/* -*- 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/. */

#include <minizinc/astexception.hh>
#include <minizinc/aststring.hh>
#include <minizinc/flatten_internal.hh>
#include <minizinc/model.hh>
#include <minizinc/prettyprinter.hh>
#include <minizinc/type.hh>

#include <algorithm>
#include <unordered_set>
#include <vector>

#undef MZN_DEBUG_FUNCTION_REGISTRY

namespace MiniZinc {

Model::FnEntry::FnEntry(EnvI& env, FunctionI* fi0)
    : t(fi0->paramCount()), fi(fi0), isPolymorphic(false), isPolymorphicVariant(false) {
  for (unsigned int i = 0; i < fi->paramCount(); i++) {
    t[i] = fi->param(i)->type();
    if (t[i].structBT() && t[i].typeId() == 0) {
      fi->param(i)->ti()->canonicaliseStruct(env);
      t[i] = fi->param(i)->ti()->type();
      fi->param(i)->type(t[i]);
    }
    isPolymorphic |= checkPoly(env, t[i]);
  }
  if (fi->ti()->type().structBT() && fi->ti()->type().typeId() == 0) {
    fi->ti()->canonicaliseStruct(env);
  }
}

bool Model::FnEntry::checkPoly(const EnvI& env, const Type& t) {
  if (t.bt() == Type::BT_TOP) {
    return true;
  }
  if (t.structBT()) {
    StructType* st = env.getStructType(t);
    for (unsigned int i = 0; i < st->size(); ++i) {
      if (checkPoly(env, (*st)[i])) {
        return true;
      }
    }
  }
  return false;
}

bool Model::FnEntry::compare(const EnvI& env, const Model::FnEntry& e1, const Model::FnEntry& e2) {
  if (e1.t.size() < e2.t.size()) {
    return true;
  }
  if (e1.t.size() == e2.t.size()) {
    for (unsigned int i = 0; i < e1.t.size(); i++) {
      if (e1.t[i] != e2.t[i]) {
        if (e1.t[i].isSubtypeOf(env, e2.t[i], true)) {
          assert(!e2.t[i].isSubtypeOf(env, e1.t[i], true));
          return true;
        }
        if (e2.t[i].isSubtypeOf(env, e1.t[i], true)) {
          return false;
        }
        switch (e1.t[i].cmp(e2.t[i])) {
          case -1:
            return true;
          case 1:
            return false;
          default:
            assert(false);
        }
      }
    }
  }
  return false;
}

Model::Model() : _parent(nullptr), _solveItem(nullptr), _outputItem(nullptr) {}

Model::~Model() {
  for (auto* i : _items) {
    if (auto* ii = i->dynamicCast<IncludeI>()) {
      if (ii->own()) {
        delete ii->m();
        ii->m(nullptr);
      }
    }
  }
}

VarDeclIteratorContainer Model::vardecls() { return VarDeclIteratorContainer(this); }
ConstraintIteratorContainer Model::constraints() { return ConstraintIteratorContainer(this); }
FunctionIteratorContainer Model::functions() { return FunctionIteratorContainer(this); }

VarDeclIterator VarDeclIteratorContainer::begin() { return VarDeclIterator(_m, _m->begin()); }
VarDeclIterator VarDeclIteratorContainer::end() { return VarDeclIterator(_m, _m->end()); }
ConstraintIterator ConstraintIteratorContainer::begin() {
  return ConstraintIterator(_m, _m->begin());
}
ConstraintIterator ConstraintIteratorContainer::end() { return ConstraintIterator(_m, _m->end()); }
FunctionIterator FunctionIteratorContainer::begin() { return FunctionIterator(_m, _m->begin()); }
FunctionIterator FunctionIteratorContainer::end() { return FunctionIterator(_m, _m->end()); }

SolveI* Model::solveItem() { return _solveItem; }

OutputI* Model::outputItem() { return _outputItem; }

void Model::addItem(Item* i) {
  _items.push_back(i);
  if (i->isa<SolveI>()) {
    Model* m = this;
    while (m->_parent != nullptr) {
      m = m->_parent;
    }
    m->_solveItem = i->cast<SolveI>();
  } else if (i->isa<OutputI>()) {
    Model* m = this;
    while (m->_parent != nullptr) {
      m = m->_parent;
    }
    m->_outputItem = i->cast<OutputI>();
  }
}

void Model::setOutputItem(OutputI* oi) {
  Model* m = this;
  while (m->_parent != nullptr) {
    m = m->_parent;
  }
  m->_outputItem = oi;
}

