let currentResults = null;
let searchInProgress = false;
let downloadInProgress = false;
let loadMoreInProgress = false;
let selectedBooks = new Set();
let currentQuery = "";
let currentPage = 1;
let totalPagesAvailable = 0;
let headlessMode = true;
let totalBooksCount = 0;

async function searchBooks(resetResults = true) {
  if (searchInProgress) {
    return;
  }

  const query = document.getElementById("query").value.trim();
  const headless = document.getElementById("headless").checked;

  headlessMode = headless;
  currentQuery = query;

  if (!query) {
    showError("Vui lòng nhập từ khóa tìm kiếm");
    return;
  }

  if (query.length < 2) {
    showError("Từ khóa phải có ít nhất 2 ký tự");
    return;
  }

  searchInProgress = true;

  if (resetResults) {
    selectedBooks.clear();
    currentPage = 1;
    currentResults = null;
  }

  document.getElementById("loadingIndicator").style.display = "block";
  document.getElementById("loadingMessage").textContent = resetResults
    ? "Đang tìm kiếm sách..."
    : `Đang tải trang ${currentPage + 1}...`;
  document.getElementById("errorMessage").style.display = "none";

  if (resetResults) {
    document.getElementById("resultsContent").innerHTML = "";
  }

  document.getElementById("progressText").textContent =
    "Đang khởi tạo...";

  const searchBtn = document.getElementById("searchBtn");
  searchBtn.disabled = true;
  searchBtn.textContent = resetResults ? "Đang tìm..." : "Đang tải...";

  try {
    const nextPage = resetResults ? 1 : currentPage + 1;

    const response = await fetch("/scraperZLibrary/api/search", {
      method: "POST",
      headers: {
        "Content-Type": "application/json",
      },
      body: JSON.stringify({
        query: query,
        page: nextPage,
        headless: headless,
      }),
    });

    const data = await response.json();

    if (data.success) {
      if (resetResults) {
        currentResults = data;
        currentPage = data.current_page || 1;
        totalPagesAvailable = data.total_pages || 1;
        totalBooksCount = data.total_books_count || data.books.length;
        displayResults(data);
      } else {
        // Merge new books with existing results
        if (currentResults) {
          currentResults.books = [...currentResults.books, ...data.books];
          currentResults.total_count = currentResults.books.length;
          currentPage = data.current_page;
          totalPagesAvailable = data.total_pages;
          totalBooksCount = data.total_books_count || totalBooksCount;
          appendBooksToGrid(
            data.books,
            currentResults.books.length - data.books.length,
          );
          updateStatsBar(currentResults);
          updateResultCount();
          updateSelectionInfo();
        } else {
          currentResults = data;
          currentPage = data.current_page || 1;
          totalPagesAvailable = data.total_pages || 1;
          totalBooksCount = data.total_books_count || data.books.length;
          displayResults(data);
        }
      }
    } else {
      showError(data.error || "Có lỗi xảy ra khi tìm kiếm");
    }
  } catch (error) {
    console.error("Search error:", error);
    showError("Không thể kết nối đến máy chủ.");
  } finally {
    searchInProgress = false;
    loadMoreInProgress = false;
    document.getElementById("loadingIndicator").style.display = "none";
    searchBtn.disabled = false;
    searchBtn.textContent = "Tìm kiếm";
  }
}

async function loadMoreBooks() {
  if (loadMoreInProgress || searchInProgress) {
    return;
  }

  if (currentPage >= totalPagesAvailable) {
    alert("Đã tải hết tất cả các trang!");
    return;
  }

  loadMoreInProgress = true;
  await searchBooks(false);
}

function appendBooksToGrid(newBooks, startIndex) {
  const booksGrid = document.querySelector(".books-grid");
  if (!booksGrid) return;

  let html = "";
  newBooks.forEach((book, idx) => {
    const index = startIndex + idx;
    const bookId = `book-${index}`;
    html += `
      <div class="book-card" id="${bookId}">
        <input 
          type="checkbox" 
          class="book-checkbox" 
          data-book-index="${index}"
          onchange="toggleBookSelection(${index}, this.checked)"
        >
        <div class="book-title">${index + 1}. ${escapeHtml(book.title)}</div>
        <div class="book-authors">${escapeHtml(book.authors.join(", ") || "Không rõ")}</div>
        
