// Standalone tests for reasampler::render_window — no REAPER, no framework.
// Covers the bounds-equality number (a window's exact frame count at the project
// rate), the verdict the offline backend refuses a capture on, the predicate
// that decides whether REAPER's selected-items render source can express a
// requested window at all, and the two short-render diagnostics.

#include "../src/core/capture/render_window.h"

#include <cmath>
#include <cstdio>
#include <string>

using namespace reasampler::capture;

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 contains(const std::string& haystack, const std::string& needle) {
    return haystack.find(needle) != std::string::npos;
}

// --- frameCountFor: the bounds equality, stated as a number ------------------

static void testFrameCountIsExactNotRounded() {
    // A 1.5 s window at 48 kHz is exactly 72000 frames — the number a capture of
    // that range must produce. No rounding slack in either direction.
    CHECK(frameCountFor(2.0, 3.5, 48000) == 72000);
    // The same duration at a different offset still counts the same frames when
    // both edges are frame-aligned.
    CHECK(frameCountFor(10.0, 11.5, 48000) == 72000);
    // 44.1 kHz: 0.5 s = 22050 frames.
    CHECK(frameCountFor(1.0, 1.5, 44100) == 22050);
}

static void testFrameCountIsADifferenceOfIndicesNotADuration() {
    // Both edges land mid-frame at 100 Hz (0.005 s = half a frame). Rounding the
    // DURATION would give 1 frame; rounding each EDGE gives 0.005 -> frame 1 and
    // 0.015 -> frame 2, i.e. 1 frame. Shift the window so the edges round apart
    // and the count changes — the property that makes this a window, not a length.
    CHECK(frameCountFor(0.005, 0.015, 100) == 1);
    CHECK(frameCountFor(0.004, 0.016, 100) == 2);
}

static void testFrameCountRefusesEmptyInvertedAndUnknownRate() {
    CHECK(frameCountFor(3.0, 3.0, 48000) == 0);   // empty
    CHECK(frameCountFor(3.0, 1.0, 48000) == 0);   // inverted
    CHECK(frameCountFor(1.0, 2.0, 0)     == 0);   // rate unknown
    CHECK(frameCountFor(1.0, 2.0, -1)    == 0);   // rate nonsensical
}

static void testWindowStartingAtExactlyZero() {
    CHECK(frameCountFor(0.0, 1.0, 48000) == 48000);
    // The window from the reported blocker: it starts at 0 and its end lands a
    // quarter of a frame off the grid at 48 kHz.
    CHECK(frameCountFor(0.0, 4.067797, 48000) == 195254);
}

// --- renderHonoredBounds: the gate's verdict ---------------------------------

static void testNonFrameAlignedWindowAcceptsItsAdjacentCounts() {
    // 4.067797 s at 48 kHz is 195254.26 frames — not a frame boundary. A correct
    // render lands on 195254, and both adjacent counts are inside the gate.
    const long long expected = frameCountFor(0.0, 4.067797, 48000);
    CHECK(expected == 195254);
    CHECK(renderHonoredBounds(expected, 195254));
    CHECK(renderHonoredBounds(expected, 195255));
    CHECK(renderHonoredBounds(expected, 195253));
    // The shortfall actually reported from the DAW is 38 frames — far outside any
    // alignment slack, so it is a render that missed the window, and is refused.
    CHECK(!renderHonoredBounds(expected, 195216));
}

static void testLengthDerivedAndSameConventionRenderersStayWithinOneFrame() {
    // What the one-frame tolerance is actually good for. Two families of renderer are
    // inside it at every offset swept here: one that derives its count from the
    // window's LENGTH (floor/ceil/round of (end-start)*rate), and one that resolves
    // each EDGE to a frame using the SAME convention on both edges. Every count below
    // is computed from the window, never from frameCountFor, so this compares two
    // derivations rather than restating one. Round-both-edges is omitted deliberately:
    // that IS frameCountFor's own convention, so asserting it would be tautological.
    //
    // 8192 is a power of two, so an eighth of a frame is exact in double there and the
    // .5 rounding ties are really hit; at 48000/44100 (the shipping rates) they are
    // only approached, which is why all three are swept.
    struct Window { double start; double end; };
    const int rates[] = {48000, 44100, 8192};
    const Window windows[] = {{3.0, 7.5}, {0.0, 4.067797}, {10.25, 10.75}};
    for (int rate : rates) {
        for (const Window& w : windows) {
            for (int s = 0; s < 8; ++s) {
                for (int e = 0; e < 8; ++e) {
                    const double start = w.start + s / (8.0 * rate);
                    const double end   = w.end   + e / (8.0 * rate);
                    const long long expected = frameCountFor(start, end, rate);

