#include <iostream>
#include <SDL.h>
#include <SDL_ttf.h>
#include <SDL_image.h>



#define FNCross(x1, y1, x2, y2) x1 * y2 - y1 * x2

void Intersect(float& x1, float& y1, float& x2, float& y2, float x3, float y3, float x4, float y4, float& x, float& y)
{
	x = FNCross(x1, y1, x2, y2);
	y = FNCross(x3, y3, x4, y4);
	float det = FNCross(x1 - x2, y1 - y2, x3 - x4, y3 - y4);
	x = FNCross(x, x1 - x2, y, x3 - x4) / det;
	y = FNCross(x, y1 - y2, y, y3 - y4) / det;
}

void QuitSDL(SDL_Window* w = nullptr, SDL_Renderer* r = nullptr, SDL_Surface* s[] = nullptr, int numSurfaces = 0, SDL_Texture* t[] = nullptr, int numTextures = 0, TTF_Font* f[] = nullptr, int NumFonts = 0)
{
	if (t != nullptr) for (int nt = 0; nt < numTextures; nt++) SDL_DestroyTexture(t[nt]);
	if (s != nullptr) for (int ns = 0; ns < numSurfaces; ns++) SDL_FreeSurface(s[ns]);
	if (f != nullptr) for (int nf = 0; nf < NumFonts; nf++) TTF_CloseFont(f[nf]);
	if (r != nullptr) SDL_DestroyRenderer(r);
	if (w != nullptr) SDL_DestroyWindow(w);
	TTF_Quit();
	IMG_Quit();
	SDL_Quit();
}

void Init()
{
	SDL_Init(SDL_INIT_EVERYTHING);
	IMG_Init(IMG_INIT_PNG | IMG_INIT_JPG);
	TTF_Init();
}

int main(int args, char* argc[])
{
	// before SDL init
	const int WinW{ 600 }; const int WinH{ 400 };

	// SDL init
	Init();
	SDL_Window* win{ SDL_CreateWindow("SDL DOOM LIKE ENGINE DEMO", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, WinW, WinH, SDL_WINDOW_SHOWN) };
	SDL_Renderer* ren{ SDL_CreateRenderer(win, -1, SDL_RENDERER_PRESENTVSYNC) };

	// other variables
	SDL_Event e; bool q{ false };

	// player variables
	float angle = 0.0;
	float px{ 100 }; float py{ 100 };

	// view port rects
	SDL_Rect Viewport1{ 0, 100, 200, 200 };
	SDL_Rect Viewport2{ 200, 100, 200, 200 };
	SDL_Rect Viewport3{ 400, 100, 200, 200 };

	SDL_Rect Border{0, 0, 200, 200};

	// wall variables
	float wall_x1 = 140; float wall_y1 = 40;
	float wall_x2 = 140; float wall_y2 = 140;

	// main loop
	while (!q)
	{
		// render clear
		SDL_SetRenderDrawColor(ren, 0, 0, 0, 255);
		SDL_RenderClear(ren);

		// view box 1
		SDL_RenderSetViewport(ren, &Viewport1);
		SDL_SetRenderDrawColor(ren, 200, 200, 0, 255);
		SDL_RenderDrawLineF(ren, wall_x1, wall_y1, wall_x2, wall_y2);
		SDL_SetRenderDrawColor(ren, 255, 255, 255, 255);
		SDL_RenderDrawLineF(ren, px, py, (cosf(angle) * 8) + px, (sinf(angle) * 8) + py);
		SDL_RenderSetScale(ren, 2, 2);
		SDL_RenderDrawPointF(ren, (px / 2), (py / 2));
		SDL_RenderSetScale(ren, 1, 1);
		SDL_SetRenderDrawColor(ren, 0, 0, 250, 255);
		SDL_RenderDrawRect(ren, &Border);

		// view box 2
		SDL_RenderSetViewport(ren, &Viewport2);