        <div class="book-details">
          <div class="detail-item">
            <div class="detail-label">NXB</div>
            <div class="detail-value">${escapeHtml(book.publisher)}</div>
          </div>
          <div class="detail-item">
            <div class="detail-label">Năm</div>
            <div class="detail-value">${escapeHtml(book.year)}</div>
          </div>
          <div class="detail-item">
            <div class="detail-label">Số trang</div>
            <div class="detail-value">${escapeHtml(book.pages)}</div>
          </div>
          <div class="detail-item">
            <div class="detail-label">Ngôn ngữ</div>
            <div class="detail-value">${escapeHtml(book.language)}</div>
          </div>
          <div class="detail-item">
            <div class="detail-label">Định dạng</div>
            <div class="detail-value">${escapeHtml(book.file)}</div>
          </div>
        </div>
        
        ${
          book.link !== "N/A"
            ? `<a href="${escapeHtml(book.link)}" target="_blank" class="book-link" rel="noopener noreferrer">Xem sách →</a>`
            : '<span style="color: #999; font-size: 0.85em;">Không có liên kết</span>'
        }
      </div>
    `;
  });

  booksGrid.insertAdjacentHTML("beforeend", html);

  // Update load more button
  updateLoadMoreButton();
}

function updateResultCount() {
  const resultHeader = document.querySelector("#resultCountHeader");
  if (resultHeader) {
    resultHeader.textContent = `Kết quả (${currentResults.books.length} sách đã tải / ${totalBooksCount} tổng cộng)`;
  }
}

function updateStatsBar(data) {
  const statsBar = document.querySelector(".stats-bar");
  if (statsBar) {
    statsBar.innerHTML = `
      <div class="stat-item">
        <div class="stat-label">Tổng số sách</div>
        <div class="stat-value">${totalBooksCount}</div>
      </div>
      <div class="stat-item">
        <div class="stat-label">Từ khóa</div>
        <div class="stat-value" style="font-size: 1.5em;">"${escapeHtml(data.query)}"</div>
      </div>
      <div class="stat-item">
        <div class="stat-label">Trang hiện tại</div>
        <div class="stat-value" style="font-size: 1.5em;">${currentPage} / ${totalPagesAvailable}</div>
      </div>
    `;
  }
}

function updateLoadMoreButton() {
  const loadMoreContainer = document.getElementById("loadMoreContainer");
  if (loadMoreContainer) {
    if (currentPage >= totalPagesAvailable) {
      loadMoreContainer.innerHTML = `
        <button class="btn btn-secondary load-more-btn" disabled>
          ✅ Đã tải hết ${totalPagesAvailable} trang (${currentResults.books.length} sách)
        </button>
      `;
    } else {
      loadMoreContainer.innerHTML = `
        <button class="btn btn-secondary load-more-btn" onclick="loadMoreBooks()">
          📄 Tải thêm trang ${currentPage + 1} / ${totalPagesAvailable} (mỗi trang 50 sách)
        </button>
      `;
    }
  }
}

function displayResults(data) {
  const resultsDiv = document.getElementById("resultsContent");

  if (!data.books || data.books.length === 0) {
    resultsDiv.innerHTML = `
      <div class="empty-state">
        <div style="font-size: 3em; margin-bottom: 20px; font-weight: 300;">🔍</div>
        <h3>Không tìm thấy sách</h3>
        <p>Thử từ khóa khác hoặc kiểm tra lại chính tả</p>
        <p style="margin-top: 10px; font-size: 0.9em;">Từ khóa: "${escapeHtml(data.query)}"</p>
      </div>
    `;
    return;
  }

