(() => {
  const fileInput = document.getElementById("fileInput");
  const uploadCard = document.getElementById("uploadCard");
  const placeholder = document.getElementById("placeholder");
  const preview = document.getElementById("preview");
  const previewThumb = document.getElementById("previewThumb");
  const previewName = document.getElementById("previewName");
  const previewSize = document.getElementById("previewSize");
  const uploadProgress = document.getElementById("uploadProgress");
  const progressText = document.getElementById("progressText");
  const uploadBtn = document.getElementById("uploadBtn");
  const copyBtn = document.getElementById("copyBtn");
  const viewBtn = document.getElementById("viewBtn");
  const dlBtn = document.getElementById("dlBtn");
  const historyList = document.getElementById("historyList");
  const clearHistoryBtn = document.getElementById("clearHistory");
  const apiBtn = document.getElementById("apiBtn");
  // NOTE: these might be null in some edge cases, so guard below
  const apiModal = document.getElementById("apiModal");
  const closeApi = document.getElementById("closeApi");
  const copyCurl = document.getElementById("copyCurl");
  const curlExample = document.getElementById("curlExample");

  const MAX_BYTES = window.APP_CONFIG.MAX_BYTES || (2 * 1024 * 1024 * 1024);
  const EXPIRE_SECONDS = window.APP_CONFIG.EXPIRE_SECONDS || (3 * 3600);

  let currentFile = null;
  let currentSlug = null;
  let currentUrl = null;

  // helper
  function humanFileSize(bytes) {
    if (bytes === 0) return "0 B";
    const k = 1024;
    const dm = 1;
    const sizes = ["B","KB","MB","GB","TB"];
    const i = Math.floor(Math.log(bytes) / Math.log(k));
    return parseFloat((bytes / Math.pow(k, i)).toFixed(dm)) + " " + sizes[i];
  }

  // show placeholder click to open file picker
  if (placeholder && fileInput) {
    placeholder.addEventListener("click", () => fileInput.click());
  }

  if (fileInput) {
    fileInput.addEventListener("change", (ev) => {
      const f = ev.target.files[0];
      if (!f) return;
      selectFile(f);
    });
  }

  function selectFile(file) {
    // client-side checks
    if (file.size > MAX_BYTES) {
      alert("File larger than max allowed (2GB).");
      return;
    }
    const banned = ["bat","exe","cmd","sh","msi","ps1","com","scr"];
    const ext = (file.name.split(".").pop() || "").toLowerCase();
    if (banned.includes(ext)) {
      alert("File type not allowed.");
      return;
    }
    currentFile = file;
    previewName.textContent = file.name;
    previewSize.textContent = humanFileSize(file.size);
    // preview thumb for images
    if (file.type && file.type.startsWith("image/")) {
      const url = URL.createObjectURL(file);
      previewThumb.style.backgroundImage = `url(${url})`;
      previewThumb.textContent = "";
    } else {
      previewThumb.style.backgroundImage = 'none';
      previewThumb.textContent = ext ? ext.toUpperCase() : "";
    }
    if (placeholder) placeholder.hidden = true;
    if (preview) preview.hidden = false;
    if (uploadProgress) uploadProgress.value = 0;
    if (progressText) progressText.textContent = "";
  }

  async function uploadSelectedFile(customSlug = "") {
    if (!currentFile) {
      // trigger file picker
      if (fileInput) fileInput.click();
      return;
    }
    const fd = new FormData();
    fd.append("file", currentFile);
    if (customSlug) fd.append("custom_slug", customSlug);

    const xhr = new XMLHttpRequest();
    xhr.open("POST", "/api/upload", true);

    xhr.upload.onprogress = (e) => {
      if (e.lengthComputable) {
        const pct = Math.floor((e.loaded / e.total) * 100);
        if (uploadProgress) uploadProgress.value = pct;
        if (progressText) progressText.textContent = `${pct}%`;
      }
    };

    xhr.onload = function () {
      if (xhr.status >= 200 && xhr.status < 300) {
        const data = JSON.parse(xhr.responseText);
        currentSlug = data.slug;
        currentUrl = data.url;
        // show toast and copy to clipboard
        try {
          navigator.clipboard.writeText(window.location.origin + currentUrl);
          showToast("Link copied to clipboard");
        } catch (e) {}
        // save history
        addHistory({
          slug: data.slug,
          url: data.url,
          filename: data.filename,
          size: data.size,
          created_at: Date.now(),
          expires_at: data.expires_at * 1000
        });
        renderHistory();
      } else {
        const err = tryParseJSON(xhr.responseText);
        alert((err && err.detail) ? err.detail : "Upload failed.");
      }
      if (progressText) progressText.textContent = "";
      if (uploadProgress) uploadProgress.value = 0;
      // keep preview visible and set currentUrl for view/download
      if (currentSlug) {
        currentUrl = `/f/${currentSlug}`;
      }
    };

    xhr.onerror = function () {
      alert("Upload failed due to network error.");
    };

    xhr.send(fd);
  }

  // wire upload button
  if (uploadBtn) {
    uploadBtn.addEventListener("click", async (ev) => {
      // Shift-click allows custom slug (legacy behavior)
      const isShift = ev.shiftKey;
      let custom = "";
      if (isShift) {
        custom = prompt("Enter custom slug (letters, numbers, -, _ )");
        if (!custom) custom = "";
      }
      await uploadSelectedFile(custom);
    });
  }

  if (copyBtn) {
    copyBtn.addEventListener("click", () => {
      if (!currentUrl && !currentSlug) return showToast("No link yet");
      const u = window.location.origin + (currentUrl || `/f/${currentSlug}`);
      navigator.clipboard.writeText(u).then(() => showToast("Copied"));
    });
  }

  if (viewBtn) {
    viewBtn.addEventListener("click", () => {
      if (!currentUrl && !currentSlug) return showToast("No file to view");
      const u = (currentUrl || `/f/${currentSlug}`);
      window.open(u, "_blank");
    });
  }

  if (dlBtn) {
    dlBtn.addEventListener("click", () => {
      if (!currentUrl && !currentSlug) return showToast("No file to download");
      const u = (currentUrl || `/f/${currentSlug}`) + "?dl=1";
      window.open(u, "_blank");
    });
  }

