// QR Clipboard
//
// The popup shows a persistent log of every QR code ever decoded.
// Clicking "Scan visible tab" captures the viewport, decodes all QR codes,
// appends them to the log, and copies the LAST one to the clipboard.
//
// Decode strategy: jsQR finds ONE code per scan, so we loop — decode,
// white-out the detected region, re-scan — until nothing is found.

const api = typeof browser !== "undefined" ? browser : chrome;

const STORAGE_KEY = "qrLog";
const MAX_ENTRIES = 500;

const statusEl = document.getElementById("status");
const logEl = document.getElementById("log");
const scanBtn = document.getElementById("scan");
const clearBtn = document.getElementById("clear");

function setStatus(text, cls) {
  statusEl.textContent = text || "";
  statusEl.className = cls || "";
}

// --- storage ---------------------------------------------------------------

async function getLog() {
  const stored = await api.storage.local.get(STORAGE_KEY);
  return Array.isArray(stored[STORAGE_KEY]) ? stored[STORAGE_KEY] : [];
}

// entries: newest-first (entries[0] is the last decoded code of the scan).
async function appendEntries(entries) {
  const log = await getLog();
  const result = log.slice(); // existing log, newest-first
  let added = 0;
  let lastSkipped = false; // was the last decoded code (entries[0]) a duplicate?

  // Walk oldest→newest so the last decoded code ends up at the front.
  // Skip any code that matches the current front (the most recent entry),
  // keeping the existing entry rather than re-adding it.
  for (let i = entries.length - 1; i >= 0; i--) {
    const entry = entries[i];
    const isDuplicate = result[0] && result[0].text === entry.text;
    if (i === 0) lastSkipped = !!isDuplicate;
    if (isDuplicate) continue;
    result.unshift(entry);
    added++;
  }

  const next = result.slice(0, MAX_ENTRIES); // cap total size
  await api.storage.local.set({ [STORAGE_KEY]: next });
  return { log: next, added, lastSkipped };
}

async function clearLog() {
  await api.storage.local.remove(STORAGE_KEY);
}

// --- rendering -------------------------------------------------------------

function renderLog(log) {
  logEl.replaceChildren();

  if (!log.length) {
    const li = document.createElement("li");
    li.className = "empty";
    li.textContent = "No QR codes logged yet.";
    logEl.appendChild(li);
    return;
  }

  log.forEach((entry, index) => {
    const li = document.createElement("li");

    const body = document.createElement("div");
    body.className = "entry-body";

    const text = document.createElement("div");
    text.className = "entry-text";
    text.textContent = entry.text; // textContent: QR payloads are untrusted
    body.appendChild(text);

    const meta = document.createElement("div");
    meta.className = "entry-meta";
    const when = new Date(entry.time).toLocaleString();
    meta.textContent = entry.url ? `${when} · ${entry.url}` : when;
    body.appendChild(meta);

    li.appendChild(body);

    const del = document.createElement("button");
    del.className = "entry-del";
    del.textContent = "✕";
    del.title = "Delete this entry";
    del.addEventListener("click", () => deleteEntry(index));
    li.appendChild(del);

    logEl.appendChild(li);
  });
}

// --- decoding --------------------------------------------------------------

function dataUrlToImageData(dataUrl) {
  return new Promise((resolve, reject) => {
    const img = new Image();
    img.onload = () => {
      const canvas = document.createElement("canvas");
      canvas.width = img.naturalWidth;
      canvas.height = img.naturalHeight;
      const ctx = canvas.getContext("2d", { willReadFrequently: true });
      ctx.drawImage(img, 0, 0);
      resolve(ctx.getImageData(0, 0, canvas.width, canvas.height));
    };
    img.onerror = () => reject(new Error("Failed to load captured image"));
    img.src = dataUrl;
  });
}

