#include "actors/ScatterActor.hpp"

#include <cstddef>
#include <vector>

#include <vtkCellArray.h>
#include <vtkDoubleArray.h>
#include <vtkNew.h>
#include <vtkPointData.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>

#include "ColorLutBuilder.hpp"

namespace geopro::render {

namespace {
// LUT 级数。
constexpr int kLutLevels = 256;
}  // namespace

vtkSmartPointer<vtkActor> buildScatter(const geopro::core::ScatterField& s,
                                       const geopro::core::ColorScale& cs,
                                       float pointSize)
{
    const std::size_t n = s.v.size();

    // 退化输入：无值或 x/y 长度不足 → 空 actor(调用方仍可安全 add，mapper 无输入则不绘制)。
    if (n == 0 || s.x.size() < n || s.y.size() < n) {
        return vtkSmartPointer<vtkActor>::New();
    }

    vtkNew<vtkPoints> points;
    points->SetNumberOfPoints(static_cast<vtkIdType>(n));

    vtkNew<vtkCellArray> verts;  // 每点一个 vtkVertex(GL_POINTS)，渲染为方块点

    vtkNew<vtkDoubleArray> sc;
    sc->SetName("v");
    sc->SetNumberOfTuples(static_cast<vtkIdType>(n));

    for (std::size_t i = 0; i < n; ++i) {
        const auto id = static_cast<vtkIdType>(i);
        // y=深度(越大越深)→取负，使深部在下、剖面不倒置(与 GridContourActor 一致)。
        points->SetPoint(id, s.x[i], -s.y[i], 0.0);
        verts->InsertNextCell(1, &id);
        sc->SetValue(id, s.v[i]);
    }

    vtkNew<vtkPolyData> poly;
    poly->SetPoints(points);
    poly->SetVerts(verts);
    poly->GetPointData()->SetScalars(sc);

    // 色阶范围：优先 colorBar 真实分段值(非均匀)，否则回退到 v 实测范围。
    const std::vector<double> stops = cs.stopValues();
    double vmin, vmax;
    if (stops.size() >= 2) {
        vmin = stops.front();
        vmax = stops.back();
    } else {
        vmin = s.v.front();
        vmax = vmin;
        for (double v : s.v) {
            if (v < vmin) vmin = v;
            if (v > vmax) vmax = v;
        }
        if (vmin >= vmax) vmax = vmin + 1.0;
    }

    auto lut = buildLut(cs, vmin, vmax, kLutLevels);

    vtkNew<vtkPolyDataMapper> mapper;
    mapper->SetInputData(poly);
    mapper->SetScalarModeToUsePointData();
    mapper->SetLookupTable(lut);
    mapper->SetScalarRange(vmin, vmax);

    auto actor = vtkSmartPointer<vtkActor>::New();
    actor->SetMapper(mapper);
    actor->GetProperty()->SetPointSize(pointSize);
    return actor;
}

}  // namespace geopro::render