/**
 * AKSRT Page Navigation — v3.0
 *
 * 功能：
 * - TOC 高亮 + 平滑滚动（文档阅读页）
 * - 文档导航搜索 + 结果接管（文档导航页）
 * - 分类切换 AJAX 加载 + 分页（文档导航页）
 * - 加载状态和分页控件
 *
 * @package AKSRT
 */

(function () {
  'use strict';

  var API_BASE = (window.aksrtData && window.aksrtData.restNonce)
    ? (window.aksrtData.siteUrl || '') + '/wp-json/aksrt/v1'
    : '';
  var NONCE = (window.aksrtData && window.aksrtData.restNonce) || '';

  var PAGE_NAVS = {
    tocItems: [],
    headings: [],
    scrollTimer: null,
    activeCategory: 0,
    currentPage: 1,
    totalPages: 1,
    searchQuery: '',
    ajaxInFlight: null,

    init: function () {
      this.initTocHighlight();
      this.initSmoothScroll();
      this.initDocSearch();
      this.initCategoryChips();
      this.initPagination();
    },

    /* ============================================================
     * TOC 高亮（文档阅读页）
     * ============================================================ */
    initTocHighlight: function () {
      var toc = document.querySelector('.aksrt-doc-toc');
      if (!toc) return;

      this.tocItems = Array.from(toc.querySelectorAll('.aksrt-doc-toc__item a'));
      if (this.tocItems.length === 0) return;

      this.headings = this.tocItems.map(function (link) {
        var id = link.getAttribute('href');
        if (id && id.startsWith('#')) {
          return document.getElementById(id.substring(1));
        }
        return null;
      }).filter(Boolean);

      if (this.headings.length === 0) return;

      var self = this;
      window.addEventListener('scroll', function () {
        if (self.scrollTimer) clearTimeout(self.scrollTimer);
        self.scrollTimer = setTimeout(function () { self.updateTocHighlight(); }, 50);
      }, { passive: true });

      this.updateTocHighlight();
    },

    updateTocHighlight: function () {
      var scrollY = window.scrollY + 100;
      var currentIndex = -1;

      for (var i = this.headings.length - 1; i >= 0; i--) {
        if (this.headings[i].offsetTop <= scrollY) {
          currentIndex = i;
          break;
        }
      }

      this.tocItems.forEach(function (link, index) {
        var li = link.parentElement;
        if (index === currentIndex) {
          li.classList.add('is-active');
          link.classList.add('is-active');
        } else {
          li.classList.remove('is-active');
          link.classList.remove('is-active');
        }
      });
    },

    /* ============================================================
     * 平滑滚动
     * ============================================================ */
    initSmoothScroll: function () {
      document.addEventListener('click', function (e) {
        var link = e.target.closest('a[href^="#"]');
        if (!link) return;

        var id = link.getAttribute('href').substring(1);
        if (!id) return;

        var target = document.getElementById(id);
        if (!target) return;

        e.preventDefault();
        var offset = 80; // nav height
        var top = target.getBoundingClientRect().top + window.scrollY - offset;
        window.scrollTo({ top: top, behavior: 'smooth' });
      });
    },

    /* ============================================================
     * 文档搜索（AJAX 接管）
     * ============================================================ */
    initDocSearch: function () {
      var searchInput = document.querySelector('.aksrt-doc-search__input');
      if (!searchInput) return;

      var resultsContainer = document.querySelector('.aksrt-doc-search__results');
      var takeover = document.querySelector('.aksrt-doc-takeover');
      var self = this;

      var debounceTimer = null;
      searchInput.addEventListener('input', function () {
        var query = searchInput.value.trim();
        if (debounceTimer) clearTimeout(debounceTimer);

        if (query.length < 2) {
          self.clearSearch(resultsContainer, takeover);
          return;
        }

        debounceTimer = setTimeout(function () {
          self.searchDocs(query, resultsContainer, takeover);
        }, 300);
      });

      searchInput.addEventListener('keydown', function (e) {
        if (e.key === 'Escape') {
          searchInput.value = '';
          self.clearSearch(resultsContainer, takeover);
        }
      });
    },

    searchDocs: function (query, resultsContainer, takeover) {
      if (this.ajaxInFlight) {
        this.ajaxInFlight.abort();
      }

      var self = this;
      this.showLoading(takeover || resultsContainer);

      var url = API_BASE + '/docs/search?q=' + encodeURIComponent(query);
      this.ajaxInFlight = this.ajaxRequest(url, function (data) {
        self.hideLoading(takeover || resultsContainer);
        self.renderSearchResults(data, resultsContainer, takeover, query);
      }, function () {
        self.hideLoading(takeover || resultsContainer);
      });
    },

    renderSearchResults: function (data, resultsContainer, takeover, query) {
      var items = data.items || data.data || [];
      if (items.length === 0) {
        if (resultsContainer) {
          resultsContainer.hidden = false;
          resultsContainer.innerHTML = '<div class="aksrt-doc-search__empty">未找到相关文档</div>';
        }
        return;
      }

