#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"
#include "panels/chart/ContourSimplify.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 double kLabelMinLenPx = 24.0;   // 整条线像素长度小于此不标注（极短碎线）
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();
        linesRaw_.clear();
        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);
        linesRaw_ = std::move(res.lines);
        lines_ = linesRaw_;
        // 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());
        linesRaw_ = lines_;        // level 回填后同步到原始集（简化保留 level）。
        applySimplify();           // 按当前容差抽稀（首次 tol=0 即原样）。
    } else {
        linesRaw_.clear();
        lines_.clear();
    }
}

void ContourPlotItem::setSimplifyTolerance(double tol) {
    simplifyTol_ = tol < 0.0 ? 0.0 : tol;
    applySimplify();
}

void ContourPlotItem::applySimplify() {
    if (simplifyTol_ <= 0.0) {
        lines_ = linesRaw_;
        return;
    }
    lines_.clear();
    lines_.reserve(linesRaw_.size());
    for (const auto& ln : linesRaw_) {
        render::ContourLine s;
        s.level = ln.level;
        s.pts = douglasPeucker(ln.pts, simplifyTol_);
        lines_.push_back(std::move(s));
    }
}

double ContourPlotItem::contourLevelNear(double dataX, double dataY, double hitDataRadius) const {
    // 在已绘制等值线（简化后）找最近线段，命中半径内返回该线 level。
    double bestD2 = hitDataRadius * hitDataRadius;
    double bestLevel = std::nan("");
    for (const auto& ln : lines_) {
        if (std::isnan(ln.level)) continue;
        for (std::size_t i = 1; i < ln.pts.size(); ++i) {
            const auto& a = ln.pts[i - 1];
            const auto& b = ln.pts[i];
            const double dx = b.x - a.x, dy = b.y - a.y;
            const double len2 = dx * dx + dy * dy;
            double t = len2 > 0 ? ((dataX - a.x) * dx + (dataY - a.y) * dy) / len2 : 0.0;
            t = std::clamp(t, 0.0, 1.0);
            const double px = a.x + t * dx, py = a.y + t * dy;
            const double d2 = (dataX - px) * (dataX - px) + (dataY - py) * (dataY - py);
            if (d2 < bestD2) { bestD2 = d2; bestLevel = ln.level; }
        }
    }
    return bestLevel;
}

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**统一比例**降采样（W/H 独立截断会使采样非均匀→内容横/纵失真）。
    if (W > kMaxFillDim || H > kMaxFillDim) {
        const double s = std::min(static_cast<double>(kMaxFillDim) / W,
                                  static_cast<double>(kMaxFillDim) / H);
        W = std::max(2, static_cast<int>(W * s));
        H = std::max(2, static_cast<int>(H * s));
    }

    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_;
}

QRectF ContourPlotItem::anomalyBoundingRect(int index) const {
    if (index < 0 || index >= static_cast<int>(anoms_.size())) return {};
    const auto& pts = anoms_[index].localPts;
    if (pts.empty()) return {};
    double minX = pts.front().x, maxX = pts.front().x;
    double minY = pts.front().y, maxY = pts.front().y;
    for (const auto& p : pts) {
        minX = std::min(minX, p.x); maxX = std::max(maxX, p.x);
        minY = std::min(minY, p.y); maxY = std::max(maxY, p.y);
    }
    return QRectF(minX, minY, maxX - minX, maxY - minY);
}

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：按线形⚙ 配置取色/虚实（默认黑实线）。
    if (showLines_ && !lines_.empty()) {
        painter->save();
        painter->setRenderHint(QPainter::Antialiasing, true);
        QPen pen(QColor(lineColor_.r, lineColor_.g, lineColor_.b, lineColor_.a));
        pen.setWidthF(1.0);  // 1px 等值线
        pen.setStyle(lineDashed_ ? Qt::DashLine : Qt::SolidLine);
        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：每条等值线只标一个（对齐原版），放弧长中点，随该处方向旋转。
        if (showLabels_) {
            painter->save();
            painter->setRenderHint(QPainter::Antialiasing, true);
            QFont f = painter->font();
            f.setPixelSize(kLabelFontPx);
            painter->setFont(f);
            painter->setPen(QColor(labelColor_.r, labelColor_.g, labelColor_.b, labelColor_.a));
            const QFontMetricsF fm(f);
            for (const auto& ln : lines_) {
                if (ln.pts.size() < 2 || std::isnan(ln.level)) continue;
                // 映射到像素 + 累计像素弧长。
                std::vector<QPointF> px;
                px.reserve(ln.pts.size());
                for (const auto& p : ln.pts) px.push_back(mapPt(p));
                double total = 0.0;
                for (std::size_t i = 1; i < px.size(); ++i)
                    total += std::hypot(px[i].x() - px[i - 1].x(), px[i].y() - px[i - 1].y());
                if (total < kLabelMinLenPx) continue;  // 极短碎线不标注
                const QString txt = QString::number(ln.level, 'g', 4);
                const double halfW = fm.horizontalAdvance(txt) * 0.5;
                const double targetAt = total * 0.5;  // 弧长中点
                double acc = 0.0;
                for (std::size_t i = 1; i < px.size(); ++i) {
                    const double seg =
                        std::hypot(px[i].x() - px[i - 1].x(), px[i].y() - px[i - 1].y());
                    if (acc + seg >= targetAt || i == px.size() - 1) {
                        const double t = seg > 1e-6 ? (targetAt - acc) / seg : 0.0;
                        const QPointF pos(px[i - 1].x() + (px[i].x() - px[i - 1].x()) * t,
                                          px[i - 1].y() + (px[i].y() - px[i - 1].y()) * t);
                        double ang =
                            std::atan2(px[i].y() - px[i - 1].y(), px[i].x() - px[i - 1].x()) *
                            kRad2Deg;
                        if (ang > 90.0) ang -= 180.0;  // 文字大体正向
                        if (ang < -90.0) ang += 180.0;
                        painter->save();
                        painter->translate(pos);
                        painter->rotate(ang);
                        painter->drawText(QPointF(-halfW, -2), txt);
                        painter->restore();
                        break;  // 只标一个
                    }
                    acc += seg;
                }
            }
            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 (int ai = 0; ai < static_cast<int>(anoms_.size()); ++ai) {
            const auto& a = anoms_[ai];
            if (a.localPts.empty()) continue;
            const bool hl = (ai == highlightIdx_);  // I12 当前定位高亮
            QColor col(QString::fromStdString(a.lineColor));
            if (!col.isValid()) col = QColor(0, 0, 0);
            QPen pen(hl ? QColor(255, 255, 0) : col);  // 高亮黄（对照原版 #ffff00）
            pen.setWidthF(hl ? std::max(3.0, a.lineWidth) : (a.lineWidth > 0 ? a.lineWidth : 1.0));
            pen.setStyle(hl ? Qt::SolidLine : (a.dashed ? Qt::DashLine : Qt::SolidLine));
            painter->setPen(pen);

            if (a.markType == core::AnomalyMarkType::Point) {
                const QPointF c = mapPt(a.localPts.front());
                const double r = hl ? 5.0 : 3.0;
                painter->drawRect(QRectF(c.x() - r, c.y() - r, 2 * r, 2 * r));
            } 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