namespace {

enum PossibleBaseTypes { PBT_ANY, PBT_ALL, PBT_BIFS, PBT_BIF, PBT_I };
PossibleBaseTypes pbt_from_type(const Type& t) {
  if (t.any()) {
    return PBT_ANY;
  }
  if (t.isvar()) {
    if (t.isOpt()) {
      return PBT_BIF;
    }
    if (t.isSet()) {
      return PBT_I;
    }
    return PBT_BIFS;
  }
  if (t.isSet()) {
    return PBT_BIF;
  }
  return PBT_ALL;
}
PossibleBaseTypes pbt_join(PossibleBaseTypes pbt0, PossibleBaseTypes pbt1) {
  if (pbt0 == PBT_ANY) {
    return pbt1;
  }
  if (pbt1 == PBT_ANY) {
    return pbt0;
  }
  if (pbt0 == PBT_ALL) {
    return pbt1;
  }
  if (pbt1 == PBT_ALL) {
    return pbt0;
  }
  if (pbt0 == PBT_BIFS) {
    return pbt1;
  }
  if (pbt1 == PBT_BIFS) {
    return pbt0;
  }
  if (pbt0 == PBT_I || pbt1 == PBT_I) {
    return PBT_I;
  }
  assert(pbt0 == PBT_BIF && pbt1 == PBT_BIF);
  return PBT_BIF;
}
void set_to_lowest(Type& t, PossibleBaseTypes pbt) {
  t.any(false);
  if (pbt == PBT_ALL || pbt == PBT_ANY || pbt == PBT_BIFS) {
    t.st(Type::ST_PLAIN);
  }
  if (pbt == PBT_ANY) {
    t.ot(Type::OT_OPTIONAL);
    t.ti(Type::TI_PAR);
  }
  t.bt(pbt == PBT_I ? Type::BT_INT : Type::BT_BOOL);
}
bool can_increment_type(const Type& t, PossibleBaseTypes pbt) {
  switch (pbt) {
    case PBT_ANY:
      return t.ot() == Type::OT_OPTIONAL || t.ti() == Type::TI_PAR || t.st() == Type::ST_PLAIN;
    case PBT_ALL:
      return t.st() == Type::ST_PLAIN || t.bt() != Type::BT_FLOAT;
    case PBT_BIFS:
      return t.st() == Type::ST_PLAIN || t.bt() != Type::BT_INT;
    case PBT_BIF:
      return t.bt() != Type::BT_FLOAT;
    case PBT_I:
      return false;
  }
  throw InternalError("Invalid BaseType");
}
void increment_type(Type& t, PossibleBaseTypes pbt) {
  assert(pbt != PBT_I);
  if (pbt == PBT_ANY) {
    if (t.ti() == Type::TI_PAR) {
      if (t.ot() == Type::OT_OPTIONAL) {
        if (t.st() == Type::ST_PLAIN) {
          if (t.bt() != Type::BT_ANN) {
            t.bt(static_cast<Type::BaseType>(t.bt() + 1));
          } else {
            t.bt(Type::BT_BOOL);
            t.st(Type::ST_SET);
          }
        } else {
          if (t.bt() != Type::BT_ANN) {
            t.bt(static_cast<Type::BaseType>(t.bt() + 1));
          } else {
            t.bt(Type::BT_BOOL);
            t.st(Type::ST_PLAIN);
            t.ot(Type::OT_PRESENT);
          }
        }
      } else {
        if (t.st() == Type::ST_PLAIN) {
          if (t.bt() != Type::BT_ANN) {
            t.bt(static_cast<Type::BaseType>(t.bt() + 1));
          } else {
            t.bt(Type::BT_BOOL);
            t.st(Type::ST_SET);
          }
        } else {
          if (t.bt() != Type::BT_ANN) {
            t.bt(static_cast<Type::BaseType>(t.bt() + 1));
          } else {
            t.bt(Type::BT_BOOL);
            t.st(Type::ST_PLAIN);
            t.ot(Type::OT_OPTIONAL);
            t.ti(Type::TI_VAR);
          }
        }
      }
    } else {
      if (t.ot() == Type::OT_OPTIONAL) {
        if (t.bt() != Type::BT_FLOAT) {
          t.bt(static_cast<Type::BaseType>(t.bt() + 1));
        } else {
          t.bt(Type::BT_BOOL);
          t.ot(Type::OT_PRESENT);
        }
      } else {
        assert(t.st() != Type::ST_SET);
        if (t.bt() != Type::BT_FLOAT) {
          t.bt(static_cast<Type::BaseType>(t.bt() + 1));
        } else {
          t.bt(Type::BT_INT);
          t.st(Type::ST_SET);
        }
      }
    }
  } else if (pbt == PBT_ALL) {
    if (t.bt() != Type::BT_ANN) {
      t.bt(static_cast<Type::BaseType>(t.bt() + 1));
    } else {
      t.bt(Type::BT_BOOL);
      t.st(Type::ST_SET);
    }
  } else {
    if (t.bt() != Type::BT_FLOAT) {
      t.bt(static_cast<Type::BaseType>(t.bt() + 1));
    } else {
      assert(pbt == PBT_BIFS);
      t.bt(Type::BT_INT);
      t.st(Type::ST_SET);
    }
  }
}

}  // namespace

// For each TIId, store pointers to the type objects that refer to this TIId
struct TIIDInfo {
  std::vector<Type*> t;
  PossibleBaseTypes pbt;
  TIIDInfo(std::vector<Type*> t0, PossibleBaseTypes pbt0) : t(std::move(t0)), pbt(pbt0) {}
};

void TypeInst::collectTypeIds(std::unordered_map<ASTString, size_t>& seen_tiids,
                              std::vector<TIIDInfo>& type_ids) const {
  auto* al = Expression::cast<ArrayLit>(domain());
  for (unsigned int i = 0; i < al->size(); i++) {
    auto* ti = Expression::cast<TypeInst>((*al)[i]);
    if (ti->type().bt() == Type::BT_TOP) {
      // If type is top, either this is a TIId, or it is caused by <>
      if (ti->domain() != nullptr) {
        assert(Expression::isa<TIId>(ti->domain()));
        TIId* id0 = Expression::cast<TIId>(ti->domain());
        auto it = seen_tiids.find(id0->v());
        if (it == seen_tiids.end()) {
          type_ids.emplace_back(
              std::vector<Type*>({&ti->_type}),
              pbt_join(ti->type().any() ? PBT_ANY : PBT_ALL, pbt_from_type(ti->type())));
          seen_tiids.emplace(id0->v(), type_ids.size() - 1);
        } else {
          TIIDInfo& info = type_ids[it->second];
          info.pbt = pbt_join(info.pbt, pbt_from_type(ti->type()));
          info.t.push_back(&ti->_type);
        }
      }
    } else if (ti->type().structBT()) {
      size_t size = seen_tiids.size();
      ti->collectTypeIds(seen_tiids, type_ids);
    }
  }
}

