output_metadata.h

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// SPDX-License-Identifier: GPL-2.0-only
//
// Copyright (c) 2026-present FERS Contributors (see AUTHORS.md).
//
// See the GNU GPLv2 LICENSE file in the FERS project root for more information.
 
#pragma once
 
#include <cstdint>
#include <mutex>
#include <optional>
#include <string>
#include <vector>
 
#include "core/config.h"
#include "core/output_config.h"
#include "core/sim_id.h"
#include "core/vita49_timestamp.h"
 
namespace core
{
    /// Metadata for one pulsed output chunk written to HDF5.
    struct PulseChunkMetadata
    {
        unsigned chunk_index = 0; ///< Zero-based chunk index in the receiver output sequence.
        std::string i_dataset; ///< HDF5 dataset path containing the in-phase samples.
        std::string q_dataset; ///< HDF5 dataset path containing the quadrature samples.
        RealType start_time = 0.0; ///< Simulation time of the first sample in seconds.
        std::uint64_t sample_count = 0; ///< Number of samples in the chunk.
        std::uint64_t sample_start = 0; ///< Inclusive global sample index for the chunk start.
        std::uint64_t sample_end_exclusive = 0; ///< Exclusive global sample index for the chunk end.
    };
 
    /// Metadata for one contiguous streaming output segment.
    struct StreamingSegmentMetadata
    {
        RealType start_time = 0.0; ///< Segment start time in seconds.
        RealType end_time = 0.0; ///< Segment end time in seconds.
        std::uint64_t sample_count = 0; ///< Number of samples emitted for the segment.
        std::uint64_t sample_start = 0; ///< Inclusive global sample index for the segment start.
        std::uint64_t sample_end_exclusive = 0; ///< Exclusive global sample index for the segment end.
        std::optional<RealType> first_chirp_start_time = std::nullopt; ///< First emitted FMCW chirp start time.
        std::optional<std::uint64_t> emitted_chirp_count = std::nullopt; ///< Number of FMCW chirps emitted.
        std::optional<RealType> first_triangle_start_time = std::nullopt; ///< First emitted FMCW triangle start time.
        std::optional<std::uint64_t> emitted_triangle_count = std::nullopt; ///< Number of FMCW triangles emitted.
        std::optional<RealType> first_sfcw_step_start_time = std::nullopt; ///< First emitted SFCW step start time.
        std::optional<std::uint64_t> emitted_sfcw_step_count = std::nullopt; ///< Number of SFCW steps emitted.
    };
 
    /// FMCW waveform metadata captured for a streaming output file.
    struct FmcwMetadata
    {
        std::string waveform_shape = "linear"; ///< FMCW waveform shape token: linear or triangle.
        RealType chirp_bandwidth = 0.0; ///< Chirp bandwidth in hertz.
        RealType chirp_duration = 0.0; ///< Active chirp duration in seconds.
        RealType chirp_period = 0.0; ///< Chirp repetition period in seconds.
        RealType chirp_rate = 0.0; ///< Frequency sweep rate in hertz per second.
        RealType chirp_rate_signed = 0.0; ///< Signed frequency sweep rate in hertz per second.
        std::string chirp_direction = "up"; ///< Frequency sweep direction token.
        RealType start_frequency_offset = 0.0; ///< Start frequency offset relative to carrier in hertz.
        std::optional<std::uint64_t> chirp_count = std::nullopt; ///< Optional finite chirp count.
        std::optional<RealType> triangle_period = std::nullopt; ///< Full triangle period in seconds.
        std::optional<std::uint64_t> triangle_count = std::nullopt; ///< Optional finite triangle count.
    };
 
    /// Metadata for one active FMCW transmitter schedule segment.
    struct FmcwSourceSegmentMetadata
    {
        RealType start_time = 0.0; ///< Transmitter segment start time in seconds.
        RealType end_time = 0.0; ///< Transmitter segment end time in seconds.
        std::optional<RealType> first_chirp_start_time = std::nullopt; ///< First emitted chirp start in the segment.
        std::optional<std::uint64_t> emitted_chirp_count = std::nullopt; ///< Number of chirps emitted in the segment.
        std::optional<RealType> first_triangle_start_time =
            std::nullopt; ///< First emitted triangle start in the segment.
        std::optional<std::uint64_t> emitted_triangle_count = std::nullopt; ///< Number of triangles emitted.
    };
 
