/**
 * AKSRT AJAX Pagination & Lazy Load
 */
(function () {
  "use strict";

  function hasAjaxConfig() {
    return !!(window.aksrtData && aksrtData.ajaxUrl && aksrtData.nonce);
  }

  function initAjaxPagination(root) {
    var containers = (root || document).querySelectorAll(".aksrt-pagination-ajax, .ajax-pagination");
    if (!containers.length) return;

    var triggerText = (window.aksrtData && aksrtData.ajaxTrigger) || "加载更多";
    var nomoreText = (window.aksrtData && aksrtData.ajaxNomore) || "没有更多了";
    var loadingText = (window.aksrtData && aksrtData.ajaxLoading) || "正在加载...";
    var errorText = (window.aksrtData && aksrtData.ajaxLoadError) || "加载失败，请重试";

    containers.forEach(function (container) {
      if (container.dataset.aksrtPaginationBound === "1") return;
      container.dataset.aksrtPaginationBound = "1";

      var mode = container.dataset.mode || "load_more";
      var nextPage = parseInt(container.dataset.nextPage, 10) || 2;
      var maxPages = parseInt(container.dataset.maxPages, 10) || 1;
      var isComment = container.classList.contains("aksrt-comment-pagination");
      var postId = container.dataset.postId || "";
      var commentOrder = container.dataset.commentOrder || "newest";
      var loading = false;
      var failed = false;
      var loadMoreBtn = container.querySelector(".aksrt-load-more-btn, .ajax-next");
      var indicator = container.querySelector(".aksrt-loading-indicator");
      var observer = null;
      var iasEnabled = false;
      var successfulAutoLoads = 0;
      var target = container.previousElementSibling;
      if (target && target.classList && target.classList.contains("content-stream__footer")) {
        target = target.previousElementSibling;
      }
      if (isComment) {
        var commentList = document.getElementById("comment-list") ||
          (container.parentElement && container.parentElement.querySelector("#comment-list, .commentlist, ol.commentlist"));
        if (commentList) target = commentList;
      }
      if (!target && container.parentElement) {
        target = container.parentElement.querySelector(".post-grid, .comment-list, .commentlist, .content-stream__list");
      }

      function showSkeleton() {
        if (!target) return;
        var loader = target.querySelector(".post-ajax-loader");
        if (loader) {
          loader.classList.add("is-loading");
        }
      }

      function hideSkeleton() {
        if (!target) return;
        var loader = target.querySelector(".post-ajax-loader");
        if (loader) {
          loader.classList.remove("is-loading");
        }
      }

      function stopInfinite(markNomore) {
        if (observer) {
          observer.disconnect();
          observer = null;
        }
        iasEnabled = false;
        container.classList.remove("ias-pending");
        if (markNomore && loadMoreBtn) {
          loadMoreBtn.textContent = nomoreText;
          loadMoreBtn.classList.remove("is-loading");
          loadMoreBtn.classList.add("ajax-nomore");
          loadMoreBtn.style.pointerEvents = "none";
        } else if (loadMoreBtn && !loadMoreBtn.classList.contains("ajax-nomore")) {
          loadMoreBtn.classList.remove("is-loading");
          loadMoreBtn.textContent = failed ? errorText : triggerText;
          loadMoreBtn.style.pointerEvents = "";
        }
      }

      function markFailed(message) {
        failed = true;
        stopInfinite(false);
        if (loadMoreBtn) {
          loadMoreBtn.textContent = message || errorText;
          loadMoreBtn.classList.remove("is-loading");
          loadMoreBtn.classList.remove("ajax-nomore");
          loadMoreBtn.style.pointerEvents = "";
        }
      }

      function loadNextPage(fromAuto) {
        if (loading || failed || nextPage > maxPages || !target) return Promise.resolve(false);
        if (!hasAjaxConfig()) {
          markFailed(errorText);
          return Promise.resolve(false);
        }

        loading = true;
        if (indicator) indicator.style.display = "flex";
        if (loadMoreBtn) {
          loadMoreBtn.classList.add("is-loading");
          loadMoreBtn.textContent = loadingText;
        }
        showSkeleton();

