#include <iostream>  // For standard input/output operations (e.g., std::cout, std::cerr)
#include <vector>    // For dynamic arrays (e.g., std::vector<float>)
#include <fstream>   // For file input/output operations (e.g., std::ifstream, std::ofstream)
#include <cstdint>   // For fixed-width integer types (e.g., int16_t, uint32_t)
#include <cmath>     // For mathematical functions (e.g., std::sin, M_PI, std::log)
#include <numeric>   // For numerical operations (e.g., std::iota)
#include <algorithm> // For algorithms like std::min, std::max
#include <string>    // For std::string

// Include the ONNX Runtime C++ API header
#include <onnxruntime_cxx_api.h>

// Include Eigen for powerful matrix operations.
// You need to download Eigen and set up your include paths.
// E.g., if Eigen is in 'C:/Libraries/eigen-3.4.0', you'd compile with -I C:/Libraries/eigen-3.4.0
#include <Eigen/Dense>

// Include KissFFT for Fast Fourier Transform.
// You need to download KissFFT and set up your include paths.
// E.g., if KissFFT is in 'C:/Libraries/kissfft-1.3.0', you'd compile with -I C:/Libraries/kissfft-1.3.0
// You also need to compile kiss_fft.c and kiss_fftr.c and link them.
#include <kiss_fft.h>
#include <kiss_fftr.h> // For real-valued FFT

// Define M_PI if it's not already defined by cmath or your compiler.
#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif

// --- Global parameters for feature extraction (matching Python script) ---
const float PREEMPHASIS_COEFF = 0.97f;
const int N_FFT = 512;       // FFT size
const int WIN_LENGTH = 400;  // Window length (samples)
const int HOP_LENGTH = 160;  // Hop length (samples)
const int N_MELS = 80;       // Number of Mel filterbank channels
const int TARGET_SAMPLE_RATE = 16000; // Target sample rate for feature extraction

// --- WAV File Header Structures ---
// These structures are for parsing the WAV file format.
// They assume little-endian byte order, which is standard for WAV files on most systems.
#pragma pack(push, 1) // Ensure no padding for these structures

struct WavHeader {
    char     riff_id[4];     // Contains "RIFF"
    uint32_t file_size;      // Size of the overall file - 8 bytes
    char     wave_id[4];     // Contains "WAVE"
    char     fmt_id[4];      // Contains "fmt " (note the space)
    uint32_t fmt_size;       // Size of the fmt chunk (16 for PCM)
    uint16_t audio_format;   // Audio format (1 for PCM)
    uint16_t num_channels;   // Number of channels (1 for mono, 2 for stereo)
    uint32_t sample_rate;    // Sample rate (e.g., 44100 Hz)
    uint32_t byte_rate;      // (SampleRate * NumChannels * BitsPerSample) / 8
    uint16_t block_align;    // (NumChannels * BitsPerSample) / 8
    uint16_t bits_per_sample;// Bits per sample (e.g., 16)
};

struct WavDataChunk {
    char     data_id[4];     // Contains "data"
    uint32_t data_size;      // Size of the data chunk
};

#pragma pack(pop) // Restore default packing alignment

/**
 * @brief Loads audio data from a WAV file into a float vector.
 *
 * This function reads a WAV file, parses its header, extracts 16-bit signed
 * integer PCM samples, converts them to floating-point values, and normalizes
 * them to the range [-1.0, 1.0]. It supports mono and stereo (converting stereo to mono
 * by averaging channels).
 *
 * @param filename The path to the WAV audio file.
 * @param actual_sample_rate Output parameter to store the sample rate read from the WAV file.
 * @return A std::vector<float> containing the normalized mono audio samples, or an empty
 * vector if the file cannot be opened or is not a supported WAV format.
 */
std::vector<float> loadWavToFloatArray(const std::string& filename, int& actual_sample_rate) {
    std::ifstream file(filename, std::ios::binary);
    if (!file.is_open()) {
        std::cerr << "Error: Could not open WAV file: " << filename << std::endl;
        return {};
    }

    WavHeader header;
    file.read(reinterpret_cast<char*>(&header), sizeof(WavHeader));

