#include "panels/chart/ContourPlotItem.hpp"

#include <algorithm>
#include <cmath>

#include <QFont>
#include <QPainter>
#include <QPen>
#include <QPolygonF>
#include <qwt_plot.h>
#include <qwt_scale_map.h>

#include "panels/chart/ColorMapService.hpp"

namespace geopro::app {

namespace {
constexpr int kFillUpsample = 4;        // 填充图像每网格格细分 K（双线性插值平滑带边界）
constexpr int kMaxFillDim = 2400;       // 填充图像单边像素上限（防极端网格爆内存）
constexpr int kLabelFontPx = 10;        // 等值线标注字号
constexpr int kLabelMinSegPx = 60;      // 太短的等值线不标注（像素长度阈值，draw 期判定）
constexpr double kRad2Deg = 57.29577951308232;  // 180/π（避免依赖 M_PI）
}  // namespace

ContourPlotItem::ContourPlotItem() : QwtPlotItem() {
    setRenderHint(QwtPlotItem::RenderAntialiased, false);
    // 网格数据 x 轴在底部（与 RawDataChartView 的顶部 x 轴不同）；y 轴在左。
    setXAxis(QwtPlot::xBottom);
    setYAxis(QwtPlot::yLeft);
}

void ContourPlotItem::setData(const core::Grid& g, ColorMapService* svc,
                              const std::vector<core::Anomaly>& anoms, bool showLines,
                              bool showLabels) {
    showLines_ = showLines;
    showLabels_ = showLabels;
    anoms_ = anoms;

    const int nx = g.nx(), ny = g.ny();
    if (nx < 2 || ny < 2 || static_cast<int>(g.x.size()) < nx ||
        static_cast<int>(g.y.size()) < ny) {
        fillImage_ = QImage();
        dataBBox_ = QRectF();
        lines_.clear();
        return;
    }

    const double xmin = g.x.front(), xmax = g.x.back();
    const double ymin = g.y.front(), ymax = g.y.back();
    dataBBox_ = QRectF(xmin, ymin, xmax - xmin, ymax - ymin);

    buildFillImage(g, svc);

    // 等值线（矢量）：复用 render 管线，仅取 lines（填充走栅格）。
    if (showLines_) {
        render::ContourOptions opt;
        opt.upsample = 2;
        opt.makeLines = true;
        auto res = render::buildContourBands(g, svc->scale(), opt);
        lines_ = std::move(res.lines);
        // buildContourBands 当前未回填 level（恒 0）；在此按线上代表点采网格值并吸附到最近色阶级，
        // 使标注显示真实等值线值。
        resolveLineLevels(g, svc->scale());
    } else {
        lines_.clear();
    }
}

void ContourPlotItem::resolveLineLevels(const core::Grid& g, const core::ColorScale& cs) {
    const auto stops = cs.stopValues();
    if (stops.empty() || lines_.empty()) return;

    const int nx = g.nx(), ny = g.ny();
    const double xmin = g.x.front(), xmax = g.x.back();
    const double ymin = g.y.front(), ymax = g.y.back();
    const double xspan = (xmax - xmin), yspan = (ymax - ymin);

    // 在数据坐标点做双线性采样（NaN 安全）。
    auto sampleAt = [&](const core::Vec2& p) -> double {
        if (xspan <= 0 || yspan <= 0) return std::nan("");
        double fi = (p.x - xmin) / xspan * (nx - 1);
        double fj = (p.y - ymin) / yspan * (ny - 1);
        fi = std::clamp(fi, 0.0, static_cast<double>(nx - 1));
        fj = std::clamp(fj, 0.0, static_cast<double>(ny - 1));
        int i0 = std::min(static_cast<int>(fi), nx - 2);
        int j0 = std::min(static_cast<int>(fj), ny - 2);
        double ti = fi - i0, tj = fj - j0;
        double v00 = g.valueAt(i0, j0), v10 = g.valueAt(i0 + 1, j0);
        double v01 = g.valueAt(i0, j0 + 1), v11 = g.valueAt(i0 + 1, j0 + 1);
        if (std::isnan(v00) || std::isnan(v10) || std::isnan(v01) || std::isnan(v11))
            return std::nan("");
        return (v00 * (1 - ti) + v10 * ti) * (1 - tj) + (v01 * (1 - ti) + v11 * ti) * tj;
    };

