/* Copyright (C) 2024 Aryadev Chavali

 * 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 Version 2 for
 * details.

 * You may distribute and modify this code under the terms of the GNU General
 * Public License Version 2, which you should have received a copy of along with
 * this program.  If not, please go to <https://www.gnu.org/licenses/>.

 * Created: 2024-07-25
 * Author: Aryadev Chavali
 * Description: Entrypoint
 */

#include "./numerics.hpp"

#include <cmath>
#include <cstdio>
#include <iostream>
#include <sstream>
#include <stack>
#include <tuple>

#include <raylib.h>

#define WIDTH       1024
#define HEIGHT      1024
#define FONT_SIZE   20
#define CIRCLE_SIZE 2
#define LINE_TOP    (7 * HEIGHT / 16)
#define LINE_BOTTOM (9 * HEIGHT / 16)

Node rightmost_node(const NodeAllocator &allocator)
{
  auto node = allocator.getVal(0);
  while (node.right.has_value())
    node = allocator.getVal(node.right.value());
  return node;
}

Node leftmost_node(const NodeAllocator &allocator)
{
  auto node = allocator.getVal(0);
  while (node.left.has_value())
    node = allocator.getVal(node.left.value());
  return node;
}

constexpr word_t clamp_to_width(long double value, long double min,
                                long double max)
{
  // translate v in [min, max] -> v' in [0, WIDTH]
  // [min, max] -> [0, max-min] -> [0, WIDTH]
  return WIDTH / (max - min) * (value - min);
}

void draw_fraction(Fraction f, word_t x, word_t y)
{
  std::string s{to_string(f)};
  // Centered at (x, y)
  int width = MeasureText(s.c_str(), FONT_SIZE);
  DrawText(s.c_str(), x - width / 2, y - FONT_SIZE, FONT_SIZE, WHITE);
}

void draw_node_number_line(const NodeAllocator &allocator, long double lower,
                           long double upper)
{
  std::stack<Node> stack;
  stack.push(allocator.getVal(0));
  while (!stack.empty())
  {
    Node n = stack.top();
    stack.pop();
    word_t x = clamp_to_width(n.value.norm, lower, upper);
    DrawLine(x, LINE_TOP, x, LINE_BOTTOM, RED);
    if (n.left.has_value())
      stack.push(allocator.getVal(n.left.value()));
    if (n.right.has_value())
      stack.push(allocator.getVal(n.right.value()));
  }
}

void draw_number_line(const NodeAllocator &allocator)
{
  // Draw a general guide number line
  DrawLine(0, HEIGHT / 2, WIDTH, HEIGHT / 2, WHITE);
  // Figure out the leftmost and rightmost nodes for bounds
  const auto right       = rightmost_node(allocator);
  const auto left        = leftmost_node(allocator);
  const auto upper_bound = std::ceill(right.value.norm);
  const auto lower_bound = std::floorl(left.value.norm);

  // Draw all the nodes
  draw_node_number_line(allocator, lower_bound, upper_bound);

  // Draw the bounds, with their values, in white
  word_t lower_x = clamp_to_width(left.value.norm, lower_bound, upper_bound);
  word_t upper_x = clamp_to_width(right.value.norm, lower_bound, upper_bound);
  draw_fraction(left.value, lower_x, 3 * HEIGHT / 8);
  draw_fraction(right.value, upper_x, 3 * HEIGHT / 8);
  DrawLine(lower_x, LINE_TOP, lower_x, LINE_BOTTOM, WHITE);
  DrawLine(upper_x, LINE_TOP, upper_x, LINE_BOTTOM, WHITE);
}

int main(void)
{
  // Setup CW tree
  NodeAllocator allocator{0};
  std::queue<word_t> to_iterate;
  Fraction best_frac{1, 2};
  word_t root = allocator.alloc({best_frac});
  to_iterate.push(root);

  // Setup meta text (counter, iterations, etc)
  word_t count = 1, prev_count = 0;
  std::stringstream format_stream;
  std::string format_str;
  word_t format_str_width = 0;

  InitWindow(WIDTH, HEIGHT, "Calkin-Wilf Tree");
  while (!WindowShouldClose())
  {
    if (IsKeyPressed(KEY_SPACE))
    {
      iterate(to_iterate, allocator);
      count += 2;
    }
    if (prev_count != count)
    {
      prev_count = count;
      format_stream << "Count=" << count << "\n\n";
      format_stream << "Iterations=" << (count - 1) / 2;
      format_str = format_stream.str();
      format_stream.str("");
      format_str_width = MeasureText(format_str.c_str(), FONT_SIZE * 2);
    }

    ClearBackground(BLACK);
    BeginDrawing();
    draw_number_line(allocator);
    DrawText(format_str.c_str(), WIDTH / 2 - format_str_width / 2,
             LINE_TOP - HEIGHT / 4, FONT_SIZE * 2, WHITE);
    EndDrawing();
  }
  CloseWindow();
  return 0;
}