    // Basic header validation
    if (std::string(header.riff_id, 4) != "RIFF" ||
        std::string(header.wave_id, 4) != "WAVE" ||
        std::string(header.fmt_id, 4) != "fmt ") {
        std::cerr << "Error: Invalid WAV header (RIFF, WAVE, or fmt chunk missing/invalid)." << std::endl;
        file.close();
        return {};
    }

    if (header.audio_format != 1) { // 1 = PCM
        std::cerr << "Error: Only PCM audio format (1) is supported. Found: " << header.audio_format << std::endl;
        file.close();
        return {};
    }

    if (header.bits_per_sample != 16) {
        std::cerr << "Error: Only 16-bit PCM is supported. Found: " << header.bits_per_sample << " bits per sample." << std::endl;
        file.close();
        return {};
    }

    actual_sample_rate = header.sample_rate;
    std::cout << "WAV file info: Sample Rate=" << header.sample_rate
              << ", Channels=" << header.num_channels
              << ", Bit Depth=" << header.bits_per_sample << std::endl;

    // Find the "data" chunk
    WavDataChunk data_chunk;
    bool data_chunk_found = false;
    while (!file.eof()) {
        file.read(reinterpret_cast<char*>(&data_chunk.data_id), 4);
        file.read(reinterpret_cast<char*>(&data_chunk.data_size), 4);

        if (std::string(data_chunk.data_id, 4) == "data") {
            data_chunk_found = true;
            break;
        } else {
            // Skip unknown chunks
            file.seekg(data_chunk.data_size, std::ios::cur);
        }
    }

    if (!data_chunk_found) {
        std::cerr << "Error: 'data' chunk not found in WAV file." << std::endl;
        file.close();
        return {};
    }

    std::vector<float> audioData;
    int16_t sample_buffer;
    long num_samples_to_read = data_chunk.data_size / sizeof(int16_t);

    for (long i = 0; i < num_samples_to_read; ++i) {
        file.read(reinterpret_cast<char*>(&sample_buffer), sizeof(int16_t));
        float normalized_sample = static_cast<float>(sample_buffer) / 32768.0f;

        if (header.num_channels == 1) {
            audioData.push_back(normalized_sample);
        } else if (header.num_channels == 2) {
            // For stereo, read both left and right, then average for mono output
            // Read next sample (right channel)
            int16_t right_sample;
            if (file.read(reinterpret_cast<char*>(&right_sample), sizeof(int16_t))) {
                float normalized_right_sample = static_cast<float>(right_sample) / 32768.0f;
                audioData.push_back((normalized_sample + normalized_right_sample) / 2.0f);
                i++; // Increment i again as we read two samples
            } else {
                std::cerr << "Warning: Unexpected end of file while reading stereo data." << std::endl;
                break;
            }
        } else {
            std::cerr << "Error: Unsupported number of channels: " << header.num_channels << std::endl;
            file.close();
            return {};
        }
    }

    file.close();
    return audioData;
}

/**
 * @brief Generates a Hamming window.
 * @param window_length The length of the window.
 * @return A std::vector<float> containing the Hamming window coefficients.
 */
std::vector<float> generateHammingWindow(int window_length) {
    std::vector<float> window(window_length);
    for (int i = 0; i < window_length; ++i) {
        window[i] = 0.54f - 0.46f * std::cos(2 * M_PI * i / static_cast<float>(window_length - 1));
    }
    return window;
}

/**
 * @brief Extracts spectrogram features from waveform, matching Python's _extract_spectrogram.
 *
 * @param wav The input waveform (1D array of floats).
 * @param fs The sampling rate of the waveform (fixed to 16000 Hz for this model).
 * @return A 2D Eigen::MatrixXf representing the spectrogram (frames x (N_FFT/2 + 1)).
 */
Eigen::MatrixXf extractSpectrogram(const std::vector<float>& wav, int fs) {
    // Calculate number of frames
    int n_batch = (wav.size() - WIN_LENGTH) / HOP_LENGTH + 1;
    if (n_batch <= 0) {
        std::cerr << "Warning: Input waveform too short for feature extraction. Returning empty spectrogram." << std::endl;
        return Eigen::MatrixXf(0, N_FFT / 2 + 1);
    }

    // Generate Hamming window once
    std::vector<float> fft_window = generateHammingWindow(WIN_LENGTH);

    // Initialize KissFFT for real-valued input
    kiss_fftr_cfg fft_cfg = kiss_fftr_alloc(N_FFT, 0 /* is_inverse_fft */, nullptr, nullptr);
    if (!fft_cfg) {
        std::cerr << "Error: Failed to allocate KissFFT configuration." << std::endl;
        return Eigen::MatrixXf(0, N_FFT / 2 + 1);
    }