void Model::addPolymorphicInstances(EnvI& env, Model::FnEntry& fe, std::vector<FnEntry>& entries) {
  auto addEntry = [&](Model::FnEntry& toAdd) {
    for (auto& entry : entries) {
      if (entry.t == toAdd.t) {
        bool more_specific = true;
        for (unsigned int i = 0; i < toAdd.fi->paramCount(); i++) {
          // If all parameters of the entry we are adding are subtypes of an
          // existing function, this one should take priority
          //
          // E.g. (bool, int) is preferred over ($T, $U)
          auto oldParamType = entry.fi->param(i)->type();
          auto newParamType = toAdd.fi->param(i)->type();
          if (!newParamType.isSubtypeOf(env, oldParamType, false)) {
            more_specific = false;
            break;
          }
        }
        if (more_specific) {
          entry = toAdd;
        }
        return;
      }
    }
    // Entry not yet added
    entries.push_back(toAdd);
  };

  addEntry(fe);
  if (fe.isPolymorphic) {
    GCLock lock;
    FnEntry cur = fe;
    cur.isPolymorphicVariant = true;

    /*

     Polymorphic functions use type variables $T that stand for concrete types.

     Depending on the inst and opt used with $T, it can stand for different types:

     $T           : any type (including set types)
     opt $T       : any type (including set types)
     var $T       : bool, int, float, set of int
     var opt $T   : bool, int, float
     set of $T    : bool, int, float
     var set of $T: int
     any $T       : any type, both par and var

     The types it can stand for are the intersection of these sets over all uses
     of $T.

     */

    std::unordered_map<ASTString, size_t> type_id_map;
    std::vector<TIIDInfo> type_ids;

    // Create a parameter TypeInst in the format of a tuple TypeInst
    // Immediately copy so the internal TypeInst values can be changed
    auto* paramtuple = Expression::cast<TypeInst>(copy(env, cur.fi->paramTypes()));
    paramtuple->collectTypeIds(type_id_map, type_ids);

    std::vector<size_t> stack;
    for (size_t i = 0; i < type_ids.size(); i++) {
      stack.push_back(i);
      for (auto* j : type_ids[i].t) {
        set_to_lowest(*j, type_ids[i].pbt);
      }
    }
    size_t final_id = type_ids.size() - 1;

    while (!stack.empty()) {
      if (stack.back() == final_id) {
        // New complete instance
        // First, update cur types
        auto* tis = Expression::cast<ArrayLit>(paramtuple->domain());
        for (unsigned int i = 0; i < tis->size(); ++i) {
          cur.t[i] = Expression::type((*tis)[i]);
          if (cur.t[i].bt() == Type::BT_TUPLE && cur.t[i].typeId() == 0) {
            env.registerTupleType(Expression::cast<TypeInst>((*tis)[i]));
            cur.t[i] = Expression::type((*tis)[i]);
          } else if (cur.t[i].bt() == Type::BT_RECORD && cur.t[i].typeId() == 0) {
            env.registerRecordType(Expression::cast<TypeInst>((*tis)[i]));
            cur.t[i] = Expression::type((*tis)[i]);
          }
        }
        addEntry(cur);
      }

      const Type& back_t = *type_ids[stack.back()].t[0];
      if (can_increment_type(back_t, type_ids[stack.back()].pbt)) {
        for (auto* i : type_ids[stack.back()].t) {
          increment_type(*i, type_ids[stack.back()].pbt);
        }
        // Reset types of all further items and push them
        for (size_t i = stack.back() + 1; i < type_ids.size(); i++) {
          for (auto* j : type_ids[i].t) {
            set_to_lowest(*j, type_ids[i].pbt);
          }
          stack.push_back(i);
        }
      } else {
        // last type, remove this item
        stack.pop_back();
      }
    }
  }
}