// Paint a code's bounding box white so the next jsQR pass can't see it.
function maskRegion(imageData, location) {
  const xs = [
    location.topLeftCorner.x,
    location.topRightCorner.x,
    location.bottomLeftCorner.x,
    location.bottomRightCorner.x,
  ];
  const ys = [
    location.topLeftCorner.y,
    location.topRightCorner.y,
    location.bottomLeftCorner.y,
    location.bottomRightCorner.y,
  ];
  const minX = Math.max(0, Math.floor(Math.min(...xs)));
  const maxX = Math.min(imageData.width, Math.ceil(Math.max(...xs)));
  const minY = Math.max(0, Math.floor(Math.min(...ys)));
  const maxY = Math.min(imageData.height, Math.ceil(Math.max(...ys)));
  const data = imageData.data;
  for (let y = minY; y < maxY; y++) {
    for (let x = minX; x < maxX; x++) {
      const i = (y * imageData.width + x) * 4;
      data[i] = data[i + 1] = data[i + 2] = 255;
      data[i + 3] = 255;
    }
  }
}

function decodeAll(imageData) {
  const found = [];
  const MAX_PASSES = 20; // safety cap against pathological loops
  for (let pass = 0; pass < MAX_PASSES; pass++) {
    const code = jsQR(imageData.data, imageData.width, imageData.height, {
      inversionAttempts: "attemptBoth",
    });
    if (!code || !code.location) break;
    found.push(code.data);
    maskRegion(imageData, code.location);
  }
  return found;
}

async function copyToClipboard(text) {
  try {
    await navigator.clipboard.writeText(text);
    return true;
  } catch (e) {
    const ta = document.createElement("textarea");
    ta.value = text;
    document.body.appendChild(ta);
    ta.select();
    const ok = document.execCommand("copy");
    ta.remove();
    return ok;
  }
}

// --- actions ---------------------------------------------------------------

async function scan() {
  scanBtn.disabled = true;
  setStatus("Scanning visible tab…", "muted");
  try {
    const [tab] = await api.tabs.query({ active: true, currentWindow: true });
    const dataUrl = await api.tabs.captureVisibleTab();
    const imageData = await dataUrlToImageData(dataUrl);
    const codes = decodeAll(imageData);

    if (codes.length === 0) {
      console.log("[QR Clipboard] No QR codes found.");
      setStatus("No QR codes found in the visible area.", "muted");
      return;
    }

    console.log(`[QR Clipboard] Decoded ${codes.length} code(s):`, codes);

    const now = new Date().toISOString();
    const url = tab ? tab.url : "";
    // Newest first within this scan too, so the LAST decoded sits on top.
    const entries = codes
      .map((text) => ({ text, time: now, url }))
      .reverse();
    const { log, added, lastSkipped } = await appendEntries(entries);
    renderLog(log);

    const last = codes[codes.length - 1];
    const copied = await copyToClipboard(last);
    const skipped = codes.length - added;

    let msg = `Found ${codes.length} code(s)`;
    if (skipped) msg += `, ${skipped} duplicate(s) skipped`;
    msg += ".";
    if (!copied) {
      msg += " Clipboard write failed.";
    } else if (!lastSkipped) {
      msg += " Last one copied to clipboard.";
    }
    setStatus(msg, copied ? "ok" : "err");
  } catch (e) {
    setStatus("Could not scan this tab: " + e.message, "err");
  } finally {
    scanBtn.disabled = false;
  }
}

async function deleteEntry(index) {
  const log = await getLog();
  log.splice(index, 1);
  await api.storage.local.set({ [STORAGE_KEY]: log });
  renderLog(log);
  setStatus("Entry deleted.", "muted");
}

async function clear() {
  await clearLog();
  renderLog([]);
  setStatus("Log cleared.", "muted");
}

// --- init ------------------------------------------------------------------

scanBtn.addEventListener("click", scan);
clearBtn.addEventListener("click", clear);

(async () => {
  renderLog(await getLog());
})();