UI frame that never sampled the loud block.
//  * the GR lamp — lit only while the limiter actually reduces, and decaying afterwards.

#include "../src/core/instrument/ui/master_meter.h"
#include "../src/core/instrument/ui/waveform_view.h"

#include <cmath>
#include <cstdio>

using namespace reasampler;
using namespace reasampler::instrument::ui;
using reasampler::instrument::engine::kMeterFallDbPerSecond;
using reasampler::instrument::engine::kMeterFloorDb;
using reasampler::instrument::engine::kMeterPeakHoldSeconds;
using reasampler::instrument::engine::kMeterTopDb;

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

// The shipped column: 62 px wide, 186 tall (knob_deck's spanning geometry).
static const Rect kColumn = Rect::ltrb(1114, 40, 1176, 226);

static void testColumnDividesIntoGutterAndBarField() {
    const MeterRects m = meterRects(kColumn, LaneSplit::Single);
    CHECK(m.labels.x == kColumn.x);
    CHECK(m.labels.width == kMeterLabelW);
    CHECK(m.field.x == m.labels.right() + kMeterLabelGap);
    CHECK(m.field.width == kMeterFieldW);
    // The three parts account for the column exactly — a residue would leave dead pixels the
    // scale's numerals would then be centred against.
    CHECK(kMeterLabelW + kMeterLabelGap + kMeterFieldW == kColumn.width);
    CHECK(m.field.right() == kColumn.right());
    // Full height in both rects: the column spans both row baselines as ONE readout.
    CHECK(m.labels.y == kColumn.y && m.labels.bottom() == kColumn.bottom());
    CHECK(m.field.y == kColumn.y && m.field.bottom() == kColumn.bottom());
}

static void testMonoDrawsOneWideBarAndStereoDrawsTwo() {
    const MeterRects mono = meterRects(kColumn, LaneSplit::Single);
    CHECK(mono.barA == mono.field);  // the one bar IS the field
    CHECK(mono.barB.empty());

    const MeterRects st = meterRects(kColumn, LaneSplit::Stereo);
    CHECK(!st.barB.empty());
    CHECK(st.barA.width == st.barB.width);
    CHECK(st.barA.width == (kMeterFieldW - kMeterBarGap) / 2);
    CHECK(st.barA.width == 17);
    CHECK(st.barB.x - st.barA.right() == kMeterBarGap);
    // Both bars inside the field, and the pair fills it to the pixel.
    CHECK(st.barA.x == st.field.x);
    CHECK(st.barB.right() == st.field.right());
    CHECK(st.barA.y == st.field.y && st.barB.bottom() == st.field.bottom());
}

// The bar count is NOT a second rule: it is whatever waveformSurface resolved for the same
// (mode, source) pair. A mono source under stereo mode is dual-mono — one source, two views.
static void testBarCountFollowsTheWaveformsOwnLaneSplit() {
    const Rect band = Rect::ltrb(8, 100, 1182, 458);
    for (bool stereoMode : {false, true}) {
        for (int sourceChannels : {1, 2}) {
            const WaveformSurface s = waveformSurface(band, stereoMode, sourceChannels);
            const LaneSplit split =
                s.laneCount == 2 ? LaneSplit::Stereo : LaneSplit::Single;
            const MeterRects m = meterRects(kColumn, split);
            const int bars = m.barB.empty() ? 1 : 2;
            CHECK(bars == s.laneCount);
            // Spelled out per combination so a regression names which one broke.
            const bool expectTwo = stereoMode && sourceChannels >= 2;
            CHECK(bars == (expectTwo ? 2 : 1));
        }
    }
}

static void testDbAxisSpansTheFieldAndClamps() {
    const MeterRects m = meterRects(kColumn, LaneSplit::Single);
    CHECK(meterDbToY(m.field, kMeterTopDb) == m.field.y);
    CHECK(meterDbToY(m.field, kMeterFloorDb) == m.field.bottom());
    // Monotone downward as the level falls.
    int prev = m.field.y;
    for (double db = kMeterTopDb; db >= kMeterFloorDb; db -= 6.0) {
        const int y = meterDbToY(m.field, db);
        CHECK(y >= prev);
        prev = y;
    }
    // Clamped outside the scale rather than drawn off the field.
    CHECK(meterDbToY(m.field, kMeterTopDb + 40.0) == m.field.y);
    CHECK(meterDbToY(m.field, kMeterFloorDb - 40.0) == m.field.bottom());
}

static void testPeakRisesAtOnceAndFallsAtTwentyDbPerSecond() {
    MasterMeterUi s;
    // Unity on the left, silence on the right: the two channels are independent.
    s = advanceMasterMeter(s, {1.0, 0.0, 1.0, false}, 0.1);
    CHECK(std::fabs(s.left.levelDb - 0.0) < 1e-9);   // rise is instantaneous, this very frame
    CHECK(s.right.levelDb == kMeterFloorDb);

