// Standalone tests for reasampler::sample_map — no VST3, no REAPER, no test framework.
// Same fast assert loop as the sibling pure tests. This module is the S4 mapping heart:
// bank blob -> selected sample (through the SHARED bank_book JSON parse), interleaved ->
// mono downmix (the Tier-0 channel policy), the Tier-0 chromatic keymap build, and the
// selected-sample instance-state (de)serialization.
//
// Every assertion is written to FAIL if the mapping were wrong: the bank blobs are built
// by serializing a real BankBook (so we exercise the shared parse, not a fixture string),
// and the selection / downmix / keymap / state values are checked against independently
// computed expectations.
//
// Covers: selectSample by-id hit (across pool + named banks), first-sample fallback for
// an empty / unknown id, empty & malformed blob -> nullopt, zero-samples -> nullopt,
// rootNote/loop intrinsic threading incl. the middle-C default; listSamples ordinal
// order + empty/malformed; downmixToMono mono passthrough / stereo average / 3-ch
// average / zero-stride / empty; buildTier0Keymap single full-keyboard zone with the
// root + loop + rate threaded and rate defaulting; selection state round-trip + empty id
// + wrong-version / truncated -> "".
// wav_trim -> extractFloatFrames -> downmixToMono integration: locks the interleave-
// stride contract across the seam (that the byte stride wav_trim reports matches the
// channel-count stride downmixToMono divides by).

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

#include <cmath>
#include <cstdio>
#include <cstring>
#include <string>
#include <vector>

#include "../src/bank_book.h"
#include "../src/bank_model.h"

using namespace reasampler;

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

// Build a Sample with the fields sample_map reads. Relative path is required by
// BankIndex::add (relative-only invariant); a content hash is set so dedup does not
// collapse distinct entries.
static Sample makeSample(const std::string& id, const std::string& name,
                         const std::string& rel, std::optional<int> root) {
    Sample s;
    s.id = id;
    s.displayName = name;
    s.relativePath = rel;
    s.contentHash = "hash-" + id;
    s.rootNote = root;
    return s;
}

// A serialized BankBook: the pool carries `poolSamples`, and one named bank "Drums"
// carries `drumSamples`. Returns the JSON the instrument would read from ext-state.
static std::string bookJson(const std::vector<Sample>& poolSamples,
                            const std::vector<Sample>& drumSamples) {
    BankBook book;
    for (const Sample& s : poolSamples) book.pool().index.add(s);
    if (!drumSamples.empty()) {
        book.createBank("drums-id", "Drums");
        BankIndex* di = book.index("drums-id");
        for (const Sample& s : drumSamples) di->add(s);
    }
    return book.serialize();
}

// --- selectSample -------------------------------------------------------------

static void testSelectByIdHit() {
    const std::string json = bookJson(
        {makeSample("a", "Kick", "reasampler_bank/a.wav", 36)},
        {makeSample("b", "Snare", "reasampler_bank/b.wav", 38)});
    // A sample in the NAMED bank resolves by id (search spans every bank).
    auto sel = selectSample(json, "b");
    CHECK(sel.has_value());
    CHECK(sel && sel->relativePath == "reasampler_bank/b.wav");
    CHECK(sel && sel->rootNote == 38);
}

static void testSelectFirstSampleFallbackOnEmptyId() {
    const std::string json = bookJson(
        {makeSample("a", "Kick", "reasampler_bank/a.wav", 36)},
        {makeSample("b", "Snare", "reasampler_bank/b.wav", 38)});
    // No stored selection -> the FIRST sample in ordinal order (pool first).
    auto sel = selectSample(json, "");
    CHECK(sel.has_value());
    CHECK(sel && sel->relativePath == "reasampler_bank/a.wav");
    CHECK(sel && sel->rootNote == 36);
}

static void testSelectFirstSampleFallbackOnUnknownId() {
    const std::string json = bookJson(
        {makeSample("a", "Kick", "reasampler_bank/a.wav", 36)}, {});
    // A stored id that no longer resolves falls back to the first sample, not silence.
    auto sel = selectSample(json, "deleted-id");
    CHECK(sel.has_value());
    CHECK(sel && sel->relativePath == "reasampler_bank/a.wav");
}