  currentPage = data.current_page || 1;
  totalPagesAvailable = data.total_pages || 1;
  totalBooksCount = data.total_books_count || data.books.length;

  let html = `
    <div class="stats-bar">
      <div class="stat-item">
        <div class="stat-label">Tổng số sách</div>
        <div class="stat-value">${totalBooksCount}</div>
      </div>
      <div class="stat-item">
        <div class="stat-label">Từ khóa</div>
        <div class="stat-value" style="font-size: 1.5em;">"${escapeHtml(data.query)}"</div>
      </div>
      <div class="stat-item">
        <div class="stat-label">Trang hiện tại</div>
        <div class="stat-value" style="font-size: 1.5em;">${currentPage} / ${totalPagesAvailable}</div>
      </div>
    </div>
    
    <div class="download-section">
      <button class="btn btn-secondary" onclick="downloadResults('txt')">
        ↓ Tải TXT
      </button>
      <button class="btn btn-secondary" onclick="downloadResults('json')">
        ↓ Tải JSON
      </button>
      <button class="btn btn-secondary" onclick="copyResultsToClipboard()">
        📋 Sao chép
      </button>
      <button class="btn btn-download" onclick="downloadSelectedBooks()">
        📦 Tải sách đã chọn
      </button>
    </div>
    
    <div class="selection-bar">
      <div class="selection-controls">
        <label>
          <input type="checkbox" id="selectAllCheckbox" onchange="toggleSelectAll(this.checked)">
          Chọn tất cả sách đã tải
        </label>
        <button class="btn btn-secondary" style="padding: 6px 16px; font-size: 12px;" onclick="clearSelection()">
          Bỏ chọn
        </button>
      </div>
      <div class="selection-info" id="selectionInfo">
        Đã chọn 0 sách
      </div>
    </div>
    
    <h3 id="resultCountHeader" style="font-weight: 400; margin: 24px 0 16px 0; text-transform: uppercase; font-size: 0.9em; letter-spacing: 0.5px;">
      Kết quả (${data.books.length} sách đã tải / ${totalBooksCount} tổng cộng)
    </h3>
    <div class="books-grid">
  `;

  data.books.forEach((book, index) => {
    const bookId = `book-${index}`;
    html += `
      <div class="book-card" id="${bookId}">
        <input 
          type="checkbox" 
          class="book-checkbox" 
          data-book-index="${index}"
          onchange="toggleBookSelection(${index}, this.checked)"
        >
        <div class="book-title">${index + 1}. ${escapeHtml(book.title)}</div>
        <div class="book-authors">${escapeHtml(book.authors.join(", ") || "Không rõ")}</div>
        
        <div class="book-details">
          <div class="detail-item">
            <div class="detail-label">NXB</div>
            <div class="detail-value">${escapeHtml(book.publisher)}</div>
          </div>
          <div class="detail-item">
            <div class="detail-label">Năm</div>
            <div class="detail-value">${escapeHtml(book.year)}</div>
          </div>
          <div class="detail-item">
            <div class="detail-label">Số trang</div>
            <div class="detail-value">${escapeHtml(book.pages)}</div>
          </div>
          <div class="detail-item">
            <div class="detail-label">Ngôn ngữ</div>
            <div class="detail-value">${escapeHtml(book.language)}</div>
          </div>
          <div class="detail-item">
            <div class="detail-label">Định dạng</div>
            <div class="detail-value">${escapeHtml(book.file)}</div>
          </div>
        </div>
        
        ${
          book.link !== "N/A"
            ? `<a href="${escapeHtml(book.link)}" target="_blank" class="book-link" rel="noopener noreferrer">Xem sách →</a>`
            : '<span style="color: #999; font-size: 0.85em;">Không có liên kết</span>'
        }
      </div>
    `;
  });

  html += "</div>";

