#ifndef BZ_ARRAYWHERE_H
#define BZ_ARRAYWHERE_H

#ifndef BZ_ARRAYEXPR_H
 #error <blitz/array/where.h> must be included via <blitz/array/expr.h>
#endif

BZ_NAMESPACE(blitz)

template<class P_expr1, class P_expr2, class P_expr3>
class _bz_ArrayWhere {

public:
    typedef P_expr1 T_expr1;
    typedef P_expr2 T_expr2;
    typedef P_expr3 T_expr3;
    typedef _bz_typename T_expr2::T_numtype T_numtype2;
    typedef _bz_typename T_expr3::T_numtype T_numtype3;
    typedef BZ_PROMOTE(T_numtype2, T_numtype3) T_numtype;
    typedef T_expr1 T_ctorArg1;
    typedef T_expr2 T_ctorArg2;
    typedef T_expr3 T_ctorArg3;

    enum { numArrayOperands = BZ_ENUM_CAST(P_expr1::numArrayOperands)
                            + BZ_ENUM_CAST(P_expr2::numArrayOperands)
                            + BZ_ENUM_CAST(P_expr3::numArrayOperands),
           numIndexPlaceholders = BZ_ENUM_CAST(P_expr1::numIndexPlaceholders)
                            + BZ_ENUM_CAST(P_expr2::numIndexPlaceholders)
                            + BZ_ENUM_CAST(P_expr3::numIndexPlaceholders),
           rank = _bz_meta_max<_bz_meta_max<P_expr1::rank,P_expr2::rank>::max,
                            P_expr3::rank>::max
    };

    _bz_ArrayWhere(const _bz_ArrayWhere<T_expr1,T_expr2,T_expr3>& a)
      : iter1_(a.iter1_), iter2_(a.iter2_), iter3_(a.iter3_)
    { }

    template<class T1, class T2, class T3>
    _bz_ArrayWhere(T1 a, T2 b, T3 c)
      : iter1_(a), iter2_(b), iter3_(c)
    { }

    T_numtype operator*()
    { return (*iter1_) ? (*iter2_) : (*iter3_); }

    template<int N_rank>
    T_numtype operator()(const TinyVector<int, N_rank>& i)
    { return iter1_(i) ? iter2_(i) : iter3_(i); }

    int lbound(int rank)
    {
        return bounds::compute_lbound(rank, bounds::compute_lbound(
          rank, iter1_.lbound(rank), iter2_.lbound(rank)), 
          iter3_.lbound(rank));
    }
   
    int ubound(int rank)
    {
        return bounds::compute_ubound(rank, bounds::compute_ubound(
          rank, iter1_.ubound(rank), iter2_.ubound(rank)), 
          iter3_.ubound(rank));
    } 

    void push(int position)
    {
        iter1_.push(position);
        iter2_.push(position);
        iter3_.push(position);
    }

    void pop(int position)
    {
        iter1_.pop(position);
        iter2_.pop(position);
        iter3_.pop(position);
    }

    void advance()
    {
        iter1_.advance();
        iter2_.advance();
        iter3_.advance();
    }

    void advance(int n)
    {
        iter1_.advance(n);
        iter2_.advance(n);
        iter3_.advance(n);
    }

    void loadStride(int rank)
    {
        iter1_.loadStride(rank);
        iter2_.loadStride(rank);
        iter3_.loadStride(rank);
    }

    _bz_bool isUnitStride(int rank) const
    { 
        return iter1_.isUnitStride(rank) 
            && iter2_.isUnitStride(rank) 
            && iter3_.isUnitStride(rank);
    }

    void advanceUnitStride()
    {
        iter1_.advanceUnitStride();
        iter2_.advanceUnitStride();
        iter3_.advanceUnitStride();
    }

    _bz_bool canCollapse(int outerLoopRank, int innerLoopRank) const
    {
        // BZ_DEBUG_MESSAGE("_bz_ArrayExprOp<>::canCollapse");
        return iter1_.canCollapse(outerLoopRank, innerLoopRank)
            && iter2_.canCollapse(outerLoopRank, innerLoopRank)
            && iter3_.canCollapse(outerLoopRank, innerLoopRank);
    }

    template<int N_rank>
    void moveTo(const TinyVector<int,N_rank>& i)
    {
        iter1_.moveTo(i);
        iter2_.moveTo(i);
        iter3_.moveTo(i);
    }

    T_numtype operator[](int i)
    { return iter1_[i] ? iter2_[i] : iter3_[i]; }

    T_numtype fastRead(int i)
    { return iter1_.fastRead(i) ? iter2_.fastRead(i) : iter3_.fastRead(i); }

    int suggestStride(int rank) const
    {
        int stride1 = iter1_.suggestStride(rank);
        int stride2 = iter2_.suggestStride(rank);
        int stride3 = iter3_.suggestStride(rank);
        return max(max(stride1,stride2),stride3);
    }

    _bz_bool isStride(int rank, int stride) const
    {
        return iter1_.isStride(rank,stride) 
            && iter2_.isStride(rank,stride)
            && iter3_.isStride(rank,stride);
    }

    void prettyPrint(string& str, prettyPrintFormat& format) const
    {
        str += "[WHERE]";
        // NEEDS_WORK
    }

    template<class T_shape>
    _bz_bool shapeCheck(const T_shape& shape)
    { 
        return iter1_.shapeCheck(shape) 
            && iter2_.shapeCheck(shape)
            && iter3_.shapeCheck(shape); 
    }

private:
    _bz_ArrayWhere() { }

    T_expr1 iter1_;
    T_expr2 iter2_;
    T_expr3 iter3_;
};

template<class T1, class T2, class T3>
inline
_bz_ArrayExpr<_bz_ArrayWhere<_bz_typename asExpr<T1>::T_expr,
    _bz_typename asExpr<T2>::T_expr, _bz_typename asExpr<T3>::T_expr> >
where(const T1& a, const T2& b, const T3& c)
{
    return _bz_ArrayExpr<_bz_ArrayWhere<_bz_typename asExpr<T1>::T_expr,
       _bz_typename asExpr<T2>::T_expr, 
       _bz_typename asExpr<T3>::T_expr> >(a,b,c);
}

BZ_NAMESPACE_END

#endif // BZ_ARRAYWHERE_H