                    const double length = (end - start) * rate;
                    CHECK(renderHonoredBounds(expected,
                                              static_cast<long long>(std::floor(length))));
                    CHECK(renderHonoredBounds(expected,
                                              static_cast<long long>(std::ceil(length))));
                    CHECK(renderHonoredBounds(expected, std::llround(length)));

                    const double startFrames = start * rate;
                    const double endFrames   = end * rate;
                    CHECK(renderHonoredBounds(
                        expected, static_cast<long long>(std::floor(endFrames) -
                                                         std::floor(startFrames))));
                    CHECK(renderHonoredBounds(
                        expected, static_cast<long long>(std::ceil(endFrames) -
                                                         std::ceil(startFrames))));
                }
            }
        }
    }
}

static void testMixedEdgeConventionsCanMissByTwoAndAreRefused() {
    // The hole in that bound, stated rather than hidden. A renderer that resolves the
    // two edges by DIFFERENT conventions lands two frames from frameCountFor's answer
    // whenever the start sits past mid-frame and the end before it (resolved outward),
    // or the mirror image (resolved inward). The gate refuses both — correctly if
    // REAPER derives its count from the window's length, wrongly if it resolves edges
    // this way. No unit test can settle which; see render_window.h.
    const int rate = 8192;  // power of two: the eighth-frame offsets below are exact

    // Outward: start .625 into a frame, end .375 into one.
    const double start = 10.25 + 5.0 / (8.0 * rate);
    const double end   = 10.75 + 3.0 / (8.0 * rate);
    CHECK(start * rate == 83968.625);   // the premise, not an outcome — pinned so a
    CHECK(end   * rate == 88064.375);   // representability slip can't fake the result
    const long long expected = frameCountFor(start, end, rate);
    CHECK(expected == 4095);
    const long long outward = static_cast<long long>(std::ceil(end * rate) -
                                                     std::floor(start * rate));
    CHECK(outward == 4097);
    CHECK(!renderHonoredBounds(expected, outward));

    // Inward, mirrored fractions.
    const double start2 = 10.25 + 3.0 / (8.0 * rate);
    const double end2   = 10.75 + 5.0 / (8.0 * rate);
    const long long expected2 = frameCountFor(start2, end2, rate);
    CHECK(expected2 == 4097);
    const long long inward = static_cast<long long>(std::floor(end2 * rate) -
                                                    std::ceil(start2 * rate));
    CHECK(inward == 4095);
    CHECK(!renderHonoredBounds(expected2, inward));
}

static void testWholeItemWideningIsStillRefused() {
    // The defect the gate was built for: a 1 s window inside a 30 s item printing
    // the whole item.
    const long long expected = frameCountFor(5.0, 6.0, 48000);
    CHECK(expected == 48000);
    CHECK(!renderHonoredBounds(expected, 30 * 48000));
}

static void testLargeShortfallIsStillRefused() {
    const long long expected = frameCountFor(0.0, 4.067797, 48000);
    CHECK(!renderHonoredBounds(expected, 190000));
    // Two frames is the smallest miss outside the tolerance, in both directions —
    // the tolerance is one frame and stays one frame.
    CHECK(!renderHonoredBounds(expected, expected - 2));
    CHECK(!renderHonoredBounds(expected, expected + 2));
}

static void testEmptyRenderIsRefusedAgainstARealWindow() {
    // A render that produced nothing is a bounds miss like any other. A render whose
    // frames could not be MEASURED never reaches this predicate — shell/capture/
    // render_bounds_gate refuses it before the comparison.
    CHECK(!renderHonoredBounds(48000, 0));
}