  // Add load more button
  html += `<div id="loadMoreContainer" class="load-more-container">`;

  if (currentPage < totalPagesAvailable) {
    html += `
      <button class="btn btn-secondary load-more-btn" onclick="loadMoreBooks()">
        📄 Tải thêm trang ${currentPage + 1} / ${totalPagesAvailable} (mỗi trang 50 sách)
      </button>
    `;
  } else {
    html += `
      <button class="btn btn-secondary load-more-btn" disabled>
        ✅ Đã tải hết ${totalPagesAvailable} trang (${data.books.length} sách)
      </button>
    `;
  }

  html += `</div>`;

  // Add statistics if available
  if (data.statistics && Object.keys(data.statistics).length > 0) {
    html += '<div class="stats-detail">';
    html += "<h3>Thống kê</h3>";
    html += '<div class="stats-bar" style="border-bottom: none;">';

    const stats = data.statistics;

    if (stats.languages && Object.keys(stats.languages).length > 0) {
      const langHtml = Object.entries(stats.languages)
        .sort((a, b) => b[1] - a[1])
        .slice(0, 5)
        .map(([lang, count]) => {
          const percentage = ((count / totalBooksCount) * 100).toFixed(1);
          return `<div style="margin-bottom: 4px;">${escapeHtml(lang)}: ${count} (${percentage}%)</div>`;
        })
        .join("");

      html += `
        <div class="stat-item">
          <div class="stat-label">Ngôn ngữ phổ biến</div>
          <div class="stat-value" style="font-size: 0.9em; font-weight: 400;">${langHtml}</div>
        </div>
      `;
    }

    if (stats.formats && Object.keys(stats.formats).length > 0) {
      const formatHtml = Object.entries(stats.formats)
        .sort((a, b) => b[1] - a[1])
        .slice(0, 5)
        .map(([fmt, count]) => {
          const percentage = ((count / totalBooksCount) * 100).toFixed(1);
          return `<div style="margin-bottom: 4px;">${escapeHtml(fmt)}: ${count} (${percentage}%)</div>`;
        })
        .join("");

      html += `
        <div class="stat-item">
          <div class="stat-label">Định dạng phổ biến</div>
          <div class="stat-value" style="font-size: 0.9em; font-weight: 400;">${formatHtml}</div>
        </div>
      `;
    }

    if (stats.years && Object.keys(stats.years).length > 0) {
      const yearHtml = Object.entries(stats.years)
        .sort((a, b) => parseInt(b[0]) - parseInt(a[0]))
        .slice(0, 5)
        .map(
          ([year, count]) =>
            `<div style="margin-bottom: 4px;">${escapeHtml(year)}: ${count} sách</div>`,
        )
        .join("");

      html += `
        <div class="stat-item">
          <div class="stat-label">Năm xuất bản gần đây</div>
          <div class="stat-value" style="font-size: 0.9em; font-weight: 400;">${yearHtml}</div>
        </div>
      `;
    }

    html += "</div>";
    html += "</div>";
  }

  resultsDiv.innerHTML = html;
  updateSelectionInfo();
  resultsDiv.scrollIntoView({ behavior: "smooth", block: "nearest" });
}

function toggleBookSelection(index, checked) {
  if (checked) {
    selectedBooks.add(index);
    const card = document.getElementById(`book-${index}`);
    if (card) card.classList.add("selected");
  } else {
    selectedBooks.delete(index);
    const card = document.getElementById(`book-${index}`);
    if (card) card.classList.remove("selected");
  }
  updateSelectionInfo();
  updateSelectAllCheckbox();
}

function toggleSelectAll(checked) {
  if (!currentResults || !currentResults.books) return;

  if (checked) {
    currentResults.books.forEach((_, index) => {
      selectedBooks.add(index);
      const card = document.getElementById(`book-${index}`);
      if (card) card.classList.add("selected");
      const checkbox = document.querySelector(
        `[data-book-index="${index}"]`,
      );
      if (checkbox) checkbox.checked = true;
    });
  } else {
    selectedBooks.clear();
    document
      .querySelectorAll(".book-card")
      .forEach((card) => card.classList.remove("selected"));
    document
      .querySelectorAll(".book-checkbox")
      .forEach((cb) => (cb.checked = false));
  }
  updateSelectionInfo();
}

