document.addEventListener('DOMContentLoaded', () => {
  // We instantiate the class when the DOM is ready
  new PartnerExpoSearch();
});

class PartnerExpoSearch {
  constructor() {
    this.els = {
      shell: document.getElementById("pexpo-core-shell"),
      topbar: document.getElementById("pexpo-core-topbar"),
      filterWrap: document.getElementById("pexpo-core-filterWrap"),
      filterBtn: document.getElementById("pexpo-core-filterBtn"),
      filterDrawer: document.getElementById("pexpo-core-filterDrawer"),
      drawerBackdrop: document.getElementById("pexpo-core-drawerBackdrop"),
      filterFTag: document.getElementById("pexpo-core-tag-toggle"),
      filterTags: document.getElementById("pexpo-core-tags"),
      qInput: document.getElementById("pexpo-core-q"),
      masonry: document.getElementById("pexpo-core-masonry"),
      measure: document.getElementById("pexpo-core-measure"),
      emptyResult: document.getElementById("pexpo-core-emptyResult"),
      count: document.getElementById("pexpo-core-count"),
      layoutMeta: document.getElementById("pexpo-core-layoutMeta"),
      sortSelect: document.getElementById("pexpo-core-sortSelect"),
      filterApply: document.getElementById("pexpo-core-filterApply"),
      pageNum: document.getElementById("pexpo-core-page-number"),
      pagePrev: document.getElementById("pexpo-core-page-prev"),
      pageNext: document.getElementById("pexpo-core-page-next"),
    };

    this.state = {
      filters: {
        q: "",
        sort: "relevance",
        force_tags: false,
        tags: [],
        resultsPerPage: 20,
        page: 1,
      },
      activeSortKey: "relevance",
      total: '',
      pages: 1,
      results: [],
      layoutQueued: false
    };

    this.SORTS = {
      relevance: "Relevánsság (legjobb → legrosszabb)",
      date_desc: "Dátum (új → régi)",
      date_asc: "Dátum (régi → új)",
      title_asc: "Cím (A → Z)",
      title_desc: "Cím (Z → A)",
    };

    if (this.els.shell) {
      this.init();
    }
  }

  init() {
    this.initMultiSelect();
    this.initSortDropdown();
    this.bindEvents();
    this.syncTopbarHeight();
    this.initResizeObserver();
    
    // Initial Fetch
    this.fetchData();
  }

  // ---------- Initialization Helpers ----------

  initMultiSelect() {
    if (typeof MultiSelect !== 'undefined') {
      new MultiSelect(this.els.filterTags, {
        placeholder: 'Címkék kiválasztása',
        search: true,
        selectAll: false,
        onSelect: (value) => {
          if (!this.state.filters.tags.includes(value)) {
            this.state.filters.tags.push(value);
          }
        },
        onUnselect: (value) => {
          this.state.filters.tags = this.state.filters.tags.filter(tag => tag !== value);
        }
      });
    } else {
      console.warn("MultiSelect library not found.");
    }
  }

  initSortDropdown() {
    if (!this.els.sortSelect) return;
    this.els.sortSelect.innerHTML = Object.entries(this.SORTS)
      .map(([k, label]) => `<option value="${this.escapeHtml(k)}">${this.escapeHtml(label)}</option>`)
      .join("");
    this.els.sortSelect.value = this.state.activeSortKey;
  }

  initResizeObserver() {
    const ro = new ResizeObserver(() => {
      this.syncTopbarHeight();
      this.requestLayout();
    });
    ro.observe(this.els.shell);
    ro.observe(this.els.masonry);
  }

  // ---------- Event Binding ----------

  bindEvents() {
    // Sort 
    if (this.els.sortSelect) {
      this.els.sortSelect.addEventListener("change", () => {
        this.state.activeSortKey = this.els.sortSelect.value;
        this.state.filters.sort = this.state.activeSortKey;
        this.fetchData();
      });
    }

    // Search 
    this.els.qInput.addEventListener("keyup", (e) => {
      if (e.key === "Enter") {
        this.state.filters.q = this.els.qInput.value.trim();
        this.fetchData();
      }
    });

    // Tag Toggle
    this.els.filterFTag.addEventListener("change", () => {
      this.state.filters.force_tags = this.els.filterFTag.checked;
    });

