// -*- coding: utf-8 -*-
// Copyright (C) 2009, 2011, 2013, 2014 Laboratoire de Recherche et
// Développement de l'Epita (LRDE).
// Copyright (C) 2003, 2004 Laboratoire d'Informatique de Paris 6 (LIP6),
// département Systèmes Répartis Coopératifs (SRC), Université Pierre
// et Marie Curie.
//
// This file is part of Spot, a model checking library.
//
// Spot 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.
//
// Spot 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 <http://www.gnu.org/licenses/>.

#include <cassert>
#include "reachiter.hh"

namespace spot
{
  // tgba_reachable_iterator
  //////////////////////////////////////////////////////////////////////

  tgba_reachable_iterator::tgba_reachable_iterator(const const_tgba_ptr& a)
    : aut_(a)
  {
  }

  tgba_reachable_iterator::~tgba_reachable_iterator()
  {
    seen_map::const_iterator s = seen.begin();
    while (s != seen.end())
      {
	// Advance the iterator before deleting the "key" pointer.
	const state* ptr = s->first;
	++s;
	ptr->destroy();
      }
  }

  void
  tgba_reachable_iterator::run()
  {
    int n = 0;
    start();
    state* i = aut_->get_init_state();
    if (want_state(i))
      add_state(i);
    seen[i] = ++n;
    const state* t;
    while ((t = next_state()))
      {
	assert(seen.find(t) != seen.end());
	int tn = seen[t];
	tgba_succ_iterator* si = aut_->succ_iter(t);
	process_state(t, tn, si);
	if (si->first())
	  do
	    {
	      const state* current = si->current_state();
	      seen_map::const_iterator s = seen.find(current);
	      bool ws = want_state(current);
	      if (s == seen.end())
		{
		  seen[current] = ++n;
		  if (ws)
		    {
		      add_state(current);
		      process_link(t, tn, current, n, si);
		    }
		}
	      else
		{
		  if (ws)
		    process_link(t, tn, s->first, s->second, si);
		  current->destroy();
		}
	    }
	  while (si->next());
	aut_->release_iter(si);
      }
    end();
  }

  bool
  tgba_reachable_iterator::want_state(const state*) const
  {
    return true;
  }

  void
  tgba_reachable_iterator::start()
  {
  }

  void
  tgba_reachable_iterator::end()
  {
  }

  void
  tgba_reachable_iterator::process_state(const state*, int,
					 tgba_succ_iterator*)
  {
  }

  void
  tgba_reachable_iterator::process_link(const state*, int,
					const state*, int,
					const tgba_succ_iterator*)
  {
  }

  // tgba_reachable_iterator_breadth_first
  //////////////////////////////////////////////////////////////////////

  tgba_reachable_iterator_breadth_first::
    tgba_reachable_iterator_breadth_first(const const_tgba_ptr& a)
      : tgba_reachable_iterator(a)
  {
  }

  void
  tgba_reachable_iterator_breadth_first::add_state(const state* s)
  {
    todo.push_back(s);
  }

  const state*
  tgba_reachable_iterator_breadth_first::next_state()
  {
    if (todo.empty())
      return 0;
    const state* s = todo.front();
    todo.pop_front();
    return s;
  }

  // tgba_reachable_iterator_depth_first
  //////////////////////////////////////////////////////////////////////

  tgba_reachable_iterator_depth_first::
    tgba_reachable_iterator_depth_first(const const_tgba_ptr& a)
      : aut_(a)
  {
  }

  tgba_reachable_iterator_depth_first::~tgba_reachable_iterator_depth_first()
  {
    seen_map::const_iterator s = seen.begin();
    while (s != seen.end())
      {
	// Advance the iterator before deleting the "key" pointer.
	const state* ptr = s->first;
	++s;
	ptr->destroy();
      }
  }

  void
  tgba_reachable_iterator_depth_first::push(const state* s, int sn)
  {
    tgba_succ_iterator* si = aut_->succ_iter(s);
    process_state(s, sn, si);
    stack_item item = { s, sn, si };
    todo.push_back(item);
    si->first();
  }

  void
  tgba_reachable_iterator_depth_first::pop()
  {
    aut_->release_iter(todo.back().it);
    todo.pop_back();
    if (!todo.empty())
      todo.back().it->next();
  }

  void
  tgba_reachable_iterator_depth_first::run()
  {
    int n = 1;
    start();
    state* i = aut_->get_init_state();
    if (want_state(i))
      push(i, n);
    seen[i] = n++;
    const state* dst;
    while (!todo.empty())
      {
	tgba_succ_iterator* si = todo.back().it;
	if (si->done())
	  {
	    pop();
	    continue;
	  }

	dst = si->current_state();
	auto res = seen.emplace(dst, n);
	if (!res.second)
	  {
	    // The state has already been seen.
	    dst->destroy();
	    // 0-numbered states are not wanted.
	    if (res.first->second == 0)
	      {
		si->next();
		continue;
	      }
	    dst = res.first->first;
	  }
	else if (!want_state(dst))
	  {
	    // Mark this state as non-wanted in case we see it again.
	    res.first->second = 0;
	    si->next();
	    continue;
	  }
	else
	  {
	    ++n;
	  }

	int dst_n = res.first->second;
	process_link(todo.back().src, todo.back().src_n, dst, dst_n, si);

	if (res.second)
	  push(dst, dst_n);
	else
	  si->next();
      }
    end();
  }

  bool
  tgba_reachable_iterator_depth_first::want_state(const state*) const
  {
    return true;
  }

  void
  tgba_reachable_iterator_depth_first::start()
  {
  }

  void
  tgba_reachable_iterator_depth_first::end()
  {
  }

  void
  tgba_reachable_iterator_depth_first::process_state(const state*, int,
						     tgba_succ_iterator*)
  {
  }

  void
  tgba_reachable_iterator_depth_first::process_link(const state*, int,
						    const state*, int,
						    const tgba_succ_iterator*)
  {
  }

  // tgba_reachable_iterator_depth_first_stack
  //////////////////////////////////////////////////////////////////////


  tgba_reachable_iterator_depth_first_stack::
  tgba_reachable_iterator_depth_first_stack(const const_tgba_ptr& a)
    : tgba_reachable_iterator_depth_first(a)
  {
  }

  void
  tgba_reachable_iterator_depth_first_stack::push(const state* s, int sn)
  {
    stack_.insert(sn);
    this->tgba_reachable_iterator_depth_first::push(s, sn);
  }

  void
  tgba_reachable_iterator_depth_first_stack::pop()
  {
    stack_.erase(todo.back().src_n);
    this->tgba_reachable_iterator_depth_first::pop();
  }

  bool
  tgba_reachable_iterator_depth_first_stack::on_stack(int sn) const
  {
    return stack_.find(sn) != stack_.end();
  }


}