function clearSelection() {
  selectedBooks.clear();
  document
    .querySelectorAll(".book-card")
    .forEach((card) => card.classList.remove("selected"));
  document
    .querySelectorAll(".book-checkbox")
    .forEach((cb) => (cb.checked = false));
  const selectAllCheckbox = document.getElementById("selectAllCheckbox");
  if (selectAllCheckbox) selectAllCheckbox.checked = false;
  updateSelectionInfo();
}

function updateSelectionInfo() {
  const count = selectedBooks.size;
  const infoElement = document.getElementById("selectionInfo");
  if (infoElement) {
    infoElement.textContent = `Đã chọn ${count} / ${currentResults?.books.length || 0} sách`;
  }
}

function updateSelectAllCheckbox() {
  if (!currentResults || !currentResults.books) return;
  const selectAll = document.getElementById("selectAllCheckbox");
  if (selectAll) {
    selectAll.checked =
      selectedBooks.size === currentResults.books.length &&
      currentResults.books.length > 0;
  }
}

async function downloadSelectedBooks() {
  if (downloadInProgress) {
    alert("Đang tải sách, vui lòng đợi...");
    return;
  }
  if (!currentResults || !currentResults.books) {
    alert("Không có sách để tải");
    return;
  }
  if (selectedBooks.size === 0) {
    alert("Vui lòng chọn ít nhất một cuốn sách");
    return;
  }

  const selectedBooksList = Array.from(selectedBooks)
    .sort((a, b) => a - b)
    .map((index) => currentResults.books[index]);

  downloadInProgress = true;
  const headless = document.getElementById("headless").checked;

  // Show progress UI
  document.getElementById("loadingIndicator").style.display = "block";
  document.getElementById("loadingMessage").textContent =
    `Đang tải ${selectedBooksList.length} sách...`;

  let successCount = 0;
  let failedCount = 0;

  try {
    // POST to get the SSE stream
    const response = await fetch("/scraperZLibrary/api/download/stream", {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({
        books: selectedBooksList,
        query: currentResults.query,
        headless: headless,
      }),
    });

    if (!response.ok) throw new Error("Không thể bắt đầu tải xuống");

    const reader = response.body.getReader();
    const decoder = new TextDecoder();
    let buffer = "";

    while (true) {
      const { done, value } = await reader.read();
      if (done) break;

      buffer += decoder.decode(value, { stream: true });
      const lines = buffer.split("\n\n");
      buffer = lines.pop(); // keep incomplete chunk

      for (const chunk of lines) {
        const line = chunk.replace(/^data:\s*/, "").trim();
        if (!line) continue;

        let event;
        try {
          event = JSON.parse(line);
        } catch {
          continue;
        }

        if (event.type === "progress") {
          document.getElementById("loadingMessage").textContent =
            `[${event.index}/${event.total}] Đang tải: ${event.title.substring(0, 50)}...`;
          document.getElementById("progressText").textContent =
            `Đã xong: ${successCount} ✓  Lỗi: ${failedCount} ✗`;
        } else if (event.type === "ready") {
          successCount++;
          document.getElementById("progressText").textContent =
            `Đã xong: ${successCount} ✓  Lỗi: ${failedCount} ✗`;

          // Trigger instant download via hidden <a>
          const a = document.createElement("a");
          a.href = `/scraperZLibrary/api/download/file/${event.token}`;
          a.download = event.filename;
          document.body.appendChild(a);
          a.click();
          document.body.removeChild(a);

