#include "Runtime/World/CPathFindSearch.hpp"

#include "Runtime/Graphics/CGraphics.hpp"

namespace urde {

CPathFindSearch::CPathFindSearch(CPFArea* area, u32 flags, u32 index, float chRadius, float chHeight)
: x0_area(area), xd0_chHeight(chHeight), xd4_chRadius(chRadius), xdc_flags(flags), xe0_indexMask(1u << index) {}

CPathFindSearch::EResult CPathFindSearch::FindClosestReachablePoint(const zeus::CVector3f& p1,
                                                                    zeus::CVector3f& p2) const {
  if (!x0_area)
    return EResult::InvalidArea;

  /* Work in local PFArea coordinates */
  zeus::CVector3f localP1 = x0_area->x188_transform.transposeRotate(p1 - x0_area->x188_transform.origin);
  zeus::CVector3f localP2 = x0_area->x188_transform.transposeRotate(p2 - x0_area->x188_transform.origin);

  /* Raise a bit above ground for step-up resolution */
  if (!(xdc_flags & 0x2) && !(xdc_flags & 0x4)) {
    localP2.z() += 0.3f;
    localP1.z() += 0.3f;
  }

  rstl::reserved_vector<CPFRegion*, 4> regions;
  if (x0_area->FindRegions(regions, localP1, xdc_flags, xe0_indexMask) == 0) {
    /* Point outside PATH; find nearest region point */
    CPFRegion* region = x0_area->FindClosestRegion(localP1, xdc_flags, xe0_indexMask, xd8_padding);
    if (!region)
      return EResult::NoSourcePoint;

    regions.push_back(region);
  }

  /* Override dest point to be reachable */
  zeus::CVector3f closestPoint =
      x0_area->FindClosestReachablePoint(regions, localP2, xdc_flags, xe0_indexMask) + zeus::CVector3f(0.f, 0.f, 3.f);
  p2 = x0_area->x188_transform * closestPoint;

  return EResult::Success;
}

CPathFindSearch::EResult CPathFindSearch::PathExists(const zeus::CVector3f& p1, const zeus::CVector3f& p2) const {
  if (!x0_area)
    return EResult::InvalidArea;

  /* Work in local PFArea coordinates */
  zeus::CVector3f localP1 = x0_area->x188_transform.transposeRotate(p1 - x0_area->x188_transform.origin);
  zeus::CVector3f localP2 = x0_area->x188_transform.transposeRotate(p2 - x0_area->x188_transform.origin);

  /* Raise a bit above ground for step-up resolution */
  if (!(xdc_flags & 0x2) && !(xdc_flags & 0x4)) {
    localP2.z() += 0.3f;
    localP1.z() += 0.3f;
  }

  rstl::reserved_vector<CPFRegion*, 4> regions1;
  if (x0_area->FindRegions(regions1, localP1, xdc_flags, xe0_indexMask) == 0)
    return EResult::NoSourcePoint;

  rstl::reserved_vector<CPFRegion*, 4> regions2;
  if (x0_area->FindRegions(regions2, localP2, xdc_flags, xe0_indexMask) == 0)
    return EResult::NoDestPoint;

  for (CPFRegion* reg1 : regions1)
    for (CPFRegion* reg2 : regions2)
      if (reg1 == reg2 || x0_area->PathExists(reg1, reg2, xdc_flags))
        return EResult::Success;

  return EResult::NoPath;
}

CPathFindSearch::EResult CPathFindSearch::OnPath(const zeus::CVector3f& p1) const {
  if (!x0_area)
    return EResult::InvalidArea;

  /* Work in local PFArea coordinates */
  zeus::CVector3f localP1 = x0_area->x188_transform.transposeRotate(p1 - x0_area->x188_transform.origin);