      var html = '<div class="aksrt-doc-search__list">';
      items.forEach(function (item) {
        html += '<a class="aksrt-doc-search__item" href="' + this.escHtml(item.url) + '">';
        html += '<span class="aksrt-doc-search__item-title">' + this.highlightQuery(this.escHtml(item.title), query) + '</span>';
        if (item.excerpt) {
          html += '<span class="aksrt-doc-search__item-excerpt">' + this.highlightQuery(this.escHtml(item.excerpt), query) + '</span>';
        }
        html += '</a>';
      }.bind(this));
      html += '</div>';

      if (takeover) {
        takeover.innerHTML = html;
        takeover.hidden = false;
      } else if (resultsContainer) {
        resultsContainer.innerHTML = html;
        resultsContainer.hidden = false;
      }
    },

    highlightQuery: function (text, query) {
      if (!query) return text;
      var escaped = query.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
      return text.replace(new RegExp('(' + escaped + ')', 'gi'), '<mark>$1</mark>');
    },

    clearSearch: function (resultsContainer, takeover) {
      if (takeover) {
        takeover.hidden = true;
        takeover.innerHTML = '';
      }
      if (resultsContainer) {
        resultsContainer.hidden = true;
        resultsContainer.innerHTML = '';
      }
      // 显示所有卡片
      var cards = document.querySelectorAll('.aksrt-doc-index-card');
      cards.forEach(function (card) { card.style.display = ''; });
    },

    showLoading: function (container) {
      if (!container) return;
      var existing = container.querySelector('.aksrt-doc-loading');
      if (existing) return;

      var loader = document.createElement('div');
      loader.className = 'aksrt-doc-loading';
      loader.innerHTML = '<div class="aksrt-doc-loading__spinner"></div><span>搜索中...</span>';
      container.appendChild(loader);
    },

    hideLoading: function (container) {
      if (!container) return;
      var loader = container.querySelector('.aksrt-doc-loading');
      if (loader) loader.remove();
    },

    /* ============================================================
     * 分类切换 — AJAX 加载 + 分页
     * ============================================================ */
    initCategoryChips: function () {
      var toolbar = document.querySelector('.aksrt-doc-toolbar');
      if (!toolbar) return;

      var chips = toolbar.querySelectorAll('.aksrt-doc-toolbar__chip[data-cat-id]');
      if (chips.length === 0) return;

      var self = this;
      chips.forEach(function (chip) {
        chip.addEventListener('click', function (e) {
          e.preventDefault();
          var catId = parseInt(chip.getAttribute('data-cat-id') || '0', 10);

          // 切换激活状态
          chips.forEach(function (c) { c.classList.remove('is-active'); });
          chip.classList.add('is-active');

          self.activeCategory = catId;
          self.currentPage = 1;
          self.loadCategoryDocs(catId, 1);
        });
      });
    },

    loadCategoryDocs: function (catId, page) {
      if (this.ajaxInFlight) {
        this.ajaxInFlight.abort();
      }

      var self = this;
      var grid = document.querySelector('.aksrt-doc-grid');
      if (!grid) return;

      // 显示加载状态
      grid.classList.add('is-loading');

      var url = API_BASE + '/docs/list?cat_id=' + catId + '&page=' + page + '&per_page=12';
      this.ajaxInFlight = this.ajaxRequest(url, function (data) {
        grid.classList.remove('is-loading');
        self.renderCategoryDocs(data, grid);
        self.updatePagination(data.total || 0, data.pages || 1, page);
        self.updateMetaCount(data.total || 0);
      }, function () {
        grid.classList.remove('is-loading');
      });
    },

    renderCategoryDocs: function (data, grid) {
      var items = data.items || data.data || [];
      if (items.length === 0) {
        grid.innerHTML = '<div class="aksrt-doc-empty">暂无文档</div>';
        return;
      }

      var html = '';
      items.forEach(function (item) {
        html += '<a class="aksrt-doc-index-card" href="' + this.escHtml(item.url) + '" data-cat-id="' + (item.cat_id || 0) + '">';
        if (item.thumbnail) {
          html += '<img src="' + this.escHtml(item.thumbnail) + '" class="aksrt-doc-index-card__thumb" alt="">';
        }
        html += '<div class="aksrt-doc-index-card__body">';
        html += '<h3 class="aksrt-doc-index-card__title">' + this.escHtml(item.title) + '</h3>';
        if (item.excerpt) {
          html += '<p class="aksrt-doc-index-card__desc">' + this.escHtml(item.excerpt) + '</p>';
        }
        html += '<div class="aksrt-doc-index-card__meta">';
        if (item.child_count) html += '<span>' + item.child_count + ' 篇子文档</span>';
        if (item.date) html += '<span>' + this.escHtml(item.date) + '</span>';
        html += '</div></div></a>';
      }.bind(this));

      grid.innerHTML = html;
    },

    updateMetaCount: function (total) {
      var meta = document.querySelector('.aksrt-doc-toolbar__meta');
      if (meta) {
        meta.textContent = total + ' 篇文档';
      }
    },