static void testSelectRootNoteDefault() {
    const std::string json = bookJson(
        {makeSample("a", "Loop", "reasampler_bank/a.wav", std::nullopt)}, {});
    // A sample with no root-note intrinsic defaults to middle C (60).
    auto sel = selectSample(json, "a");
    CHECK(sel.has_value());
    CHECK(sel && sel->rootNote == 60);
}

static void testSelectLoopThreaded() {
    Sample s = makeSample("a", "Pad", "reasampler_bank/a.wav", 60);
    s.loop = LoopPoints{100, 500};
    const std::string json = bookJson({s}, {});
    auto sel = selectSample(json, "a");
    CHECK(sel.has_value());
    CHECK(sel && sel->loop.hasLoop);
    CHECK(sel && sel->loop.start == 100 && sel->loop.end == 500);
}

static void testSelectNoLoopIsAbsent() {
    const std::string json = bookJson(
        {makeSample("a", "OneShot", "reasampler_bank/a.wav", 60)}, {});
    auto sel = selectSample(json, "a");
    CHECK(sel.has_value());
    CHECK(sel && !sel->loop.hasLoop);  // absent loop -> hasLoop false (not a zero loop)
}

static void testSelectEmptyBlob() {
    CHECK(!selectSample("", "a").has_value());
}

static void testSelectMalformedBlob() {
    CHECK(!selectSample("{not valid json", "a").has_value());
}

static void testSelectZeroSamples() {
    // A valid book with NO samples anywhere -> nothing to play.
    const std::string json = bookJson({}, {});
    CHECK(!selectSample(json, "").has_value());
    CHECK(!selectSample(json, "anything").has_value());
}

// --- listSamples --------------------------------------------------------------

static void testListSamplesOrdinalOrder() {
    const std::string json = bookJson(
        {makeSample("a", "Kick", "reasampler_bank/a.wav", 36),
         makeSample("c", "Hat", "reasampler_bank/c.wav", 42)},
        {makeSample("b", "Snare", "reasampler_bank/b.wav", 38)});
    const std::vector<SampleChoice> list = listSamples(json);
    // Pool samples (insertion order) come before the named bank's.
    CHECK(list.size() == 3);
    CHECK(list.size() == 3 && list[0].id == "a" && list[0].displayName == "Kick");
    CHECK(list.size() == 3 && list[1].id == "c");
    CHECK(list.size() == 3 && list[2].id == "b" && list[2].displayName == "Snare");
}

static void testListSamplesEmptyAndMalformed() {
    CHECK(listSamples("").empty());
    CHECK(listSamples("{garbage").empty());
    CHECK(listSamples(bookJson({}, {})).empty());
}

// --- downmixToMono ------------------------------------------------------------

static bool approx(double a, double b) { return std::fabs(a - b) < 1e-6; }

static void testDownmixMonoPassthrough() {
    const std::vector<AudioSample> in{0.1f, -0.2f, 0.3f};
    const std::vector<AudioSample> out = downmixToMono(in, 1);
    CHECK(out.size() == 3);
    CHECK(out.size() == 3 && approx(out[0], 0.1) && approx(out[1], -0.2) &&
          approx(out[2], 0.3));
}

static void testDownmixStereoAverages() {
    // Two frames, stereo interleaved: frame0 = (1.0, 0.0) -> 0.5; frame1 = (0.4, 0.6) -> 0.5.
    const std::vector<AudioSample> in{1.0f, 0.0f, 0.4f, 0.6f};
    const std::vector<AudioSample> out = downmixToMono(in, 2);
    CHECK(out.size() == 2);
    CHECK(out.size() == 2 && approx(out[0], 0.5) && approx(out[1], 0.5));
}

static void testDownmixThreeChannelAverages() {
    // One 3-channel frame (0.3, 0.3, 0.6) -> 0.4.
    const std::vector<AudioSample> in{0.3f, 0.3f, 0.6f};
    const std::vector<AudioSample> out = downmixToMono(in, 3);
    CHECK(out.size() == 1);
    CHECK(out.size() == 1 && approx(out[0], 0.4));
}

static void testDownmixDegenerate() {
    CHECK(downmixToMono({}, 2).empty());          // empty input
    CHECK(downmixToMono({0.1f, 0.2f}, 0).empty()); // zero stride
    CHECK(downmixToMono({0.1f, 0.2f}, -1).empty()); // negative stride
}

