#include "FrameDecoder.h"

#include <gtest/gtest.h>

#include <vector>

using namespace udpscope;

namespace {

/** Builds a FrameView over vectors the test owns. */
struct FrameBuilder {
    std::vector<std::vector<double>> storage;
    std::vector<const double*>       ptrs;
    std::vector<uint32_t>            counts;
    FrameView                        view;

    void addSignal(std::vector<double> vals) {
        storage.push_back(std::move(vals));
    }

    const FrameView& build(uint64_t hrt, double recvTime, uint32_t numSamples = 1) {
        ptrs.clear();
        counts.clear();
        for (const auto& s : storage) {
            ptrs.push_back(s.data());
            counts.push_back(static_cast<uint32_t>(s.size()));
        }
        view.hrt        = hrt;
        view.recvTime   = recvTime;
        view.numSamples = numSamples;
        view.numSignals = static_cast<uint32_t>(storage.size());
        view.values     = ptrs.data();
        view.counts     = counts.data();
        return view;
    }
};

SignalMeta burst(const char* name, uint8_t timeMode, double rate,
                 uint32_t elems, uint32_t timeIdx) {
    SignalMeta m;
    m.name          = name;
    m.typeCode      = 8;              /* float32 */
    m.numRows       = elems;
    m.numCols       = 1;
    m.timeMode      = timeMode;
    m.samplingRate  = rate;
    m.timeSignalIdx = timeIdx;
    return m;
}

SignalMeta timeSignal(const char* name, uint32_t elems) {
    SignalMeta m;
    m.name     = name;
    m.typeCode = 6;                   /* uint64 -> nanoseconds */
    m.numRows  = elems;
    m.numCols  = 1;
    return m;
}

} /* namespace */

TEST(FrameDecoder, FullArrayTakesOneStampPerElementFromTheTimeSignal) {
    FrameDecoder dec;
    dec.setSignals({burst("Sine", kTimeFullArray, 1000.0, 4, 1),
                    timeSignal("Time", 4)});

    FrameBuilder fb;
    fb.addSignal({1.0, 2.0, 3.0, 4.0});
    /* Nanoseconds: 5.000, 5.001, 5.002, 5.003 s of producer time. */
    fb.addSignal({5.0e9, 5.001e9, 5.002e9, 5.003e9});
    const FrameView& f = fb.build(0, 1000.0);

    dec.beginFrame(f);
    std::vector<double> ts;
    ASSERT_TRUE(dec.timestamps(f, 0, ts));
    ASSERT_EQ(ts.size(), 4u);

    /* Element 0 lands on the arrival time; the rest keep the producer spacing. */
    EXPECT_NEAR(ts[0], 1000.000, 1e-9);
    EXPECT_NEAR(ts[1], 1000.001, 1e-9);
    EXPECT_NEAR(ts[2], 1000.002, 1e-9);
    EXPECT_NEAR(ts[3], 1000.003, 1e-9);
}

TEST(FrameDecoder, FirstSampleAnchorsElementZeroAndCountsForward) {
    FrameDecoder dec;
    dec.setSignals({burst("Sine", kTimeFirstSample, 1000.0, 4, 1),
                    timeSignal("Time", 1)});

    FrameBuilder fb;
    fb.addSignal({1.0, 2.0, 3.0, 4.0});
    fb.addSignal({7.0e9});
    const FrameView& f = fb.build(0, 2000.0);

    dec.beginFrame(f);
    std::vector<double> ts;
    ASSERT_TRUE(dec.timestamps(f, 0, ts));
    ASSERT_EQ(ts.size(), 4u);
    EXPECT_NEAR(ts[0], 2000.000, 1e-9);
    EXPECT_NEAR(ts[3], 2000.003, 1e-9);
}

TEST(FrameDecoder, LastSampleAnchorsTheFinalElementAndCountsBackward) {
    FrameDecoder dec;
    dec.setSignals({burst("Sine", kTimeLastSample, 1000.0, 4, 1),
                    timeSignal("Time", 1)});

    FrameBuilder fb;
    fb.addSignal({1.0, 2.0, 3.0, 4.0});
    fb.addSignal({7.0e9});
    const FrameView& f = fb.build(0, 3000.0);

    dec.beginFrame(f);
    std::vector<double> ts;
    ASSERT_TRUE(dec.timestamps(f, 0, ts));
    ASSERT_EQ(ts.size(), 4u);
    EXPECT_NEAR(ts[3], 3000.000, 1e-9);
    EXPECT_NEAR(ts[0], 3000.000 - 0.003, 1e-9);
}