    for (auto& ln : lines_) {
        double sampled = std::nan("");
        for (const auto& p : ln.pts) {  // 取首个非 NaN 采样点
            sampled = sampleAt(p);
            if (!std::isnan(sampled)) break;
        }
        if (std::isnan(sampled)) {
            ln.level = std::nan("");
            continue;
        }
        // 吸附到最近色阶级（等值线恰落在某级上）。
        double best = stops.front();
        double bestD = std::fabs(sampled - best);
        for (double s : stops) {
            double d = std::fabs(sampled - s);
            if (d < bestD) { bestD = d; best = s; }
        }
        ln.level = best;
    }
}

void ContourPlotItem::buildFillImage(const core::Grid& g, ColorMapService* svc) {
    const int nx = g.nx(), ny = g.ny();
    int W = (nx - 1) * kFillUpsample + 1;
    int H = (ny - 1) * kFillUpsample + 1;
    // 限幅：极端网格下按比例降采样，保证内存/性能可控。
    if (W > kMaxFillDim) W = kMaxFillDim;
    if (H > kMaxFillDim) H = kMaxFillDim;

    QImage img(W, H, QImage::Format_ARGB32);
    img.fill(Qt::transparent);

    // 每像素 → 归一化网格坐标 (fi,fj) → 四邻格双线性插值；任一邻格 NaN 则该像素透明。
    for (int py = 0; py < H; ++py) {
        // 图像顶行 py=0 对应 y 最大（ymax，地表）；底行对应 y 最小（最深）。
        double fj = static_cast<double>(H - 1 - py) / (H - 1) * (ny - 1);
        int j0 = std::min(static_cast<int>(fj), ny - 2);
        double tj = fj - j0;
        auto* scan = reinterpret_cast<QRgb*>(img.scanLine(py));
        for (int px = 0; px < W; ++px) {
            double fi = static_cast<double>(px) / (W - 1) * (nx - 1);
            int i0 = std::min(static_cast<int>(fi), nx - 2);
            double ti = fi - i0;

            double v00 = g.valueAt(i0, j0), v10 = g.valueAt(i0 + 1, j0);
            double v01 = g.valueAt(i0, j0 + 1), v11 = g.valueAt(i0 + 1, j0 + 1);
            if (std::isnan(v00) || std::isnan(v10) || std::isnan(v01) || std::isnan(v11))
                continue;  // 含无数据格 → 像素透明（不规则白边）

            double v = (v00 * (1 - ti) + v10 * ti) * (1 - tj) +
                       (v01 * (1 - ti) + v11 * ti) * tj;
            auto c = svc->colorAtDiscrete(v);  // 离散色带 → 平滑填充带边界
            scan[px] = qRgba(c.r, c.g, c.b, c.a ? c.a : 255);
        }
    }
    fillImage_ = std::move(img);
}

QRectF ContourPlotItem::boundingRect() const {
    return dataBBox_;
}

void ContourPlotItem::draw(QPainter* painter, const QwtScaleMap& xMap, const QwtScaleMap& yMap,
                           const QRectF& /*canvasRect*/) const {
    if (dataBBox_.isNull()) return;

    const double xmin = dataBBox_.left(), xmax = dataBBox_.right();
    const double ymin = dataBBox_.top(), ymax = dataBBox_.bottom();

    // 1) 填充：数据 bbox → 像素矩形（注意 y 翻转：ymax→画布上沿、ymin→下沿），blit + 平滑缩放。
    if (!fillImage_.isNull()) {
        const double pxL = xMap.transform(xmin);
        const double pxR = xMap.transform(xmax);
        const double pyTop = yMap.transform(ymax);
        const double pyBot = yMap.transform(ymin);
        QRectF target(pxL, pyTop, pxR - pxL, pyBot - pyTop);
        painter->save();
        painter->setRenderHint(QPainter::SmoothPixmapTransform, true);
        painter->drawImage(target, fillImage_);
        painter->restore();
    }

    auto mapPt = [&](const core::Vec2& p) {
        return QPointF(xMap.transform(p.x), yMap.transform(p.y));
    };