  /* Raise a bit above ground for step-up resolution */
  if (!(xdc_flags & 0x2) && !(xdc_flags & 0x4))
    localP1.z() += 0.3f;

  rstl::reserved_vector<CPFRegion*, 4> regions1;
  if (x0_area->FindRegions(regions1, localP1, xdc_flags, xe0_indexMask) == 0)
    return EResult::NoSourcePoint;

  return EResult::Success;
}

CPathFindSearch::EResult CPathFindSearch::Search(const zeus::CVector3f& p1, const zeus::CVector3f& p2) {
  u32 firstPoint = 0;
  u32 flyToOutsidePoint = 0;
  x4_waypoints.clear();
  xc8_curWaypoint = 0;

  if (!x0_area || x0_area->x150_regions.size() > 512) {
    xcc_result = EResult::InvalidArea;
    return xcc_result;
  }

  if (zeus::close_enough(p1, p2)) {
    /* That was easy */
    x4_waypoints.push_back(p1);
    xcc_result = EResult::Success;
    return xcc_result;
  }

  /* Work in local PFArea coordinates */
  zeus::CVector3f localP1 = x0_area->x188_transform.transposeRotate(p1 - x0_area->x188_transform.origin);
  zeus::CVector3f localP2 = x0_area->x188_transform.transposeRotate(p2 - x0_area->x188_transform.origin);

  /* Raise a bit above ground for step-up resolution */
  if (!(xdc_flags & 0x2) && !(xdc_flags & 0x4)) {
    localP2.z() += 0.3f;
    localP1.z() += 0.3f;
  }

  rstl::reserved_vector<CPFRegion*, 4> regions1;
  rstl::reserved_vector<zeus::CVector3f, 16> points;
  if (x0_area->FindRegions(regions1, localP1, xdc_flags, xe0_indexMask) == 0) {
    /* Point outside PATH; find nearest region point */
    CPFRegion* region = x0_area->FindClosestRegion(localP1, xdc_flags, xe0_indexMask, xd8_padding);
    if (!region) {
      xcc_result = EResult::NoSourcePoint;
      return xcc_result;
    }

    if (xdc_flags & 0x2 || xdc_flags & 0x4) {
      points.push_back(localP1);
      firstPoint = 1;
    }
    regions1.push_back(region);
    localP1 = x0_area->GetClosestPoint();
  }

  zeus::CVector3f finalP2 = localP2;
  rstl::reserved_vector<CPFRegion*, 4> regions2;
  if (x0_area->FindRegions(regions2, localP2, xdc_flags, xe0_indexMask) == 0) {
    /* Point outside PATH; find nearest region point */
    CPFRegion* region = x0_area->FindClosestRegion(localP2, xdc_flags, xe0_indexMask, xd8_padding);
    if (!region) {
      xcc_result = EResult::NoDestPoint;
      return xcc_result;
    }

    if (xdc_flags & 0x2 || xdc_flags & 0x4) {
      flyToOutsidePoint = 1;
    }
    regions2.push_back(region);
    localP2 = x0_area->GetClosestPoint();
  }

  rstl::reserved_vector<CPFRegion*, 4> regions1Uniq;
  rstl::reserved_vector<CPFRegion*, 4> regions2Uniq;
  bool noPath = true;
  for (CPFRegion* reg1 : regions1) {
    for (CPFRegion* reg2 : regions2) {
      if (reg1 == reg2) {
        /* Route within one region */
        if (!(xdc_flags & 0x2) && !(xdc_flags & 0x4)) {
          reg2->DropToGround(localP1);
          reg2->DropToGround(localP2);
        }
        x4_waypoints.push_back(x0_area->x188_transform * localP1);
        if (!zeus::close_enough(localP1, localP2))
          x4_waypoints.push_back(x0_area->x188_transform * localP2);
        if (flyToOutsidePoint && !zeus::close_enough(localP2, finalP2))
          x4_waypoints.push_back(x0_area->x188_transform * finalP2);
        xcc_result = EResult::Success;
        return xcc_result;
      }

      if (x0_area->PathExists(reg1, reg2, xdc_flags)) {
        /* Build unique source/dest region lists */
        if (std::find(regions1Uniq.rbegin(), regions1Uniq.rend(), reg1) == regions1Uniq.rend())
          regions1Uniq.push_back(reg1);
        if (std::find(regions2Uniq.rbegin(), regions2Uniq.rend(), reg2) == regions2Uniq.rend())
          regions2Uniq.push_back(reg2);
        noPath = false;
      }
    }
  }

