/*
 *  <Short Description>
 *  Copyright (C) 2024  Brett Terpstra
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
#include "blt/std/logging.h"
#include <shifting.h>
#include <blt/math/vectors.h>
#include <vector>
#include <blt/std/hashmap.h>

inline constexpr char from_char(char c)
{
    return c;
}

struct vertex_data
{
    char name;
    HASHSET<char> neighbours;
    blt::vec2 pos;
    
    vertex_data(char name, const HASHSET<char>& n): name(from_char(name))
    {
        for (const auto& v : n)
            neighbours.insert(from_char(v));
    }
    
    vertex_data(char name, const blt::vec2& pos): name(from_char(name)), pos(pos)
    {}
};

using Point = const blt::vec2&;

bool onSegment(Point p, Point q, Point r)
{
    if (q.x() <= std::max(p.x(), r.x()) && q.x() >= std::min(p.x(), r.x()) &&
        q.y() <= std::max(p.y(), r.y()) && q.y() >= std::min(p.y(), r.y()))
        return true;
    return false;
}

int orientation(Point p, Point q, Point r)
{
    // for details of below formula.
    int val = (q.y() - p.y()) * (r.x() - q.x()) -
              (q.x() - p.x()) * (r.y() - q.y());
    
    if (val == 0) return 0;  // collinear
    
    return (val > 0) ? 1 : 2; // clock or counterclock wise
}

bool doIntersect(Point p1, Point q1, Point p2, Point q2)
{
    // Find the four orientations needed for general and
    // special cases
    int o1 = orientation(p1, q1, p2);
    int o2 = orientation(p1, q1, q2);
    int o3 = orientation(p2, q2, p1);
    int o4 = orientation(p2, q2, q1);
    
    // General case
    if (o1 != o2 && o3 != o4)
        return true;
    
    // Special Cases
    // p1, q1 and p2 are collinear and p2 lies on segment p1q1
    if (o1 == 0 && onSegment(p1, p2, q1)) return true;
    
    // p1, q1 and q2 are collinear and q2 lies on segment p1q1
    if (o2 == 0 && onSegment(p1, q2, q1)) return true;
    
    // p2, q2 and p1 are collinear and p1 lies on segment p2q2
    if (o3 == 0 && onSegment(p2, p1, q2)) return true;
    
    // p2, q2 and q1 are collinear and q1 lies on segment p2q2
    if (o4 == 0 && onSegment(p2, q1, q2)) return true;
    
    return false; // Doesn't fall in any of the above cases
}

float ccw(const blt::vec2& A, const blt::vec2& B, const blt::vec2& C)
{
    return (C.y() - A.y()) * (B.x() - A.x()) > (B.y() - A.y()) * (C.x() - A.x());
}

// Return true if line segments AB and CD intersect
bool intersects(const blt::vec2& A, const blt::vec2& B, const blt::vec2& C, const blt::vec2& D)
{
    return ccw(A, C, D) != ccw(B, C, D) and ccw(A, B, C) != ccw(A, B, D);
}

std::vector<vertex_data> edges = {
        vertex_data{'a', HASHSET<char>{'i', 'e', 'b', 'j', 'h'}},
        vertex_data{'b', HASHSET<char>{'a', 'e', 'c', 'j'}},
        vertex_data{'c', HASHSET<char>{'e', 'd', 'f', 'j', 'b'}},
        vertex_data{'d', HASHSET<char>{'e', 'f', 'c'}},
        vertex_data{'e', HASHSET<char>{'h', 'f', 'd', 'c', 'b', 'a', 'i'}},
        vertex_data{'f', HASHSET<char>{'d', 'e', 'h', 'g', 'j', 'c'}},
        vertex_data{'g', HASHSET<char>{'j', 'f', 'h'}},
        vertex_data{'h', HASHSET<char>{'j', 'g', 'f', 'e', 'i', 'a'}},
        vertex_data{'i', HASHSET<char>{'e', 'a', 'h'}},
        vertex_data{'j', HASHSET<char>{'a', 'b', 'c', 'f', 'g', 'h'}},
};

HASHSET<char>& getEdges(char c)
{
    for (auto& e : edges)
        if (e.name == c)
            return e.neighbours;
    BLT_FATAL("Failed to find character in edge set");
    std::exit(2);
}

std::vector<char> order = {
        from_char('f'),
        from_char('d'),
        from_char('c'),
        from_char('g'),
        from_char('j'),
        from_char('b'),
        from_char('e'),
        from_char('i'),
        from_char('a'),
        from_char('h'),
};

std::vector<vertex_data> out;

bool has_intersection(Point p, char c)
{
    return false;
}

void shift_right(int units)
{

}

void calculate_ordering()
{
    out.push_back(vertex_data{order.back(), blt::vec2{0, 0}});
    out.back().neighbours = getEdges(out.back().name);
    order.pop_back();
    
    out.push_back(vertex_data{order.back(), blt::vec2{2, 0}});
    out.back().neighbours = getEdges(out.back().name);
    order.pop_back();
    
    while (!order.empty())
    {
    
    }
}