Jungfraujoch/reader/HDF5ImageSource.h

// SPDX-FileCopyrightText: 2026 Filip Leonarski, Paul Scherrer Institute <filip.leonarski@psi.ch>
// SPDX-License-Identifier: GPL-3.0-only

#pragma once

#include <cstdint>
#include <optional>
#include <vector>

#include "HDF5ImageLocator.h"
#include "../common/CompressedImage.h"

// Raw-pixel side of the reader. Turns a global image number into a CompressedImage, using
// HDF5ImageLocator to find the file (with its open-file cache). This is the part whose "links
// to files stay" constant: switching which master the per-image metadata is read from never
// touches it. Caller must hold the global hdf5_mutex (HDF5 is not thread-safe).
class HDF5ImageSource {
public:
    void Configure(HDF5ImageLocator::Layout layout);
    void Clear();

    // Where image `global` physically lives. Also used by the metadata source to find the data
    // file that holds a legacy/VDS image's per-image metadata.
    HDF5ImageLocator::Location Resolve(int64_t global) const;

    // Read the pixels at a resolved location into a CompressedImage backed by `buffer`.
    CompressedImage ReadImageAt(std::vector<uint8_t> &buffer, const HDF5ImageLocator::Location &loc) const;

    std::vector<HDF5DataSourceMessage> GetSourceMapping(uint64_t first_image,
                                                        std::optional<uint64_t> image_count,
                                                        uint64_t total_images,
                                                        uint64_t stride = 1) const;

private:
    HDF5ImageLocator locator_;
    static CompressedImage LoadImageDataset(std::vector<uint8_t> &tmp, HDF5Object &file, hsize_t number);
};