bool Model::registerFn(EnvI& env, FunctionI* fi, bool keepSorted, bool throwIfDuplicate) {
  Model* m = this;
  while (m->_parent != nullptr) {
    m = m->_parent;
  }
  auto i_id = m->_fnmap.find(fi->id());
  if (i_id == m->_fnmap.end()) {
    // new element
    std::vector<FnEntry> v;
    FnEntry fe(env, fi);
    addPolymorphicInstances(env, fe, v);
    m->_fnmap.insert(std::pair<ASTString, std::vector<FnEntry> >(fi->id(), v));
  } else {
    // add to list of existing elements
    std::vector<FnEntry>& v = i_id->second;
    FnEntry fe(env, fi);  // Create now so that struct types get canonicalised
    for (auto& i : v) {
      if (i.fi == fi) {
        return true;
      }
      if (i.fi->paramCount() == fi->paramCount()) {
        bool alleq = true;
        bool eqExceptInst = true;
        for (unsigned int j = 0; j < fi->paramCount(); j++) {
          Type t1 = i.fi->param(j)->type();
          Type t2 = fi->param(j)->type();
          if (t1 != t2) {
            alleq = false;
          }
          t1.mkPar(env);
          t2.mkPar(env);
          if (t1 != t2) {
            eqExceptInst = false;
          }
        }
        if (alleq) {
          if ((i.fi->e() != nullptr) && (fi->e() != nullptr) && !i.isPolymorphic) {
            if (throwIfDuplicate) {
              throw TypeError(
                  env, fi->loc(),
                  "function with the same type already defined in " + i.fi->loc().toString());
            }
            return false;
          }
          if ((fi->e() != nullptr) || i.isPolymorphic) {
            if (Call* deprecated = i.fi->ann().getCall(env.constants.ann.mzn_deprecated)) {
              fi->ann().add(deprecated);
            }
            FunctionI* old_fi = i.fi;
            i = FnEntry(env, fi);
            // If we are replacing a polymorphic function using a new polymorphic function, then
            // replace in all entries generated using addPolymorphicInstances
            if (i.isPolymorphic) {
              for (auto& j : v) {
                if (j.fi == old_fi) {
                  j.fi = fi;
                }
              }
            }
          } else if (Call* deprecated = fi->ann().getCall(env.constants.ann.mzn_deprecated)) {
            i.fi->ann().add(deprecated);
          }
          return true;
        }
        if (eqExceptInst) {
          Type t1 = i.fi->ti()->type();
          Type t2 = fi->ti()->type();
          t1.mkPar(env);
          t2.mkPar(env);
          t1.mkPresent(env);
          t2.mkPresent(env);
          if (t1.bt() == Type::BT_INT) {
            t1.typeId(0);
          }
          if (t2.bt() == Type::BT_INT) {
            t2.typeId(0);
          }
          if (t1 != t2) {
            throw TypeError(env, fi->loc(),
                            "function with same type up to par/var but different return type "
                            "already defined in " +
                                i.fi->loc().toString());
          }
        }
      }
    }
    addPolymorphicInstances(env, fe, v);
    if (keepSorted) {
      std::sort(v.begin(), v.end(), [&env](const Model::FnEntry& e1, const Model::FnEntry& e2) {
        return Model::FnEntry::compare(env, e1, e2);
      });
    }
  }
  if (fi->id() == env.constants.ids.mzn_reverse_map_var) {
    if (fi->paramCount() != 1 || fi->ti()->type() != Type::varbool()) {
      throw TypeError(env, fi->loc(),
                      "functions called `mzn_reverse_map_var` must have a single argument and "
                      "return type var bool");
    }
    Type t = fi->param(0)->type();
    _revmapmap.insert(std::pair<int, FunctionI*>(t.toInt(), fi));
  }
  return true;
}

bool Model::fnExists(EnvI& env, const ASTString& id) const {
  const Model* m = this;
  while (m->_parent != nullptr) {
    m = m->_parent;
  }
  auto i_id = m->_fnmap.find(id);
  return i_id != m->_fnmap.end();
}

namespace {

void compute_possible_matches(EnvI& env, const Model* m, const ASTString& ident,
                              const std::vector<Type>& ta, std::unordered_set<FunctionI*>& matched,
                              std::vector<FunctionI*>& ret) {
  // Go through the types in this order: var opt, var, par opt, par
  std::vector<Type> vp(ta.size());
  auto reset_types_from = [&](size_t from) {
    for (size_t i = from; i < ta.size(); i++) {
      vp[i] = ta[i];
      vp[i].mkVar(env);
      if (vp[i].st() == Type::ST_PLAIN) {
        vp[i].mkOpt(env);
      }
    }
  };
  reset_types_from(0);
  int finalType = static_cast<int>(ta.size()) - 1;

  for (;;) {
    auto* fi = m->matchFn(env, ident, vp, false);
    if (fi != nullptr) {
      auto it = matched.insert(fi);
      if (it.second) {
        ret.push_back(fi);
      }
    }
    int i = finalType;
    for (; i >= 0; i--) {
      Type& t = vp[i];
      if (t.decrement(env)) {
        reset_types_from(i + 1);
        break;
      }
    }
    if (i < 0) {
      break;
    }
  }
}

}  // namespace

std::vector<FunctionI*> Model::possibleMatches(EnvI& env, const ASTString& ident,
                                               const std::vector<Type>& ta) const {
  // Find all functions that could match the call c:
  // - based on the types of the arguments in c
  // - and based on all combinations of more restricted versions of the arguments
  //   (par vs var, non-opt vs opt)

  std::unordered_set<FunctionI*> matched;
  std::vector<FunctionI*> ret;

  compute_possible_matches(env, this, ident, ta, matched, ret);