    // Output spectrogram matrix: rows = frames, columns = FFT bins
    Eigen::MatrixXf spec_matrix(n_batch, N_FFT / 2 + 1);

    std::vector<float> frame_buffer(WIN_LENGTH);
    kiss_fft_scalar fft_input[N_FFT]; // KissFFT requires input buffer of size N_FFT
    kiss_fft_cpx fft_output[N_FFT / 2 + 1]; // KissFFT real output size

    for (int i = 0; i < n_batch; ++i) {
        int start_idx = i * HOP_LENGTH;

        // Extract current frame
        for (int j = 0; j < WIN_LENGTH; ++j) {
            frame_buffer[j] = wav[start_idx + j];
        }

        // Apply pre-emphasis and scale by 32768 (as in Python)
        // Python: y_frames = (y_frames - preemphasis * y_frames_prev) * 32768
        // where y_frames_prev[:, 0] = y_frames_prev[:, 1]
        // This means for j=0, it's frame_buffer[0] - PREEMPHASIS_COEFF * frame_buffer[1]
        // For j>0, it's frame_buffer[j] - PREEMPHASIS_COEFF * frame_buffer[j-1]
        // Let's re-evaluate the pre-emphasis based on the Python snippet:
        // y_frames_prev = np.roll(y_frames, 1, axis=1)
        // y_frames_prev[:, 0] = y_frames_prev[:, 1]
        // This means the first element of `y_frames_prev` for each frame is the second element of `y_frames`.
        // So, for the first sample in a frame, it's `frame_buffer[0] - PREEMPHASIS_COEFF * frame_buffer[1]`.
        // For subsequent samples, it's `frame_buffer[j] - PREEMPHASIS_COEFF * frame_buffer[j-1]`.
        // This is a common pre-emphasis filter, but the first sample handling is specific.

        // Corrected pre-emphasis implementation to match the Python `np.roll` behavior:
        // The Python code effectively does:
        // preemphasized_sample[0] = frame_buffer[0] - PREEMPHASIS_COEFF * frame_buffer[1] (if WIN_LENGTH > 1)
        // preemphasized_sample[j] = frame_buffer[j] - PREEMPHASIS_COEFF * frame_buffer[j-1] for j > 0
        // If WIN_LENGTH is 1, then it's just frame_buffer[0] (no pre-emphasis)
        if (WIN_LENGTH > 0) {
            if (WIN_LENGTH > 1) {
                fft_input[0] = (frame_buffer[0] - PREEMPHASIS_COEFF * frame_buffer[1]) * 32768.0f;
                for (int j = 1; j < WIN_LENGTH; ++j) {
                    fft_input[j] = (frame_buffer[j] - PREEMPHASIS_COEFF * frame_buffer[j - 1]) * 32768.0f;
                }
            } else { // WIN_LENGTH == 1
                fft_input[0] = frame_buffer[0] * 32768.0f;
            }
        }
        // Zero-pad the rest of the FFT input if WIN_LENGTH < N_FFT
        for (int j = WIN_LENGTH; j < N_FFT; ++j) {
            fft_input[j] = 0.0f;
        }

        // Apply Hamming window
        for (int j = 0; j < WIN_LENGTH; ++j) {
            fft_input[j] *= fft_window[j];
        }

        // Perform real FFT
        kiss_fftr(fft_cfg, fft_input, fft_output);

        // Calculate magnitude spectrogram
        for (int j = 0; j <= N_FFT / 2; ++j) {
            spec_matrix(i, j) = std::sqrt(fft_output[j].r * fft_output[j].r + fft_output[j].i * fft_output[j].i);
        }
    }

    kiss_fftr_free(fft_cfg); // Free KissFFT configuration
    return spec_matrix;
}

/**
 * @brief Creates a Mel filter-bank matrix, matching Python's speechlib_mel.
 *
 * @param sample_rate Sample rate in Hz.
 * @param n_fft FFT size.
 * @param n_mels Mel filter size.
 * @param fmin Lowest frequency (in Hz).
 * @param fmax Highest frequency (in Hz).
 * @return An Eigen::MatrixXf representing the Mel transform matrix (n_mels x (1 + n_fft/2)).
 */
Eigen::MatrixXf speechlibMel(int sample_rate, int n_fft, int n_mels, float fmin, float fmax) {
    int bank_width = n_fft / 2 + 1;
    if (fmax == 0.0f) fmax = sample_rate / 2.0f; // Use 0.0f as a sentinel for None
    if (fmin == 0.0f) fmin = 0.0f; // Use 0.0f as a sentinel for None