    // One second of silence: exactly kMeterFallDbPerSecond of fall, not a smoothed decay.
    s = advanceMasterMeter(s, {0.0, 0.0, 1.0, false}, 1.0);
    CHECK(std::fabs(s.left.levelDb - -kMeterFallDbPerSecond) < 1e-9);
}

static void testPeakHoldSitsForItsFullWindowThenReleases() {
    MasterMeterUi s;
    s = advanceMasterMeter(s, {1.0, 1.0, 1.0, false}, 0.1);
    const double held = s.left.holdDb;
    CHECK(std::fabs(held - 0.0) < 1e-9);

    // Just under the hold window: the bar has fallen a long way, the tick has not moved.
    s = advanceMasterMeter(s, {0.0, 0.0, 1.0, false}, kMeterPeakHoldSeconds - 0.01);
    CHECK(s.left.levelDb < held - 20.0);
    CHECK(std::fabs(s.left.holdDb - held) < 1e-9);

    // Past it, the tick releases at the same 20 dB/s the bar uses.
    s = advanceMasterMeter(s, {0.0, 0.0, 1.0, false}, 0.5);
    CHECK(s.left.holdDb < held);
    CHECK(s.left.holdDb >= s.left.levelDb);
}

// The published latch is the authoritative one: a clip between two UI frames never appears in
// the block peak this frame samples, so dropping it would silently lose the report.
static void testClipLatchesFromThePublishedFlagAndClearsOnDemand() {
    MasterMeterUi s;
    CHECK(!meterClipped(s));
    s = advanceMasterMeter(s, {0.25, 0.25, 1.0, /*clip=*/true}, 0.1);
    CHECK(meterClipped(s));
    // Latched: quiet frames do not lower it.
    s = advanceMasterMeter(s, {0.0, 0.0, 1.0, false}, 5.0);
    CHECK(meterClipped(s));
    s = clearMasterMeterClip(s);
    CHECK(!meterClipped(s));
    // And the UI's own sample latches it too, when the loud block IS the one sampled.
    s = advanceMasterMeter(s, {1.0, 0.0, 1.0, false}, 0.1);
    CHECK(meterClipped(s));
}

static void testGrLampLitOnlyWhileTheLimiterReduces() {
    MasterMeterUi s;
    CHECK(!grLampLit(s));
    // A gain of 1 is no reduction, however long it is held.
    s = advanceMasterMeter(s, {0.5, 0.5, 1.0, false}, 0.1);
    CHECK(s.reductionDb == 0.0);
    CHECK(!grLampLit(s));

    // ~6 dB of reduction lights it.
    s = advanceMasterMeter(s, {0.5, 0.5, 0.5, false}, 0.1);
    CHECK(std::fabs(s.reductionDb - 6.0206) < 1e-3);
    CHECK(grLampLit(s));

    // It decays at the meter's own rate rather than snapping dark, so a transient catch is
    // visible for more than the single frame it happened on.
    s = advanceMasterMeter(s, {0.5, 0.5, 1.0, false}, 0.1);
    CHECK(grLampLit(s));
    CHECK(s.reductionDb < 6.0206);
    s = advanceMasterMeter(s, {0.5, 0.5, 1.0, false}, 1.0);
    CHECK(!grLampLit(s));
    CHECK(s.reductionDb == 0.0);
}

// The tick repaints only on a change, so what counts as a change has to cover every drawn
// quantity — and only those.
static void testDrawEqualityCoversTheDrawnQuantities() {
    MasterMeterUi a;
    CHECK(meterDrawEqual(a, a));

    MasterMeterUi loud = advanceMasterMeter(a, {1.0, 0.0, 1.0, false}, 0.1);
    CHECK(!meterDrawEqual(a, loud));           // bar + hold tick moved

    MasterMeterUi clipped = a;
    clipped.left.clip = true;
    CHECK(!meterDrawEqual(a, clipped));        // the cap appeared

    MasterMeterUi lamp = a;
    lamp.reductionDb = kGrLampFloorDb;
    CHECK(!meterDrawEqual(a, lamp));           // the lamp lit

    // Reduction that does not cross the lamp's floor draws identically — the state differs,
    // the picture does not, and a repaint there would be pure cost.
    MasterMeterUi graze = a;
    graze.reductionDb = kGrLampFloorDb / 2.0;
    CHECK(meterDrawEqual(a, graze));
}

static void testDegenerateColumnYieldsNothing() {
    const MeterRects m = meterRects(Rect::ltrb(0, 0, 0, 0), LaneSplit::Stereo);
    CHECK(m.field.empty() && m.barA.empty() && m.barB.empty());
}

int main() {
    testColumnDividesIntoGutterAndBarField();
    testMonoDrawsOneWideBarAndStereoDrawsTwo();
    testBarCountFollowsTheWaveformsOwnLaneSplit();
    testDbAxisSpansTheFieldAndClamps();
    testPeakRisesAtOnceAndFallsAtTwentyDbPerSecond();
    testPeakHoldSitsForItsFullWindowThenReleases();
    testClipLatchesFromThePublishedFlagAndClearsOnDemand();
    testGrLampLitOnlyWhileTheLimiterReduces();
    testDrawEqualityCoversTheDrawnQuantities();
    testDegenerateColumnYieldsNothing();
    if (g_fail) {
        std::printf("%d FAILURE(S)\n", g_fail);
        return 1;
    }
    std::printf("master_meter tests passed\n");
    return 0;
}