// --- itemExtentPrintsWindow: can the selected-items source express this? -----

static void testRangeInsideItemCannotBeExpressed() {
    // The defect this whole module exists for: a 1 s selection inside a 30 s item.
    // The selected-items source would print the item's 30 s, not the 1 s asked for,
    // so the capture must NOT take that path.
    CHECK(!itemExtentPrintsWindow(5.0, 6.0, /*item*/ 0.0, 30.0, 48000));
}

static void testRangeWiderThanItemCannotBeExpressedEither() {
    // The same violation in the other direction: a 10 s selection over a 6 s item
    // would print 6 s. Under-printing is a bounds violation exactly as much as
    // over-printing is.
    CHECK(!itemExtentPrintsWindow(0.0, 10.0, /*item*/ 2.0, 8.0, 48000));
}

static void testEachEdgeAloneDisqualifies() {
    // Matching start, drifting end.
    CHECK(!itemExtentPrintsWindow(2.0, 8.0, 2.0, 9.0, 48000));
    // Matching end, drifting start.
    CHECK(!itemExtentPrintsWindow(2.0, 8.0, 1.0, 8.0, 48000));
}

static void testExtentEqualToWindowIsExpressible() {
    // The regression floor: a capture whose range IS the item's extent keeps the
    // selected-items render, byte-identical to what it produces today.
    CHECK(itemExtentPrintsWindow(2.0, 8.0, 2.0, 8.0, 48000));
}

static void testSubFrameDriftStillPrintsTheSameFrames() {
    // A time selection snapped a fraction of a sample off the item edge prints the
    // identical frames, so it must NOT be pushed onto the time-bounded path — that
    // would swap the render mechanism under a capture that was already exact.
    const double eighthOfAFrameAt48k = 1.0 / (48000.0 * 8.0);
    CHECK(itemExtentPrintsWindow(2.0 + eighthOfAFrameAt48k, 8.0 - eighthOfAFrameAt48k,
                                 2.0, 8.0, 48000));
    // A full frame of drift is a real difference and must disqualify.
    const double oneFrameAt48k = 1.0 / 48000.0;
    CHECK(!itemExtentPrintsWindow(2.0 + oneFrameAt48k, 8.0, 2.0, 8.0, 48000));
}

static void testUnknownRateFallsBackToExactEquality() {
    // With no project rate there is no frame grid to compare on. Exact equality
    // still recognizes the regression floor...
    CHECK(itemExtentPrintsWindow(2.0, 8.0, 2.0, 8.0, 0));
    // ...and anything else takes the time-bounded render, which honors the request
    // whatever the rate turns out to be.
    const double eighthOfAFrameAt48k = 1.0 / (48000.0 * 8.0);
    CHECK(!itemExtentPrintsWindow(2.0 + eighthOfAFrameAt48k, 8.0, 2.0, 8.0, 0));
    CHECK(!itemExtentPrintsWindow(5.0, 6.0, 0.0, 30.0, 0));
}

static void testMultiItemUnionExtent() {
    // Two items spanning 1..4 and 6..9 present a 1..9 union extent to the render.
    // A selection over the whole union is expressible; one over only the first
    // item's half is not.
    CHECK(itemExtentPrintsWindow(1.0, 9.0, 1.0, 9.0, 48000));
    CHECK(!itemExtentPrintsWindow(1.0, 4.0, 1.0, 9.0, 48000));
}

// --- msFlooredEndFrameCount: the shape both live short renders had ------------

static void testMillisecondFlooredEndReproducesBothShortRenders() {
    // Both DAW observations, as arithmetic. 48 kHz, TailMode::None, start at 0: the
    // requested window's count, and the count its end floored to the millisecond
    // holds — which is what each render actually printed.
    CHECK(frameCountFor(0.0, 4.067797, 48000) == 195254);
    CHECK(msFlooredEndFrameCount(0.0, 4.067797, 48000) == 195216);
    CHECK(frameCountFor(0.0, 4.067797, 48000) -
          msFlooredEndFrameCount(0.0, 4.067797, 48000) == 38);