  /* Perform A* algorithm if path is known to exist */
  if (noPath || !Search(regions1Uniq, localP1, regions2Uniq, localP2)) {
    xcc_result = EResult::NoPath;
    return xcc_result;
  }

  /* Set forward links with best path */
  CPFRegion* reg = regions2Uniq[0];
  u32 lastPoint = 0;
  do {
    reg->Data()->GetParent()->SetLinkTo(reg->GetIndex());
    reg = reg->Data()->GetParent();
    ++lastPoint;
  } while (reg != regions1Uniq[0]);

  /* Setup point range */
  bool includeP2 = true;
  lastPoint -= 1;
  firstPoint += 1;
  lastPoint += firstPoint;
  if (lastPoint > 15)
    lastPoint = 15;
  if (lastPoint + flyToOutsidePoint + 1 > 15)
    includeP2 = false;

  /* Ensure start and finish points are on ground */
  if (!(xdc_flags & 0x2) && !(xdc_flags & 0x4)) {
    regions1Uniq[0]->DropToGround(localP1);
    regions2Uniq[0]->DropToGround(localP2);
  }

  /* Gather link points using midpoints */
  float chHalfHeight = 0.5f * xd0_chHeight;
  points.push_back(localP1);
  reg = regions1Uniq[0];
  for (u32 i = firstPoint; i <= lastPoint; ++i) {
    const CPFLink* link = reg->GetPathLink();
    CPFRegion* linkReg = &x0_area->x150_regions[link->GetRegion()];
    zeus::CVector3f midPoint = reg->GetLinkMidPoint(*link);
    if (xdc_flags & 0x2 || xdc_flags & 0x4) {
      float minHeight = std::min(reg->GetHeight(), linkReg->GetHeight());
      midPoint.z() = zeus::clamp(chHalfHeight + midPoint.z(), p2.z(), minHeight + midPoint.z() - chHalfHeight);
    }
    points.push_back(midPoint);
    reg = linkReg;
  }

  /* Gather finish points */
  if (includeP2) {
    points.push_back(localP2);
    if (flyToOutsidePoint)
      points.push_back(finalP2);
  }

  /* Optimize link points using character radius and height */
  for (int i = 0; i < 2; ++i) {
    reg = regions1Uniq[0];
    for (u32 j = firstPoint; j <= (includeP2 ? lastPoint : lastPoint - 1); ++j) {
      const CPFLink* link = reg->GetPathLink();
      CPFRegion* linkReg = &x0_area->x150_regions[link->GetRegion()];
      if (xdc_flags & 0x2 || xdc_flags & 0x4) {
        float minHeight = std::min(reg->GetHeight(), linkReg->GetHeight());
        points[j] = reg->FitThroughLink3d(points[j - 1], *link, minHeight, points[j + 1], xd4_chRadius, chHalfHeight);
      } else {
        points[j] = reg->FitThroughLink2d(points[j - 1], *link, points[j + 1], xd4_chRadius);
      }
      reg = linkReg;
    }
  }

  /* Write out points */
  for (u32 i = 0; i < points.size(); ++i)
    if (i == points.size() - 1 || !zeus::close_enough(points[i], points[i + 1]))
      x4_waypoints.push_back(x0_area->x188_transform * points[i]);