        var action = isComment ? "aksrt_load_more_comments" : "aksrt_load_more_posts";
        var queryContext = container.dataset.queryContext || "";
        var queryVars = container.dataset.queryVars || "";
        var renderConfig = container.dataset.renderConfig || "";
        var body = new URLSearchParams();
        body.set("action", action);
        body.set("nonce", aksrtData.nonce);
        body.set("page", String(nextPage));
        if (queryContext) {
          body.set("query_context", queryContext);
        }
        if (!isComment && queryVars) {
          body.set("query_vars", queryVars);
        }
        if (!isComment && renderConfig) {
          body.set("render_config", renderConfig);
        }
        if (isComment && postId) {
          body.set("post_id", postId);
          body.set("comment_order", commentOrder);
          var authorOnly = container.dataset.authorOnly || "0";
          if (authorOnly === "1") body.set("author_only", "1");
        }

        return fetch(aksrtData.ajaxUrl, {
          method: "POST",
          headers: { "Content-Type": "application/x-www-form-urlencoded; charset=UTF-8" },
          credentials: "same-origin",
          body: body.toString(),
        })
          .then(function (r) {
            if (!r.ok) {
              throw new Error("HTTP " + r.status);
            }
            return r.text().then(function (text) {
              try {
                return JSON.parse(text);
              } catch (err) {
                throw new Error("Invalid JSON");
              }
            });
          })
          .then(function (res) {
            if (!(res && res.success && res.data && typeof res.data.html === "string")) {
              var msg = res && res.data && res.data.message ? res.data.message : errorText;
              markFailed(msg);
              return false;
            }

            var temp = document.createElement("div");
            temp.innerHTML = res.data.html;
            var newItems = temp.children;
            while (newItems.length > 0) {
              target.appendChild(newItems[0]);
            }
            if (isComment && window.AksrtFrontend) {
              AksrtFrontend.rehydrate(target, "ajax");
            }
            nextPage++;
            container.dataset.nextPage = String(nextPage);
            if (fromAuto) {
              successfulAutoLoads++;
            }

            if (typeof initLazyLoad === "function") initLazyLoad(target);

            if (nextPage > maxPages || !res.data.has_more) {
              stopInfinite(true);
              if (!loadMoreBtn) {
                container.innerHTML = '<span class="ajax-nomore">' + nomoreText + '</span>';
              }
            }
            return true;
          })
          .catch(function () {
            markFailed(errorText);
            return false;
          })
          .finally(function () {
            loading = false;
            hideSkeleton();
            if (indicator) indicator.style.display = "none";
            if (loadMoreBtn && !loadMoreBtn.classList.contains("ajax-nomore") && !failed) {
              loadMoreBtn.classList.remove("is-loading");
              loadMoreBtn.textContent = triggerText;
            }
          });
      }

      if (loadMoreBtn) {
        loadMoreBtn.addEventListener("click", function(e) {
          e.preventDefault();
          if (loadMoreBtn.dataset.jumpComments === "1") {
            var jumpInput = container.querySelector(".jump-input");
            if (!jumpInput) return;
            var targetPage = parseInt(jumpInput.value, 10) || 1;
            var max = parseInt(jumpInput.dataset.maxPages || String(maxPages), 10) || maxPages;
            targetPage = Math.max(1, Math.min(max, targetPage));
            var url = new URL(window.location.href);
            url.searchParams.set("cpage", String(targetPage));
            window.location.href = url.toString();
            return;
          }
          if (loadMoreBtn.dataset.jumpArchive === "1") {
            var archiveJumpInput = container.querySelector(".jump-input");
            if (!archiveJumpInput) return;
            var archiveTargetPage = parseInt(archiveJumpInput.value, 10) || 1;
            var archiveMax = parseInt(archiveJumpInput.dataset.maxPages || String(maxPages), 10) || maxPages;
            archiveTargetPage = Math.max(1, Math.min(archiveMax, archiveTargetPage));
            var archiveUrl = new URL(window.location.href);
            archiveUrl.searchParams.set("paged", String(archiveTargetPage));
            window.location.href = archiveUrl.toString();
            return;
          }
          // Manual click can recover from a previous auto-load failure.
          failed = false;
          loadNextPage(false);
        });
      }

