crop.js

let _pdfLibPromise = null;
function getPdfLib() {
  if (!_pdfLibPromise) _pdfLibPromise = import("./vendor/pdf-lib.esm.min.js");
  return _pdfLibPromise;
}

const dropzone = document.getElementById("dropzone");
const fileInput = document.getElementById("fileInput");
const fileListEl = document.getElementById("fileList");
const actionsEl = document.getElementById("actions");
const cropBtn = document.getElementById("cropBtn");
const cropBtnLabel = document.getElementById("cropBtnLabel");
const clearBtn = document.getElementById("clearBtn");
const resultEl = document.getElementById("result");
const cropPanel = document.getElementById("cropPanel");
const cropMeta = document.getElementById("cropMeta");
const cropTopInput = document.getElementById("cropTopInput");
const cropBottomInput = document.getElementById("cropBottomInput");
const cropLeftInput = document.getElementById("cropLeftInput");
const cropRightInput = document.getElementById("cropRightInput");

/** @type {{file: File, pageCount: number} | null} */
let loaded = null;

// Live, honest proof: count real network requests made after page load.
const proofLiveText = document.getElementById("proofLiveText");
let requestsSinceLoad = 0;
if ("PerformanceObserver" in window) {
  try {
    new PerformanceObserver((list) => {
      requestsSinceLoad += list.getEntries().length;
      if (proofLiveText) {
        proofLiveText.textContent = `${requestsSinceLoad} network request${
          requestsSinceLoad === 1 ? "" : "s"
        } since page load · verified live, not our word for it`;
      }
    }).observe({ type: "resource", buffered: false });
  } catch (e) {
    // observer unsupported — static claim stays as-is
  }
}

function formatSize(bytes) {
  if (bytes < 1024) return `${bytes} B`;
  const kb = bytes / 1024;
  if (Math.round(kb) < 1024) return `${kb.toFixed(0)} KB`;
  return `${(bytes / (1024 * 1024)).toFixed(1)} MB`;
}

function escapeHtml(str) {
  const div = document.createElement("div");
  div.textContent = str;
  return div.innerHTML.replace(/"/g, "&quot;").replace(/'/g, "&#39;");
}

function renderFile() {
  fileListEl.innerHTML = "";
  if (!loaded) return;
  const li = document.createElement("li");
  li.className = "file-row";
  li.innerHTML = `
    <span class="handle" aria-hidden="true">◆</span>
    <span class="name">${escapeHtml(loaded.file.name)} — ${loaded.pageCount} page${loaded.pageCount === 1 ? "" : "s"}</span>
    <span class="size">${formatSize(loaded.file.size)}</span>
  `;
  fileListEl.appendChild(li);
}

function updateActions() {
  actionsEl.hidden = !loaded;
  cropPanel.hidden = !loaded;
  resultEl.hidden = true;
  if (!loaded) return;
  cropMeta.textContent = `${loaded.pageCount} page${loaded.pageCount === 1 ? "" : "s"} detected`;
}

async function loadFile(file) {
  try {
    const { PDFDocument } = await getPdfLib();
    const bytes = await file.arrayBuffer();
    const doc = await PDFDocument.load(bytes, { ignoreEncryption: true });
    loaded = { file, pageCount: doc.getPageCount() };
    renderFile();
    updateActions();
  } catch (err) {
    loaded = null;
    fileInput.value = "";
    renderFile();
    updateActions();
    resultEl.hidden = false;
    resultEl.className = "result result-error";
    resultEl.setAttribute("role", "alert");
    resultEl.setAttribute("aria-live", "assertive");
    resultEl.innerHTML = `<span><strong>Couldn't load file.</strong> ${escapeHtml(
      "This file may be corrupted or password-protected."
    )}</span>`;
  }
}

dropzone.addEventListener("click", () => fileInput.click());
dropzone.addEventListener("keydown", (e) => {
  if (e.key === "Enter" || e.key === " ") {
    e.preventDefault();
    fileInput.click();
  }
});
fileInput.addEventListener("change", (e) => {
  const file = e.target.files[0];
  if (file) loadFile(file);
});

["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) => {
  const file = e.dataTransfer?.files?.[0];
  if (file) loadFile(file);
});

clearBtn.addEventListener("click", () => {
  loaded = null;
  fileInput.value = "";
  renderFile();
  updateActions();
});

function baseName(fileName) {
  return fileName.replace(/\.pdf$/i, "");
}

/** Marks an error as a known, user-facing validation message (safe to show verbatim),
 * as opposed to a raw pdf-lib/parser exception (which must stay hidden from users). */
class ValidationError extends Error {}

function readMargin(input, label) {
  const value = parseFloat(input.value);
  if (!Number.isFinite(value) || value < 0) {
    throw new ValidationError(`Enter a valid ${label} margin (0 or higher).`);
  }
  return value;
}

