#include <isogfx/backend.h>
#include <isogfx/isogfx.h>

#include <gfx/app.h>

#include <assert.h>
#include <stdbool.h>
#include <stdio.h>

static const int WINDOW_WIDTH  = 1408;
static const int WINDOW_HEIGHT = 960;
static const int MAX_FPS       = 60;

// Virtual screen dimensions.
static const int SCREEN_WIDTH  = 704;
static const int SCREEN_HEIGHT = 480;

static const int TILE_WIDTH   = 32;
static const int TILE_HEIGHT  = TILE_WIDTH / 2;
static const int WORLD_WIDTH  = 20;
static const int WORLD_HEIGHT = 20;

static const TileDesc tile_set[] = {
    {.type   = TileFromColour,
     .width  = TILE_WIDTH,
     .height = TILE_HEIGHT,
     .colour = (Pixel){.r = 0x38, .g = 0x3b, .b = 0x46, .a = 0xff}},
    {.type   = TileFromColour,
     .width  = TILE_WIDTH,
     .height = TILE_HEIGHT,
     .colour = (Pixel){.r = 0xA5, .g = 0xb3, .b = 0xc0, .a = 0xff}},
    {.type   = TileFromColour,
     .width  = TILE_WIDTH,
     .height = TILE_HEIGHT,
     .colour = (Pixel){.r = 0xdc, .g = 0x76, .b = 0x84, .a = 0xff}},
};

typedef enum Colour {
  Black,
  White,
  Red,
} Colour;

typedef struct GfxAppState {
  IsoBackend* backend;
  IsoGfx*     iso;
  Tile        red;
  int         xpick;
  int         ypick;
} GfxAppState;

static void make_checkerboard(IsoGfx* iso, Tile black, Tile white) {
  assert(iso);
  for (int y = 0; y < isogfx_world_height(iso); ++y) {
    for (int x = 0; x < isogfx_world_width(iso); ++x) {
      const int  odd_col = x & 1;
      const int  odd_row = y & 1;
      const Tile value   = (odd_row ^ odd_col) == 0 ? black : white;
      isogfx_set_tile(iso, x, y, value);
    }
  }
}

static bool init(GfxAppState* state, int argc, const char** argv) {
  assert(state);

  (void)argc;
  (void)argv;

  if (!(state->iso = isogfx_new(&(IsoGfxDesc){
            .screen_width = SCREEN_WIDTH, .screen_height = SCREEN_HEIGHT}))) {
    return false;
  }
  IsoGfx* iso = state->iso;

  isogfx_resize(iso, SCREEN_WIDTH, SCREEN_HEIGHT);

  if (!isogfx_make_world(
          iso, &(WorldDesc){
                   .tile_width   = TILE_WIDTH,
                   .tile_height  = TILE_HEIGHT,
                   .world_width  = WORLD_WIDTH,
                   .world_height = WORLD_HEIGHT})) {
    return false;
  }

  const Tile black = isogfx_make_tile(iso, &tile_set[Black]);
  const Tile white = isogfx_make_tile(iso, &tile_set[White]);
  state->red       = isogfx_make_tile(iso, &tile_set[Red]);
  make_checkerboard(iso, black, white);

  if (!(state->backend = IsoBackendInit(iso))) {
    return false;
  }

  return true;
}

static void shutdown(GfxAppState* state) {
  assert(state);

  IsoBackendShutdown(&state->backend);
  isogfx_del(&state->iso);
}

static void update(GfxAppState* state, double t, double dt) {
  assert(state);
  (void)dt;

  IsoGfx* iso = state->iso;

  isogfx_update(iso, t);

  // Get mouse position in window coordinates.
  double mouse_x, mouse_y;
  gfx_app_get_mouse_position(&mouse_x, &mouse_y);

  // Map from window coordinates to virtual screen coordinates.
  IsoBackendGetMousePosition(
      state->backend, mouse_x, mouse_y, &mouse_x, &mouse_y);

  isogfx_pick_tile(iso, mouse_x, mouse_y, &state->xpick, &state->ypick);

  printf("Picked tile: (%d, %d)\n", state->xpick, state->ypick);
}

static void render(GfxAppState* state) {
  assert(state);

  IsoGfx* iso = state->iso;

  isogfx_render(iso);

  if ((state->xpick != -1) && (state->ypick != -1)) {
    isogfx_draw_tile(iso, state->xpick, state->ypick, state->red);
  }

  IsoBackendRender(state->backend, iso);
}

static void resize(GfxAppState* state, int width, int height) {
  assert(state);

  IsoBackendResizeWindow(state->backend, state->iso, width, height);
}

int main(int argc, const char** argv) {
  GfxAppState state = {0};
  gfx_app_run(
      &(GfxAppDesc){
          .argc              = argc,
          .argv              = argv,
          .width             = WINDOW_WIDTH,
          .height            = WINDOW_HEIGHT,
          .max_fps           = MAX_FPS,
          .update_delta_time = MAX_FPS > 0 ? 1.0 / (double)MAX_FPS : 0.0,
          .title             = "Isometric Renderer",
          .app_state         = &state},
      &(GfxAppCallbacks){
          .init     = init,
          .update   = update,
          .render   = render,
          .resize   = resize,
          .shutdown = shutdown});
  return 0;
}