/* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */

/*
 *  Main authors:
 *     Guido Tack <guido.tack@monash.edu>
 */

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef __MINIZINC_ITER_HH__
#define __MINIZINC_ITER_HH__

#include <minizinc/values.hh>

#include <cmath>

#ifdef _MSC_VER
#define _CRT_SECURE_NO_WARNINGS
#undef ERROR  // MICROsoft.
#undef min
#undef max
#endif

namespace MiniZinc {
namespace Ranges {

/**
 * \brief Base for range iterators with explicit min and max
 *
 * The iterator provides members \a mi and \a ma for storing the
 * limits of the currently iterated range. The iterator
 * continues until \a mi becomes greater than \a ma. The member function
 * finish does exactly that.
 *
 * \ingroup FuncIterRanges
 */

template <class Val>
class MinMax {
protected:
  /// Minimum of current range
  Val mi;
  /// Maximum of current range
  Val ma;
  /// %Set range such that iteration stops
  void finish(void);

public:
  /// \name Constructors and initialization
  //@{
  /// Default constructor
  MinMax(void);
  /// Initialize with range \a min to \a max
  MinMax(Val min, Val max);
  //@}

  /// \name Iteration control
  //@{
  /// Test whether iterator is still at a range or done
  bool operator()(void) const;
  //@}

  /// \name Range access
  //@{
  /// Return smallest value of range
  Val min(void) const;
  /// Return largest value of range
  Val max(void) const;
  /// Return width of range (distance between minimum and maximum)
  Val width(void) const;
  //@}
};

template <class Val>
inline void MinMax<Val>::finish(void) {
  mi = 1;
  ma = 0;
}

template <class Val>
inline MinMax<Val>::MinMax(void) {}

template <class Val>
inline MinMax<Val>::MinMax(Val min, Val max) : mi(min), ma(max) {}

template <class Val>
inline bool MinMax<Val>::operator()(void) const {
  return mi <= ma;
}

template <class Val>
inline Val MinMax<Val>::min(void) const {
  return mi;
}
template <class Val>
inline Val MinMax<Val>::max(void) const {
  return ma;
}
template <class Val>
inline Val MinMax<Val>::width(void) const {
  if (mi > ma) return 0;
  if (mi.isFinite() && ma.isFinite()) return ma - mi + 1;
  return Val::infinity();
}

template <class Val, class I>
class Bounded {
protected:
  I i;
  Val _min;
  bool use_min;
  Val _max;
  bool use_max;
  Bounded(I& i, Val min0, bool umin0, Val max0, bool umax0);

public:
  static Bounded miniter(I& i, Val min);
  static Bounded maxiter(I& i, Val max);
  static Bounded minmaxiter(I& i, Val min, Val max);

  /// \name Iteration control
  //@{
  /// Test whether iterator is still at a range or done
  bool operator()(void) const;
  /// Move iterator to next range (if possible)
  void operator++(void);
  //@}

  /// \name Range access
  //@{
  /// Return smallest value of range
  Val min(void) const;
  /// Return largest value of range
  Val max(void) const;
  /// Return width of range (distance between minimum and maximum)
  Val width(void) const;
  //@}
};

template <class Val, class I>
inline Bounded<Val, I>::Bounded(I& i0, Val min0, bool umin0, Val max0, bool umax0)
    : i(i0), _min(min0), use_min(umin0), _max(max0), use_max(umax0) {
  while (i() && use_min && i.max() < _min) ++i;
}
template <class Val, class I>
inline Bounded<Val, I> Bounded<Val, I>::miniter(I& i, Val min) {
  return Bounded(i, min, true, 0, false);
}
template <class Val, class I>
inline Bounded<Val, I> Bounded<Val, I>::maxiter(I& i, Val max) {
  return Bounded(i, 0, false, max, true);
}
template <class Val, class I>
inline Bounded<Val, I> Bounded<Val, I>::minmaxiter(I& i, Val min, Val max) {
  return Bounded(i, min, true, max, true);
}

