/* =========================================================
   DeepFake Detection System - script.js
   Upload tabs, drag & drop, preview, client validation,
   and the scanning overlay shown while the model runs.
   ========================================================= */

(function () {
  "use strict";

  const IMAGE_ACCEPT = ".png,.jpg,.jpeg,.webp,.bmp";
  const VIDEO_ACCEPT = ".mp4,.mov,.avi,.mkv,.webm";
  const IMAGE_MAX_MB = 10;
  const VIDEO_MAX_MB = 100;

  const form = document.getElementById("detectForm");
  if (!form) return;

  const mediaTypeInput = document.getElementById("mediaType");
  const fileInput = document.getElementById("fileInput");
  const dropzone = document.getElementById("dropzone");
  const dzTitle = document.getElementById("dzTitle");
  const dzSub = document.getElementById("dzSub");
  const preview = document.getElementById("preview");
  const previewImg = document.getElementById("previewImg");
  const previewVideo = document.getElementById("previewVideo");
  const previewName = document.getElementById("previewName");
  const previewSize = document.getElementById("previewSize");
  const removeBtn = document.getElementById("removeFile");
  const overlay = document.getElementById("scanningOverlay");
  const scanStatus = document.getElementById("scanStatus");
  const detectBtn = document.getElementById("detectBtn");

  let currentMaxMb = IMAGE_MAX_MB;

  /* ---------------- Tabs ---------------- */
  document.querySelectorAll(".tab").forEach((tab) => {
    tab.addEventListener("click", () => {
      document.querySelectorAll(".tab").forEach((t) => {
        t.classList.remove("active");
        t.setAttribute("aria-selected", "false");
      });
      tab.classList.add("active");
      tab.setAttribute("aria-selected", "true");

      const type = tab.dataset.type;
      mediaTypeInput.value = type;

      clearSelection();
      if (type === "image") {
        fileInput.accept = IMAGE_ACCEPT;
        currentMaxMb = IMAGE_MAX_MB;
        dzTitle.textContent = "Drag & drop an image here";
        dzSub.textContent =
          "PNG / JPG / WEBP / BMP \u00b7 max " + IMAGE_MAX_MB + " MB \u2014 or click to browse";
      } else {
        fileInput.accept = VIDEO_ACCEPT;
        currentMaxMb = VIDEO_MAX_MB;
        dzTitle.textContent = "Drag & drop a video here";
        dzSub.textContent =
          "MP4 / MOV / AVI / MKV / WEBM \u00b7 max " + VIDEO_MAX_MB + " MB \u2014 or click to browse";
      }
    });
  });

  /* ---------------- Drag & drop ---------------- */
  ["dragenter", "dragover"].forEach((evt) => {
    dropzone.addEventListener(evt, (e) => {
      e.preventDefault();
      dropzone.classList.add("dragover");
    });
  });
  ["dragleave", "drop"].forEach((evt) => {
    dropzone.addEventListener(evt, (e) => {
      e.preventDefault();
      dropzone.classList.remove("dragover");
    });
  });
  dropzone.addEventListener("drop", (e) => {
    if (e.dataTransfer && e.dataTransfer.files.length) {
      fileInput.files = e.dataTransfer.files;
      showPreview(fileInput.files[0]);
    }
  });

  fileInput.addEventListener("change", () => {
    if (fileInput.files.length) showPreview(fileInput.files[0]);
    else clearPreview();
  });

  removeBtn.addEventListener("click", (e) => {
    e.preventDefault();
    e.stopPropagation();
    clearSelection();
  });

  function clearSelection() {
    fileInput.value = "";
    clearPreview();
  }

  function clearPreview() {
    preview.hidden = true;
    previewImg.hidden = true;
    previewVideo.hidden = true;
    previewImg.src = "";
    previewVideo.pause();
    previewVideo.src = "";
  }

  function formatSize(bytes) {
    if (bytes >= 1024 * 1024) return (bytes / (1024 * 1024)).toFixed(1) + " MB";
    return Math.max(1, Math.round(bytes / 1024)) + " KB";
  }

  function showPreview(file) {
    clearPreview();

    if (file.size > currentMaxMb * 1024 * 1024) {
      alert(
        'File "' +
          file.name +
          '" is too large (' +
          formatSize(file.size) +
          "). The limit is " +
          currentMaxMb +
          " MB."
      );
      clearSelection();
      return;
    }

    previewName.textContent = file.name;
    previewSize.textContent = formatSize(file.size);

    const isImage = /\.(png|jpe?g|webp|bmp)$/i.test(file.name);
    const url = URL.createObjectURL(file);
    if (isImage) {
      previewImg.src = url;
      previewImg.hidden = false;
    } else {
      previewVideo.src = url;
      previewVideo.hidden = false;
    }
    preview.hidden = false;
  }

  /* ---------------- Scanning overlay on submit ---------------- */
  const statusMessages = [
    "Scanning for faces\u2026",
    "Extracting frames\u2026",
    "Running neural network\u2026",
    "Comparing against deepfake signatures\u2026",
    "Almost done\u2026"
  ];
  let statusTimer = null;

  form.addEventListener("submit", (e) => {
    if (!fileInput.files.length) {
      e.preventDefault();
      alert("Please choose a file to analyze first.");
      return;
    }
    detectBtn.disabled = true;
    overlay.hidden = false;
    let i = 0;
    scanStatus.textContent = statusMessages[0];
    statusTimer = setInterval(() => {
      i = (i + 1) % statusMessages.length;
      scanStatus.textContent = statusMessages[i];
    }, 1400);
  });

  window.addEventListener("pageshow", () => {
    // Re-enable the UI if the user navigates back to this page.
    if (statusTimer) clearInterval(statusTimer);
    if (overlay) overlay.hidden = true;
    if (detectBtn) detectBtn.disabled = false;
  });

  /* ---------------- Auto-dismiss flash messages ---------------- */
  document.querySelectorAll(".flash").forEach((el) => {
    setTimeout(() => {
      el.style.transition = "opacity .5s ease";
      el.style.opacity = "0";
      setTimeout(() => el.remove(), 550);
    }, 6000);
  });
})();