#define _POSIX_C_SOURCE 200809L

#include <bits/time.h>
#include <math.h>
#include <pthread.h>
#include <raylib.h>
#include <stdio.h>
#include <stdlib.h>
#include <threads.h>
#include <time.h>
#include <unistd.h>
#include "consts.h"
#include "mechanics.h"

int center_x_text(const char *text, int width, int size) {
  return (width - MeasureText(text, size)) / 2;
}

static inline int center_y_text(int height, int size) {
  return (height - size) / 2;
}



long long timespec_diff_ns(struct timespec end, struct timespec start) {
  return (end.tv_sec - start.tv_sec) * 1000000000LL +
         (end.tv_nsec - start.tv_nsec);
}

void *physics(void *args) {
  universe_t *uni = (universe_t *)args;
  struct timespec ot, ct;
  while (true) {
    mechanics(uni);
    ot = ct;
    clock_gettime(CLOCK_MONOTONIC, &ct);
    long long elapsed = timespec_diff_ns(ct, ot);
    long long remaining = TIMESTEP / simx - elapsed;

    if (remaining > 0) {
      long long sleep_time = remaining * 9 / 10;

      struct timespec sleep_time_spec = {0, sleep_time};
      thrd_sleep(&sleep_time_spec, NULL);
    }

    do {
      clock_gettime(CLOCK_MONOTONIC, &ct);
    } while (timespec_diff_ns(ct, ot) < TIMESTEP / simx);
  }
}

int main(void) {
  pthread_t physics_thread;
  const char *welcome_text = "Welcome to Fucked Physics!";
  universe_t universe = {0, NULL};
  universe.bodies = malloc(1024 * sizeof(mass_body_t));
  universe.num_bodies = 0;
  for (int slot = -1; slot < 32 * 20 && universe.num_bodies < 1024; slot++) {
    float radius = 12.0f + 8.0f / (universe.num_bodies + 1);
    float x = slot < 0
                  ? 0.0f
                  : -387.5f + 25.0f * (slot % 32) + (slot / 32 % 2) * 12.5f;
    float y = slot < 0 ? 0.0f : -209.0f + 22.0f * (slot / 32);
    if (fabsf(x) + radius > 400.0f || fabsf(y) + radius > 225.0f) {
      continue;
    }

    bool overlaps = false;
    for (unsigned int j = 0; j < universe.num_bodies; j++) {
      float dx = x - universe.bodies[j].position.x;
      float dy = y - universe.bodies[j].position.y;
      float min_distance = radius + universe.bodies[j].radius;
      if (dx * dx + dy * dy <= min_distance * min_distance) {
        overlaps = true;
        break;
      }
    }
    if (overlaps) {
      continue;
    }

    unsigned int i = universe.num_bodies++;
    universe.bodies[i] = (mass_body_t){
        radius,
        radius,
        {x, y},
        {-0.1f, 0.8f - i * 0.005f},
    };
  }
  SetConfigFlags(FLAG_WINDOW_RESIZABLE);
  InitWindow(800, 450, "Fucked Physics");
  SetTargetFPS(120);
  pthread_create(&physics_thread, NULL, physics, (void *)&universe);

  while (!WindowShouldClose()) {

    BeginDrawing();
    ClearBackground(RAYWHITE);
    for (unsigned int i = 0; i < universe.num_bodies; i++) {
      DrawCircleV(transform_to_center(universe.bodies[i].position),
                  universe.bodies[i].radius,
                  (Color){((256 / universe.num_bodies) * i) % 256,
                          255 * (i % 2), 255 * (i % 2) * (i % 3), 255});
    }

    DrawText(welcome_text, center_x_text(welcome_text, GetRenderWidth(), 20),
             center_y_text(GetRenderHeight(), 20), 20, BLACK);
    EndDrawing();
  }

  CloseWindow();
  return EXIT_SUCCESS;
}