    // Drawer Toggle
    this.els.filterBtn.addEventListener("click", () => {
        const isOpen = this.els.filterDrawer.classList.contains("pexpo-core-open");
        this.setDrawerOpen(!isOpen);
    });
    
    this.els.filterApply.addEventListener("click", () => {
      this.fetchData();
      this.setDrawerOpen(false);
    });

    this.els.drawerBackdrop.addEventListener("click", () => this.setDrawerOpen(false));
    
    document.addEventListener("keydown", (e) => {
      if (e.key === "Escape" && this.els.filterDrawer.classList.contains("pexpo-core-open")) {
        this.setDrawerOpen(false);
      }
    });

    this.els.pageNext.addEventListener("click", () => {
      if (this.state.filters.page < this.state.pages) {
        this.state.filters.page += 1;
        this.fetchData();
      }
    });

    this.els.pagePrev.addEventListener("click", () => {
      if (this.state.filters.page > 1) {
        this.state.filters.page -= 1;
        this.fetchData();
      }
    });
  }

  // ---------- Fetch ----------

  async fetchData() {
    this.els.masonry.style.opacity = "0.5";

    try {
      const queryString = this.encodeDataToURL(this.state.filters);
      const response = await fetch(`/wp-json/pexpo/v1/query?${queryString}`);
      const data = await response.json();

      this.state.results = data['results'] || [];
      this.state.total = data['found'] || 0;
      this.state.pages = data['pages'] || 1;
      console.log("Fetched data:", data['pages']);
      this.requestLayout();

    } catch (error) {
      console.error("Search failed:", error);
      this.els.masonry.innerHTML = `<div style="padding:20px; color:red;">Hiba történt a keresés során.</div>`;
    } finally {
      this.els.masonry.style.opacity = "1";
    }
  }

  // ---------- UI & Layout Methods ----------

  setDrawerOpen(open) {
    this.els.filterWrap.classList.toggle("pexpo-core-open", open);
    this.els.filterBtn.setAttribute("aria-expanded", String(open));
    
    this.els.filterDrawer.classList.toggle("pexpo-core-open", open);
    this.els.filterDrawer.setAttribute("aria-hidden", String(!open));
    
    this.els.drawerBackdrop.classList.toggle("pexpo-core-show", open);
    this.els.shell.classList.toggle("pexpo-core-drawerOpen", open);

    this.syncTopbarHeight();
  }

  syncTopbarHeight() {
    const h = this.els.topbar.offsetHeight;
    document.documentElement.style.setProperty("--topbarH", h + "px");
  }

  // ---------- Masonry Engine ----------

  minCard() {
    return Number(getComputedStyle(document.documentElement).getPropertyValue("--cardMin")) || 240;
  }

  gap() {
    return Number(getComputedStyle(document.documentElement).getPropertyValue("--gap")) || 12;
  }

  requestLayout() {
    if (this.state.layoutQueued) return;
    this.state.layoutQueued = true;
    requestAnimationFrame(() => {
      this.state.layoutQueued = false;
      this.applyMasonry();
    });
  }

  getColumnCount() {
    const w = this.els.masonry.clientWidth || this.els.masonry.getBoundingClientRect().width || 1;
    const mc = this.minCard();
    const g = this.gap();
    return Math.max(1, Math.floor((w + g) / (mc + g)));
  }

  measureCardHeights(cols, list) {
    const w = this.els.masonry.clientWidth || 1;
    const g = this.gap();
    const colW = Math.floor((w - (cols - 1) * g) / cols);
    
    this.els.measure.style.width = colW + "px";
    this.els.measure.innerHTML = "";

    const measured = list.map((r, idx) => {
      const el = this.createCardElement(r);
      this.els.measure.appendChild(el);
      const h = el.offsetHeight;
      this.els.measure.removeChild(el);
      return { r, idx, h };
    });

    return { measured, colW };
  }

  packStandard(measured, cols) {
    // 1. Create an array to track the current height of each column
    const colHeights = new Array(cols).fill(0);
    
    // 2. Prepare the array to store where each item goes
    const placements = [];

    // 3. Loop through every item strictly in order
    for (const item of measured) {
      
      // 4. Find the column that is currently the shortest
      let bestCol = 0;
      for (let c = 1; c < cols; c++) {
        if (colHeights[c] < colHeights[bestCol]) {
          bestCol = c;
        }
      }

