/*
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * Copyright 2010-2015 Danny Robson <danny@nerdcruft.net>
 */


#ifndef __UTIL_REGION_HPP
#define __UTIL_REGION_HPP

#include "extent.hpp"
#include "point.hpp"
#include "vector.hpp"
#include "types/traits.hpp"

#include <ostream>

namespace util {
    /**
     * A two-dimensional rectangle, with size and position.
     */
    template <size_t S, typename T>
    struct region {
        using extent_t = util::extent<S,T>;
        using point_t  = util::point<S,T>;

        using value_type = T;

        //---------------------------------------------------------------------
        static constexpr size_t dimension = S;
        static constexpr size_t elements = extent_t::elements + point_t::elements;

        point_t  p;
        extent_t e;

        //---------------------------------------------------------------------
        region () = default;
        explicit region (extent_t);
        region (point_t, extent_t);
        region (point_t, point_t);

        //---------------------------------------------------------------------
        template <typename U>
        constexpr region<S,U> cast (void) const;

        //---------------------------------------------------------------------
        T area (void) const;
        T diameter (void) const;
        extent_t magnitude (void) const;
        extent_t magnitude (extent_t);

        void scale (T factor);

        bool empty (void) const;

        //---------------------------------------------------------------------
        point_t base    (void) const;
        point_t away    (void) const;
        point_t centre  (void) const;
        point_t closest (point_t) const;

        //---------------------------------------------------------------------
        // Point and region relation queries
        bool includes (point_t) const; // inclusive of borders
        bool contains (point_t) const; // exclusive of borders
        bool intersects (region<S,T>) const;  // exclusive of borders
        bool has (point_t) const noexcept; // inclusive of top and left borders

        // Move a point to be within the region bounds
        void constrain (point_t&) const;
        point_t constrained (point_t) const;

        // Compute binary region combinations
        region intersection (region<S,T>) const;

        // Test if a region lies completely within our space
        bool encloses (region<S,T>) const noexcept;

        //---------------------------------------------------------------------
        // Compute a region `mag` units into the region
        region inset (T mag) const;
        region inset (vector<S,T> mag) const;

        region expand (T mag) const;
        region expand (vector<S,T>) const;

        // arithmetic operators
        region operator+ (vector<S,T>) const;
        region operator- (vector<S,T>) const;

        // Logical comparison operators
        bool operator ==(region<S,T> rhs) const;
        bool operator !=(region<S,T> rhs) const
            { return !(*this == rhs); }

        // Utility constants
        static constexpr region<S,T> max  (void);
        static constexpr region<S,T> unit (void);

        void sanity (void) const;
    };


    ///////////////////////////////////////////////////////////////////////////
    /// constructs the minimal region that encompasses a region and a point.
    template <typename T, size_t S>
    region<S,T>
    make_union (region<S,T> r, point<S,T> p)
    {
        const auto p0 = select (r.p < p,       r.p,       p);
        const auto p1 = select (r.away () > p, r.away (), p);
        return { p0, p1 };
    }


    template <typename T> using region2 = region<2,T>;
    template <typename T> using region3 = region<3,T>;

    using region2u = region2<unsigned>;
    using region2i = region2<int>;
    using region2f = region2<float>;
    using region2d = region2<double>;

    template <size_t S, typename T>
    std::ostream& operator<< (std::ostream&, const util::region<S,T>&);
}

#include "region.ipp"

#endif