reasampler/src/vst/sample_map.cpp

// sample_map — pure implementation. See sample_map.h. NO VST3 / REAPER / SWELL /
// vendor includes; standard library + the pure bank_book / wav_trim / sampler_core.

#include "sample_map.h"

#include <algorithm>  // std::min
#include <cstring>    // std::memcpy
#include <utility>    // std::move

namespace reasampler {

namespace {

// Translate a bank_model Sample's S2 intrinsics into the core's SampleLoop. The bank
// stores loop points as an optional LoopPoints (both-or-neither); the core wants a
// SampleLoop with an explicit hasLoop. Absent -> no loop.
SampleLoop loopFromSample(const Sample& s) {
    SampleLoop out;
    if (s.loop) {
        out.hasLoop = true;
        out.start = s.loop->start;
        out.end = s.loop->end;
    }
    return out;
}

// A distilled SelectedSample from a bank_model Sample. rootNote defaults to middle C
// (60) when the bank left the intrinsic empty — Tier 0 still plays, just centered on
// C rather than a captured pitch (surfaced: an un-rooted sample plays unity at C4).
SelectedSample distill(const Sample& s) {
    SelectedSample out;
    out.relativePath = s.relativePath;
    out.rootNote = s.rootNote ? *s.rootNote : 60;
    out.loop = loopFromSample(s);
    return out;
}

}  // namespace

std::optional<SelectedSample> selectSample(const std::string& banksJson,
                                           const std::string& sampleId) {
    if (banksJson.empty()) return std::nullopt;
    std::optional<BankBook> book = BankBook::deserialize(banksJson);
    if (!book) return std::nullopt;  // malformed -> nothing to play (never throw)

    // Search every bank (pool first, then named — banks() is ordinal order) for the
    // stored id. A sample lives in exactly one bank, so first hit wins.
    if (!sampleId.empty()) {
        for (const Bank& b : book->banks()) {
            if (const Sample* s = b.index.query(sampleId)) {
                return distill(*s);
            }
        }
    }

    // No stored id, or the id no longer resolves (the sample was deleted/moved out):
    // fall back to the FIRST sample in ordinal order so a fresh instance plays.
    for (const Bank& b : book->banks()) {
        if (!b.index.all().empty()) {
            return distill(b.index.all().front());
        }
    }
    return std::nullopt;  // bank has zero samples anywhere
}

std::vector<SampleChoice> listSamples(const std::string& banksJson) {
    std::vector<SampleChoice> out;
    if (banksJson.empty()) return out;
    std::optional<BankBook> book = BankBook::deserialize(banksJson);
    if (!book) return out;
    for (const Bank& b : book->banks()) {
        for (const Sample& s : b.index.all()) {
            out.push_back(SampleChoice{s.id, s.displayName});
        }
    }
    return out;
}

std::vector<AudioSample> downmixToMono(const std::vector<AudioSample>& interleaved,
                                       int channelCount) {
    std::vector<AudioSample> out;
    if (channelCount <= 0 || interleaved.empty()) return out;
    const std::size_t stride = static_cast<std::size_t>(channelCount);
    const std::size_t frames = interleaved.size() / stride;
    out.resize(frames);
    const double inv = 1.0 / static_cast<double>(channelCount);
    for (std::size_t f = 0; f < frames; ++f) {
        double acc = 0.0;
        const std::size_t base = f * stride;
        for (std::size_t c = 0; c < stride; ++c) {
            acc += static_cast<double>(interleaved[base + c]);
        }
        out[f] = static_cast<AudioSample>(acc * inv);
    }
    return out;
}

Keymap buildTier0Keymap(std::vector<AudioSample> monoFrames, int sampleRate,
                        int rootNote, const SampleLoop& loop) {
    SampleData data;
    data.frames = std::move(monoFrames);
    data.sampleRate = sampleRate > 0 ? sampleRate : 44100;
    data.rootNote = rootNote;
    data.loop = loop;
    return Keymap::singleSampleChromatic(std::move(data));
}