template <class Val, class I>
inline bool Bounded<Val, I>::operator()(void) const {
  return i() && (!use_max || i.min() <= _max);
}
template <class Val, class I>
inline void Bounded<Val, I>::operator++(void) {
  ++i;
  while (i() && use_min && i.max() < _min) ++i;
}
template <class Val, class I>
inline Val Bounded<Val, I>::min(void) const {
  return use_min ? std::max(_min, i.min()) : i.min();
}
template <class Val, class I>
inline Val Bounded<Val, I>::max(void) const {
  return use_max ? std::min(_max, i.max()) : i.max();
}
template <class Val, class I>
inline Val Bounded<Val, I>::width(void) const {
  if (min() > max()) return 0;
  if (min().isFinite() && max().isFinite()) return max() - min() + 1;
  return Val::infinity();
}

template <class Val>
class Const {
protected:
  Val _min;
  Val _max;
  bool done;

public:
  Const(Val min0, Val max0);

  /// \name Iteration control
  //@{
  /// Test whether iterator is still at a range or done
  bool operator()(void) const;
  /// Move iterator to next range (if possible)
  void operator++(void);
  //@}

  /// \name Range access
  //@{
  /// Return smallest value of range
  Val min(void) const;
  /// Return largest value of range
  Val max(void) const;
  /// Return width of range (distance between minimum and maximum)
  Val width(void) const;
  //@}
};

template <class Val>
inline Const<Val>::Const(Val min0, Val max0) : _min(min0), _max(max0), done(min0 > max0) {}
template <class Val>
inline bool Const<Val>::operator()(void) const {
  return !done;
}
template <class Val>
inline void Const<Val>::operator++(void) {
  done = true;
}
template <class Val>
inline Val Const<Val>::min(void) const {
  return _min;
}
template <class Val>
inline Val Const<Val>::max(void) const {
  return _max;
}
template <class Val>
inline Val Const<Val>::width(void) const {
  if (min() > max()) return 0;
  if (min().isFinite() && max().isFinite()) return max() - min() + 1;
  return Val::infinity();
}

/**
 * \brief Range iterator for computing union (binary)
 *
 * \ingroup FuncIterRanges
 */
template <class Val, class I, class J>
class Union : public MinMax<Val> {
protected:
  /// First iterator
  I i;
  /// Second iterator
  J j;

public:
  /// \name Constructors and initialization
  //@{
  /// Default constructor
  Union(void);
  /// Initialize with iterator \a i and \a j
  Union(I& i, J& j);
  /// Initialize with iterator \a i and \a j
  void init(I& i, J& j);
  //@}

  /// \name Iteration control
  //@{
  /// Move iterator to next range (if possible)
  void operator++(void);
  //@}
};

/// Return whether an interval ending with \a x overlaps with an interval starting at \a y
inline bool overlaps(const IntVal& x, const IntVal& y) { return x.plus(1) >= y; }
/// Return whether an interval ending with \a x overlaps with an interval starting at \a y
inline bool overlaps(const FloatVal& x, const FloatVal& y) {
  if (x.isPlusInfinity()) return true;
  if (y.isMinusInfinity()) return true;
  if (x.isFinite() && y.isFinite()) {
    return std::nextafter(x.toDouble(), INFINITY) >= y.toDouble();
  }
  return x >= y;
}
inline IntVal nextHigher(const IntVal& x) { return x.plus(1); }
inline IntVal nextLower(const IntVal& x) { return x.minus(1); }
inline FloatVal nextHigher(const FloatVal& x) {
  if (x.isFinite()) return std::nextafter(x.toDouble(), INFINITY);
  return x;
}
inline FloatVal nextLower(const FloatVal& x) {
  if (x.isFinite()) return std::nextafter(x.toDouble(), -INFINITY);
  return x;
}

