#include <stdbool.h> // bool
#include "util.h" // warn()/die()
#include "color.h" // set_color()
#include "draw.h"

static size_t
get_cell_size(
  const draw_ctx_t * const draw_ctx
) {
  return 32 + 8 * *draw_ctx->zoom;
}

static SDL_Rect
get_cell_rect(
  const draw_ctx_t * const draw_ctx,
  const sok_pos_t pos
) {
  const size_t cell_size = get_cell_size(draw_ctx);

  return (SDL_Rect) {
    draw_ctx->render_ofs.x + pos.x * cell_size,
    draw_ctx->render_ofs.y + pos.y * cell_size,
    cell_size,
    cell_size
  };
}

static bool
draw_on_size(
  const sok_ctx_t * const ctx,
  const sok_pos_t level_size,
  void * const data
) {
  draw_ctx_t * const draw_ctx = data;
  const size_t cell_size = get_cell_size(draw_ctx);

  // get renderer size
  int renderer_x, renderer_y;
  if (SDL_GetRendererOutputSize(draw_ctx->renderer, &renderer_x, &renderer_y)) {
    die("SDL_GetRendererOutputSize(): %s", SDL_GetError());
  }

  // calculate renderer offset
  draw_ctx->render_ofs.x = (renderer_x - level_size.x * cell_size) / 2;
  draw_ctx->render_ofs.y = (renderer_y - level_size.y * cell_size) / 2;

  return true;
}

static bool
draw_on_walls_start(
  const sok_ctx_t * const ctx,
  void * const data
) {
  draw_ctx_t * const draw_ctx = data;
  set_color(draw_ctx->renderer, COLOR_WALL);

  return true;
}

static bool
draw_on_wall(
  const sok_ctx_t * const ctx,
  const sok_pos_t pos,
  void * const data
) {
  draw_ctx_t * const draw_ctx = data;
  const SDL_Rect rect = get_cell_rect(draw_ctx, pos);

  if (SDL_RenderFillRect(draw_ctx->renderer, &rect)) {
    die("SDL_RenderFillRect(): %s", SDL_GetError());
  }

  return true;
}

static bool
draw_on_goals_start(
  const sok_ctx_t * const ctx,
  void * const data
) {
  draw_ctx_t * const draw_ctx = data;
  set_color(draw_ctx->renderer, COLOR_GOAL);

  return true;
}

static bool
draw_on_goal(
  const sok_ctx_t * const ctx,
  const sok_pos_t pos,
  const bool has_player,
  const bool has_box,
  void * const data
) {
  draw_ctx_t * const draw_ctx = data;
  const SDL_Rect rect = get_cell_rect(draw_ctx, pos);

  if (SDL_RenderFillRect(draw_ctx->renderer, &rect)) {
    die("SDL_RenderFillRect(): %s", SDL_GetError());
  }

  return true;
}

static bool
draw_on_home(
  const sok_ctx_t * const ctx,
  const sok_pos_t pos,
  const bool has_goal,
  void * const data
) {
  draw_ctx_t * const draw_ctx = data;
  const SDL_Rect rect = get_cell_rect(draw_ctx, pos);

  set_color(draw_ctx->renderer, has_goal ? COLOR_HOME_GOAL : COLOR_HOME);

  if (SDL_RenderFillRect(draw_ctx->renderer, &rect)) {
    die("SDL_RenderFillRect(): %s", SDL_GetError());
  }

  return true;
}

static bool
draw_on_box(
  const sok_ctx_t * const ctx,
  const sok_pos_t pos,
  const bool has_goal,
  void * const data
) {
  draw_ctx_t * const draw_ctx = data;
  const SDL_Rect rect = get_cell_rect(draw_ctx, pos);

  set_color(draw_ctx->renderer, has_goal ? COLOR_BOX_GOAL : COLOR_BOX);

  if (SDL_RenderFillRect(draw_ctx->renderer, &rect)) {
    die("SDL_RenderFillRect(): %s", SDL_GetError());
  }

  return true;
}

static const sok_ctx_walk_cbs_t
DRAW_CBS = {
  .on_size        = draw_on_size,
  .on_walls_start = draw_on_walls_start,
  .on_wall        = draw_on_wall,
  .on_goals_start = draw_on_goals_start,
  .on_goal        = draw_on_goal,
  .on_home        = draw_on_home,
  .on_box         = draw_on_box,
};

void
draw(
  draw_ctx_t * const draw_ctx
) {
  // clear background
  set_color(draw_ctx->renderer, sok_ctx_is_done(draw_ctx->ctx) ? COLOR_BG_WON : COLOR_BG);
  SDL_RenderClear(draw_ctx->renderer);

  // render
  sok_ctx_walk(draw_ctx->ctx, &DRAW_CBS, draw_ctx);

  // flip
  SDL_RenderPresent(draw_ctx->renderer);
}