import { firstLineRange, currentLine, advance, copyText, adjustCopiedLine, trimTrailing } from './queue.mjs';
import { serializePrefs, parsePrefs } from './prefs.mjs';

const pasteField = document.getElementById('pasteField');
const queueSwitch = document.getElementById('queueSwitch');
const advanceBtn = document.getElementById('advanceBtn');
const focusSwitch = document.getElementById('focusSwitch');
const newlineSwitch = document.getElementById('newlineSwitch');

const savedPrefs = parsePrefs(localStorage.getItem('queued-paste-prefs'));
newlineSwitch.checked = savedPrefs.newLines;
focusSwitch.checked = savedPrefs.advanceFocus;

function savePrefs() {
  localStorage.setItem('queued-paste-prefs', serializePrefs({
    newLines: newlineSwitch.checked,
    advanceFocus: focusSwitch.checked,
  }));
}

// Focus-based advancing is a heuristic: a paste outside this page cannot be
// observed, so a window blur followed by a refocus is treated as one paste.
// blurredSinceAdvance gates that, and armedAt suppresses the focus events
// fired by clipboard permission prompts right after arming.
let blurredSinceAdvance = false;
let armedAt = 0;

async function copyCurrentLine() {
  await navigator.clipboard.writeText(copyText(pasteField.value, newlineSwitch.checked));
}

function selectCurrentLine() {
  const { start, end } = firstLineRange(pasteField.value);
  pasteField.setSelectionRange(start, end);
}

function setQueueing(on) {
  queueSwitch.checked = on;
  pasteField.readOnly = on;
  pasteField.classList.toggle('paste-active', on);
  advanceBtn.disabled = !on;
  if (!on) {
    pasteField.setSelectionRange(pasteField.value.length, pasteField.value.length);
  }
}

async function startQueueing() {
  pasteField.value = trimTrailing(pasteField.value);
  if (pasteField.value === '') {
    // Nothing to queue.
    setQueueing(false);
    return;
  }
  try {
    await copyCurrentLine();
  } catch (err) {
    alert('Could not access the clipboard: ' + err.message);
    setQueueing(false);
    return;
  }
  setQueueing(true);
  selectCurrentLine();
  blurredSinceAdvance = false;
  armedAt = Date.now();
}

async function advanceQueue() {
  pasteField.value = advance(pasteField.value);
  if (pasteField.value === '') {
    setQueueing(false);
    return;
  }
  try {
    await copyCurrentLine();
  } catch (err) {
    alert('Could not copy the next line: ' + err.message);
    setQueueing(false);
    return;
  }
  selectCurrentLine();
}

queueSwitch.addEventListener('change', () => {
  if (queueSwitch.checked) {
    startQueueing();
  } else {
    setQueueing(false);
  }
});

advanceBtn.addEventListener('click', () => {
  advanceQueue();
});

focusSwitch.addEventListener('change', () => {
  blurredSinceAdvance = false;
  armedAt = Date.now();
  savePrefs();
});

newlineSwitch.addEventListener('change', async () => {
  savePrefs();
  if (!queueSwitch.checked) return;
  try {
    const clipboardText = await navigator.clipboard.readText();
    const adjusted = adjustCopiedLine(clipboardText, currentLine(pasteField.value), newlineSwitch.checked);
    if (adjusted !== null) {
      await navigator.clipboard.writeText(adjusted);
    }
  } catch (err) {
    alert('Could not update the clipboard: ' + err.message);
  }
});

window.addEventListener('blur', () => {
  blurredSinceAdvance = true;
});

window.addEventListener('focus', () => {
  if (!queueSwitch.checked || !focusSwitch.checked) return;
  if (!blurredSinceAdvance) return;
  if (Date.now() - armedAt < 1000) return;
  blurredSinceAdvance = false;
  advanceQueue();
});