/*
 * Binary union
 *
 */

template <class Val, class I, class J>
inline void Union<Val, I, J>::operator++(void) {
  if (!i() && !j()) {
    MinMax<Val>::finish();
    return;
  }

  if (!i() || (j() && (!overlaps(j.max(), i.min())))) {
    MinMax<Val>::mi = j.min();
    MinMax<Val>::ma = j.max();
    ++j;
    return;
  }
  if (!j() || (i() && (!overlaps(i.max(), j.min())))) {
    MinMax<Val>::mi = i.min();
    MinMax<Val>::ma = i.max();
    ++i;
    return;
  }

  MinMax<Val>::mi = std::min(i.min(), j.min());
  MinMax<Val>::ma = std::max(i.max(), j.max());

  ++i;
  ++j;

next:
  if (i() && (overlaps(MinMax<Val>::ma, i.min()))) {
    MinMax<Val>::ma = std::max(MinMax<Val>::ma, i.max());
    ++i;
    goto next;
  }
  if (j() && (overlaps(MinMax<Val>::ma, j.min()))) {
    MinMax<Val>::ma = std::max(MinMax<Val>::ma, j.max());
    ++j;
    goto next;
  }
}

template <class Val, class I, class J>
inline Union<Val, I, J>::Union(void) {}

template <class Val, class I, class J>
inline Union<Val, I, J>::Union(I& i0, J& j0) : i(i0), j(j0) {
  operator++();
}

template <class Val, class I, class J>
inline void Union<Val, I, J>::init(I& i0, J& j0) {
  i = i0;
  j = j0;
  operator++();
}

/**
 * \brief Range iterator for computing intersection (binary)
 *
 * \ingroup FuncIterRanges
 */
template <class Val, class I, class J>
class Inter : public MinMax<Val> {
protected:
  /// First iterator
  I i;
  /// Second iterator
  J j;

public:
  /// \name Constructors and initialization
  //@{
  /// Default constructor
  Inter(void);
  /// Initialize with iterator \a i and \a j
  Inter(I& i, J& j);
  /// Initialize with iterator \a i and \a j
  void init(I& i, J& j);
  //@}

  /// \name Iteration control
  //@{
  /// Move iterator to next range (if possible)
  void operator++(void);
  //@}
};

/*
 * Binary intersection
 *
 */

template <class Val, class I, class J>
inline void Inter<Val, I, J>::operator++(void) {
  if (!i() || !j()) goto done;
  do {
    while (i() && (i.max() < j.min())) ++i;
    if (!i()) goto done;
    while (j() && (j.max() < i.min())) ++j;
    if (!j()) goto done;
  } while (i.max() < j.min());
  // Now the intervals overlap: consume the smaller interval
  MinMax<Val>::ma = std::min(i.max(), j.max());
  MinMax<Val>::mi = std::max(i.min(), j.min());
  if (i.max() < j.max())
    ++i;
  else
    ++j;
  return;
done:
  MinMax<Val>::finish();
}

template <class Val, class I, class J>
inline Inter<Val, I, J>::Inter(void) {}

template <class Val, class I, class J>
inline Inter<Val, I, J>::Inter(I& i0, J& j0) : i(i0), j(j0) {
  operator++();
}

template <class Val, class I, class J>
inline void Inter<Val, I, J>::init(I& i0, J& j0) {
  i = i0;
  j = j0;
  operator++();
}

/**
 * \brief Range iterator for computing set difference
 *
 * \ingroup FuncIterRanges
 */

template <class Val, class I, class J>
class Diff : public MinMax<Val> {
protected:
  /// Iterator from which to subtract
  I i;
  /// Iterator to be subtracted
  J j;

public:
  /// \name Constructors and initialization
  //@{
  /// Default constructor
  Diff(void);
  /// Initialize with iterator \a i and \a j
  Diff(I& i, J& j);
  /// Initialize with iterator \a i and \a j
  void init(I& i, J& j);
  //@}