  // Try reified/non-reified versions
  if (ident.endsWith("_reif")) {
    std::string ident_s(ident.c_str());
    ASTString baseIdent(ident_s.substr(0, ident_s.length() - 5));
    std::vector<Type> ta_b = ta;
    compute_possible_matches(env, this, EnvI::halfReifyId(baseIdent), ta_b, matched, ret);
    ta_b.pop_back();
    compute_possible_matches(env, this, baseIdent, ta_b, matched, ret);
  } else if (ident.endsWith("_imp")) {
    std::string ident_s(ident.c_str());
    ASTString baseIdent(ident_s.substr(0, ident_s.length() - 4));
    std::vector<Type> ta_b = ta;
    compute_possible_matches(env, this, env.reifyId(baseIdent), ta_b, matched, ret);
    ta_b.pop_back();
    compute_possible_matches(env, this, baseIdent, ta_b, matched, ret);
  } else {
    std::vector<Type> ta_b = ta;
    ta_b.push_back(Type::varbool());
    compute_possible_matches(env, this, env.reifyId(ident), ta_b, matched, ret);
    compute_possible_matches(env, this, EnvI::halfReifyId(ident), ta_b, matched, ret);
  }

  return ret;
}

FunctionI* Model::matchFn(EnvI& env, const ASTString& id, const std::vector<Type>& t,
                          bool strictEnums) const {
  if (id == env.constants.varRedef->id()) {
    return env.constants.varRedef;
  }
  const Model* m = this;
  while (m->_parent != nullptr) {
    m = m->_parent;
  }
  auto i_id = m->_fnmap.find(id);
  if (i_id == m->_fnmap.end()) {
    return nullptr;
  }
  const std::vector<FnEntry>& v = i_id->second;
  for (const auto& i : v) {
    const std::vector<Type>& fi_t = i.t;
#ifdef MZN_DEBUG_FUNCTION_REGISTRY
    std::cerr << "try " << *i.fi;
#endif
    if (fi_t.size() == t.size()) {
      bool match = true;
      for (unsigned int j = 0; j < t.size(); j++) {
        if (!env.isSubtype(t[j], fi_t[j], strictEnums)) {
#ifdef MZN_DEBUG_FUNCTION_REGISTRY
          std::cerr << t[j].toString(env) << " does not match " << fi_t[j].toString(env) << "\n";
#endif
          match = false;
          break;
        }
      }
      if (match) {
        return i.fi;
      }
    }
  }
  return nullptr;
}

void Model::mergeStdLib(EnvI& env, Model* m) const {
  for (const auto& it : _fnmap) {
    for (const auto& cit : it.second) {
      if (cit.fi->fromStdLib()) {
        (void)m->registerFn(env, cit.fi);
      }
    }
  }
  m->sortFn(env);
}

void Model::sortFn(const EnvI& env, FunctionI* fi) {
  Model* m = this;
  while (m->_parent != nullptr) {
    m = m->_parent;
  }
  auto& it = *m->_fnmap.find(fi->id());
  // Sort all functions by type
  std::sort(it.second.begin(), it.second.end(),
            [&env](const Model::FnEntry& e1, const Model::FnEntry& e2) {
              return Model::FnEntry::compare(env, e1, e2);
            });
}

void Model::sortFn(const EnvI& env) {
  Model* m = this;
  while (m->_parent != nullptr) {
    m = m->_parent;
  }
  for (auto& it : m->_fnmap) {
    // Sort all functions by type
    std::sort(it.second.begin(), it.second.end(),
              [&env](const Model::FnEntry& e1, const Model::FnEntry& e2) {
                return Model::FnEntry::compare(env, e1, e2);
              });
  }
}

void Model::fixFnMap(FunctionI* fi) {
  Model* m = this;
  while (m->_parent != nullptr) {
    m = m->_parent;
  }

  auto& it = *m->_fnmap.find(fi->id());
  for (auto& i : it.second) {
    if (i.fi == fi) {
      for (unsigned int j = 0; j < i.t.size(); j++) {
        if (i.t[j].isunknown() || i.t[j].structBT()) {
          i.t[j] = i.fi->param(j)->type();
        }
      }
    }
  }
}

void Model::checkFnValid(EnvI& env, std::vector<TypeError>& errors) {
  Model* m = this;
  while (m->_parent != nullptr) {
    m = m->_parent;
  }
  // Walk through registered functions check that functions that contain a non-FlatZinc type
  // argument are either a builtin (registed with a C++ function), or have a body.
  for (const auto& it : m->_fnmap) {
    const std::vector<FnEntry>& variants = it.second;
    for (const auto& fe : variants) {
      FunctionI* fi = fe.fi;
      Type ret = fi->ti()->type();
      if (fi->e() != nullptr || fi->builtins.e != nullptr || fi->builtins.b != nullptr ||
          fi->builtins.f != nullptr || fi->builtins.i != nullptr || fi->builtins.s != nullptr ||
          fi->builtins.fs != nullptr || fi->builtins.str != nullptr ||
          fi->ann().contains(env.constants.ann.mzn_internal_representation)) {
        continue;
      }
      if (fi->ann().contains(env.constants.ann.output_only)) {
        std::vector<Type> tys(fi->paramCount());
        for (unsigned int i = 0; i < fi->paramCount(); ++i) {
          tys[i] = fi->param(i)->type();
          tys[i].mkPar(env);
        }
        fi = matchFn(env, fi->id(), tys, true);
        ret.mkPar(env);
        if (fi != nullptr && ret == fi->ti()->type()) {
          continue;
        }
        errors.emplace_back(env, fe.fi->loc(),
                            "Missing parameter type variant of output only function");
        continue;
      }
      // Par functions that are not implemented in the compiler should have an implementation
      if (!ret.isAnn() && ret.isPar()) {
        errors.emplace_back(env, fi->loc(),
                            "Parameter type function is missing its implementation");
        continue;
      }
      if (!ret.isAnn() && !ret.isvarbool()) {
        errors.emplace_back(
            env, fi->loc(),
            "FlatZinc builtin functions must be predicates (i.e., have `var bool` return type)");
        continue;
      }
      for (unsigned int i = 0; i < fi->paramCount(); ++i) {
        const Type& t = fi->param(i)->type();
        if (t.isOpt() || t.structBT() || t.bt() == Type::BT_TOP) {
          errors.emplace_back(
              env, Expression::loc(fi->param(i)),
              "FlatZinc builtins are not allowed to have arguments of type " + t.toString(env));
          break;  // Break from parameter, but does continue in FnMap
        }
        if (t.dim() > 1) {
          errors.emplace_back(env, Expression::loc(fi->param(i)),
                              "Type " + t.toString(env) +
                                  " is not allowed in as a FlatZinc builtin argument, arrays must "
                                  "be one dimensional");
          break;  // Break from parameter, but does continue in FnMap
        }
      }
    }
  }
}