    CHECK(frameCountFor(0.0, 1.655172, 48000) == 79448);
    CHECK(msFlooredEndFrameCount(0.0, 1.655172, 48000) == 79440);
    CHECK(frameCountFor(0.0, 1.655172, 48000) -
          msFlooredEndFrameCount(0.0, 1.655172, 48000) == 8);
}

static void testTheSixDecimalDisplayDidNotCreateTheEffect() {
    // Both reported ends were printed to six decimals by the refusal. Each is one 4/4
    // bar — at 59 BPM and at 145 BPM — so the full-precision doubles behind them are
    // 240/59 and 240/145. Same counts either way: the display rounding is not what
    // produces the shortfall.
    CHECK(frameCountFor(0.0, 240.0 / 59.0, 48000) == 195254);
    CHECK(msFlooredEndFrameCount(0.0, 240.0 / 59.0, 48000) == 195216);
    CHECK(frameCountFor(0.0, 240.0 / 145.0, 48000) == 79448);
    CHECK(msFlooredEndFrameCount(0.0, 240.0 / 145.0, 48000) == 79440);
}

static void testWindowAlreadyOnTheMillisecondGridLosesNothing() {
    // The "sometimes it works" case: a bar at 120 BPM is exactly 2 s.
    CHECK(msFlooredEndFrameCount(0.0, 2.0, 48000) == frameCountFor(0.0, 2.0, 48000));

    // The binary-representation trap a bare floor would fall into. The premise, not an
    // outcome: 1.007 s is a whole millisecond that really does land BELOW 1007 ms in
    // double, so flooring it without a tolerance drops a millisecond from a window
    // already on the grid.
    CHECK(1.007 * 1000.0 < 1007.0);
    CHECK(frameCountFor(0.0, 1.007, 48000) == 48336);
    CHECK(msFlooredEndFrameCount(0.0, 1.007, 48000) == 48336);
    // Same end reached from a non-zero start, so nothing here rests on the window
    // beginning at 0.
    CHECK(msFlooredEndFrameCount(0.5, 1.007, 48000) ==
          frameCountFor(0.5, 1.007, 48000));
}

static void testOneFrameOfRemainderStillFloors() {
    // The whole-millisecond tolerance must sit far below a frame, or it would swallow
    // the very remainder this diagnostic exists to find. One frame at 48 kHz is 20.8 us
    // — four orders of magnitude above the nanosecond tolerance.
    const double oneFrame = 1.0 / 48000.0;
    CHECK(frameCountFor(0.0, 1.0 + oneFrame, 48000) == 48001);
    CHECK(msFlooredEndFrameCount(0.0, 1.0 + oneFrame, 48000) == 48000);
}

static void testMillisecondFloorAt44100WhereAMillisecondIsNotWholeFrames() {
    // 44.1 kHz: a millisecond is 44.1 frames, so a floored end cannot be described as
    // dropping a whole number of frames — the count still resolves exactly.
    CHECK(frameCountFor(0.0, 0.0105, 44100) == 463);
    CHECK(msFlooredEndFrameCount(0.0, 0.0105, 44100) == 441);
    // And a window that IS on the millisecond grid there is untouched, even though its
    // edge is not on a frame boundary.
    CHECK(frameCountFor(0.0, 0.010, 44100) == 441);
    CHECK(msFlooredEndFrameCount(0.0, 0.010, 44100) == 441);
}

static void testASubMillisecondStartWouldNotHideItself() {
    // Both observations started at 0.000000s, the one value that hides a start-side
    // truncation. A window whose START carries a sub-millisecond remainder counts from
    // that exact start...
    const double start = 1.0001724, end = 2.0001724;
    CHECK(frameCountFor(start, end, 48000) == 48000);
    // ...so a start floored to the millisecond would print a DIFFERENT count — 8 frames
    // more, the same remainder the second observation lost off its end. A start-side
    // truncation is therefore visible to the same frame-count gate, not silent.
    CHECK(frameCountFor(1.000, end, 48000) == 48008);
    CHECK(!renderHonoredBounds(frameCountFor(start, end, 48000),
                               frameCountFor(1.000, end, 48000)));
}