    // Helper functions for Mel scale conversion
    auto mel = [](float f) { return 1127.0f * std::log(1.0f + f / 700.0f); };
    auto bin2mel = [&](int fft_bin) { return 1127.0f * std::log(1.0f + static_cast<float>(fft_bin) * sample_rate / (static_cast<float>(n_fft) * 700.0f)); };
    auto f2bin = [&](float f) { return static_cast<int>((f * n_fft / sample_rate) + 0.5f); };

    // Spec 1: FFT bin range [f2bin(fmin) + 1, f2bin(fmax)]
    int klo = f2bin(fmin) + 1;
    int khi = f2bin(fmax);
    khi = std::max(khi, klo);

    // Spec 2: SpeechLib uses triangles in Mel space
    float mlo = mel(fmin);
    float mhi = mel(fmax);
    
    // Generate Mel centers
    std::vector<float> m_centers(n_mels + 2);
    float ms = (mhi - mlo) / (n_mels + 1);
    for (int i = 0; i < n_mels + 2; ++i) {
        m_centers[i] = mlo + i * ms;
    }

    Eigen::MatrixXf matrix = Eigen::MatrixXf::Zero(n_mels, bank_width);

    for (int m = 0; m < n_mels; ++m) {
        float left = m_centers[m];
        float center = m_centers[m + 1];
        float right = m_centers[m + 2];
        for (int fft_bin = klo; fft_bin < bank_width; ++fft_bin) { // Loop up to bank_width-1
            float mbin = bin2mel(fft_bin);
            if (left < mbin && mbin < right) {
                matrix(m, fft_bin) = 1.0f - std::abs(center - mbin) / ms;
            }
        }
    }
    return matrix;
}

/**
 * @brief Extracts log filterbank features from waveform, matching Python's _extract_features.
 *
 * @param wav The input waveform (1D array of floats).
 * @param fs The sampling rate of the waveform (fixed to 16000 Hz).
 * @param mel_filterbank The pre-computed Mel filterbank matrix.
 * @return An Eigen::MatrixXf representing the log Mel filterbank features (frames x N_MELS).
 */
Eigen::MatrixXf extractFeatures(const std::vector<float>& wav, int fs, const Eigen::MatrixXf& mel_filterbank) {
    // Extract spectrogram
    Eigen::MatrixXf spec = extractSpectrogram(wav, fs);
    if (spec.rows() == 0) {
        return Eigen::MatrixXf(0, N_MELS); // Return empty matrix if spectrogram extraction failed
    }

    // spec_power = spec**2
    Eigen::MatrixXf spec_power = spec.array().square();

    // fbank_power = np.clip(spec_power.dot(_mel), 1.0, None)
    // Note: Eigen's matrix multiplication is `*`, not `dot`.
    // The Python `dot` for 2D arrays is matrix multiplication.
    // Python: (frames, N_FFT/2+1) . (N_FFT/2+1, N_MELS) -> (frames, N_MELS)
    // C++ Eigen: spec_power (rows, cols) * mel_filterbank (cols, N_MELS)
    // So, mel_filterbank should be (N_FFT/2+1, N_MELS)
    Eigen::MatrixXf fbank_power = spec_power * mel_filterbank.transpose(); // Transpose because Python's _mel is already transposed

    // Apply clipping: np.clip(..., 1.0, None)
    // This means any value less than 1.0 becomes 1.0.
    fbank_power = fbank_power.array().max(1.0f);

    // log_fbank = np.log(fbank_power).astype(np.float32)
    Eigen::MatrixXf log_fbank = fbank_power.array().log();

    return log_fbank;
}

// Function to write a dummy WAV file
void createDummyWavFile(const std::string& filename, int sampleRate, int numChannels, int bitsPerSample, double durationSeconds) {
    std::ofstream file(filename, std::ios::binary);
    if (!file.is_open()) {
        std::cerr << "Error: Could not create dummy WAV file: " << filename << std::endl;
        return;
    }

    WavHeader header;
    std::memcpy(header.riff_id, "RIFF", 4);
    std::memcpy(header.wave_id, "WAVE", 4);
    std::memcpy(header.fmt_id, "fmt ", 4);
    header.fmt_size = 16;
    header.audio_format = 1; // PCM
    header.num_channels = numChannels;
    header.sample_rate = sampleRate;
    header.bits_per_sample = bitsPerSample;
    header.byte_rate = (sampleRate * numChannels * bitsPerSample) / 8;
    header.block_align = (numChannels * bitsPerSample) / 8;