    /* ============================================================
     * 分页控件
     * ============================================================ */
    initPagination: function () {
      var self = this;
      var paginationContainer = document.querySelector('.aksrt-doc-pagination');
      if (!paginationContainer) return;

      paginationContainer.addEventListener('click', function (e) {
        var btn = e.target.closest('[data-page]');
        if (!btn) return;

        e.preventDefault();
        var page = parseInt(btn.getAttribute('data-page'), 10);
        if (page < 1 || page > self.totalPages || page === self.currentPage) return;

        self.currentPage = page;
        self.loadCategoryDocs(self.activeCategory, page);

        // 滚动到顶部
        var grid = document.querySelector('.aksrt-doc-grid');
        if (grid) {
          grid.scrollIntoView({ behavior: 'smooth', block: 'start' });
        }
      });
    },

    updatePagination: function (total, totalPages, currentPage) {
      this.totalPages = totalPages;
      this.currentPage = currentPage;

      var container = document.querySelector('.aksrt-doc-pagination');
      if (!container) return;

      if (totalPages <= 1) {
        container.innerHTML = '';
        return;
      }

      var html = '<div class="aksrt-doc-pagination__inner">';

      // 上一页
      if (currentPage > 1) {
        html += '<button class="aksrt-doc-pagination__btn" data-page="' + (currentPage - 1) + '"><i class="fa fas fa-chevron-left"></i></button>';
      }

      // 页码
      var start = Math.max(1, currentPage - 2);
      var end = Math.min(totalPages, currentPage + 2);

      if (start > 1) {
        html += '<button class="aksrt-doc-pagination__btn" data-page="1">1</button>';
        if (start > 2) html += '<span class="aksrt-doc-pagination__ellipsis">...</span>';
      }

      for (var i = start; i <= end; i++) {
        html += '<button class="aksrt-doc-pagination__btn' + (i === currentPage ? ' is-active' : '') + '" data-page="' + i + '">' + i + '</button>';
      }

      if (end < totalPages) {
        if (end < totalPages - 1) html += '<span class="aksrt-doc-pagination__ellipsis">...</span>';
        html += '<button class="aksrt-doc-pagination__btn" data-page="' + totalPages + '">' + totalPages + '</button>';
      }

      // 下一页
      if (currentPage < totalPages) {
        html += '<button class="aksrt-doc-pagination__btn" data-page="' + (currentPage + 1) + '"><i class="fa fas fa-chevron-right"></i></button>';
      }

      html += '</div>';
      container.innerHTML = html;
    },

    /* ============================================================
     * 工具函数
     * ============================================================ */
    escHtml: function (str) {
      var div = document.createElement('div');
      div.appendChild(document.createTextNode(str || ''));
      return div.innerHTML;
    },

    filterDocItems: function (query) {
      var cards = document.querySelectorAll('.aksrt-doc-index-card');
      if (cards.length > 0) {
        cards.forEach(function (card) {
          var title = card.querySelector('.aksrt-doc-index-card__title');
          var desc = card.querySelector('.aksrt-doc-index-card__desc');
          var text = (title ? title.textContent : '') + ' ' + (desc ? desc.textContent : '');
          if (query === '' || text.toLowerCase().indexOf(query) >= 0) {
            card.style.display = '';
          } else {
            card.style.display = 'none';
          }
        });
      }

      var sidebarItems = document.querySelectorAll('.aksrt-doc-sidebar__item');
      if (sidebarItems.length > 0) {
        sidebarItems.forEach(function (item) {
          var link = item.querySelector('.aksrt-doc-sidebar__link');
          var text = link ? link.textContent : '';
          if (query === '' || text.toLowerCase().indexOf(query) >= 0) {
            item.style.display = '';
          } else {
            item.style.display = 'none';
          }
        });
      }
    },

    ajaxRequest: function (url, onSuccess, onError) {
      var xhr = new XMLHttpRequest();
      xhr.open('GET', url, true);
      if (NONCE) {
        xhr.setRequestHeader('X-WP-Nonce', NONCE);
      }
      xhr.onreadystatechange = function () {
        if (xhr.readyState !== 4) return;
        if (xhr.status >= 200 && xhr.status < 300) {
          try {
            var data = JSON.parse(xhr.responseText);
            if (onSuccess) onSuccess(data);
          } catch (e) {
            if (onError) onError(e);
          }
        } else {
          if (onError) onError(new Error('HTTP ' + xhr.status));
        }
      };
      xhr.send();
      return xhr;
    }
  };

  jQuery(document).off('auto_fun.aksrt-page-navs').on('auto_fun.aksrt-page-navs', function () { PAGE_NAVS.init(); });
})();