void Model::checkFnOverloading(EnvI& env) {
  Model* m = this;
  while (m->_parent != nullptr) {
    m = m->_parent;
  }
  for (auto& it : m->_fnmap) {
    std::vector<FnEntry>& fs = it.second;
    for (unsigned int i = 0; i < fs.size() - 1; i++) {
      FunctionI* cur = fs[i].fi;
      for (unsigned int j = i + 1; j < fs.size(); j++) {
        FunctionI* cmp = fs[j].fi;
        if (cur == cmp || cur->paramCount() != cmp->paramCount()) {
          break;
        }
        bool allEqual = true;
        for (unsigned int i = 0; i < cur->paramCount(); i++) {
          Type t1 = cur->param(i)->type();
          Type t2 = cmp->param(i)->type();
          if (t1.bt() == Type::BT_INT) {
            t1.typeId(0);
          }
          if (t2.bt() == Type::BT_INT) {
            t2.typeId(0);
          }
          if (t1 != t2) {
            allEqual = false;
            break;
          }
        }
        if (allEqual) {
          throw TypeError(env, cur->loc(),
                          "unsupported type of overloading. \nFunction/predicate with equivalent "
                          "signature defined in " +
                              cmp->loc().toString());
        }
      }
    }
  }
}

namespace {
int match_idx(std::vector<FunctionI*>& matched, Expression*& botarg, EnvI& env,
              const std::vector<Model::FnEntry>& v, const std::vector<Expression*>& args,
              bool strictEnums) {
  botarg = nullptr;
  for (unsigned int i = 0; i < v.size(); i++) {
    const std::vector<Type>& fi_t = v[i].t;
#ifdef MZN_DEBUG_FUNCTION_REGISTRY
    std::cerr << "try " << *v[i].fi;
#endif
    if (fi_t.size() == args.size()) {
      bool match = true;
      for (unsigned int j = 0; j < args.size(); j++) {
        if (!env.isSubtype(Expression::type(args[j]), fi_t[j], strictEnums)) {
#ifdef MZN_DEBUG_FUNCTION_REGISTRY
          std::cerr << Expression::type(args[j]).toString(env) << " does not match "
                    << fi_t[j].toString(env) << "\n";
#endif
          match = false;
          break;
        }
        if (Expression::type(args[j]).isbot() && fi_t[j].bt() != Type::BT_TOP) {
          botarg = args[j];
        }
      }
      if (match) {
        matched.push_back(v[i].fi);
        if (botarg == nullptr) {
          return static_cast<int>(i);
        }
      }
    }
  }
  return -1;
}
}  // namespace

FunctionI* Model::matchReification(EnvI& env, const ASTString& id,
                                   const std::vector<Expression*>& args, bool canHalfReify,
                                   bool strictEnums) const {
  std::vector<Type> t;
  t.reserve(args.size());
  for (const auto* e : args) {
    t.push_back(Expression::type(e));
  }
  return this->matchReification(env, id, t, canHalfReify, strictEnums);
}

FunctionI* Model::matchReification(EnvI& env, const ASTString& id, const std::vector<Type>& t,
                                   bool canHalfReify, bool strictEnums) const {
  ASTString reif_id = env.reifyId(id);
  FunctionI* reif_decl = this->matchFn(env, reif_id, t, strictEnums);
  if (canHalfReify) {
    ASTString imp_id = EnvI::halfReifyId(id);
    if (FunctionI* imp_decl = this->matchFn(env, imp_id, t, strictEnums)) {
      // If reification failed, then go with half-reification immediately
      if (reif_decl == nullptr) {
        return imp_decl;
      }

      // If there is both a reification and a half-reification, then make sure the half-reification
      // is at least as specific as the reification. That is the parameters of the matching
      // half-reification declaration should be the same or subtypes of the matching reification.
      assert(imp_decl->paramCount() == reif_decl->paramCount());
      for (unsigned int i = 0; i < imp_decl->paramCount(); ++i) {
        Type a = imp_decl->param(i)->ti()->type();
        Type b = reif_decl->param(i)->ti()->type();
        if (!env.isSubtype(a, b, strictEnums)) {
          return reif_decl;
        }
      }
      return imp_decl;
    }
  }
  return reif_decl;
}

