1 /*
2     SPDX-FileCopyrightText: 2010 Akarsh Simha <akarshsimha@gmail.com>
3 
4     SPDX-License-Identifier: GPL-2.0-or-later
5 */
6 
7 #pragma once
8 
9 #include <QHash>
10 #include <QList>
11 
12 class QStringList;
13 
14 class SkyPoint;
15 class StarObject;
16 
17 /**
18  * @class StarHopper
19  * @short Helps planning star hopping
20  *
21  * @version 1.0
22  * @author Akarsh Simha
23  */
24 class StarHopper
25 {
26   public:
27     /**
28      * @short Computes path for Star Hop
29      * @param src SkyPoint to source of the Star Hop
30      * @param dest SkyPoint to destination of the Star Hop
31      * @param fov__ Field of view within which stars are considered
32      * @param maglim__ Magnitude limit of stars to consider
33      * @param metadata_ Directions for starhopping
34      * @return QList of StarObject pointers which are the resultant path to Star Hop
35      * @note The StarObjects in the list returned are mutable and not constant
36      */
37     QList<StarObject *> *computePath(const SkyPoint &src, const SkyPoint &dest, float fov__, float maglim__,
38                                      QStringList *metadata_ = nullptr);
39 
40   protected:
41     // Returns a list of constant StarObject pointers which form the resultant path of Star Hop
42     QList<const StarObject *> computePath_const(const SkyPoint &src, const SkyPoint &dest, float fov_, float maglim_,
43                                                 QStringList *metadata = nullptr);
44 
45   private:
46     /**
47      * @short The cost function for hopping from current position to the a given star, in view of the final destination
48      * @param curr Source SkyPoint
49      * @param next Next point in the hop.
50      * @note If 'next' is neither the starting point of the hop, nor
51      * the ending point, it _has_ to be a StarObject. A dynamic cast
52      * followed by a Q_ASSERT will ensure this.
53      */
54     float cost(const SkyPoint *curr, const SkyPoint *next);
55 
56     /**
57      * @short For internal use by the A* Search Algorithm. Completes
58      * the star-hop path. See https://en.wikipedia.org/wiki/A*_search_algorithm for details
59      */
60     void reconstructPath(SkyPoint const *curr_node);
61 
62     float fov { 0 };
63     float maglim { 0 };
64     QString starHopDirections;
65     // Useful for internal computations
66     SkyPoint const *start { nullptr };
67     SkyPoint const *end { nullptr };
68     QHash<const SkyPoint *, const SkyPoint *> came_from; // Used by the A* search algorithm
69     QList<StarObject const *> result_path;
70     QHash<SkyPoint const *, QString> patternNames; // if patterns were identified, they are added to this hash.
71 };
72