    /// Metadata for one FMCW illuminator represented in a streaming output file.
    struct FmcwSourceMetadata
    {
        SimId transmitter_id = 0; ///< FMCW transmitter SimId.
        std::string transmitter_name; ///< FMCW transmitter display name.
        SimId waveform_id = 0; ///< FMCW waveform SimId.
        std::string waveform_name; ///< FMCW waveform display name.
        RealType carrier_frequency = 0.0; ///< Waveform carrier frequency in hertz.
        FmcwMetadata waveform; ///< FMCW chirp parameters.
        std::vector<FmcwSourceSegmentMetadata> segments = {}; ///< Active transmitter segments.
    };
 
    /// SFCW waveform metadata captured for a streaming output file.
    struct SfcwMetadata
    {
        RealType carrier_frequency = 0.0; ///< Waveform carrier frequency in hertz.
        RealType start_frequency_offset = 0.0; ///< First-step offset relative to carrier in hertz.
        RealType step_size = 0.0; ///< Uniform frequency step in hertz.
        std::uint64_t step_count = 0; ///< Steps per sweep.
        RealType dwell_time = 0.0; ///< Active dwell time per step in seconds.
        RealType step_period = 0.0; ///< Step period in seconds.
        std::optional<std::uint64_t> sweep_count = std::nullopt; ///< Optional finite sweep count.
        RealType first_frequency = 0.0; ///< First RF step frequency in hertz.
        RealType last_frequency = 0.0; ///< Last RF step frequency in hertz.
        RealType frequency_span = 0.0; ///< First-to-last absolute span in hertz.
        RealType effective_bandwidth = 0.0; ///< DFT-convention effective bandwidth in hertz.
        RealType range_resolution = 0.0; ///< Approximate range resolution in meters.
        RealType unambiguous_range = 0.0; ///< Uniform-step unambiguous range in meters.
    };
 
    /// Metadata for one active SFCW transmitter schedule segment.
    struct SfcwSourceSegmentMetadata
    {
        RealType start_time = 0.0; ///< Transmitter segment start time in seconds.
        RealType end_time = 0.0; ///< Transmitter segment end time in seconds.
        std::optional<RealType> first_step_start_time = std::nullopt; ///< First emitted step start in the segment.
        std::optional<std::uint64_t> emitted_step_count = std::nullopt; ///< Number of step starts in the segment.
    };
 
    /// Metadata for one SFCW illuminator represented in a streaming output file.
    struct SfcwSourceMetadata
    {
        SimId transmitter_id = 0; ///< SFCW transmitter SimId.
        std::string transmitter_name; ///< SFCW transmitter display name.
        SimId waveform_id = 0; ///< SFCW waveform SimId.
        std::string waveform_name; ///< SFCW waveform display name.
        SfcwMetadata waveform; ///< SFCW waveform parameters.
        std::vector<SfcwSourceSegmentMetadata> segments = {}; ///< Active transmitter segments.
    };
 