FunctionI* Model::matchFn(EnvI& env, const ASTString& id, const std::vector<Expression*>& args,
                          bool strictEnums) const {
  if (id == env.constants.varRedef->id()) {
    return env.constants.varRedef;
  }
  const Model* m = this;
  while (m->_parent != nullptr) {
    m = m->_parent;
  }
  auto it = m->_fnmap.find(id);
  if (it == m->_fnmap.end()) {
    return nullptr;
  }
  const std::vector<FnEntry>& v = it->second;
  std::vector<FunctionI*> matched;
  Expression* botarg;
  (void)match_idx(matched, botarg, env, v, args, strictEnums);
  if (matched.empty()) {
    return nullptr;
  }
  if (matched.size() == 1) {
    return matched[0];
  }
  Type t = matched[0]->ti()->type();
  t.mkPar(env);
  for (unsigned int i = 1; i < matched.size(); i++) {
    if (!env.isSubtype(t, matched[i]->ti()->type(), strictEnums)) {
      throw TypeError(env, Expression::loc(botarg),
                      "ambiguous overloading on return type of function");
    }
  }
  return matched[0];
}

FunctionI* Model::matchFn(EnvI& env, Call* c, bool strictEnums, bool throwIfNotFound) const {
  if (c->id() == env.constants.varRedef->id()) {
    return env.constants.varRedef;
  }
  const Model* m = this;
  while (m->_parent != nullptr) {
    m = m->_parent;
  }
  auto it = m->_fnmap.find(c->id());
  if (it == m->_fnmap.end()) {
    if (throwIfNotFound) {
      std::ostringstream oss;
      oss << "no function or predicate with name `";
      oss << c->id() << "' found";

      ASTString mostSimilar;
      int minEdits = 3;
      for (const auto& decls : m->_fnmap) {
        if (std::abs(static_cast<int>(c->id().size()) - static_cast<int>(decls.first.size())) <=
            3) {
          int edits = c->id().levenshteinDistance(decls.first);
          if (edits < minEdits && edits < std::min(c->id().size(), decls.first.size())) {
            minEdits = edits;
            mostSimilar = decls.first;
          }
        }
      }
      if (!mostSimilar.empty()) {
        oss << ", did you mean `" << mostSimilar << "'?";
      }
      throw TypeError(env, Expression::loc(c), oss.str());
    }
    return nullptr;
  }
  const std::vector<FnEntry>& v = it->second;
  std::vector<FunctionI*> matched;
  Expression* botarg = nullptr;
  for (const auto& i : v) {
    const std::vector<Type>& fi_t = i.t;
#ifdef MZN_DEBUG_FUNCTION_REGISTRY
    std::cerr << "try " << *i.fi;
#endif
    if (fi_t.size() == c->argCount()) {
      bool match = true;
      for (unsigned int j = 0; j < c->argCount(); j++) {
        if (!env.isSubtype(Expression::type(c->arg(j)), fi_t[j], strictEnums)) {
#ifdef MZN_DEBUG_FUNCTION_REGISTRY
          std::cerr << Expression::type(c->arg(j)).toString(env) << " does not match "
                    << fi_t[j].toString(env) << "\n";
          std::cerr << "Wrong argument is " << *c->arg(j) << "\n";
#endif
          match = false;
          break;
        }
        if (Expression::type(c->arg(j)).isbot() && fi_t[j].bt() != Type::BT_TOP) {
          botarg = c->arg(j);
        }
      }
      if (match) {
        if (botarg != nullptr) {
          matched.push_back(i.fi);
        } else {
          return i.fi;
        }
      }
    }
  }
  if (matched.empty()) {
    if (throwIfNotFound) {
      std::ostringstream oss;
      oss << "no function or predicate with this signature found: `";
      oss << c->id() << "(";
      for (unsigned int i = 0; i < c->argCount(); i++) {
        oss << Expression::type(c->arg(i)).toString(env);
        if (i < c->argCount() - 1) {
          oss << ",";
        }
      }
      oss << ")'\n";
      oss << "Cannot use the following functions or predicates with the same identifier:\n";
      Printer pp(oss, 0, false, &env);
      for (const auto& i : v) {
        if (i.fi->isMonomorphised() || i.isPolymorphicVariant) {
          continue;
        }
        const std::vector<Type>& fi_t = i.t;
        Expression* body = i.fi->e();
        i.fi->e(nullptr);
        pp.print(i.fi);
        i.fi->e(body);
        if (fi_t.size() == c->argCount()) {
          for (unsigned int j = 0; j < c->argCount(); j++) {
            if (!env.isSubtype(Expression::type(c->arg(j)), fi_t[j], strictEnums)) {
              oss << "    (argument " << (j + 1) << " expects type " << fi_t[j].toString(env);
              oss << ", but type " << Expression::type(c->arg(j)).toString(env) << " given)\n";
            }
          }
        } else {
          oss << "    (requires " << i.fi->paramCount() << " argument"
              << (i.fi->paramCount() == 1 ? "" : "s") << ", but " << c->argCount() << " given)\n";
        }
      }
      throw TypeError(env, Expression::loc(c), oss.str());
    }
    return nullptr;
  }
  if (matched.size() == 1) {
    return matched[0];
  }
  Type t = matched[0]->ti()->type();
  t.mkPar(env);
  for (unsigned int i = 1; i < matched.size(); i++) {
    if (!env.isSubtype(t, matched[i]->ti()->type(), strictEnums)) {
      throw TypeError(env, Expression::loc(botarg),
                      "ambiguous overloading on return type of function");
    }
  }
  return matched[0];
}

std::vector<FunctionI*> Model::potentialOverloads(EnvI& env, Call* c) const {
  if (c->id() == env.constants.varRedef->id()) {
    return {env.constants.varRedef};
  }
  const Model* m = this;
  while (m->_parent != nullptr) {
    m = m->_parent;
  }
  auto it = m->_fnmap.find(c->id());
  if (it == m->_fnmap.end()) {
    std::ostringstream oss;
    oss << "no function or predicate with name `";
    oss << c->id() << "' found";

