#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <stdint.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <unistd.h>
#include <math.h>

#include <ft2build.h>
#include FT_FREETYPE_H

#include <SDL3/SDL.h>

#include "math/vec2.hpp"
#include "math/mat2x2.hpp"

struct glyph {
  int32_t width;
  int32_t height;

  int32_t horiBearingX;
  int32_t horiBearingY;
  int32_t horiAdvance;

  SDL_Texture * texture;
};

static struct glyph glyphs[0x80 - 0x20] = {0};
int32_t face_height;

int
load_outline_char(SDL_Renderer * renderer,
		  const FT_Face face,
                  const FT_Int32 load_flags,
                  const FT_Render_Mode render_mode,
                  const FT_ULong char_code)
{
  FT_Error error;
  FT_UInt glyph_index = FT_Get_Char_Index(face, char_code);

  error = FT_Load_Glyph(face, glyph_index, load_flags);
  if (error) {
    printf("FT_Load_Glyph %s\n", FT_Error_String(error));
    return -1;
  }

  error = FT_Render_Glyph(face->glyph, render_mode);
  if (error) {
    printf("FT_Render_Glyph %s\n", FT_Error_String(error));
    return -1;
  }

  struct glyph * glyph = &glyphs[char_code - 0x20];

  glyph->width = face->glyph->bitmap.width;
  glyph->height = face->glyph->bitmap.rows;
  glyph->horiBearingX = face->glyph->metrics.horiBearingX;
  glyph->horiBearingY = face->glyph->metrics.horiBearingY;
  glyph->horiAdvance = face->glyph->metrics.horiAdvance;

  if (face->glyph->bitmap.pitch != 0) {
    SDL_Surface * surface = SDL_CreateSurface(face->glyph->bitmap.width,
					      face->glyph->bitmap.rows,
					      SDL_PIXELFORMAT_RGBA8888);

    SDL_LockSurface(surface);

    for (unsigned int y = 0; y < face->glyph->bitmap.rows; y++) {
      for (unsigned int x = 0; x < face->glyph->bitmap.width; x++) {
	int s_ix = y * face->glyph->bitmap.pitch + x;
	int d_ix = y * surface->pitch + x * 4;
	uint8_t gray = face->glyph->bitmap.buffer[s_ix];
	((uint8_t *)surface->pixels)[d_ix + 0] = gray;
	((uint8_t *)surface->pixels)[d_ix + 1] = gray;
	((uint8_t *)surface->pixels)[d_ix + 2] = gray;
	((uint8_t *)surface->pixels)[d_ix + 3] = 255;
      }
    }

    SDL_UnlockSurface(surface);

    if (glyph->texture != NULL)
      SDL_DestroyTexture(glyph->texture);
    glyph->texture = SDL_CreateTextureFromSurface(renderer, surface);
    if (glyph->texture == NULL) {
      printf("%s\n", SDL_GetError());
    }
    assert(glyph->texture != NULL);

    SDL_DestroySurface(surface);
  }

  return 0;
}

int load_font(SDL_Renderer * renderer, int font_size)
{
  FT_Library library;
  FT_Face face;
  FT_Error error;

  error = FT_Init_FreeType(&library);
  if (error) {
    printf("FT_Init_FreeType\n");
    return -1;
  }

  error = FT_New_Face(library, "/home/bilbo/timer/DejaVuSansMono.ttf", 0, &face);
  if (error) {
    printf("FT_New_Face\n");
    return -1;
  }

  error = FT_Set_Pixel_Sizes(face, 0, font_size);
  if (error) {
    printf("FT_Set_Pixel_Sizes: %s %d\n", FT_Error_String(error), error);
    return -1;
  }

  for (int char_code = 0x20; char_code <= 0x7f; char_code++) {
    load_outline_char(renderer, face, FT_LOAD_DEFAULT, FT_RENDER_MODE_NORMAL, char_code);
  }

  printf("loaded size %ld\n", face->size->metrics.height >> 6);
  face_height = face->size->metrics.height;

  return 0;
}

int32_t render_text(SDL_Renderer * renderer, int32_t x, int32_t y, const char * s, int length)
{
  int32_t x_advance = x;
  int32_t y_advance = y;
  for (int i = 0; i < length; i++) {
    char c = s[i];
    struct glyph * glyph = &glyphs[c - 0x20];
    x_advance += glyph->horiAdvance;
    if (glyph->texture != NULL) {
      float x = (float)(x_advance + glyph->horiBearingX) / 64.f;
      float y = (float)(y_advance - glyph->horiBearingY) / 64.f;
      SDL_FRect srect = {
	.x = 0.f,
	.y = 0.f,
	.w = (float)glyph->width,
	.h = (float)glyph->height
      };
      SDL_FRect drect = {
	.x = x,
	.y = y,
	.w = (float)glyph->width,
	.h = (float)glyph->height
      };
      SDL_RenderTexture(renderer, glyph->texture, &srect, &drect);
    }
  }
  return x_advance;
}

using vec2 = vec<2, float>;
using mat2x2 = mat<2, 2, float>;

struct line {
  vec2 a;
  vec2 b;
};

struct state {
  struct line line;
  vec2 normal;
  vec2 mouse_position;
};

struct state state = {
  .line = {
    { 0, -0.5 },
    { 0,  0.5 },
  },
  .normal = { -1, 0 },
};

static int window_width = 1;
static int window_height = 1;

static inline int min(int a, int b)
{
  return (a > b) ? b : a;
}

vec2 transform_vertex(vec2 v, float scale)
{
  float dim = ((float)min(window_height, window_width)) / 2.0f;