TEST(FrameDecoder, PlainScalarUsesArrivalTime) {
    FrameDecoder dec;
    SignalMeta m;
    m.name = "Level";
    m.typeCode = 9;
    dec.setSignals({m});

    FrameBuilder fb;
    fb.addSignal({42.0});
    const FrameView& f = fb.build(0, 1234.5);

    dec.beginFrame(f);
    std::vector<double> ts;
    ASSERT_TRUE(dec.timestamps(f, 0, ts));
    ASSERT_EQ(ts.size(), 1u);
    EXPECT_DOUBLE_EQ(ts[0], 1234.5);
}

// This is the failure UDPSourceSession.cpp:560 documents. The kernel delivers
// two queued datagrams microseconds apart even though each carries 10 ms of
// signal. Dating from arrival crams the second packet's samples into that gap
// and the trace becomes a sawtooth; dating from the producer hrt does not.
TEST(FrameDecoder, AccumulatedScalarSurvivesBurstyDelivery) {
    FrameDecoder dec;
    SignalMeta m;
    m.name         = "Acc";
    m.typeCode     = 9;
    m.numRows      = 1;
    m.samplingRate = 1000.0;          /* 1 kHz, 10 samples = 10 ms per packet */
    dec.setSignals({m});

    const double ticks = 1.0e9;
    std::vector<double> all;

    for (int p = 0; p < 40; p++) {
        FrameBuilder fb;
        fb.addSignal(std::vector<double>(10, static_cast<double>(p)));
        const double producerSec = 100.0 + p * 0.010;
        /* Packets 20+ arrive in a burst, all within 50 us of each other. */
        const double arrival = (p < 20) ? (500.0 + p * 0.010)
                                        : (500.2 + (p - 20) * 0.00005);
        const FrameView& f = fb.build(static_cast<uint64_t>(producerSec * ticks),
                                      arrival, 10);
        dec.beginFrame(f);
        std::vector<double> ts;
        if (dec.timestamps(f, 0, ts)) {
            all.insert(all.end(), ts.begin(), ts.end());
        }
    }

    ASSERT_GT(all.size(), 300u);
    for (size_t i = 1; i < all.size(); i++) {
        EXPECT_GT(all[i], all[i - 1]) << "non-monotonic at " << i;
        EXPECT_NEAR(all[i] - all[i - 1], 0.001, 2e-4)
            << "spacing collapsed at " << i << " (sawtooth)";
    }
}

// The counterweight to the test above. Suppressing arrival jitter by chaining
// each burst onto the previous one is only safe while the chain is checked: on
// UDP, packets are lost, and a chain that ignores arrival entirely closes the
// hole silently and dates every later sample a full second early — for the rest
// of the run, because nothing ever pulls it back. The prediction has to be
// abandoned once arrival contradicts it by more than a delivery backlog could.
TEST(FrameDecoder, AccumulatedScalarResynchronisesAfterLostPackets) {
    FrameDecoder dec;
    SignalMeta m;
    m.name         = "Acc";
    m.typeCode     = 9;
    m.numRows      = 1;
    m.samplingRate = 1000.0;          /* 10 samples = 10 ms per packet */
    dec.setSignals({m});

    std::vector<double> ts;
    for (int p = 0; p < 10; p++) {
        FrameBuilder fb;
        fb.addSignal(std::vector<double>(10, 1.0));
        const FrameView& f = fb.build(0, 500.0 + p * 0.010, 10);
        dec.beginFrame(f);
        ASSERT_TRUE(dec.timestamps(f, 0, ts));
    }
    /* Contiguous so far: burst 9 ends at 500.090. */
    EXPECT_NEAR(ts[9], 500.090, 1e-9);

    /* A full second of packets never arrives. The next one lands at 501.100. */
    FrameBuilder fb;
    fb.addSignal(std::vector<double>(10, 1.0));
    const FrameView& f = fb.build(0, 501.100, 10);
    dec.beginFrame(f);
    ASSERT_TRUE(dec.timestamps(f, 0, ts));

    /* Chaining blindly would put this burst at 500.091..500.100, overlapping
     * the gap as though no data were missing. */
    EXPECT_NEAR(ts[0], 501.091, 1e-9);
    EXPECT_NEAR(ts[9], 501.100, 1e-9);
}