      if (mode === "infinite" && "IntersectionObserver" in window) {
        if (isComment && window.aksrtData && aksrtData.commentIasAuto === false) {
          return;
        }
        if (!hasAjaxConfig()) {
          return;
        }

        var sentinel = document.createElement("div");
        sentinel.className = "aksrt-scroll-sentinel";
        container.appendChild(sentinel);
        var lazyloadAction = container.dataset.lazyloadAction || "";
        var iasMax = isComment
          ? ((window.aksrtData && typeof aksrtData.commentIasMax !== "undefined") ? parseInt(aksrtData.commentIasMax, 10) : 0)
          : ((window.aksrtData && typeof aksrtData.iasMax !== "undefined") ? parseInt(aksrtData.iasMax, 10) : 0);

        observer = new IntersectionObserver(
          function (entries) {
            if (!iasEnabled || failed) return;
            if (!(entries[0] && entries[0].isIntersecting) || loading) return;
            if (iasMax > 0 && successfulAutoLoads >= iasMax) {
              stopInfinite(true);
              return;
            }
            loadNextPage(true);
          },
          { rootMargin: "200px" }
        );

        if (lazyloadAction === "ias") {
          container.classList.add("ias-pending");
        }

        // Policy A: do not auto-fire on first paint; wait for real user scroll.
        var enableOnScroll = function () {
          if (iasEnabled || failed) return;
          iasEnabled = true;
          container.classList.remove("ias-pending");
          observer.observe(sentinel);
        };
        window.addEventListener("scroll", enableOnScroll, { passive: true, once: true });
        window.addEventListener("touchmove", enableOnScroll, { passive: true, once: true });
        window.addEventListener("wheel", enableOnScroll, { passive: true, once: true });
      }
    });
  }

  function initLazyLoad(root) {
    var scope = root || document;
    var lazyImages = scope.querySelectorAll("img.aksrt-lazy");
    if (!lazyImages.length) return;

    if (!("IntersectionObserver" in window)) {
      lazyImages.forEach(function (img) {
        var src = img.dataset.src;
        if (src) {
          img.src = src;
          img.classList.remove("aksrt-lazy");
          img.classList.add("aksrt-loaded");
        }
        var skeleton = img.previousElementSibling;
        if (skeleton && skeleton.classList.contains("aksrt-skeleton")) {
          skeleton.remove();
        }
      });
      return;
    }

    var observer = new IntersectionObserver(function (entries) {
      entries.forEach(function (entry) {
        if (!entry.isIntersecting) return;

        var img = entry.target;
        var src = img.dataset.src;
        if (!src) {
          observer.unobserve(img);
          return;
        }

        var tempImg = new Image();
        tempImg.onload = function () {
          img.src = src;
          img.classList.remove("aksrt-lazy");
          img.classList.add("aksrt-loaded");
          var skeleton = img.previousElementSibling;
          if (skeleton && skeleton.classList.contains("aksrt-skeleton")) {
            skeleton.remove();
          }
        };
        tempImg.onerror = function () {
          img.classList.remove("aksrt-lazy");
          img.classList.add("aksrt-error");
          var skeleton = img.previousElementSibling;
          if (skeleton && skeleton.classList.contains("aksrt-skeleton")) {
            skeleton.remove();
          }
        };
        tempImg.src = src;

        observer.unobserve(img);
      });
    }, {
      rootMargin: "200px 0px",
      threshold: 0.01
    });

    lazyImages.forEach(function (img) {
      observer.observe(img);
    });
  }

  window.AksrtFrontend.register("aksrt-ajax-pagination", function (root) { initAjaxPagination(root); });
  window.AksrtFrontend.register("aksrt-lazy-load", function (root) { initLazyLoad(root); });
})();