    WavDataChunk data_chunk;
    std::memcpy(data_chunk.data_id, "data", 4);
    uint32_t num_samples = static_cast<uint32_t>(sampleRate * durationSeconds);
    data_chunk.data_size = num_samples * numChannels * (bitsPerSample / 8);
    header.file_size = 36 + data_chunk.data_size; // 36 is size of header before data chunk

    file.write(reinterpret_cast<const char*>(&header), sizeof(WavHeader));
    file.write(reinterpret_cast<const char*>(&data_chunk), sizeof(WavDataChunk));

    // Generate a 440 Hz sine wave
    for (uint32_t i = 0; i < num_samples; ++i) {
        int16_t sample = static_cast<int16_t>(30000 * std::sin(2 * M_PI * 440 * i / static_cast<double>(sampleRate)));
        for (int c = 0; c < numChannels; ++c) {
            file.write(reinterpret_cast<const char*>(&sample), sizeof(int16_t));
        }
    }

    file.close();
    std::cout << "Dummy WAV file '" << filename << "' created successfully." << std::endl;
}


int main(int argc, char* argv[]) {
    // --- 1. Process command-line arguments ---
    if (argc != 3) {
        std::cerr << "Usage: " << argv[0] << " <path_to_onnx_model> <path_to_wav_file>" << std::endl;
        std::cerr << "Example: " << argv[0] << " model.onnx audio.wav" << std::endl;
        return 1;
    }

    std::string onnxModelPath = argv[1];
    std::string wavFilename = argv[2]; // Changed to wavFilename

    // --- Configuration for Audio and ONNX Model ---
    // These are fixed by the Python preprocessor code and model requirements.
    // The actual sample rate will be read from the WAV file.
    int actual_wav_sample_rate = 0;

    // --- Create a dummy WAV file if it doesn't exist for demonstration ---
    std::ifstream wavCheck(wavFilename, std::ios::binary);
    if (!wavCheck.is_open()) {
        std::cerr << "WAV file '" << wavFilename << "' not found. Creating a dummy one for demonstration." << std::endl;
        // Create a 2-second, 16kHz, mono, 16-bit WAV file
        createDummyWavFile(wavFilename, TARGET_SAMPLE_RATE, 1, 16, 2.0);
    } else {
        wavCheck.close();
    }

    // --- 2. Load WAV audio data into a float array ---
    std::vector<float> audioWav = loadWavToFloatArray(wavFilename, actual_wav_sample_rate);

    if (audioWav.empty()) {
        std::cerr << "Failed to load audio data from " << wavFilename << ". Exiting." << std::endl;
        return 1;
    }

    std::cout << "Successfully loaded " << audioWav.size() << " samples from " << wavFilename << std::endl;

    // --- Validate WAV sample rate against target sample rate ---
    if (actual_wav_sample_rate != TARGET_SAMPLE_RATE) {
        std::cerr << "Warning: WAV file sample rate (" << actual_wav_sample_rate
                  << " Hz) does not match the target sample rate for feature extraction ("
                  << TARGET_SAMPLE_RATE << " Hz)." << std::endl;
        std::cerr << "This example does NOT include resampling. Features will be extracted at "
                  << TARGET_SAMPLE_RATE << " Hz, which might lead to incorrect results if the WAV file's sample rate is different." << std::endl;
        // In a real application, you would implement resampling here (e.g., using libsamplerate).
    }


    // --- 3. Precompute Mel filterbank (as it's constant for a given sample rate/FFT size) ---
    // The Python example uses fmax=16000//2-80-230. This translates to TARGET_SAMPLE_RATE/2 - 80 - 230.
    // Using 0.0f for fmin as sentinel for None.
    float mel_fmax = static_cast<float>(TARGET_SAMPLE_RATE) / 2.0f - 80.0f - 230.0f;
    Eigen::MatrixXf mel_filterbank = speechlibMel(TARGET_SAMPLE_RATE, N_FFT, N_MELS, 0.0f, mel_fmax);

    if (mel_filterbank.rows() == 0 || mel_filterbank.cols() == 0) {
        std::cerr << "Error: Failed to create Mel filterbank. Exiting." << std::endl;
        return 1;
    }
    std::cout << "Mel filterbank created with shape: [" << mel_filterbank.rows() << ", " << mel_filterbank.cols() << "]" << std::endl;