  float x = v.x;
  float y = v.y;

  x *= scale;
  y *= scale;

  return {
    x * dim + window_width / 2.0f,
    y * dim + window_height / 2.0f,
  };
}

vec2 inverse_transform(float x, float y)
{
  float dim = ((float)min(window_height, window_width)) / 2.0f;
  assert(dim != 0);

  return {
    -(window_width - 2 * x) / (2 * dim),
    -(window_height - 2 * y) / (2 * dim),
  };
}

struct line transform_line(struct line line, float scale)
{
  return {
    transform_vertex(line.a, scale),
    transform_vertex(line.b, scale),
  };
}

static inline void render_line(SDL_Renderer * renderer, struct line line)
{
  assert(SDL_RenderLine(renderer, line.a.x, line.a.y, line.b.x, line.b.y));
}

void render_lines(SDL_Renderer * renderer)
{
  // line
  assert(SDL_SetRenderDrawColorFloat(renderer, 1, 0.5, 0.5, 1));
  struct line tl = transform_line(state.line, 1.0f);
  render_line(renderer, tl);

  // normal
  assert(SDL_SetRenderDrawColorFloat(renderer, 1, 0, 0, 1));
  struct line normal_line = {{0, 0}, state.normal};
  render_line(renderer, transform_line(normal_line, 0.5f));

  // mouse
  assert(SDL_SetRenderDrawColorFloat(renderer, 0, 0, 1, 1));
  struct line mouse_line = {{0, 0}, state.mouse_position};
  render_line(renderer, transform_line(mouse_line, 0.5f));

  // foo
  float s = cross(state.normal, -state.mouse_position);
  float c = dot(state.normal, -state.mouse_position);
  mat2x2 r = {
    c, -s,
    s, c,
  };

  vec2 nr = r * state.normal;
  assert(SDL_SetRenderDrawColorFloat(renderer, 0, 1, 0, 1));
  struct line nr_line = {{0, 0}, nr};
  render_line(renderer, transform_line(nr_line, 0.5f));

  {
      assert(SDL_SetRenderDrawColorFloat(renderer, 0.5, 1, 0.5, 1));
      vec2 ar = r * state.line.a;
      vec2 br = r * state.line.b;
      struct line tl = transform_line({ar, br}, 1.0f);
      render_line(renderer, tl);
  }
}

void render_text_state(SDL_Renderer * renderer)
{
  int32_t x_advance = 10 << 6;
  int32_t y_advance = face_height;
  x_advance = render_text(renderer, x_advance, y_advance, "dot: ", 5);


  //float d = dot(state.normal, state.mouse_position);
  float d = dot({0, 1}, state.mouse_position);
  char buf[64];
  int len = snprintf(buf, 64, "%.03f", d);
  x_advance = render_text(renderer, x_advance, y_advance, buf, len);
}

int main()
{
  SDL_Window * window;
  SDL_Renderer * renderer;

  bool success = SDL_Init(SDL_INIT_VIDEO);
  if (!success) printf("error: `%s`\n", SDL_GetError());
  assert(success == true);

  window = SDL_CreateWindow("sandbox",
			    512, // w
			    512, // h
			    SDL_WINDOW_RESIZABLE);// | SDL_WINDOW_MAXIMIZED);

  int num_drivers = SDL_GetNumRenderDrivers();
  printf("available drivers:\n");
  for (int i = 0; i < num_drivers; i++) {
    const char * s = SDL_GetRenderDriver(i);
    printf("  %s\n", s);
  }
  renderer = SDL_CreateRenderer(window, "software");
  SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);

  SDL_PropertiesID props = SDL_GetRendererProperties(renderer);

  const char * name = SDL_GetRendererName(renderer);
  assert(name != NULL);
  printf("renderer: %s\n", name);
  const SDL_PixelFormat * formats = (const SDL_PixelFormat *)SDL_GetPointerProperty(props, SDL_PROP_RENDERER_TEXTURE_FORMATS_POINTER, NULL);
  assert(formats != NULL);
  while (*formats != SDL_PIXELFORMAT_UNKNOWN) {
    printf("%s\n", SDL_GetPixelFormatName(*formats++));
  }

  uint64_t ticks = SDL_GetTicks();

  int font_size = 25;
  load_font(renderer, font_size);

  while (1) {
    SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
    SDL_RenderClear(renderer);
    bool success = SDL_GetWindowSizeInPixels(window, &window_width, &window_height);
    assert(success == true);

    render_text_state(renderer);
    render_lines(renderer);

    while (SDL_GetTicks() - ticks < (1000 / 60)) { SDL_Delay(1); }
    SDL_RenderPresent(renderer);
    ticks = SDL_GetTicks();

    SDL_Event event;
    while (SDL_PollEvent(&event)) {
      switch (event.type) {
      case SDL_EVENT_QUIT:
	goto exit;
      case SDL_EVENT_KEY_DOWN:
	if (event.key.key == SDLK_ESCAPE)
	  goto exit;
	break;
      case SDL_EVENT_MOUSE_BUTTON_DOWN:
        if (event.button.button == 1) {
          vec2 mv = inverse_transform(event.button.x, event.button.y);
          float m = magnitude(mv);
          state.mouse_position = mv / m;
        }
	break;
      default:
	break;
      }
    }
  }

 exit:
  SDL_DestroyRenderer(renderer);
  SDL_DestroyWindow(window);
  SDL_Quit();
}