Jungfraujoch/viewer/JFJochHttpReader.h

// SPDX-FileCopyrightText: 2025 Filip Leonarski, Paul Scherrer Institute <filip.leonarski@psi.ch>
// SPDX-License-Identifier: GPL-3.0-only

#pragma once

#include <curl/curl.h>

#include "../reader/JFJochReader.h"
#include "../common/BrokerStatus.h"
#include "../common/ImageBuffer.h"
#include "../common/ROIDefinition.h"

class JFJochHttpReader : public JFJochReader {
    mutable std::mutex http_mutex;
    std::string addr;

    // Persistent libcurl handle: created lazily on the first request (i.e. as soon as an address
    // is selected) and then reused for every subsequent request so the TCP/TLS connection is kept
    // alive. libcurl transparently reopens the connection if it was dropped (idle timeout,
    // server-side session limit, ...). curl_mutex serialises access because a single easy handle
    // must never be used from two threads at once; it is a leaf lock (nothing else is taken while
    // it is held), so it cannot deadlock with http_mutex.
    mutable std::mutex curl_mutex;
    mutable CURL *curl_handle = nullptr;

    std::optional<int64_t> last_image_buffer_counter;
    bool last_op_http_sync = false;

    // Cache of the (constant-per-acquisition) pixel mask, keyed on arm date, so the per-refresh
    // dataset rebuild reuses one shared mask instead of reconstructing it every tick.
    std::shared_ptr<const PixelMask> cached_pixel_mask;
    std::string cached_pixel_mask_arm_date;

    // Minimal HTTP result: whether a response arrived (transport-level success), the HTTP status
    // code, and the (possibly binary) response body.
    struct HttpResult {
        bool ok = false;
        long status = 0;
        std::string body;
    };
    // Single libcurl request helper behind every endpoint call. method is "GET" or "PUT"; for PUT
    // the body is sent with the given content_type.
    HttpResult Request(const std::string &method, const std::string &path,
                       const std::string &body = {}, const std::string &content_type = {}) const;

    // Tear down the persistent connection (on disconnect, when a new address is selected, and in
    // the destructor); the next Request transparently re-opens it.
    void ResetConnection() const;

    ImageBufferStatus GetImageBufferStatus() const;

    bool LoadImage_i(std::shared_ptr<JFJochReaderDataset> &dataset,
                     DataMessage& message,
                     std::vector<uint8_t> &buffer,
                     int64_t image_number,
                     bool update_dataset) override;
    std::shared_ptr<JFJochReaderDataset> UpdateDataset_i();
    std::vector<float> GetPlot_i(const std::string &plot_type, float fill_value = 0.0) const;
public:
    ~JFJochHttpReader() override;

    void ReadURL(const std::string& url);
    uint64_t GetNumberOfImages() const override;
    void Close() override;

    // Refresh dataset/plots if the image buffer changed since the last poll (returns nullptr if
    // unchanged). Always writes the current number of images to num_images_out. Does not load an image.
    std::shared_ptr<const JFJochReaderDataset> RefreshDatasetIfChanged(int64_t &num_images_out);

    void UploadUserMask(const std::vector<uint32_t>& mask);

    [[nodiscard]] ROIDefinition GetROIDefinitions() const;          // GET  /config/roi
    void UploadROIDefinitions(const ROIDefinition &rois) const;     // PUT  /config/roi

    BrokerStatus GetBrokerStatus() const;

    std::shared_ptr<JFJochReaderRawImage> GetRawImage(int64_t image_number) override;
    std::vector<SpotToSave> ReadSpots(int64_t image) const override;
};