/*****************************************************************************
 *
 * This file is part of Mapnik (c++ mapping toolkit)
 *
 * Copyright (C) 2021 Artem Pavlenko
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 *****************************************************************************/

#ifndef PLACEMENTS_BASE_HPP
#define PLACEMENTS_BASE_HPP

// mapnik
#include <mapnik/config.hpp>
#include <mapnik/text/text_properties.hpp>
#include <mapnik/text/formatting/base.hpp>

namespace mapnik
{
using dimension_type = std::pair<double,double>;

class MAPNIK_DECL text_placements;
class feature_impl;
struct attribute;

// Generate a possible placement.
// This placement has first to be tested by placement_finder to verify it
// can actually be used.

class MAPNIK_DECL text_placement_info : util::noncopyable
{
public:
    // Constructor. Takes the parent text_placements object as a parameter
    // to read defaults from it.
    text_placement_info(text_placements const* parent, double _scale_factor);
    // Get next placement.
    // This function is also called before the first placement is tried.
    // Each class has to return at least one position!
    // If this functions returns false the placement data should be
    // considered invalid!

    virtual bool next() const = 0;
    virtual ~text_placement_info() {}

    // Properties actually used by placement finder and renderer. Values in
    // here are modified each time next() is called.
    mutable text_symbolizer_properties properties;

    // Scale factor used by the renderer.
    double scale_factor;

};

using text_placement_info_ptr = std::shared_ptr<text_placement_info>;

// This object handles the management of all TextSymbolizer properties. It can
// be used as a base class for own objects which implement new processing
// semantics. Basically this class just makes sure a pointer of the right
// class is returned by the get_placement_info call.

class MAPNIK_DECL text_placements
{
public:
    text_placements();
    // Get a text_placement_info object to use in rendering.
    // The returned object creates a list of settings which is
    // used to try to find a placement and stores all
    // information that is generated by
    // the placement finder.

    // This function usually is implemented as
    // text_placement_info_ptr text_placements_XXX::get_placement_info() const
    // {
    //     return text_placement_info_ptr(new text_placement_info_XXX(this));
    // }

    virtual text_placement_info_ptr get_placement_info(double _scale_factor, feature_impl const& feature, attributes const& vars) const = 0;
    // Get a list of all expressions used in any placement.
    // This function is used to collect attributes.

    virtual void add_expressions(expression_set & output) const;

    virtual ~text_placements() {}

    // List of all properties used as the default for the subclasses.
    text_symbolizer_properties defaults;
};

// Pointer to object of class text_placements
using text_placements_ptr = std::shared_ptr<text_placements>;

} //ns mapnik

#endif // PLACEMENTS_BASE_HPP
