package usecase.post;
   
   import common.http.ParameterConverter;
   import common.http.interceptor.InterceptableServlet;
   
   import javax.inject.Inject;
   import javax.servlet.ServletException;
   import javax.servlet.annotation.WebServlet;
   import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  import java.io.IOException;
  import java.time.Instant;
  import java.time.LocalDate;
  import java.time.ZoneOffset;
  import java.util.List;
  import java.util.Map;
  import java.util.function.Function;
  
  import static usecase.post.PostSearchForm.SortCriteria.*;
  
  /**
   * Classe che permette di visualizzare i post.
   */
  @WebServlet("/loadposts")
  class LoadPostsServlet extends InterceptableServlet {
      @Inject private PostService postService;
  
      private static final Function<LocalDate, Instant> LOCALDATE_TO_INSTANT =
              x -> x.atStartOfDay().toInstant(ZoneOffset.UTC);
  
      private static final Map<String, PostSearchForm.SortCriteria> SORT_CRITERIA = Map.of(
              "oldest", OLDEST,
              "newest", NEWEST,
              "mostvoted", MOSTVOTED);
  
      @Override
      protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
          ParameterConverter converter = new ParameterConverter(req);
          String content = req.getParameter("content");
          String section = req.getParameter("section");
          String author = req.getParameter("author");
          Instant postedAfter = converter.getDateParameter("postedAfter")
                  .map(LOCALDATE_TO_INSTANT).orElse(null);
          Instant postedBefore = converter.getDateParameter("postedBefore")
                  .map(LOCALDATE_TO_INSTANT).orElse(null);
          PostSearchForm.SortCriteria orderBy = SORT_CRITERIA.get(req.getParameter("orderby"));
          int page = converter.getIntParameter("page").orElse(1);
          boolean onlyFollow = "on".equals(req.getParameter("onlyfollow"));
          boolean includeBody = req.getParameter("includeBody") != null;
  
          PostSearchForm postSearchForm = PostSearchForm.builder()
                  .content(content)
                  .onlyFollow(onlyFollow)
                  .includeBody(includeBody)
                  .sectionName(section)
                  .authorName(author)
                  .orderBy(orderBy)
                  .postedAfter(postedAfter)
                  .postedBefore(postedBefore)
                  .page(page)
                  .build();
  
          List<PostPage> posts = postService.loadPosts(postSearchForm);
          req.setAttribute("posts",posts);
          req.getRequestDispatcher("/WEB-INF/views/partials/post-previews.jsp").forward(req,resp);
      }
  
      @Override
      protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
          doGet(req, resp);
      }
  }