    // --- 4. Apply feature extraction (preprocessor) ---
    std::cout << "Extracting features from audio..." << std::endl;
    Eigen::MatrixXf features = extractFeatures(audioWav, TARGET_SAMPLE_RATE, mel_filterbank);

    ///// check input
    // std::ofstream outputFile("matrix_output.txt");
    // // Check if the file was opened successfully
    // if (outputFile.is_open()) {
    //     // Iterate through rows and columns to write elements
    //     for (int i = 0; i < features.rows(); ++i) {
    //         for (int j = 0; j < features.cols(); ++j) {
    //             outputFile << features(i, j); // Write the element
    //             if (j < features.cols() - 1) {
    //                 outputFile << ","; // Add a space separator between elements in a row
    //             }
    //         }
    //         outputFile << std::endl; // Move to the next line after each row
    //     }
    //     outputFile.close(); // Close the file
    //     std::cout << "Matrix successfully written to matrix_output.txt" << std::endl;
    // }

    if (features.rows() == 0 || features.cols() == 0) {
        std::cerr << "Error: Feature extraction resulted in an empty matrix. Exiting." << std::endl;
        return 1;
    }
    std::cout << "Features extracted with shape: [" << features.rows() << ", " << features.cols() << "]" << std::endl;
    std::cout << "First few feature values (first frame): [";
    for (int i = 0; i < std::min((int)features.cols(), 5); ++i) {
        std::cout << features(0, i) << (i == std::min((int)features.cols(), 5) - 1 ? "" : ", ");
    }
    std::cout << "]" << std::endl;

    // --- 5. Check for ONNX model existence and provide guidance if missing ---
    std::ifstream onnxModelCheck(onnxModelPath, std::ios::binary);
    if (!onnxModelCheck.is_open()) {
        std::cerr << "\nError: ONNX model file '" << onnxModelPath << "' not found." << std::endl;
        std::cerr << "Please provide a valid ONNX model file. If you need a simple dummy one for testing, "
                  << "you can create it using Python (e.g., with PyTorch) like this:" << std::endl;
        std::cerr << "```python" << std::endl;
        std::cerr << "import torch" << std::endl;
        std::cerr << "import torch.nn as nn" << std::endl;
        std::cerr << "" << std::endl;
        std::cerr << "class SimpleAudioModel(nn.Module):" << std::endl;
        std::cerr << "    def __init__(self, input_frames, feature_size, output_size):" << std::endl;
        std::cerr << "        super(SimpleAudioModel, self).__init__()" << std::endl;
        std::cerr << "        # This model expects input of shape [batch_size, frames, feature_size]" << std::endl;
        std::cerr << "        # Example: a simple linear layer that flattens input and processes it." << std::endl;
        std::cerr << "        self.flatten = nn.Flatten()" << std::endl;
        std::cerr << "        self.linear = nn.Linear(input_frames * feature_size, output_size)" << std::endl;
        std::cerr << "" << std::endl;
        std::cerr << "    def forward(self, x):" << std::endl;
        std::cerr << "        x = self.flatten(x)" << std::endl;
        std::cerr << "        return self.linear(x)" << std::endl;
        std::cerr << "" << std::endl;
        std::cerr << "# --- IMPORTANT: Define model input and output sizes. Adjust these to match your actual model's requirements. ---" << std::endl;
        std::cerr << "# The C++ preprocessor will produce features of shape [frames, 80]." << std::endl;
        std::cerr << "# For a dummy model, we need to provide a fixed 'frames' value for ONNX export." << std::endl;
        std::cerr << "# A typical audio segment might be 2 seconds at 16kHz, which is 32000 samples." << std::endl;
        std::cerr << "# Frames = (32000 - 400) / 160 + 1 = 198.75 + 1 = 199 frames (approx)" << std::endl;
        std::cerr << "# Let's use a representative number of frames, e.g., 200 for a dummy input." << std::endl;
        std::cerr << "DUMMY_INPUT_FRAMES = 200 # This should be representative of your typical audio segment's frames" << std::endl;
        std::cerr << "DUMMY_FEATURE_SIZE = 80  # Fixed by the Mel filterbank (N_MELS)" << std::endl;
        std::cerr << "DUMMY_OUTPUT_SIZE = 10   # Example: 10 classification scores or features" << std::endl;
        std::cerr << "" << std::endl;
        std::cerr << "model = SimpleAudioModel(DUMMY_INPUT_FRAMES, DUMMY_FEATURE_SIZE, DUMMY_OUTPUT_SIZE)" << std::endl;
        std::cerr << "dummy_input_tensor = torch.randn(1, DUMMY_INPUT_FRAMES, DUMMY_FEATURE_SIZE) # Batch size 1" << std::endl;
        std::cerr << "" << std::endl;
        std::cerr << "torch.onnx.export(" << std::endl;
        std::cerr << "    model," << std::endl;
        std::cerr << "    dummy_input_tensor," << std::endl;
        std::cerr << "    \"model.onnx\"," << std::endl;
        std::cerr << "    verbose=True," << std::endl;
        std::cerr << "    input_names=['input'],   # Name of the input tensor in the ONNX graph" << std::endl;
        std::cerr << "    output_names=['output'], # Name of the output tensor in the ONNX graph" << std::endl;
        std::cerr << "    # Define dynamic axes for batch_size and frames" << std::endl;
        std::cerr << "    dynamic_axes={'input': {0: 'batch_size', 1: 'frames'}, 'output': {0: 'batch_size'}}" << std::endl;
        std::cerr << ")" << std::endl;
        std::cerr << "print(\"Dummy model.onnx created successfully. Remember to adjust DUMMY_INPUT_FRAMES in this script to match the expected number of frames from your audio segments.\")" << std::endl;
        std::cerr << "```" << std::endl;
        return 1;
    }
    onnxModelCheck.close();
    std::cout << "ONNX model '" << onnxModelPath << "' found. Proceeding with inference." << std::endl;


