#include "actors/CurtainActor.hpp"

#include <vtkBandedPolyDataContourFilter.h>
#include <vtkDataSetSurfaceFilter.h>
#include <vtkDoubleArray.h>
#include <vtkNew.h>
#include <vtkPointData.h>
#include <vtkPoints.h>
#include <vtkPolyDataMapper.h>
#include <vtkStructuredGrid.h>

#include <vector>

#include <cstddef>

#include "ColorLutBuilder.hpp"

namespace geopro::render {

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

vtkSmartPointer<vtkActor> buildCurtain(const geopro::core::Grid& g,
                                       const geopro::core::ColorScale& cs,
                                       const geopro::core::GeoLocalFrame& frame)
{
    const int nx = g.nx(), ny = g.ny();

    // 退化网格：返回空 actor（调用方仍可安全 addActor，mapper 无输入则不绘制）。
    if (nx < 1 || ny < 1 || g.y.size() < static_cast<size_t>(ny)) {
        return vtkSmartPointer<vtkActor>::New();
    }

    const bool hasLatLon =
        g.lat.size() >= static_cast<size_t>(nx) && g.lon.size() >= static_cast<size_t>(nx);

    // 结构化网格：维度 (nx, ny, 1)，点序 i 最快、j 次之（id = j*nx + i）。
    vtkNew<vtkStructuredGrid> sgrid;
    sgrid->SetDimensions(nx, ny, 1);

    vtkNew<vtkPoints> points;
    points->SetNumberOfPoints(static_cast<vtkIdType>(nx) * ny);

    vtkNew<vtkDoubleArray> sc;
    sc->SetName("v");
    sc->SetNumberOfTuples(static_cast<vtkIdType>(nx) * ny);

    for (int j = 0; j < ny; ++j) {
        for (int i = 0; i < nx; ++i) {
            double px, py;
            if (hasLatLon) {
                auto p = frame.toLocal(g.lat[i], g.lon[i]);
                px = p.x;
                py = p.y;
            } else {
                // 退化：用 g.x[i] 作 x、0 作 y。
                px = (g.x.size() > static_cast<size_t>(i)) ? g.x[i] : static_cast<double>(i);
                py = 0.0;
            }
            const vtkIdType id = static_cast<vtkIdType>(j) * nx + i;
            // g.y 是深度(越大越深)；VTK Z 向上 → 取负，使深部在下、浅部在上(剖面不倒置)。
            points->SetPoint(id, px, py, -g.y[j]);
            sc->SetValue(id, g.valueAt(i, j));
        }
    }

    sgrid->SetPoints(points);
    sgrid->GetPointData()->SetScalars(sc);

    // 用 colorBar 真实分段值做色带(与数据详情#18一致的清晰色带，而非连续插值的糊色)。
    const std::vector<double> stops = cs.stopValues();
    double vmin, vmax;
    if (stops.size() >= 2) { vmin = stops.front(); vmax = stops.back(); }
    else {
        vmin = g.vmin; vmax = g.vmax;
        if (vmin >= vmax) {
            const auto& vals = g.values();
            vmin = vals.empty() ? 0.0 : vals.front(); vmax = vmin;
            for (double v : vals) { if (v < vmin) vmin = v; if (v > vmax) vmax = v; }
            if (vmin >= vmax) vmax = vmin + 1.0;
        }
    }

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

    // structuredGrid → 表面 polydata → banded contour(分段色带)
    vtkNew<vtkDataSetSurfaceFilter> surf;
    surf->SetInputData(sgrid);
    vtkNew<vtkBandedPolyDataContourFilter> banded;
    banded->SetInputConnection(surf->GetOutputPort());
    if (stops.size() >= 2) {
        banded->SetNumberOfContours(static_cast<int>(stops.size()));
        for (int i = 0; i < static_cast<int>(stops.size()); ++i) banded->SetValue(i, stops[i]);
    } else {
        banded->GenerateValues(20, vmin, vmax);
    }
    banded->SetScalarModeToValue();

    vtkNew<vtkPolyDataMapper> mapper;
    mapper->SetInputConnection(banded->GetOutputPort());
    mapper->SetScalarModeToUseCellData();
    mapper->SetLookupTable(lut);
    mapper->SetScalarRange(vmin, vmax);

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

}  // namespace geopro::render