// --- Performance map ---------------------------------------------------------

ResolvedPerformance resolvePerformance(const std::string& banksJson,
                                       const PerformanceMap& map) {
    ResolvedPerformance out;
    if (map.zones.empty()) return out;             // empty map -> empty (shell -> Tier 0)
    if (banksJson.empty()) return out;             // no bank -> nothing resolves
    std::optional<BankBook> book = BankBook::deserialize(banksJson);
    if (!book) return out;                         // malformed -> nothing (never throw)

    for (const PerformanceZone& z : map.zones) {
        // Look the id up across every bank (pool + named) — a sample lives in exactly
        // one bank, so first hit wins.
        const Sample* found = nullptr;
        for (const Bank& b : book->banks()) {
            if (const Sample* s = b.index.query(z.sampleId)) {
                found = s;
                break;
            }
        }
        if (!found) {
            // STALE-ID POLICY: drop the zone cleanly, report the id (editor can prune).
            out.droppedSampleIds.push_back(z.sampleId);
            continue;
        }
        ResolvedZone rz;
        rz.relativePath = found->relativePath;
        rz.lowNote = z.lowNote;
        rz.highNote = z.highNote;
        // Effective root: override beats bank intrinsic beats middle-C default.
        rz.rootNote = z.rootOverride ? *z.rootOverride
                                     : (found->rootNote ? *found->rootNote : 60);
        rz.loop = loopFromSample(*found);
        out.zones.push_back(std::move(rz));
    }
    return out;
}

Keymap buildZonedKeymap(const std::vector<ResolvedZone>& zones,
                        const std::vector<DecodedZonePcm>& decoded) {
    Keymap km;
    const std::size_t n = std::min(zones.size(), decoded.size());
    for (std::size_t i = 0; i < n; ++i) {
        // An unreadable/empty WAV drops just this zone (not the whole map).
        if (decoded[i].monoFrames.empty()) continue;
        SampleData data;
        data.frames = decoded[i].monoFrames;
        data.sampleRate = decoded[i].sampleRate > 0 ? decoded[i].sampleRate : 44100;
        data.rootNote = zones[i].rootNote;
        data.loop = zones[i].loop;
        const std::size_t sampleIndex = km.samples.size();
        km.samples.push_back(std::move(data));
        KeyZone zone;
        zone.lowNote = zones[i].lowNote;
        zone.highNote = zones[i].highNote;
        zone.rootNote = zones[i].rootNote;
        zone.sampleIndex = sampleIndex;
        km.zones.push_back(zone);
    }
    return km;  // empty zones in -> empty Keymap (silence)
}

// --- Performance-map instance state (setState/getState) -----------------------

namespace {

void putU32le(std::vector<std::uint8_t>& out, std::uint32_t v) {
    out.push_back(static_cast<std::uint8_t>(v & 0xFF));
    out.push_back(static_cast<std::uint8_t>((v >> 8) & 0xFF));
    out.push_back(static_cast<std::uint8_t>((v >> 16) & 0xFF));
    out.push_back(static_cast<std::uint8_t>((v >> 24) & 0xFF));
}

// A bounded little-endian reader over a byte blob. Every read is length-checked; once a
// read runs past the end the reader latches `ok=false` and yields zeros, so a truncated
// blob degrades to a partial/empty parse rather than reading out of bounds.
struct ByteReader {
    const std::vector<std::uint8_t>& bytes;
    std::size_t pos = 0;
    bool ok = true;

    explicit ByteReader(const std::vector<std::uint8_t>& b) : bytes(b) {}

    std::uint32_t u32() {
        if (!ok || pos + 4 > bytes.size()) { ok = false; return 0; }
        const std::uint32_t v = static_cast<std::uint32_t>(bytes[pos]) |
                                (static_cast<std::uint32_t>(bytes[pos + 1]) << 8) |
                                (static_cast<std::uint32_t>(bytes[pos + 2]) << 16) |
                                (static_cast<std::uint32_t>(bytes[pos + 3]) << 24);
        pos += 4;
        return v;
    }
    std::uint8_t u8() {
        if (!ok || pos + 1 > bytes.size()) { ok = false; return 0; }
        return bytes[pos++];
    }
    std::string str(std::uint32_t len) {
        if (!ok || pos + len > bytes.size()) { ok = false; return {}; }
        std::string s(reinterpret_cast<const char*>(bytes.data() + pos), len);
        pos += len;
        return s;
    }
    // Signed ints go on the wire as u32 two's-complement (fixed 32-bit width).
    int i32() { return static_cast<int>(static_cast<std::int32_t>(u32())); }
};