          // Small gap so the browser doesn't block rapid-fire downloads
          await new Promise((r) => setTimeout(r, 600));
        } else if (event.type === "error") {
          failedCount++;
          console.warn(`Failed: ${event.title} — ${event.message}`);
          document.getElementById("progressText").textContent =
            `Đã xong: ${successCount} ✓  Lỗi: ${failedCount} ✗`;
        } else if (event.type === "done") {
          document.getElementById("loadingMessage").textContent =
            `Hoàn tất! ${event.success} thành công, ${event.failed} thất bại`;
        }
      }
    }
  } catch (error) {
    console.error("Stream download error:", error);
    alert("Không thể tải sách: " + error.message);
  } finally {
    downloadInProgress = false;
    setTimeout(() => {
      document.getElementById("loadingIndicator").style.display = "none";
    }, 2000);
  }
}

function showError(message) {
  const errorDiv = document.getElementById("errorMessage");
  errorDiv.textContent = message;
  errorDiv.style.display = "block";

  document.getElementById("resultsContent").innerHTML = `
    <div class="empty-state">
      <div style="font-size: 3em; margin-bottom: 20px; font-weight: 300;">✕</div>
      <h3>Tìm kiếm thất bại</h3>
      <p>${escapeHtml(message)}</p>
      <p style="margin-top: 20px; font-size: 0.9em;">Vui lòng thử lại với từ khóa khác.</p>
    </div>
  `;

  errorDiv.scrollIntoView({ behavior: "smooth", block: "nearest" });
}

function downloadResults(format) {
  if (!currentResults) {
    alert("Không có kết quả để tải xuống");
    return;
  }

  fetch(`/scraperZLibrary/api/download/${format}`, {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
    },
    body: JSON.stringify(currentResults),
  })
    .then((response) => {
      if (!response.ok) {
        throw new Error("Tải xuống thất bại");
      }
      return response.blob();
    })
    .then((blob) => {
      const url = window.URL.createObjectURL(blob);
      const a = document.createElement("a");
      a.href = url;
      a.download = `zlib_${currentResults.query.replace(/\s+/g, "_")}_ket_qua.${format}`;
      document.body.appendChild(a);
      a.click();
      window.URL.revokeObjectURL(url);
      document.body.removeChild(a);
    })
    .catch((error) => {
      console.error("Download error:", error);
      alert("Không thể tải file: " + error.message);
    });
}

function copyResultsToClipboard() {
  if (!currentResults) {
    alert("Không có kết quả để sao chép");
    return;
  }

  let summary = `KẾT QUẢ TÌM KIẾM Z-LIBRARY\n`;
  summary += `========================\n`;
  summary += `Từ khóa: ${currentResults.query}\n`;
  summary += `Tổng số sách: ${totalBooksCount}\n`;
  summary += `Đã tải: ${currentResults.books.length} sách\n`;
  summary += `========================\n\n`;

  currentResults.books.slice(0, 20).forEach((book, index) => {
    summary += `${index + 1}. ${book.title}\n`;
    summary += `   Tác giả: ${book.authors.join(", ")}\n`;
    summary += `   Năm: ${book.year} | Ngôn ngữ: ${book.language} | Định dạng: ${book.file}\n`;
    summary += `   Link: ${book.link}\n\n`;
  });

  if (currentResults.books.length > 20) {
    summary += `... và ${currentResults.books.length - 20} sách khác\n`;
  }

  navigator.clipboard
    .writeText(summary)
    .then(() => {
      alert("Đã sao chép tóm tắt!");
    })
    .catch((err) => {
      console.error("Failed to copy:", err);
      alert("Không thể sao chép");
    });
}

function escapeHtml(text) {
  if (typeof text !== "string") return text;
  const div = document.createElement("div");
  div.textContent = text;
  return div.innerHTML;
}

document
  .getElementById("query")
  .addEventListener("keypress", function (e) {
    if (e.key === "Enter") {
      searchBooks(true);
    }
  });

document.addEventListener("keydown", function (e) {
  if ((e.ctrlKey || e.metaKey) && e.key === "k") {
    e.preventDefault();
    document.getElementById("query").focus();
  }
});

const progressMessages = [
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