  /* Done! */
  xcc_result = EResult::Success;
  return xcc_result;
}

/* A* search algorithm
 * Reference: https://en.wikipedia.org/wiki/A*_search_algorithm
 */
bool CPathFindSearch::Search(rstl::reserved_vector<CPFRegion*, 4>& regs1, const zeus::CVector3f& p1,
                             rstl::reserved_vector<CPFRegion*, 4>& regs2, const zeus::CVector3f& p2) {
  /* Reset search sets */
  x0_area->ClosedSet().Clear();
  x0_area->OpenList().Clear();

  /* Backup dest centroids */
  rstl::reserved_vector<zeus::CVector3f, 4> centroidBackup2;
  for (CPFRegion* reg2 : regs2) {
    centroidBackup2.push_back(reg2->GetCentroid());
    reg2->SetCentroid(p2);
  }

  /* Initial heuristic */
  float h = (p2 - p1).magnitude();

  /* Backup source centroids and initialize heuristics */
  rstl::reserved_vector<zeus::CVector3f, 4> centroidBackup1;
  for (CPFRegion* reg1 : regs1) {
    centroidBackup1.push_back(reg1->GetCentroid());
    reg1->SetCentroid(p1);
    reg1->Data()->Setup(nullptr, 0.f, h);
    x0_area->OpenList().Push(reg1);
  }

  /* Resolve path */
  CPFRegion* reg;
  while ((reg = x0_area->OpenList().Pop())) {
    /* Stop if we're at the destination */
    if (std::find(regs2.begin(), regs2.end(), reg) != regs2.end())
      break;

    /* Exclude region from further resolves */
    x0_area->ClosedSet().Add(reg->GetIndex());
    for (u32 i = 0; i < reg->GetNumLinks(); ++i) {
      /* Potential link to follow */
      CPFRegion* linkReg = &x0_area->x150_regions[reg->GetLink(i)->GetRegion()];
      if (linkReg != reg->Data()->GetParent() && linkReg->GetFlags() & 0xff & xdc_flags &&
          (linkReg->GetFlags() >> 16) & 0xff & xe0_indexMask) {
        /* Next G */
        float g = (linkReg->GetCentroid() - reg->GetCentroid()).magnitude() + reg->Data()->GetG();
        if ((!x0_area->ClosedSet().Test(linkReg->GetIndex()) && !x0_area->OpenList().Test(linkReg)) ||
            linkReg->Data()->GetG() > g) {
          if (x0_area->OpenList().Test(linkReg)) {
            /* In rare cases, revisiting a region will yield a lower G (actual cost) */
            x0_area->OpenList().Pop(linkReg);
            linkReg->Data()->Setup(reg, g);
          } else {
            /* Compute next heuristic */
            x0_area->ClosedSet().Rmv(linkReg->GetIndex());
            const float nextHeuristic = (p2 - linkReg->GetCentroid()).magnitude();
            linkReg->Data()->Setup(reg, g, nextHeuristic);
          }

          /* Make next potential candidate */
          x0_area->OpenList().Push(linkReg);
        }
      }
    }
  }

  /* Restore source centroids */
  auto p1It = centroidBackup1.begin();
  for (CPFRegion* r : regs1)
    r->SetCentroid(*p1It++);

  /* Restore dest centroids */
  auto p2It = centroidBackup2.begin();
  for (CPFRegion* r : regs2)
    r->SetCentroid(*p2It++);

  /* Best destination region */
  if (reg) {
    regs2.clear();
    regs2.push_back(reg);
    /* Retrace parents to find best source region */
    while (CPFRegion* p = reg->Data()->GetParent())
      reg = p;
    regs1.clear();
    regs1.push_back(reg);
  }

  return reg != nullptr;
}

void CPathFindVisualizer::Draw(const CPathFindSearch& path) {
  m_spline.Reset();
  for (const auto& wp : path.GetWaypoints())
    m_spline.AddVertex(wp, zeus::skBlue, 2.f);
  m_spline.Render();
}

void CPathFindSearch::DebugDraw() {
  if (!m_viz) {
    m_viz.emplace();
  }
  m_viz->Draw(*this);
}

} // namespace urde