// OpenSTA, Static Timing Analyzer
// Copyright (c) 2026, Parallax Software, Inc.
// 
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// 
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// 
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
// 
// The origin of this software must not be misrepresented; you must not
// claim that you wrote the original software.
// 
// Altered source versions must be plainly marked as such, and must not be
// misrepresented as being the original software.
// 
// This notice may not be removed or altered from any source distribution.

#pragma once

#include <map>
#include <unordered_set>

#include "Delay.hh"
#include "GraphClass.hh"
#include "MinMax.hh"
#include "Mode.hh"
#include "Path.hh"
#include "Scene.hh"
#include "SdcClass.hh"
#include "SearchClass.hh"
#include "SearchPred.hh"
#include "StaState.hh"
#include "Transition.hh"

namespace sta {

class SearchPred;

// Source/target clock skew.
class ClkSkew
{
public:
  ClkSkew();
  ClkSkew(Path *src_path,
	  Path *tgt_path,
          bool include_internal_latency,
	  StaState *sta);
  ClkSkew(const ClkSkew &clk_skew);
  ClkSkew &operator=(const ClkSkew &clk_skew) = default;
  Path *srcPath() { return src_path_; }
  Path *tgtPath() { return tgt_path_; }
  Arrival srcLatency(const StaState *sta);
  float tgtLatency(const StaState *sta);
  float srcInternalClkLatency(const StaState *sta);
  float tgtInternalClkLatency(const StaState *sta);
  Crpr crpr(const StaState *sta);
  float uncertainty(const StaState *sta);
  Delay skew() const { return skew_; }
  static bool srcTgtPathNameLess(ClkSkew &clk_skew1,
                                 ClkSkew &clk_skew2,
                                 const StaState *sta);

private:
  float clkTreeDelay(Path *clk_path,
                     const StaState *sta);

  Path *src_path_;
  Path *tgt_path_;
  bool include_internal_latency_;
  Delay skew_;
};

using ClkSkewMap = std::map<const Clock*, ClkSkew[SetupHold::index_count]>;

class FanOutSrchPred : public SearchPred1
{
public:
  FanOutSrchPred(const StaState *sta);
  bool searchThru(Edge *edge,
                  const Mode *mode) const override;
  using SearchPred1::searchThru;
};

// Find and report clock skews between source/target registers.
class ClkSkews : public StaState
{
public:
  ClkSkews(StaState *sta);
  void clear();
  // Report clk skews for clks.
  void reportClkSkew(ConstClockSeq &clks,
                     const SceneSeq &scenes,
                     const SetupHold *setup_hold,
                     bool include_internal_latency,
                     int digits);
  // Find worst clock skew between src/target registers.
  Delay findWorstClkSkew(const SceneSeq &scenes,
                         const SetupHold *setup_hold,
                         bool include_internal_latency);
  
protected:
  void findClkSkew(ConstClockSeq &clks,
                   const SceneSeq &scenes,
                   bool include_internal_latency);
  bool hasClkPaths(Vertex *vertex);
  void findClkSkewFrom(Vertex *src_vertex,
                       ClkSkewMap &skews);
  void findClkSkewFrom(Vertex *src_vertex,
                       Vertex *q_vertex,
                       const RiseFallBoth *src_rf,
                       ClkSkewMap &skews);
  void findClkSkew(Vertex *src_vertex,
                   const RiseFallBoth *src_rf,
                   Vertex *tgt_vertex,
                   const RiseFallBoth *tgt_rf,
                   ClkSkewMap &skews);
  VertexSet findFanout(Vertex *from);
  void findFanout1(Vertex *from,
                   std::unordered_set<Vertex*> &visited,
                   VertexSet &endpoints);
  void reportClkSkew(ClkSkew &clk_skew,
                     int digits);

  // Node StaState scenes_ and modes_ are reused there.
  ConstClockSeq clks_;
  ConstClockSet clk_set_;
  SceneSet scenes_set_;
  bool include_internal_latency_{true};
  FanOutSrchPred fanout_pred_;
  ClkSkewMap skews_;
};

} // namespace sta