}  // namespace

std::vector<std::uint8_t> serializePerformance(const PerformanceMap& map) {
    std::vector<std::uint8_t> out;
    putU32le(out, kPerformanceStateVersion);
    putU32le(out, static_cast<std::uint32_t>(map.zones.size()));
    for (const PerformanceZone& z : map.zones) {
        putU32le(out, static_cast<std::uint32_t>(z.sampleId.size()));
        out.insert(out.end(), z.sampleId.begin(), z.sampleId.end());
        putU32le(out, static_cast<std::uint32_t>(static_cast<std::int32_t>(z.lowNote)));
        putU32le(out, static_cast<std::uint32_t>(static_cast<std::int32_t>(z.highNote)));
        out.push_back(z.rootOverride ? 1 : 0);
        if (z.rootOverride) {
            putU32le(out,
                     static_cast<std::uint32_t>(static_cast<std::int32_t>(*z.rootOverride)));
        }
    }
    return out;
}

PerformanceMap deserializePerformance(const std::vector<std::uint8_t>& bytes) {
    PerformanceMap map;
    ByteReader r(bytes);
    const std::uint32_t version = r.u32();
    if (!r.ok) return map;  // no version tag -> empty

    // BACK-COMPAT: a v1 blob is the S4 single-selection format (version 1 + id bytes,
    // no length prefix). Lift it to one full-keyboard zone playing that id.
    if (version == kSelectionStateVersion) {
        const std::string id = deserializeSelection(bytes);
        if (!id.empty()) {
            PerformanceZone z;
            z.sampleId = id;
            z.lowNote = 0;
            z.highNote = 127;
            map.zones.push_back(std::move(z));
        }
        return map;
    }
    if (version != kPerformanceStateVersion) return map;  // unknown -> empty

    const std::uint32_t count = r.u32();
    for (std::uint32_t i = 0; i < count && r.ok; ++i) {
        PerformanceZone z;
        const std::uint32_t idLen = r.u32();
        z.sampleId = r.str(idLen);
        z.lowNote = r.i32();
        z.highNote = r.i32();
        const std::uint8_t hasOverride = r.u8();
        if (hasOverride) z.rootOverride = r.i32();
        if (!r.ok) break;  // truncated mid-zone -> keep what parsed cleanly, drop the rest
        map.zones.push_back(std::move(z));
    }
    return map;
}

std::vector<std::uint8_t> serializeSelection(const std::string& sampleId) {
    std::vector<std::uint8_t> out;
    out.resize(4 + sampleId.size());
    const std::uint32_t v = kSelectionStateVersion;
    out[0] = static_cast<std::uint8_t>(v & 0xFF);
    out[1] = static_cast<std::uint8_t>((v >> 8) & 0xFF);
    out[2] = static_cast<std::uint8_t>((v >> 16) & 0xFF);
    out[3] = static_cast<std::uint8_t>((v >> 24) & 0xFF);
    std::memcpy(out.data() + 4, sampleId.data(), sampleId.size());
    return out;
}

std::string deserializeSelection(const std::vector<std::uint8_t>& bytes) {
    if (bytes.size() < 4) return {};  // no version tag -> no selection
    const std::uint32_t v = static_cast<std::uint32_t>(bytes[0]) |
                            (static_cast<std::uint32_t>(bytes[1]) << 8) |
                            (static_cast<std::uint32_t>(bytes[2]) << 16) |
                            (static_cast<std::uint32_t>(bytes[3]) << 24);
    if (v != kSelectionStateVersion) return {};  // unknown version -> ignore
    return std::string(reinterpret_cast<const char*>(bytes.data() + 4),
                       bytes.size() - 4);
}

}  // namespace reasampler