    // --- 6. ONNX Runtime Inference ---
    try {
        Ort::Env env(ORT_LOGGING_LEVEL_WARNING, "AudioInference");
        Ort::SessionOptions session_options;
        session_options.SetIntraOpNumThreads(1);
        session_options.SetGraphOptimizationLevel(ORT_ENABLE_EXTENDED);

        Ort::Session session(env, onnxModelPath.c_str(), session_options);
        Ort::AllocatorWithDefaultOptions allocator;

        // --- Get Input Node Information ---
        size_t numInputNodes = session.GetInputCount();
        std::vector<const char*> inputNodeNames(numInputNodes);

        std::cout << "\n--- Model Input Information ---" << std::endl;
        if (numInputNodes == 0) {
            std::cerr << "Error: Model has no input nodes. Exiting." << std::endl;
            return 1;
        }

        // Assuming a single input node for simplicity
        inputNodeNames[0] = "audio_embeds";
        Ort::TypeInfo type_info = session.GetInputTypeInfo(0);
        auto tensor_info = type_info.GetTensorTypeAndShapeInfo();
        std::vector<int64_t> actualInputShape = tensor_info.GetShape();

        std::cout << "  Input 0 : Name='" << inputNodeNames[0] << "', Shape=[";
        for (size_t j = 0; j < actualInputShape.size(); ++j) {
            // Print -1 for dynamic dimensions
            if (actualInputShape[j] == -1) {
                std::cout << "-1";
            } else {
                std::cout << actualInputShape[j];
            }
            std::cout << (j == actualInputShape.size() - 1 ? "" : ", ");
        }
        std::cout << "]" << std::endl;

        // --- Prepare Input Tensor Shape ---
        // The ONNX model input is [batch, frames, feature_size] = [-1, -1, 80]
        // Our extracted features are [frames, 80]. We need to add a batch dimension of 1.
        std::vector<int64_t> inputTensorShape = {1, features.rows(), features.cols()};
        std::cout << "  Preparing input tensor with shape: [" << inputTensorShape[0] << ", "
                  << inputTensorShape[1] << ", " << inputTensorShape[2] << "]" << std::endl;

        // Flatten the Eigen::MatrixXf into a std::vector<float> for ONNX Runtime
        // Eigen stores in column-major order by default. ONNX Runtime expects row-major
        // for flattened 2D data when reshaped to 3D [1, frames, features].
        // We need to copy elements row by row to ensure correct order.
        std::vector<float> inputTensorData(features.rows() * features.cols());
        for (int r = 0; r < features.rows(); ++r) {
            for (int c = 0; c < features.cols(); ++c) {
                inputTensorData[r * features.cols() + c] = features(r, c);
            }
        }