  /// \name Iteration control
  //@{
  /// Move iterator to next range (if possible)
  void operator++(void);
  //@}
};

template <class Val, class I, class J>
inline void Diff<Val, I, J>::operator++(void) {
  // Precondition: mi <= ma
  // Task: find next mi greater than ma
  while (true) {
    if (!i()) break;
    bool isInfinite = (!MinMax<Val>::ma.isFinite() && MinMax<Val>::ma > 0);
    MinMax<Val>::mi = nextHigher(MinMax<Val>::ma);
    MinMax<Val>::ma = i.max();
    if (isInfinite || MinMax<Val>::mi > i.max()) {
      ++i;
      if (!i()) break;
      MinMax<Val>::mi = i.min();
      MinMax<Val>::ma = i.max();
    }
    while (j() && (j.max() < MinMax<Val>::mi)) ++j;
    if (j() && (j.min() <= MinMax<Val>::ma)) {
      // Now the interval [mi ... ma] must be shrunken
      // Is [mi ... ma] completely consumed?
      if ((MinMax<Val>::mi >= j.min()) && (MinMax<Val>::ma <= j.max())) continue;
      // Does [mi ... ma] overlap on the left?
      if (j.min() <= MinMax<Val>::mi) {
        MinMax<Val>::mi = nextHigher(j.max());
        // Search for max!
        ++j;
        if (j() && (j.min() <= MinMax<Val>::ma)) MinMax<Val>::ma = nextLower(j.min());
      } else {
        MinMax<Val>::ma = nextLower(j.min());
      }
    }
    return;
  }
  MinMax<Val>::finish();
}

template <class Val, class I, class J>
inline Diff<Val, I, J>::Diff(void) {}

template <class Val, class I, class J>
inline Diff<Val, I, J>::Diff(I& i0, J& j0) : i(i0), j(j0) {
  if (!i()) {
    MinMax<Val>::finish();
  } else {
    MinMax<Val>::mi = nextLower(i.min());
    MinMax<Val>::ma = MinMax<Val>::mi;
    operator++();
  }
}

template <class Val, class I, class J>
inline void Diff<Val, I, J>::init(I& i0, J& j0) {
  i = i0;
  j = j0;
  if (!i()) {
    MinMax<Val>::finish();
  } else {
    MinMax<Val>::mi = nextLower(i.min());
    MinMax<Val>::ma = MinMax<Val>::mi;
    operator++();
  }
}

/**
 * \brief Value iterator from range iterator
 *
 * \ingroup FuncIterValues
 */
template <class I>
class ToValues {
protected:
  /// Range iterator used
  I i;
  /// Current value
  IntVal cur;
  /// End of current range
  IntVal max;
  /// Initialize iterator
  void start(void);

public:
  /// \name Constructors and initialization
  //@{
  /// Default constructor
  ToValues(void);
  /// Initialize with values from range iterator \a i
  ToValues(I& i);
  /// Initialize with values from range iterator \a i
  void init(I& i);
  //@}

  /// \name Iteration control
  //@{
  /// Test whether iterator is still at a value or done
  bool operator()(void) const;
  /// Move iterator to next value (if possible)
  void operator++(void);
  //@}

  /// \name Value access
  //@{
  /// Return current value
  IntVal val(void) const;
  //@}
};

template <class I>
inline ToValues<I>::ToValues(void) {}

template <class I>
inline void ToValues<I>::start(void) {
  if (i()) {
    cur = i.min();
    max = i.max();
  } else {
    cur = 1;
    max = 0;
  }
}

template <class I>
inline ToValues<I>::ToValues(I& i0) : i(i0) {
  start();
}

template <class I>
inline void ToValues<I>::init(I& i0) {
  i = i0;
  start();
}

template <class I>
inline bool ToValues<I>::operator()(void) const {
  return (cur <= max);
}

template <class I>
inline void ToValues<I>::operator++(void) {
  ++cur;
  if (cur > max) {
    ++i;
    if (i()) {
      cur = i.min();
      max = i.max();
    }
  }
}

template <class I>
inline IntVal ToValues<I>::val(void) const {
  return cur;
}

/**
 * \defgroup FuncIterRangesOp Operations on range iterators
 *
 * \ingroup FuncIterRanges
 */

