File PointSpatialIndex.hpp

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//
// SPDX-FileCopyrightText: 2026 Michal Grabarczyk
// SPDX-License-Identifier: GPL-3.0-only WITH Universal-FOSS-exception-1.0
//
// This file is also available under a separate commercial license.
// See COMMERCIAL-LICENSING.md for contact information.
//
#pragma once

#include <QtGlobal>

#include <vector>

namespace QAccelPlot {

class PointSpatialIndex {
public:
    struct Mapping {
        bool logX{false}; 
        bool logY{false}; 

        bool operator==(const Mapping& other) const;
    };

    void build(const float* data, int pointCount, int stride, Mapping mapping);
    void build(const float* data, int pointCount, int stride = 2);
    void clear();

    bool isEmpty() const;
    int validPointCount() const;
    int columnCount() const;
    int rowCount() const;
    Mapping mapping() const;

    int nearest(double x, double y, double radiusX, double radiusY) const;

    static int nearestByScan(const float* data, int pointCount, int stride, Mapping mapping, double x, double y, double radiusX, double radiusY);

    static bool mapCoordinate(double value, bool logarithmic, double& mapped);

private:
    struct IndexedPoint {
        float x;
        float y;
        int sourceIndex;
    };

    void collectValidPoints(const float* data, int pointCount, int stride);
    void computeGridDimensions();
    void fillCells();
    int cellColumn(double x) const;
    int cellRow(double y) const;

    Mapping mapping_;
    double minX_{0.0};
    double minY_{0.0};
    double cellWidth_{1.0};
    double cellHeight_{1.0};
    int columns_{0};
    int rows_{0};
    std::vector<IndexedPoint> points_;
    std::vector<int> cellStart_;   // columns_ * rows_ + 1 offsets into cellEntries_
    std::vector<int> cellEntries_; // positions in points_, grouped by cell
};

} // namespace QAccelPlot