    ASTString mostSimilar;
    int minEdits = 3;
    for (const auto& decls : m->_fnmap) {
      if (std::abs(static_cast<int>(c->id().size()) - static_cast<int>(decls.first.size())) <= 3) {
        int edits = c->id().levenshteinDistance(decls.first);
        if (edits < minEdits && edits < std::min(c->id().size(), decls.first.size())) {
          minEdits = edits;
          mostSimilar = decls.first;
        }
      }
    }
    if (!mostSimilar.empty()) {
      oss << ", did you mean `" << mostSimilar << "'?";
    }
    throw TypeError(env, Expression::loc(c), oss.str());
  }

  const std::vector<FnEntry>& v = it->second;
  std::vector<FunctionI*> matched;
  for (const auto& i : v) {
    if (i.t.size() == c->argCount()) {
      matched.push_back(i.fi);
    }
  }
  if (matched.empty()) {
    std::ostringstream oss;
    oss << "no function or predicate with this signature found: `";
    oss << c->id() << "(";
    for (unsigned int i = 0; i < c->argCount(); i++) {
      oss << Expression::type(c->arg(i)).toString(env);
      if (i < c->argCount() - 1) {
        oss << ",";
      }
    }
    oss << ")'\n";
    throw TypeError(env, Expression::loc(c), oss.str());
  }

  return matched;
}

namespace {
int first_overloaded(EnvI& env, const std::vector<Model::FnEntry>& v_f, int i_f) {
  int first_i_f = i_f;
  for (; (first_i_f--) != 0;) {
    // find first instance overloaded on subtypes
    if (v_f[first_i_f].t.size() != v_f[i_f].t.size()) {
      break;
    }
    bool allSubtypes = true;
    for (unsigned int i = 0; i < v_f[first_i_f].t.size(); i++) {
      if (!env.isSubtype(v_f[first_i_f].t[i], v_f[i_f].t[i], false)) {
        allSubtypes = false;
        break;
      }
    }
    if (!allSubtypes) {
      break;
    }
  }
  return first_i_f + 1;
}
}  // namespace

bool Model::sameOverloading(EnvI& env, const std::vector<Expression*>& args, FunctionI* f,
                            FunctionI* g) const {
  if (f->isMonomorphised() || g->isMonomorphised() || f->id() == env.constants.varRedef->id() ||
      g->id() == env.constants.varRedef->id()) {
    return false;
  }
  const Model* m = this;
  while (m->_parent != nullptr) {
    m = m->_parent;
  }
  auto it_f = m->_fnmap.find(f->id());
  auto it_g = m->_fnmap.find(g->id());
  assert(it_f != m->_fnmap.end());
  assert(it_g != m->_fnmap.end());
  const std::vector<FnEntry>& v_f = it_f->second;
  const std::vector<FnEntry>& v_g = it_g->second;

  std::vector<FunctionI*> dummyMatched;
  Expression* dummyBotarg;
  int i_f = match_idx(dummyMatched, dummyBotarg, env, v_f, args, true);
  if (i_f == -1) {
    return false;
  }
  int i_g = match_idx(dummyMatched, dummyBotarg, env, v_g, args, true);
  if (i_g == -1) {
    return false;
  }
  assert(i_f < v_f.size());
  assert(i_g < v_g.size());
  unsigned int first_i_f = first_overloaded(env, v_f, i_f);
  unsigned int first_i_g = first_overloaded(env, v_g, i_g);
  if (i_f - first_i_f != i_g - first_i_g) {
    // not the same number of overloaded versions
    return false;
  }
  for (; first_i_f <= static_cast<unsigned int>(i_f); first_i_f++, first_i_g++) {
    if (!(v_f[first_i_f].t == v_g[first_i_g].t)) {
      // one of the overloaded versions does not agree in the types
      return false;
    }
  }
  return true;
}

FunctionI* Model::matchRevMap(EnvI& env, const Type& t0) const {
  const Model* m = this;
  while (m->_parent != nullptr) {
    m = m->_parent;
  }
  Type t = t0;
  if (t.bt() == Type::BT_INT) {
    t.typeId(0);
  }
  auto it = _revmapmap.find(t.toInt());
  if (it != _revmapmap.end()) {
    return it->second;
  }
  return nullptr;
}

Item*& Model::operator[](unsigned int i) {
  assert(i < _items.size());
  return _items[i];
}
const Item* Model::operator[](unsigned int i) const {
  assert(i < _items.size());
  return _items[i];
}
unsigned int Model::size() const { return static_cast<unsigned int>(_items.size()); }
bool Model::empty() const { return _items.empty(); }

std::vector<Item*>::iterator Model::begin() { return _items.begin(); }

std::vector<Item*>::const_iterator Model::begin() const { return _items.begin(); }

std::vector<Item*>::iterator Model::end() { return _items.end(); }

std::vector<Item*>::const_iterator Model::end() const { return _items.end(); }

void Model::compact() {
  struct {
    bool operator()(const Item* i) { return i->removed(); }
  } isremoved;
  _items.erase(remove_if(_items.begin(), _items.end(), isremoved), _items.end());
}

}  // namespace MiniZinc