  // history in localStorage
  function historyKey(){ return "doto_history_v1" }
  function getHistory(){
    try {
      const raw = localStorage.getItem(historyKey());
      if (!raw) return [];
      const parsed = JSON.parse(raw);
      // filter expired entries client-side
      const now = Date.now();
      return (parsed || []).filter(it => !it.expires_at || it.expires_at > now);
    } catch (e) {
      return [];
    }
  }
  function addHistory(item){
    const arr = getHistory();
    arr.unshift(item);
    // cap to 50
    localStorage.setItem(historyKey(), JSON.stringify(arr.slice(0,50)));
  }
  function clearHistory(){
    localStorage.removeItem(historyKey());
    renderHistory();
  }

  function renderHistory(){
    const arr = getHistory();
    if (!historyList) return;
    historyList.innerHTML = "";
    if (arr.length === 0) {
      historyList.innerHTML = "<div class='muted'>No recent uploads</div>";
      return;
    }
    arr.forEach(item => {
      const el = document.createElement("div");
      el.className = "history-item";
      // show inline thumbnail only for images (browser will try to load)
      const thumbStyle = (item.filename && item.filename.match(/\.(jpg|jpeg|png|gif|webp)$/i))
        ? `background-image:url(${window.location.origin}/f/${item.slug})` : "";
      el.innerHTML = `
        <div class="history-thumb" style="${thumbStyle}"></div>
        <div class="history-meta">
          <div style="font-weight:700">${escapeHtml(item.filename || item.slug)}</div>
          <div style="font-size:12px;color:var(--muted)">${timeAgo(item.created_at)}</div>
        </div>
        <div style="display:flex;flex-direction:column;gap:6px">
          <button class="link-btn" data-slug="${item.slug}" data-action="copy">Copy</button>
          <button class="link-btn" data-slug="${item.slug}" data-action="open">Open</button>
        </div>
      `;
      historyList.appendChild(el);
    });
  }

  if (historyList) {
    historyList.addEventListener("click", (e) => {
      const btn = e.target.closest("button");
      if (!btn) return;
      const slug = btn.dataset.slug;
      const action = btn.dataset.action;
      if (action === "copy") {
        const u = window.location.origin + `/f/${slug}`;
        navigator.clipboard.writeText(u).then(()=> showToast("Copied"));
      } else if (action === "open") {
        window.open(`/f/${slug}`, "_blank");
      }
    });
  }

  if (clearHistoryBtn) {
    clearHistoryBtn.addEventListener("click", () => {
      if (confirm("Clear local history?")) clearHistory();
    });
  }

  // modal api - robust handlers
  if (apiBtn && apiModal) {
    apiBtn.addEventListener("click", () => {
      apiModal.hidden = false;
      // focus first interactive element in modal if any
      const focusable = apiModal.querySelector("button, [tabindex]:not([tabindex='-1'])");
      if (focusable) focusable.focus();
    });
  }

  // close click handler (guarded)
  if (closeApi && apiModal) {
    closeApi.addEventListener("click", () => {
      apiModal.hidden = true;
    });
  }

  // click outside modal content (backdrop)
  if (apiModal) {
    apiModal.addEventListener("click", (e) => {
      // if click directly on the backdrop (modal container) close it
      if (e.target === apiModal) {
        apiModal.hidden = true;
      }
    });
  }

  // close on Escape key
  document.addEventListener("keydown", (e) => {
    if (e.key === "Escape" && apiModal && !apiModal.hidden) {
      apiModal.hidden = true;
    }
  });

  if (copyCurl && curlExample) {
    copyCurl.addEventListener("click", () => {
      navigator.clipboard.writeText(curlExample.textContent).then(()=> showToast("Copied"));
    });
  }

  // small helpers
  function showToast(text) {
    const t = document.createElement("div");
    t.textContent = text;
    t.style.position = "fixed";
    t.style.bottom = "86px";
    t.style.left = "50%";
    t.style.transform = "translateX(-50%)";
    t.style.background = "#111";
    t.style.color = "#fff";
    t.style.padding = "10px 14px";
    t.style.borderRadius = "10px";
    t.style.zIndex = 2000;
    document.body.appendChild(t);
    setTimeout(()=> t.remove(), 1800);
  }

  function timeAgo(ts){
    const s = Math.floor((Date.now() - ts)/1000);
    if (s < 60) return `${s}s ago`;
    if (s < 3600) return `${Math.floor(s/60)}m ago`;
    if (s < 86400) return `${Math.floor(s/3600)}h ago`;
    return `${Math.floor(s/86400)}d ago`;
  }

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

  function tryParseJSON(text){
    try { return JSON.parse(text); } catch(e){ return null; }
  }

  // UI init
  renderHistory();

  // optional: restore last history item to current
  (function restoreLast(){
    const arr = getHistory();
    if (arr.length > 0) {
      currentSlug = arr[0].slug;
      currentUrl = `/f/${currentSlug}`;
      currentFile = null;
      previewName.textContent = arr[0].filename;
      previewSize.textContent = humanFileSize(arr[0].size || 0);
      if (placeholder) placeholder.hidden = true;
      if (preview) preview.hidden = false;
    }
  })();

})();