#include <cmath>
#include <vector>
#include <cstdint>
#include "raylib.h"
#include "raymath.h"

#define MAX_DEPTH 11

Color ColorLerp(Color c1, Color c2, float amount)
{
  Color ret{0};

  ret.r = Clamp(Lerp(c1.r, c2.r, amount), 0, 255);
  ret.g = Clamp(Lerp(c1.g, c2.g, amount), 0, 255);
  ret.b = Clamp(Lerp(c1.b, c2.b, amount), 0, 255);
  ret.a = Clamp(Lerp(c1.a, c2.a, amount), 0, 255);

  return ret;
}

struct branch
{
  Color color;
};

static std::vector<branch> tree(MAX_DEPTH);

Vector2 draw_line(Vector2 start, float angleDeg, float lenghth, int dep)
{
  angleDeg += 180.0f;
  float angle = (angleDeg * PI) / 180.0f;
  float nx = lenghth * std::sin(angle);
  float ny = lenghth * std::cos(angle);
  Vector2 end = {start.x + nx, start.y + ny};

  float thick = 2.0;
  float fstep = 1.0 / ((lenghth / thick) * 1.5);

  for (float i = 0; i < 1; i += fstep)
  {
    Vector2 point = Vector2Lerp(start, end, i);
    Color color = ColorLerp(tree[dep - 1].color, tree[dep].color, i);
    DrawCircleV(point, thick, color);
  }
  return end;
}

void draw_branch(Vector2 start, float angle, float len, int dep)
{
  if (dep >= MAX_DEPTH)
    return;

  Vector2 next = draw_line(start, angle, len, dep);

  float next_len = 0.7f;
  draw_branch(next, angle + 45, len * next_len, dep + 1);
  draw_branch(next, angle - 45, len * next_len, dep + 1);
}

void generate_tree()
{
  for (size_t i = 0; i < MAX_DEPTH; i++)
  {
    uint8_t r = GetRandomValue(0, 255);
    uint8_t g = GetRandomValue(0, 255);
    uint8_t b = GetRandomValue(0, 255);
    tree[i].color = (Color){r, g, b, 255};
  }

  tree[0].color = tree[1].color;
}

int main(void)
{
  const int screenWidth = 800;
  const int screenHeight = 800;

  InitWindow(screenWidth, screenHeight, "raylib");

  SetTargetFPS(60);

  const int textureWidth = screenWidth;
  const int textureHeight = screenHeight;

  RenderTexture2D target = LoadRenderTexture(textureWidth, textureHeight);
  Vector2 start = {textureWidth / 2, textureHeight};

  generate_tree();

  BeginTextureMode(target);
  ClearBackground(WHITE);
  draw_branch(start, 0, textureHeight / 4, 1);
  EndTextureMode();

  Rectangle source = {0, 0, (float)target.texture.width, (float)-target.texture.height};
  Rectangle dest = {0, 0, screenWidth, screenHeight};
  Vector2 position = {0, 0};
  Vector2 origin = {0.0f, 0.0f};

  while (!WindowShouldClose())
  {
    BeginDrawing();

    DrawTexturePro(target.texture, source, dest, origin, 0.0f, WHITE);

    EndDrawing();
  }

  CloseWindow();
  return 0;
}