		// more variables to use
		float tx1{ wall_x1 - px }; float ty1{ wall_y1 - py };
		float tx2{ wall_x2 - px }; float ty2{ wall_y2 - py };
		float tz1{ tx1 * cosf(angle) + ty1 * sinf(angle) };
		float tz2{ tx2 * cosf(angle) + ty2 * sinf(angle) };
		tx1 = tx1 * sinf(angle) - ty1 * cosf(angle);
		tx2 = tx2 * sinf(angle) - ty2 * cosf(angle);

		SDL_SetRenderDrawColor(ren, 200, 200, 0, 255);
		SDL_RenderDrawLineF(ren,  100 - tx1, 100 - tz1, 100 - tx2, 100 - tz2);
		SDL_SetRenderDrawColor(ren, 255, 255, 255, 255);
		SDL_RenderDrawLineF(ren, 100, 100, 100, 90);
		SDL_RenderSetScale(ren, 2, 2);
		SDL_RenderDrawPointF(ren, 50, 50);
		SDL_RenderSetScale(ren, 1, 1);
		SDL_SetRenderDrawColor(ren, 0, 250, 0, 255);
		SDL_RenderDrawRect(ren, &Border);

		// view box 3
		SDL_RenderSetViewport(ren, &Viewport3);
		if (tz1 > 0 || tz2 > 0)
		{
			float ix1; float iz1;
			float ix2; float iz2;
			Intersect(tx1, tz1, tx2, tz2, -0.0001, 0.0001, -20, 5, ix1, iz1);
			Intersect(tx1, tz1, tx2, tz2, 0.0001, 0.0001, 20, 5, ix2, iz2);
			if (tz1 <= 0)
			{
				if (iz1 > 0)
				{
					tx1 = iz1; tz1 = iz1;
				}
				else
				{
					tx1 = ix2; tz1 = iz2;
				}
			}
			if (tz2 <= 0)
			{
				if (iz1 > 0)
				{
					tx2 = ix1; tz2 = iz1;
				}
				else
				{
					tx2 = ix2; tz2 = iz2;
				}
			}
			float x1{ -tx1 * 16 / tz1 }; float y1a{ -50 / tz1 }; float y1b{ 50 / tz1 };
			float x2{ -tx2 * 16 / tz2 }; float y2a{ -50 / tz2 }; float y2b{ 50 / tz2 };
			SDL_SetRenderDrawColor(ren, 255, 255, 0, 255);
			SDL_RenderDrawLineF(ren, 50 + x1, 50 + y1a, 50 + x2, 50 + y2a); // top
			SDL_RenderDrawLineF(ren, 50 + x1, 50 + y1b, 50 + x2, 50 + y2b); // bottom
			SDL_RenderDrawLineF(ren, 50 + x1, 50 + y1a, 50 + x1, 50 + y1b); // left
			SDL_RenderDrawLineF(ren, 50 + x2, 50 + y2a, 50 + x2, 50 + y2b); // right
		}
		SDL_SetRenderDrawColor(ren, 255, 0, 0, 255);
		SDL_RenderDrawRect(ren, &Border);

		SDL_RenderPresent(ren);
		while (SDL_PollEvent(&e))
		{
			if (e.type == SDL_QUIT) q = true;
			else if (e.type == SDL_KEYDOWN)
			{
				switch (e.key.keysym.sym)
				{
				case SDLK_w: px += cosf(angle); py += sinf(angle); break;
				case SDLK_s: px -= cosf(angle); py -= sinf(angle); break;
				case SDLK_a: px += sinf(angle); py -= cosf(angle); break;
				case SDLK_d: px -= sinf(angle); py += cosf(angle); break;
				case SDLK_q: angle -= 0.1f; break;
				case SDLK_e: angle += 0.1f; break;
				}
			}
		}
	}

	// exit code
	QuitSDL(win, ren);
	return 0;
}