// --- buildTier0Keymap ---------------------------------------------------------

static void testBuildKeymapSingleFullZone() {
    SampleLoop loop;
    loop.hasLoop = true;
    loop.start = 10;
    loop.end = 90;
    const Keymap km = buildTier0Keymap({0.1f, 0.2f, 0.3f}, 48000, 40, loop);
    // One sample, one zone spanning the whole keyboard, rooted at 40.
    CHECK(km.samples.size() == 1);
    CHECK(km.zones.size() == 1);
    CHECK(km.zones.size() == 1 && km.zones[0].lowNote == 0 && km.zones[0].highNote == 127);
    CHECK(km.zones.size() == 1 && km.zones[0].rootNote == 40);
    CHECK(km.samples.size() == 1 && km.samples[0].sampleRate == 48000);
    CHECK(km.samples.size() == 1 && km.samples[0].rootNote == 40);
    CHECK(km.samples.size() == 1 && km.samples[0].frames.size() == 3);
    CHECK(km.samples.size() == 1 && km.samples[0].loop.hasLoop &&
          km.samples[0].loop.start == 10 && km.samples[0].loop.end == 90);
    // Resolution: any note lands in the single zone.
    CHECK(km.resolve(0, 100).matched);
    CHECK(km.resolve(127, 100).matched);
}

static void testBuildKeymapRateDefault() {
    // A zero/invalid rate defaults to 44100 rather than producing a divide-by-zero-shaped
    // sample rate downstream.
    const Keymap km = buildTier0Keymap({0.1f}, 0, 60, SampleLoop{});
    CHECK(km.samples.size() == 1 && km.samples[0].sampleRate == 44100);
}

// --- selection state (setState/getState) --------------------------------------

static void testSelectionStateRoundTrip() {
    const std::string id = "sample-guid-123";
    const std::vector<std::uint8_t> bytes = serializeSelection(id);
    // Versioned: 4-byte tag + the id bytes.
    CHECK(bytes.size() == 4 + id.size());
    CHECK(deserializeSelection(bytes) == id);
}

static void testSelectionStateEmptyId() {
    const std::vector<std::uint8_t> bytes = serializeSelection("");
    CHECK(bytes.size() == 4);            // just the version tag
    CHECK(deserializeSelection(bytes) == "");
}

static void testSelectionStateWrongVersion() {
    std::vector<std::uint8_t> bytes = serializeSelection("id");
    bytes[0] = 0xEE;  // corrupt the version tag
    CHECK(deserializeSelection(bytes) == "");  // unknown version -> no selection
}

static void testSelectionStateTruncated() {
    CHECK(deserializeSelection({}) == "");             // empty
    CHECK(deserializeSelection({1, 0, 0}) == "");      // fewer than 4 bytes (no tag)
}

// --- wav_trim -> extractFloatFrames -> downmixToMono integration ---------------
//
// Locks the interleave-stride contract at the seam between wav_trim and sample_map:
// wav_trim reports channelCount, extractFloatFrames yields interleaved samples with
// that stride, and downmixToMono divides by that same stride. If either module
// changed its understanding of the layout (e.g. extractFloatFrames started packing
// differently, or downmixToMono changed its stride divisor), this test catches it.

static void putU16sm(std::vector<std::uint8_t>& b, std::uint16_t v) {
    b.push_back(static_cast<std::uint8_t>(v & 0xFF));
    b.push_back(static_cast<std::uint8_t>((v >> 8) & 0xFF));
}
static void putU32sm(std::vector<std::uint8_t>& b, std::uint32_t v) {
    b.push_back(static_cast<std::uint8_t>(v & 0xFF));
    b.push_back(static_cast<std::uint8_t>((v >> 8) & 0xFF));
    b.push_back(static_cast<std::uint8_t>((v >> 16) & 0xFF));
    b.push_back(static_cast<std::uint8_t>((v >> 24) & 0xFF));
}
static void putTagsm(std::vector<std::uint8_t>& b, const char* t) {
    for (int i = 0; i < 4; ++i) b.push_back(static_cast<std::uint8_t>(t[i]));
}
static void putFloatsm(std::vector<std::uint8_t>& b, float f) {
    std::uint8_t tmp[4];
    std::memcpy(tmp, &f, 4);
    for (int i = 0; i < 4; ++i) b.push_back(tmp[i]);
}