      // 5. Place the item there
      placements.push({ item: item, col: bestCol });
      
      // 6. Update that column's height
      colHeights[bestCol] += item.h + this.gap();
    }
    
    return placements;
  }

  // packRankAware(measured, cols, K = 6) {
  //   const colHeights = new Array(cols).fill(0);
  //   const placements = [];
  //   const queue = measured.slice(); 

  //   while (queue.length) {
  //     // Find shortest column
  //     let bestCol = 0;
  //     for (let c = 1; c < cols; c++) {
  //       if (colHeights[c] < colHeights[bestCol]) bestCol = c;
  //     }

  //     const lookN = Math.min(K, queue.length);
  //     let pick = 0;
  //     for (let i = 1; i < lookN; i++) {
  //       if (queue[i].h > queue[pick].h) pick = i;
  //     }

  //     const picked = queue.splice(pick, 1)[0];
  //     placements.push({ item: picked, col: bestCol });
  //     colHeights[bestCol] += picked.h + this.gap();
  //   }
  //   return placements;
  // }

  applyMasonry() {
    const n = this.state.results.length || 0;
    const page = this.state.filters.page || 1;
    const pages = this.state.pages;
    this.els.count.textContent = this.state.total ? this.state.total : '';
    this.els.pageNum.textContent = page;
    this.els.masonry.innerHTML = "";

    if (page >= pages) {
      this.els.pageNext.setAttribute("disabled", "disabled");
    } else {
      this.els.pageNext.removeAttribute("disabled");
    }

    if (page <= 1) {
      this.els.pagePrev.setAttribute("disabled", "disabled");
    } else {
      this.els.pagePrev.removeAttribute("disabled");
    }

    if (n === 0) {
      if(this.els.emptyResult) {
        this.els.count.textContent = this.state.total ? this.state.total : 0;
        let emptyClone = this.els.emptyResult.cloneNode(true);
        emptyClone.style.display = "block";
        this.els.masonry.appendChild(emptyClone);
      } else {
        this.els.masonry.innerHTML = `<div style="padding:20px; color:#666;">Nincs találat.</div>`;
      }
      return;
    }

    const cols = this.getColumnCount();
    const colEls = [];
    
    // Create Columns
    for (let c = 0; c < cols; c++) {
      const col = document.createElement("div");
      col.className = "pexpo-core-mCol"; 
      this.els.masonry.appendChild(col);
      colEls.push(col);
    }

    const sliced = this.state.results.slice();
    const { measured } = this.measureCardHeights(cols, sliced);
    // const placements = this.packRankAware(measured, cols, 6);
    const placements = this.packStandard(measured, cols);

    for (const p of placements) {
      colEls[p.col].appendChild(this.createCardElement(p.item.r));
    }
  }

  createCardElement(r) {
    const div = document.createElement("div");
    div.className = "pexpo-core-card"; 
    div.innerHTML = `
      <div class="pexpo-core-imageWrap">
        <img src="${this.escapeHtml(r.image || '')}" 
             alt="${this.escapeHtml(r.title)}" 
             style="width:100%; border-radius:10px; object-fit:cover;" />
      </div>
      <div class="pexpo-core-cardTop">
        <a href="${this.escapeHtml(r.url)}" class="pexpo-core-title">${this.escapeHtml(r.title)}</a>
      </div>
      <div class="pexpo-core-desc">${this.escapeHtml(r.excerpt)}</div>
      <div class="pexpo-core-foot">
        <div class="pexpo-core-tags">
            ${
              Array.isArray(r.tag)
                ? r.tag.map(element => `<span class="pexpo-core-tag">${this.escapeHtml(element)}</span>`).join('')
                : ''
            }
        </div>
        <div>${this.escapeHtml(r.date)}</div>
      </div>
    `;
    return div;
  }

  // ---------- Utilities ----------

  escapeHtml(str) {
    return String(str).replace(/[&<>"']/g, s => ({
      "&": "&amp;", "<": "&lt;", ">": "&gt;", '"': "&quot;", "'": "&#039;"
    }[s]));
  }

  encodeDataToURL(data) {
    return Object
      .keys(data)
      .map(value => `${value}=${encodeURIComponent(data[value])}`)
      .join('&');
  }
}