//@{
/// Cardinality of the set represented by range iterator \a i
template <class I>
IntVal cardinality(I& i);

/// Check whether range iterators \a i and \a j are equal
template <class I, class J>
bool equal(I& i, J& j);

/// Check whether range iterator \a i is subset of range iterator \a j
template <class I, class J>
bool subset(I& i, J& j);

/// Check whether range iterators \a i and \a j are disjoint
template <class I, class J>
bool disjoint(I& i, J& j);

/// Comapre two iterators with each other
enum CompareStatus {
  CS_SUBSET,    ///< First is subset of second iterator
  CS_DISJOINT,  ///< Intersection is empty
  CS_NONE       ///< Neither of the above
};

/// Check whether range iterator \a i is a subset of \a j, or whether they are disjoint
template <class I, class J>
CompareStatus compare(I& i, J& j);
//@}

template <class I>
inline IntVal cardinality(I& i) {
  IntVal s = 0;
  while (i()) {
    if (i.width().isFinite()) {
      s += i.width();
      ++i;
    } else {
      return IntVal::infinity();
    }
  }
  return s;
}

template <class I, class J>
inline bool equal(I& i, J& j) {
  // Are i and j equal?
  while (i() && j())
    if ((i.min() == j.min()) && (i.max() == j.max())) {
      ++i;
      ++j;
    } else {
      return false;
    }
  return !i() && !j();
}

template <class I, class J>
inline bool subset(I& i, J& j) {
  // Is i subset of j?
  while (i() && j())
    if (j.max() < i.min()) {
      ++j;
    } else if ((i.min() >= j.min()) && (i.max() <= j.max())) {
      ++i;
    } else {
      return false;
    }
  return !i();
}

template <class I, class J>
inline bool disjoint(I& i, J& j) {
  // Are i and j disjoint?
  while (i() && j())
    if (j.max() < i.min()) {
      ++j;
    } else if (i.max() < j.min()) {
      ++i;
    } else {
      return false;
    }
  return true;
}

template <class I, class J>
inline CompareStatus compare(I& i, J& j) {
  bool subset = true;
  bool disjoint = true;
  while (i() && j()) {
    if (j.max() < i.min()) {
      ++j;
    } else if (i.max() < j.min()) {
      ++i;
      subset = false;
    } else if ((i.min() >= j.min()) && (i.max() <= j.max())) {
      ++i;
      disjoint = false;
    } else if (i.max() <= j.max()) {
      ++i;
      disjoint = false;
      subset = false;
    } else if (j.max() <= i.max()) {
      ++j;
      disjoint = false;
      subset = false;
    }
  }
  if (i()) subset = false;
  if (subset) return CS_SUBSET;
  return disjoint ? CS_DISJOINT : CS_NONE;
}

template <class I, class J>
inline bool less(I& i, J& j) {
  while (i()) {
    if (!j()) return false;
    if (i.min() < j.min()) return true;
    if (i.min() > j.min()) return false;
    if (i.max() < j.max()) return true;
    if (i.max() > j.max()) return false;
    ++i;
    ++j;
  }
  if (j()) return true;
  return false;
}

template <class I, class J>
inline bool lessEq(I& i, J& j) {
  while (i()) {
    if (!j()) return false;
    if (i.min() < j.min()) return true;
    if (i.min() > j.min()) return false;
    if (i.max() < j.max()) return true;
    if (i.max() > j.max()) return false;
    ++i;
    ++j;
  }
  return true;
}

}  // namespace Ranges
}  // namespace MiniZinc

#endif