// Build a 32-bit-float WAV byte buffer. Samples: frame f, channel c = value(f, c).
template <typename Fn>
static std::vector<std::uint8_t> buildWav(std::uint16_t channels,
                                          std::uint32_t sampleRate,
                                          std::size_t frames,
                                          Fn value) {
    const std::uint32_t dataBytes =
        static_cast<std::uint32_t>(frames * channels * 4u);
    std::vector<std::uint8_t> chunks;
    putTagsm(chunks, "fmt ");
    putU32sm(chunks, 16);
    putU16sm(chunks, 3);                                              // IEEE float
    putU16sm(chunks, channels);
    putU32sm(chunks, sampleRate);
    putU32sm(chunks, sampleRate * channels * 4u);
    putU16sm(chunks, static_cast<std::uint16_t>(channels * 4));
    putU16sm(chunks, 32);
    putTagsm(chunks, "data");
    putU32sm(chunks, dataBytes);
    for (std::size_t f = 0; f < frames; ++f)
        for (std::uint16_t c = 0; c < channels; ++c)
            putFloatsm(chunks, value(f, c));
    std::vector<std::uint8_t> wav;
    putTagsm(wav, "RIFF");
    putU32sm(wav, static_cast<std::uint32_t>(4 + chunks.size()));
    putTagsm(wav, "WAVE");
    wav.insert(wav.end(), chunks.begin(), chunks.end());
    return wav;
}

static void testWavTrimToDownmixPipelineStereo() {
    // Stereo WAV: frame f, L = f * 0.1f, R = f * 0.1f + 0.5f. Expected mono average:
    // (f * 0.1f + f * 0.1f + 0.5f) / 2 = f * 0.1f + 0.25f.
    const std::size_t kFrames = 4;
    auto wav = buildWav(2, 48000, kFrames,
                        [](std::size_t f, std::uint16_t c) {
                            return static_cast<float>(f) * 0.1f + (c == 1 ? 0.5f : 0.0f);
                        });
    WavLayout layout = parseWavLayout(wav);
    CHECK(layout.valid);
    CHECK(layout.channelCount == 2);
    CHECK(layout.frameCount() == kFrames);
    const std::vector<AudioSample> interleaved =
        extractFloatFrames(wav, layout, 0, layout.frameCount());
    CHECK(interleaved.size() == kFrames * 2);
    const std::vector<AudioSample> mono = downmixToMono(interleaved, layout.channelCount);
    CHECK(mono.size() == kFrames);
    for (std::size_t f = 0; f < kFrames; ++f) {
        const float expected = static_cast<float>(f) * 0.1f + 0.25f;
        CHECK(approx(mono[f], expected));
    }
}

static void testWavTrimToDownmixPipelineMono() {
    // Mono WAV: extractFloatFrames -> downmixToMono with channelCount==1 is a passthrough.
    const std::size_t kFrames = 3;
    auto wav = buildWav(1, 44100, kFrames,
                        [](std::size_t f, std::uint16_t) {
                            return static_cast<float>(f) * 0.5f;
                        });
    WavLayout layout = parseWavLayout(wav);
    CHECK(layout.valid);
    CHECK(layout.channelCount == 1);
    const std::vector<AudioSample> interleaved =
        extractFloatFrames(wav, layout, 0, layout.frameCount());
    CHECK(interleaved.size() == kFrames);
    const std::vector<AudioSample> mono = downmixToMono(interleaved, layout.channelCount);
    CHECK(mono.size() == kFrames);
    CHECK(approx(mono[0], 0.0) && approx(mono[1], 0.5) && approx(mono[2], 1.0));
}

int main() {
    testSelectByIdHit();
    testSelectFirstSampleFallbackOnEmptyId();
    testSelectFirstSampleFallbackOnUnknownId();
    testSelectRootNoteDefault();
    testSelectLoopThreaded();
    testSelectNoLoopIsAbsent();
    testSelectEmptyBlob();
    testSelectMalformedBlob();
    testSelectZeroSamples();
    testListSamplesOrdinalOrder();
    testListSamplesEmptyAndMalformed();
    testDownmixMonoPassthrough();
    testDownmixStereoAverages();
    testDownmixThreeChannelAverages();
    testDownmixDegenerate();
    testBuildKeymapSingleFullZone();
    testBuildKeymapRateDefault();
    testSelectionStateRoundTrip();
    testSelectionStateEmptyId();
    testSelectionStateWrongVersion();
    testSelectionStateTruncated();
    testWavTrimToDownmixPipelineStereo();
    testWavTrimToDownmixPipelineMono();

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