#include "fiko/geometri/poligon_ofset.hpp"

#include <cmath>

#include <BRepAdaptor_Curve.hxx>
#include <BRepAlgoAPI_Cut.hxx>
#include <BRepAlgoAPI_Fuse.hxx>
#include <BRepBuilderAPI_MakeFace.hxx>
#include <BRepBuilderAPI_MakePolygon.hxx>
#include <BRepOffsetAPI_MakeOffset.hxx>
#include <BRepTools_WireExplorer.hxx>
#include <BRep_Tool.hxx>
#include <GCPnts_QuasiUniformDeflection.hxx>
#include <GeomAbs_JoinType.hxx>
#include <Standard_Failure.hxx>
#include <TopExp_Explorer.hxx>
#include <TopoDS.hxx>
#include <TopoDS_Edge.hxx>
#include <TopoDS_Face.hxx>
#include <TopoDS_Shape.hxx>
#include <TopoDS_Wire.hxx>
#include <gp_Pln.hxx>
#include <gp_Pnt.hxx>

namespace fiko::geometri {

namespace {

constexpr f64 SAPMA = 0.01;  // egri (yay) dogrusallastirma sapmasi (mm)

// XY poligonundan kapali OCCT wire (Z=0 duzleminde). <3 nokta → bos.
TopoDS_Wire wireYap(const Poligon& p) {
  if (p.size() < 3) return {};
  BRepBuilderAPI_MakePolygon mp;
  for (const Vec2d& n : p) mp.Add(gp_Pnt(n.x, n.y, 0.0));
  mp.Close();
  return mp.IsDone() ? mp.Wire() : TopoDS_Wire{};
}

// Wire'i dogrusallastirilmis kapali XY poligonuna cevir (son != ilk).
Poligon wireCevir(const TopoDS_Wire& w) {
  Poligon out;
  for (BRepTools_WireExplorer ex(w); ex.More(); ex.Next()) {
    BRepAdaptor_Curve c(ex.Current());
    GCPnts_QuasiUniformDeflection ornek(c, SAPMA);
    if (!ornek.IsDone()) continue;
    const bool ters = ex.Current().Orientation() == TopAbs_REVERSED;
    const int n = ornek.NbPoints();
    // Son noktayi atla (bir sonraki kenarin ilkiyle cakisir).
    for (int k = 1; k < n; ++k) {
      const int idx = ters ? n - k + 1 : k;
      const gp_Pnt g = ornek.Value(idx);
      out.push_back({g.X(), g.Y()});
    }
  }
  return out;
}

// Poligon isaretli alani (shoelace). Pozitif = CCW.
f64 isaretliAlan(const Poligon& p) {
  f64 a = 0;
  for (size_t i = 0; i < p.size(); ++i) {
    const Vec2d& u = p[i];
    const Vec2d& v = p[(i + 1) % p.size()];
    a += u.x * v.y - v.x * u.y;
  }
  return a * 0.5;
}

// Shape icindeki tum wire'lari 2D poligonlara cikar (>=3 nokta).
// Sonuc [0] = en buyuk alanli (dis sinir), digerleri delik konvansiyonunda siralanir.
PoligonKumesi wirelariCevir(const TopoDS_Shape& s) {
  PoligonKumesi out;
  for (TopExp_Explorer ex(s, TopAbs_WIRE); ex.More(); ex.Next()) {
    Poligon p = wireCevir(TopoDS::Wire(ex.Current()));
    if (p.size() >= 3) out.push_back(std::move(p));
  }
  if (out.size() > 1) {  // en buyuk mutlak alan basa (dis sinir konvansiyonu)
    size_t enB = 0;
    f64 enA = std::abs(isaretliAlan(out[0]));
    for (size_t i = 1; i < out.size(); ++i) {
      const f64 a = std::abs(isaretliAlan(out[i]));
      if (a > enA) { enA = a; enB = i; }
    }
    std::swap(out[0], out[enB]);
  }
  return out;
}

// Poligon kumesinden planar face(ler) (ilk = dis, sonrakiler delik wire olarak).
TopoDS_Face faceYap(const PoligonKumesi& konturlar) {
  if (konturlar.empty()) return {};
  const TopoDS_Wire dis = wireYap(konturlar[0]);
  if (dis.IsNull()) return {};
  BRepBuilderAPI_MakeFace mf(gp_Pln(gp_Pnt(0, 0, 0), gp_Dir(0, 0, 1)), dis);
  for (size_t i = 1; i < konturlar.size(); ++i) {
    const TopoDS_Wire ic = wireYap(konturlar[i]);
    if (!ic.IsNull()) mf.Add(ic);
  }
  return mf.IsDone() ? mf.Face() : TopoDS_Face{};
}

}  // namespace

PoligonKumesi poligonOfset(const PoligonKumesi& konturlar, f64 delta) {
  PoligonKumesi out;
  if (konturlar.empty()) return out;
  if (std::abs(delta) < 1e-9) return konturlar;
  try {
    // Tek kontur → duz wire ofseti (profil telafisi). Cok kontur → bolge (dis+delik)
    // face ofseti: dis sinir delta kadar, delikler ters yonde buyur/kucul (dogru).
    if (konturlar.size() == 1) {
      const TopoDS_Wire w = wireYap(konturlar[0]);
      if (w.IsNull()) return out;
      BRepOffsetAPI_MakeOffset off(w, GeomAbs_Arc);
      off.Perform(delta);
      if (!off.IsDone()) return out;
      return wirelariCevir(off.Shape());
    }
    const TopoDS_Face f = faceYap(konturlar);
    if (f.IsNull()) return out;
    BRepOffsetAPI_MakeOffset off(f, GeomAbs_Arc);
    off.Perform(delta);
    if (!off.IsDone()) return out;
    return wirelariCevir(off.Shape());
  } catch (const Standard_Failure&) {
    return {};
  }
}

PoligonKumesi poligonFark(const PoligonKumesi& a, const PoligonKumesi& b) {
  try {
    const TopoDS_Face fa = faceYap(a);
    const TopoDS_Face fb = faceYap(b);
    if (fa.IsNull()) return {};
    if (fb.IsNull()) return wirelariCevir(fa);
    BRepAlgoAPI_Cut cut(fa, fb);
    if (!cut.IsDone()) return wirelariCevir(fa);
    return wirelariCevir(cut.Shape());
  } catch (const Standard_Failure&) {
    return {};
  }
}

PoligonKumesi poligonBirlesim(const PoligonKumesi& a) {
  if (a.size() <= 1) return a;
  try {
    TopoDS_Shape acc = faceYap({a[0]});
    if (acc.IsNull()) return a;
    for (size_t i = 1; i < a.size(); ++i) {
      const TopoDS_Face f = faceYap({a[i]});
      if (f.IsNull()) continue;
      BRepAlgoAPI_Fuse fuse(acc, f);
      if (fuse.IsDone()) acc = fuse.Shape();
    }
    PoligonKumesi out = wirelariCevir(acc);
    return out.empty() ? a : out;
  } catch (const Standard_Failure&) {
    return a;
  }
}

}  // namespace fiko::geometri