    // 2) 等值线：黑色 0 宽（cosmetic）细线。
    if (showLines_ && !lines_.empty()) {
        painter->save();
        painter->setRenderHint(QPainter::Antialiasing, true);
        QPen pen(QColor(0, 0, 0));
        pen.setWidthF(1.0);  // 1px 黑色等值线
        painter->setPen(pen);
        for (const auto& ln : lines_) {
            if (ln.pts.size() < 2) continue;
            QPolygonF poly;
            poly.reserve(static_cast<int>(ln.pts.size()));
            for (const auto& p : ln.pts) poly << mapPt(p);
            painter->drawPolyline(poly);
        }
        painter->restore();

        // 3) 标注：沿线中段画 level 数值（小字黑，随相邻两点方向旋转）。
        if (showLabels_) {
            painter->save();
            painter->setRenderHint(QPainter::Antialiasing, true);
            QFont f = painter->font();
            f.setPixelSize(kLabelFontPx);
            painter->setFont(f);
            painter->setPen(QColor(0, 0, 0));
            for (const auto& ln : lines_) {
                if (ln.pts.size() < 2 || std::isnan(ln.level)) continue;
                // 取折线中段两点定位置/朝向。
                const std::size_t mid = ln.pts.size() / 2;
                const QPointF a = mapPt(ln.pts[mid - 1]);
                const QPointF b = mapPt(ln.pts[mid]);
                // 整条线像素长度太短不标注（避免密集杂乱）。
                const QPointF s = mapPt(ln.pts.front());
                const QPointF e = mapPt(ln.pts.back());
                if (std::hypot(e.x() - s.x(), e.y() - s.y()) < kLabelMinSegPx) continue;
                double ang = std::atan2(b.y() - a.y(), b.x() - a.x()) * kRad2Deg;
                if (ang > 90.0) ang -= 180.0;  // 保持文字大体正向（不上下颠倒）
                if (ang < -90.0) ang += 180.0;
                const QString txt = QString::number(ln.level, 'g', 4);
                painter->save();
                painter->translate((a.x() + b.x()) * 0.5, (a.y() + b.y()) * 0.5);
                painter->rotate(ang);
                painter->drawText(QPointF(-12, -2), txt);
                painter->restore();
            }
            painter->restore();
        }
    }

    // 4) 异常叠加：点=小方块、线=折线、面=闭合多边形；颜色用 lineColor，dashed→虚线。
    if (showAnomalies_ && !anoms_.empty()) {
        painter->save();
        painter->setRenderHint(QPainter::Antialiasing, true);
        painter->setBrush(Qt::NoBrush);
        for (const auto& a : anoms_) {
            if (a.localPts.empty()) continue;
            QColor col(QString::fromStdString(a.lineColor));
            if (!col.isValid()) col = QColor(0, 0, 0);
            QPen pen(col);
            pen.setWidthF(a.lineWidth > 0 ? a.lineWidth : 1.0);
            pen.setStyle(a.dashed ? Qt::DashLine : Qt::SolidLine);
            painter->setPen(pen);

            if (a.markType == core::AnomalyMarkType::Point) {
                const QPointF c = mapPt(a.localPts.front());
                painter->drawRect(QRectF(c.x() - 3, c.y() - 3, 6, 6));
            } else {
                QPolygonF poly;
                poly.reserve(static_cast<int>(a.localPts.size()));
                for (const auto& p : a.localPts) poly << mapPt(p);
                if (a.markType == core::AnomalyMarkType::Polygon)
                    painter->drawPolygon(poly);  // 闭合
                else
                    painter->drawPolyline(poly);
            }
        }
        painter->restore();
    }
}

}  // namespace geopro::app