TEST(FrameDecoder, AccumulatedScalarDerivesDtFromTheHrtGapWhenNoRateIsDeclared) {
    FrameDecoder dec;
    SignalMeta m;
    m.name         = "Acc";
    m.typeCode     = 9;
    m.samplingRate = 0.0;             /* undeclared */
    dec.setSignals({m});

    const double ticks = 1.0e9;
    std::vector<double> last;
    for (int p = 0; p < 40; p++) {
        FrameBuilder fb;
        fb.addSignal(std::vector<double>(10, 1.0));
        const double producerSec = 100.0 + p * 0.010;   /* 10 ms per packet */
        const FrameView& f = fb.build(static_cast<uint64_t>(producerSec * ticks),
                                      700.0 + p * 0.010, 10);
        dec.beginFrame(f);
        std::vector<double> ts;
        if (dec.timestamps(f, 0, ts)) { last = ts; }
    }

    ASSERT_EQ(last.size(), 10u);
    /* 10 ms of producer time across 10 samples is a 1 ms period. */
    EXPECT_NEAR(last[1] - last[0], 0.001, 1e-5);
}

// A PACKET burst has no per-element time at all. Elements span
// (lastPacket, thisPacket] — backwards from arrival, because the samples were
// acquired before the packet landed. Forward extrapolation would let a jittered
// packet overlap the next one and break ring monotonicity.
TEST(FrameDecoder, PacketBurstDropsTheFirstFrameThenSpansBackwards) {
    FrameDecoder dec;
    dec.setSignals({burst("Raw", kTimePacket, 0.0, 5, kNoTimeSignal)});

    FrameBuilder fb1;
    fb1.addSignal({1.0, 2.0, 3.0, 4.0, 5.0});
    const FrameView& f1 = fb1.build(0, 10.0);
    dec.beginFrame(f1);
    std::vector<double> ts;
    EXPECT_FALSE(dec.timestamps(f1, 0, ts))
        << "the first packet has no previous arrival to span from";

    FrameBuilder fb2;
    fb2.addSignal({6.0, 7.0, 8.0, 9.0, 10.0});
    const FrameView& f2 = fb2.build(0, 10.05);
    dec.beginFrame(f2);
    ASSERT_TRUE(dec.timestamps(f2, 0, ts));
    ASSERT_EQ(ts.size(), 5u);
    EXPECT_GT(ts[0], 10.0);
    EXPECT_NEAR(ts[4], 10.05, 1e-12);
    EXPECT_NEAR(ts[1] - ts[0], 0.01, 1e-12);
}

TEST(FrameDecoder, PacketBurstStaysMonotonicUnderJitteredArrivals) {
    FrameDecoder dec;
    dec.setSignals({burst("Raw", kTimePacket, 0.0, 8, kNoTimeSignal)});

    const double jitter[] = {0.0, 0.004, -0.003, 0.006, -0.002, 0.0, 0.005, -0.004};
    std::vector<double> all;
    for (int p = 0; p < 8; p++) {
        FrameBuilder fb;
        fb.addSignal(std::vector<double>(8, 1.0));
        const FrameView& f = fb.build(0, 20.0 + p * 0.05 + jitter[p]);
        dec.beginFrame(f);
        std::vector<double> ts;
        if (dec.timestamps(f, 0, ts)) {
            all.insert(all.end(), ts.begin(), ts.end());
        }
    }

    ASSERT_GT(all.size(), 8u);
    for (size_t i = 1; i < all.size(); i++) {
        EXPECT_GT(all[i], all[i - 1]) << "packets overlapped at " << i;
    }
}

TEST(FrameDecoder, ResetForgetsPerSignalHistory) {
    FrameDecoder dec;
    dec.setSignals({burst("Raw", kTimePacket, 0.0, 4, kNoTimeSignal)});

    FrameBuilder fb;
    fb.addSignal({1.0, 2.0, 3.0, 4.0});
    const FrameView& f = fb.build(0, 5.0);
    dec.beginFrame(f);
    std::vector<double> ts;
    EXPECT_FALSE(dec.timestamps(f, 0, ts));

    const FrameView& f2 = fb.build(0, 5.1);
    dec.beginFrame(f2);
    EXPECT_TRUE(dec.timestamps(f2, 0, ts));

    dec.reset();
    const FrameView& f3 = fb.build(0, 5.2);
    dec.beginFrame(f3);
    EXPECT_FALSE(dec.timestamps(f3, 0, ts))
        << "after reset the next packet is again the first one";
}