    /// Metadata for one receiver output file.
    struct OutputFileMetadata
    {
        SimId receiver_id = 0; ///< Receiver SimId that owns the output file.
        std::string receiver_name; ///< Receiver display name.
        std::string mode; ///< Output mode label, such as pulsed or streaming.
        std::string path; ///< Filesystem path to the generated output file.
        RealType sampling_rate = 0.0; ///< Sample rate for this output file in hertz.
        std::uint64_t total_samples = 0; ///< Total sample count written to the file.
        std::uint64_t sample_start = 0; ///< Inclusive global sample index for the file start.
        std::uint64_t sample_end_exclusive = 0; ///< Exclusive global sample index for the file end.
        std::uint64_t pulse_count = 0; ///< Number of pulses represented in the file.
        std::uint64_t min_pulse_length_samples = 0; ///< Minimum pulse length in samples.
        std::uint64_t max_pulse_length_samples = 0; ///< Maximum pulse length in samples.
        bool uniform_pulse_length = true; ///< True when every pulse has the same sample length.
        std::vector<PulseChunkMetadata> chunks = {}; ///< Pulsed output chunks written to the file.
        std::vector<StreamingSegmentMetadata> streaming_segments = {}; ///< Streaming segments written to the file.
        std::optional<FmcwMetadata> fmcw = std::nullopt; ///< Optional FMCW metadata for streaming outputs.
        std::vector<FmcwSourceMetadata> fmcw_sources = {}; ///< FMCW illuminators represented in the output.
        std::optional<SfcwMetadata> sfcw = std::nullopt; ///< Optional SFCW metadata for streaming outputs.
        std::vector<SfcwSourceMetadata> sfcw_sources = {}; ///< SFCW illuminators represented in the output.
        std::string fmcw_dechirp_mode = "none"; ///< Receiver dechirp mode for FMCW streaming outputs.
        std::string fmcw_dechirp_reference_source = "none"; ///< Receiver dechirp reference source.
        std::optional<SimId> fmcw_dechirp_reference_transmitter_id = std::nullopt; ///< Referenced LO transmitter ID.
        std::optional<std::string> fmcw_dechirp_reference_transmitter_name = std::nullopt; ///< LO transmitter name.
        std::optional<SimId> fmcw_dechirp_reference_waveform_id = std::nullopt; ///< Custom LO waveform ID.
        std::optional<std::string> fmcw_dechirp_reference_waveform_name = std::nullopt; ///< Custom LO waveform name.
        std::optional<FmcwMetadata> fmcw_dechirp_reference_waveform = std::nullopt; ///< Custom LO waveform parameters.
        bool fmcw_if_decimation_enabled = false; ///< True when IF-rate resampling is used.
        bool fmcw_if_legacy_full_rate = false; ///< True for legacy full-rate dechirped IF output.
        std::optional<RealType> fmcw_if_requested_sample_rate = std::nullopt; ///< Requested IF ADC rate in hertz.
        std::optional<RealType> fmcw_if_sample_rate = std::nullopt; ///< Realized IF output sample rate in hertz.
        std::optional<RealType> fmcw_if_input_sample_rate = std::nullopt; ///< Input simulation sample rate in hertz.
        std::optional<unsigned> fmcw_if_resample_numerator = std::nullopt; ///< Reduced rational P.
        std::optional<unsigned> fmcw_if_resample_denominator = std::nullopt; ///< Reduced rational Q.
        std::optional<RealType> fmcw_if_decimation_factor = std::nullopt; ///< Input/output sample-rate ratio.
        std::optional<RealType> fmcw_if_filter_bandwidth = std::nullopt; ///< One-sided IF passband in hertz.
        std::optional<RealType> fmcw_if_filter_transition_width = std::nullopt; ///< IF transition width in hertz.
        std::optional<RealType> fmcw_if_filter_stopband = std::nullopt; ///< IF stopband attenuation in dB.
        std::optional<RealType> fmcw_if_filter_group_delay_seconds = std::nullopt; ///< Total filter delay.
        std::optional<std::uint64_t> fmcw_if_compensated_integer_delay_samples =
            std::nullopt; ///< Integer output-delay compensation.
        std::optional<RealType> fmcw_if_compensated_fractional_delay_samples =
            std::nullopt; ///< Fractional output-delay compensation.
        std::optional<std::uint64_t> fmcw_if_warmup_discard_samples =
            std::nullopt; ///< Startup outputs discarded by the sink.
        std::optional<unsigned> fmcw_if_phase_refinement = std::nullopt; ///< Polyphase refinement factor.
        std::optional<RealType> fmcw_if_timing_error_seconds = std::nullopt; ///< Estimated timing error.
        std::optional<RealType> fmcw_if_phase_error_radians = std::nullopt; ///< Estimated IF edge phase error.
        std::optional<RealType> fmcw_if_noise_variance = std::nullopt; ///< Post-resampling complex noise variance.
        bool fmcw_if_group_delay_compensated = false; ///< True when IF output timestamps are aligned to t_start.
    };
 