// --- describeBoundsDrift: the read-back's verdict ------------------------------

static void testBoundsThatReadBackUnchangedDescribeNothing() {
    // The answer that proves the request crossed into REAPER intact — including for a
    // window whose end is nowhere near a millisecond boundary.
    CHECK(describeBoundsDrift(0.0, 4.067797, 0.0, 4.067797, 48000).empty());
    CHECK(describeBoundsDrift(1.0001724, 2.0001724, 1.0001724, 2.0001724, 48000).empty());
}

static void testADriftedEndNamesBothWindowsAndBothCounts() {
    const std::string s =
        describeBoundsDrift(0.0, 4.067797, 0.0, 4.067, 48000);
    CHECK(!s.empty());
    // Both counts as literals from the DAW observation, not re-derived from the same
    // functions the sentence was built with.
    CHECK(contains(s, "195254"));   // what the request asks for
    CHECK(contains(s, "195216"));   // what the drifted window would hold
    CHECK(contains(s, "48000 Hz"));
}

static void testTheReportPrintsEnoughDigitsToShowTheDrift() {
    // A report whose two numbers print identically is evidence of nothing. Two ends a
    // single ULP apart — far under the sixth decimal a shorter rendering would stop at
    // — must still read as two different numbers.
    const double asked  = 4.067797;
    const double stored = std::nextafter(asked, 5.0);
    const std::string s = describeBoundsDrift(0.0, asked, 0.0, stored, 48000);
    CHECK(!s.empty());
    CHECK(!contains(s, "4.067797s, read back [0s, 4.067797s)"));
}

static void testADriftedStartIsCaughtToo() {
    // The edge both observations could not test.
    const std::string s = describeBoundsDrift(1.0001724, 2.0, 1.000, 2.0, 48000);
    CHECK(!s.empty());
    CHECK(contains(s, "1.0001724"));
}

static void testAnUnknownRateStillReportsTheDriftWithoutFrames() {
    // A project that never pinned a rate reads 0. The drift is still worth saying; a
    // frame count over an unknown rate is not.
    const std::string s = describeBoundsDrift(0.0, 4.067797, 0.0, 4.067, 0);
    CHECK(!s.empty());
    CHECK(!contains(s, "frames"));
}

int main() {
    testFrameCountIsExactNotRounded();
    testFrameCountIsADifferenceOfIndicesNotADuration();
    testFrameCountRefusesEmptyInvertedAndUnknownRate();
    testWindowStartingAtExactlyZero();
    testNonFrameAlignedWindowAcceptsItsAdjacentCounts();
    testLengthDerivedAndSameConventionRenderersStayWithinOneFrame();
    testMixedEdgeConventionsCanMissByTwoAndAreRefused();
    testWholeItemWideningIsStillRefused();
    testLargeShortfallIsStillRefused();
    testEmptyRenderIsRefusedAgainstARealWindow();
    testRangeInsideItemCannotBeExpressed();
    testRangeWiderThanItemCannotBeExpressedEither();
    testEachEdgeAloneDisqualifies();
    testExtentEqualToWindowIsExpressible();
    testSubFrameDriftStillPrintsTheSameFrames();
    testUnknownRateFallsBackToExactEquality();
    testMultiItemUnionExtent();
    testMillisecondFlooredEndReproducesBothShortRenders();
    testTheSixDecimalDisplayDidNotCreateTheEffect();
    testWindowAlreadyOnTheMillisecondGridLosesNothing();
    testOneFrameOfRemainderStillFloors();
    testMillisecondFloorAt44100WhereAMillisecondIsNotWholeFrames();
    testASubMillisecondStartWouldNotHideItself();
    testBoundsThatReadBackUnchangedDescribeNothing();
    testADriftedEndNamesBothWindowsAndBothCounts();
    testTheReportPrintsEnoughDigitsToShowTheDrift();
    testADriftedStartIsCaughtToo();
    testAnUnknownRateStillReportsTheDriftWithoutFrames();

    if (g_fail) { std::printf("%d check(s) FAILED\n", g_fail); return 1; }
    std::printf("render_window: all checks passed\n");
    return 0;
}