        Ort::MemoryInfo memory_info = Ort::MemoryInfo::CreateCpu(OrtArenaAllocator, OrtMemTypeDefault);
        Ort::Value inputTensor = Ort::Value::CreateTensor<float>(memory_info, inputTensorData.data(), inputTensorData.size(),
                                                                  inputTensorShape.data(), inputTensorShape.size());

        if (!inputTensor.IsTensor()) {
            std::cerr << "Error: Created input tensor is not valid! Exiting." << std::endl;
            return 1;
        }

        // --- Get Output Node Information ---
        size_t numOutputNodes = session.GetOutputCount();
        std::vector<const char*> outputNodeNames(numOutputNodes);

        std::cout << "\n--- Model Output Information ---" << std::endl;
        for (size_t k = 0; k < numOutputNodes; ++k) {
            outputNodeNames[k] = "audio_features";
            Ort::TypeInfo type_info_out = session.GetOutputTypeInfo(k);
            auto tensor_info_out = type_info_out.GetTensorTypeAndShapeInfo();
            std::vector<int64_t> outputShape = tensor_info_out.GetShape();
            std::cout << "  Output " << k << " : Name='" << outputNodeNames[k] << "', Shape=[";
            for (size_t l = 0; l < outputShape.size(); ++l) {
                if (outputShape[l] == -1) {
                    std::cout << "-1";
                } else {
                    std::cout << outputShape[l];
                }
                std::cout << (l == outputShape.size() - 1 ? "" : ", ");
            }
            std::cout << "]" << std::endl;
        }

        // --- Run Inference ---
        std::cout << "\nRunning ONNX model inference..." << std::endl;
        std::vector<Ort::Value> outputTensors = session.Run(Ort::RunOptions{nullptr},
                                                            inputNodeNames.data(), &inputTensor, 1,
                                                            outputNodeNames.data(), numOutputNodes);

        
        // std::ofstream output_file("f0.txt");
        // for (auto& ort_value : outputTensors) {
        //     // Example: Assuming Ort::Value contains a float tensor
        //     if (ort_value.IsTensor()) {
        //         float* data = ort_value.GetTensorMutableData<float>();
        //         Ort::TensorTypeAndShapeInfo info = ort_value.GetTensorTypeAndShapeInfo();
        //         size_t num_elements = info.GetElementCount();
    
        //         for (size_t i = 0; i < num_elements; ++i) {
        //             output_file << data[i];
        //             if (i < num_elements - 1) {
        //                 output_file << ","; // Space separator between elements
        //             }
        //         }
        //         output_file << std::endl; // Newline after each Ort::Value's content
        //     } else {
        //         // Handle other Ort::Value types if necessary (e.g., sequences, maps)
        //         output_file << "Non-tensor Ort::Value" << std::endl;
        //     }
        // }
        // output_file.close();

        // --- Process Output ---
        if (outputTensors.empty()) {
            std::cerr << "Error: No output tensors received from the model." << std::endl;
            return 1;
        }

        if (outputTensors[0].IsTensor()) {
            float* outputData = outputTensors[0].GetTensorMutableData<float>();
            Ort::TensorTypeAndShapeInfo outputShapeInfo = outputTensors[0].GetTensorTypeAndShapeInfo();
            std::vector<int64_t> outputShape = outputShapeInfo.GetShape();
            size_t outputSize = outputShapeInfo.GetElementCount();

            std::cout << "\n--- Model Inference Result (first few elements) ---" << std::endl;
            for (size_t k = 0; k < std::min((size_t)10, outputSize); ++k) {
                std::cout << outputData[k] << (k == std::min((size_t)10, outputSize) - 1 ? "" : ", ");
            }
            std::cout << std::endl;

            std::cout << "Full output tensor size: " << outputSize << " elements." << std::endl;
            std::cout << "Full output tensor shape: [";
            for (size_t k = 0; k < outputShape.size(); ++k) {
                std::cout << outputShape[k] << (k == outputShape.size() - 1 ? "" : ", ");
            }
            std::cout << "]" << std::endl;
        } else {
            std::cerr << "Error: First output tensor is not of the expected type (float tensor)." << std::endl;
        }

    } catch (const Ort::Exception& e) {
        std::cerr << "ONNX Runtime Exception: " << e.what() << std::endl;
        return 1;
    } catch (const std::exception& e) {
        std::cerr << "Standard Exception: " << e.what() << std::endl;
        return 1;
    }

    std::cout << "\nProgram finished successfully." << std::endl;
    return 0;
}