    /// Metadata for one VITA 49.2 receiver stream.
    struct Vita49StreamMetadata
    {
        SimId receiver_id = 0; ///< Receiver SimId that owns the VRT stream.
        std::string receiver_name; ///< Receiver display name.
        std::uint32_t stream_id = 0; ///< Allocated 32-bit VRT Stream ID.
        std::string mode = "unknown"; ///< Receiver mode token: pulsed, cw, fmcw, or unknown.
        RealType sample_rate = 0.0; ///< Stream sample rate in hertz.
        RealType reference_frequency = 0.0; ///< RF reference frequency in hertz.
        std::uint64_t packets_emitted = 0; ///< Signal data packets emitted.
        std::uint64_t samples_emitted = 0; ///< Complex samples emitted.
        std::uint64_t packets_dropped = 0; ///< Data packets lost to socket send failures.
        std::uint64_t samples_dropped = 0; ///< Complex samples lost to socket send failures.
        std::uint64_t over_range_count = 0; ///< Samples clipped by fixed full-scale scaling.
        std::uint64_t late_packet_count = 0; ///< Packets sent after their scheduled time.
        std::uint64_t context_packet_count = 0; ///< Context packets emitted for this stream.
        std::optional<RealType> first_sample_time = std::nullopt; ///< First signal sample time in seconds.
        std::optional<RealType> end_sample_time = std::nullopt; ///< Exclusive stream end sample time in seconds.
        std::optional<Vita49Timestamp> first_timestamp = std::nullopt; ///< First VRT UTC timestamp.
        std::optional<Vita49Timestamp> end_timestamp = std::nullopt; ///< Exclusive stream end VRT UTC timestamp.
    };
 
    /// Metadata for the VITA 49.2 UDP output backend.
    struct Vita49OutputMetadata
    {
        std::string endpoint_host; ///< Destination host.
        std::uint16_t endpoint_port = 0; ///< Destination UDP port.
        std::optional<std::uint64_t> epoch_unix_nanoseconds = std::nullopt; ///< Run epoch, if already fixed.
        RealType adc_fullscale = 0.0; ///< Fixed ADC full-scale used for int16 IQ scaling.
        std::uint16_t max_udp_payload = 1400; ///< Maximum UDP datagram payload in bytes.
        std::uint32_t queue_depth = 1024; ///< Bounded blocking sender queue depth in packets.
        std::string class_id = "0xFA52530001000101"; ///< Internal placeholder VRT Class ID.
        std::vector<Vita49StreamMetadata> streams = {}; ///< Per-receiver VRT stream metadata and stats.
    };
 
    /// Metadata summary for the full simulation output set.
    struct OutputMetadata
    {
        unsigned schema_version = 1; ///< Metadata schema version.
        std::string simulation_name; ///< Simulation name from the loaded scenario.
        std::string output_directory; ///< Directory containing generated output files.
        RealType start_time = 0.0; ///< Simulation start time in seconds.
        RealType end_time = 0.0; ///< Simulation end time in seconds.
        RealType sampling_rate = 0.0; ///< Output sampling rate in hertz.
        unsigned oversample_ratio = 1; ///< Oversampling ratio used during rendering.
        std::vector<OutputFileMetadata> files; ///< Metadata for each generated output file.
        std::optional<Vita49OutputMetadata> vita49 = std::nullopt; ///< Optional VITA 49.2 output metadata.
    };
 
    /// Thread-safe collector for simulation output metadata.
    class OutputMetadataCollector
    {
    public:
        /// Constructs a metadata collector for the specified output directory.
        explicit OutputMetadataCollector(std::string output_dir);
 
        /// Adds metadata for one generated output file.
        void addFile(OutputFileMetadata file_metadata);
 
        /// Returns a consistent snapshot of the collected metadata.
        [[nodiscard]] OutputMetadata snapshot() const;
 
    private:
        mutable std::mutex _mutex; ///< Mutex guarding the metadata aggregate.
        OutputMetadata _metadata; ///< Mutable aggregate metadata collected during simulation.
    };
 
    /// Serializes one output-file metadata entry to JSON.
    [[nodiscard]] std::string outputFileMetadataToJsonString(const OutputFileMetadata& metadata);
 
    /// Serializes a full simulation output metadata snapshot to JSON.
    [[nodiscard]] std::string outputMetadataToJsonString(const OutputMetadata& metadata);
 
    /// Builds the static VITA metadata section from runtime output configuration.
    [[nodiscard]] Vita49OutputMetadata vita49MetadataFromConfig(const Vita49OutputConfig& config);
}