/*
 * (C) Copyright 2013 ECMWF.
 *
 * This software is licensed under the terms of the Apache Licence Version 2.0
 * which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
 * In applying this licence, ECMWF does not waive the privileges and immunities
 * granted to it by virtue of its status as an intergovernmental organisation
 * nor does it submit to any jurisdiction.
 */

#include "eckit/types/Types.h"

#include "atlas/array/ArrayView.h"
#include "atlas/field/Field.h"
#include "atlas/grid/Vertical.h"

namespace atlas {

//---------------------------------------------------------------------------------------------------------------------

namespace {

std::vector<double> linspace(double start, double end, idx_t N, bool endpoint) {
    std::vector<double> x_;
    if (N > 0) {
        volatile double _N = N;  // volatile keyword prevents agressive optimization by Cray compiler
        x_.resize(N);

        double step;
        if (endpoint && N > 1) {
            step = (end - start) / (_N - 1);
        }
        else if (N > 0) {
            step = (end - start) / _N;
        }
        else {
            step = 0.;
        }

        for (idx_t i = 0; i < N; ++i) {
            x_[i] = start + i * step;
        }
    }
    return x_;
}

idx_t get_levels(const util::Config& config) {
    return config.getInt("levels", 0);
}


}  // namespace

//---------------------------------------------------------------------------------------------------------------------

Vertical::Vertical(const util::Config& config):
    Vertical(get_levels(config), linspace(0., 1., get_levels(config), true), config) {}

Field Vertical::z() const {
    auto zfield = Field("z", array::make_datatype<double>(), array::make_shape(size()));
    auto zview  = array::make_view<double, 1>(zfield);
    for (idx_t k = 0; k < size(); ++k) {
        zview(k) = z_[k];
    }
    return zfield;
}


std::ostream& operator<<(std::ostream& os, const Vertical& v) {
    os << v.z_;
    return os;
}

//---------------------------------------------------------------------------------------------------------------------

}  // namespace atlas
