// 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 <string>
#include <vector>

// Where the panels of a stills detector lie and what their pixels are worth, as the XFEL readers
// gather it from a file's own metadata (or, while it is still read, a CrystFEL geometry file): the
// panels with their pixel ranges in the stored frame, fast/slow-scan directions and corners, the camera
// length, the pixel size, the gain and the regions to leave out. The conventions are CrystFEL's - a
// corner is the very corner of the panel's first pixel, x and y in pixels in the detector plane.
//
// Lengths are in pixels, except the camera length, which is held in metres. A value taken from the
// image files (a camera length or photon energy stated per shot) is kept as its path, with the factor
// that turns the stored number into the unit held here.
namespace xfel {

// A number stated in the layout, or a path to it in the image file, times scale.
struct Value {
    std::string path;              // empty: value holds the number
    double value = 0;
    double scale = 1;              // what one stored unit at path is worth
};

struct Panel {
    std::string name;
    int64_t min_fs = 0, max_fs = 0, min_ss = 0, max_ss = 0;   // inclusive, in the stored frame
    double fs_x = 1, fs_y = 0, ss_x = 0, ss_y = 1;
    double corner_x = 0, corner_y = 0;
    double res = 0;                // pixels per metre
    std::optional<Value> clen;     // metres
    double coffset = 0;            // metres
    std::optional<double> adu_per_eV;
    std::optional<double> adu_per_photon;
    std::optional<double> max_adu;
    int64_t mask_edge_pixels = 0;
    bool no_index = false;
};

// A region to leave out: either a pixel range on one panel (or, in the old syntax, on the whole
// frame), or a box in the laboratory plane, in pixels.
struct BadRegion {
    std::string panel;             // empty: fs/ss are whole-frame coordinates
    bool in_lab = false;
    double min_x = 0, max_x = 0, min_y = 0, max_y = 0;
    int64_t min_fs = 0, max_fs = 0, min_ss = 0, max_ss = 0;
};

// A mask array: a pixel is bad where it has any of bad's bits set, or lacks any of good's - or, with
// nonzero_good, where the array is zero.
struct Mask {
    std::string data;              // HDF5 path; a % in it stands for the shot group, as in the data path
    std::string file;              // file holding it, or empty for the image file itself
    uint32_t good = 0, bad = 0;
    bool nonzero_good = false;
    std::string panel;             // empty: every panel; otherwise only this panel's pixels

    bool operator==(const Mask &) const = default;

    // Whether a pixel the mask reads as v is bad, given the mask's good, bad and nonzero_good (passed rather than
    // read from the mask, so that a loop over the pixels keeps them in registers). Each term is false where its
    // field is unset; bitwise, so that the loop has no branch.
    [[nodiscard]] static bool Bad(uint32_t v, uint32_t good, uint32_t bad, bool nonzero_good) {
        return ((v & bad) != 0) | ((v & good) != good) | (nonzero_good & (v == 0));
    }
};

struct Layout {
    std::vector<Panel> panels;
    std::vector<BadRegion> bad;
    std::vector<Mask> masks;
    std::string data = "/data/data";
    std::optional<Value> photon_energy;   // eV
    std::optional<Value> wavelength;      // Angstrom; used where no photon_energy is stated
};

}  // namespace xfel