// The four margin inputs are given in VISUAL terms (as the page displays in
// any normal viewer), but pdf-lib's box coordinates always live in the
// page's raw, unrotated space. For a page carrying a non-zero /Rotate
// (common on phone-scanned PDFs), the visual top/right/bottom/left edges are
// a rotated page's raw left/top/right/bottom (verified against pdf.js's own
// PageViewport rotation matrix) — so the visual margins must be permuted
// back into raw-space margins before they're applied, or the crop lands on
// the wrong edge once a compliant viewer rotates the page back for display.
function rawMarginsForRotation(rotation, top, bottom, left, right) {
  const rot = ((Math.round(rotation) % 360) + 360) % 360;
  if (rot === 90) return { top: right, right: bottom, bottom: left, left: top };
  if (rot === 180) return { top: bottom, right: left, bottom: top, left: right };
  if (rot === 270) return { top: left, right: top, bottom: right, left: bottom };
  return { top, right, bottom, left };
}

async function cropPdf() {
  const { PDFDocument } = await getPdfLib();
  const top = readMargin(cropTopInput, "top");
  const bottom = readMargin(cropBottomInput, "bottom");
  const left = readMargin(cropLeftInput, "left");
  const right = readMargin(cropRightInput, "right");

  const doc = await PDFDocument.load(await loaded.file.arrayBuffer(), { ignoreEncryption: true });
  const pages = doc.getPages();

  // Guard client-side against margins that would zero or negative-size any
  // page, before touching save() — never produce a broken/degenerate PDF.
  for (let i = 0; i < pages.length; i++) {
    const { width, height } = pages[i].getSize();
    const m = rawMarginsForRotation(pages[i].getRotation().angle, top, bottom, left, right);
    const cropWidth = width - m.left - m.right;
    const cropHeight = height - m.top - m.bottom;
    if (cropWidth <= 0 || cropHeight <= 0) {
      throw new ValidationError(
        `Margins too large — page ${i + 1} would have zero or negative size. Reduce the margins and try again.`
      );
    }
  }

  pages.forEach((page) => {
    // setCropBox(x, y, w, h) takes an absolute page-space origin, not a
    // (0,0)-relative one — pages whose MediaBox doesn't start at (0,0)
    // (common in scanned/print-shop PDFs) need the margins offset by the
    // MediaBox's own x/y, or the crop lands in the wrong place on the page.
    const box = page.getMediaBox();
    const m = rawMarginsForRotation(page.getRotation().angle, top, bottom, left, right);
    const cropWidth = box.width - m.left - m.right;
    const cropHeight = box.height - m.top - m.bottom;
    page.setCropBox(box.x + m.left, box.y + m.bottom, cropWidth, cropHeight);
  });

  const bytes = await doc.save();

  return {
    blob: new Blob([bytes], { type: "application/pdf" }),
    fileName: `${baseName(loaded.file.name)}-cropped.pdf`,
    pageCount: pages.length,
  };
}

cropBtn.addEventListener("click", async () => {
  cropBtn.disabled = true;
  const originalLabel = cropBtnLabel.textContent;
  cropBtnLabel.textContent = "Cropping…";
  resultEl.hidden = true;

  const startedAt = performance.now();
  const requestsBefore = requestsSinceLoad;

  try {
    const { blob, fileName, pageCount } = await cropPdf();
    const url = URL.createObjectURL(blob);
    setTimeout(() => URL.revokeObjectURL(url), 30000);
    const elapsedMs = Math.round(performance.now() - startedAt);
    const requestsDuring = requestsSinceLoad - requestsBefore;

    resultEl.hidden = false;
    resultEl.className = "result";
    resultEl.setAttribute("role", "status");
    resultEl.setAttribute("aria-live", "polite");
    resultEl.innerHTML = `
      <span><strong>Done.</strong> ${pageCount} page${pageCount === 1 ? "" : "s"} cropped —
      ${elapsedMs}ms, ${requestsDuring} network requests, entirely on this device.</span>
      <a class="btn btn-primary" href="${url}" download="${escapeHtml(fileName)}">Download ${escapeHtml(fileName)}</a>
    `;
  } catch (err) {
    resultEl.hidden = false;
    resultEl.className = "result result-error";
    resultEl.setAttribute("role", "alert");
    resultEl.setAttribute("aria-live", "assertive");
    resultEl.innerHTML = `<span><strong>Crop failed.</strong> ${escapeHtml(
      err instanceof ValidationError ? err.message : "This file may be corrupted or password-protected."
    )}</span>`;
  } finally {
    cropBtn.disabled = false;
    cropBtn.focus();
    cropBtnLabel.textContent = originalLabel;
  }
});

const proForm = document.getElementById("proForm");
const proNote = document.getElementById("proNote");
proForm.addEventListener("submit", async (e) => {
  e.preventDefault();
  const email = document.getElementById("proEmail").value.trim();
  if (!email) return;
  const proSubmitBtn = proForm.querySelector('button[type="submit"]');
  proSubmitBtn.disabled = true;
  // Keep a local copy so the signal is not lost if the network request fails.
  const saved = JSON.parse(localStorage.getItem("clientpdf_waitlist") || "[]");
  saved.push({ email, at: new Date().toISOString() });
  localStorage.setItem("clientpdf_waitlist", JSON.stringify(saved));
  try {
    await fetch("https://formsubmit.co/ajax/analytics@antikode.com", {
      method: "POST",
      headers: { "Content-Type": "application/json", Accept: "application/json" },
      body: JSON.stringify({
        email,
        _subject: "ClientPDF Pro waitlist signup",
        source: location.pathname,
      }),
    });
  } catch (err) {
    // Local copy above already preserves the signup even if this fails.
  }
  proForm.hidden = true;
  proNote.hidden = false;
});