(function () {
  if (window.__fc_addsource_injected) return;
  window.__fc_addsource_injected = true;

  // Cached probe result for the current URL so click-handlers know which
  // action to dispatch without round-tripping again.
  let currentProbe = null;
  // Bumped on every evaluate(): a probe that answers after the operator has
  // navigated on is for a page they've left, and must not repaint the chip.
  let generation = 0;
  let lastUrl = window.location.href;

  evaluate();

  // SPA navigation. Patreon, SubscribeStar and above all Discord change
  // channel/page without a reload. Patching history.pushState from here never
  // worked: a content script runs in an isolated world, so the page's own
  // pushState is not the function we'd replace. Polling the URL is the one
  // signal that sees every navigation, and costs a string compare.
  window.addEventListener('popstate', () => onUrlMaybeChanged());
  setInterval(onUrlMaybeChanged, 500);

  function onUrlMaybeChanged() {
    if (window.location.href === lastUrl) return;
    lastUrl = window.location.href;
    closePanel();
    evaluate();
  }

  async function evaluate() {
    const mine = ++generation;
    const url = window.location.href;
    const platform = getPlatformFromUrl(url);
    const onArtist = platform && isArtistPage(url, platform);
    if (!onArtist) {
      removeButton();
      currentProbe = null;
      return;
    }
    // Ask the backend what state the URL is in BEFORE drawing the button, so
    // the chip renders the right state on first paint instead of flashing the
    // generic "Add" copy and updating afterwards.
    let probe;
    try {
      probe = await browser.runtime.sendMessage({ type: 'PROBE_SOURCE', url });
    } catch (e) {
      probe = { error: e?.message || 'probe failed' };
    }
    if (mine !== generation) return;
    currentProbe = probe;
    if (probe?.state === 'unknown_platform') {
      removeButton();
      return;
    }
    renderButton(probe);
  }

  function removeButton() {
    document.getElementById('fc-add-source-btn')?.remove();
    closePanel();
  }

  function renderButton(probe) {
    let btn = document.getElementById('fc-add-source-btn');
    if (!btn) {
      btn = document.createElement('button');
      btn.id = 'fc-add-source-btn';
      btn.addEventListener('click', onClick);
      document.body.appendChild(btn);
    }
    // Reset state classes so re-renders (SPA navigation) don't stack.
    btn.className = 'fc-add-source-btn';
    btn.classList.add(`fc-add-source-btn--${chipState(probe)}`);
    btn.textContent = chipLabel(probe, PLATFORMS[probe?.platform]?.name || probe?.platform || '');
    btn.disabled = false;
  }

  async function onClick() {
    const btn = document.getElementById('fc-add-source-btn');
    if (!btn) return;
    const probe = currentProbe;

    if (probe?.state === 'source_match') {
      await openArtist(btn, probe.artist?.slug);
      return;
    }
    // A Discord URL names a channel, not a creator — ask which artist.
    if (probe?.platform === 'discord') {
      if (document.getElementById('fc-discord-panel')) closePanel();
      else openDiscordPanel(probe);
      return;
    }
    await add(btn, { url: window.location.href });
  }

  async function openArtist(btn, slug) {
    btn.disabled = true;
    const original = btn.textContent;
    btn.textContent = 'Opening…';
    try {
      const r = await browser.runtime.sendMessage({ type: 'OPEN_ARTIST_PAGE', slug });
      if (r?.error) showToast(`Error: ${r.error}`, 'error');
    } catch (e) {
      showToast(`Error: ${e.message}`, 'error');
    } finally {
      btn.disabled = false;
      btn.textContent = original;
    }
  }

  // One add, shared by the one-click chip and the Discord panel. Resolves
  // true on success.
  async function add(btn, request) {
    btn.disabled = true;
    const original = btn.textContent;
    btn.textContent = 'Adding…';
    try {
      const r = await browser.runtime.sendMessage({ type: 'ADD_AS_SOURCE', ...request });
      if (r?.error) {
        showToast(`Error: ${r.error}`, 'error');
        return false;
      }
      const verb = r.created_source ? 'Added to' : 'Already a source for';
      showToast(`${verb} ${r.artist?.name || 'artist'} (${r.source?.platform || ''})`, 'success');
      // Re-probe so the chip flips green without waiting for a navigation.
      evaluate();
      return true;
    } catch (e) {
      showToast(`Error: ${e.message}`, 'error');
      return false;
    } finally {
      btn.disabled = false;
      btn.textContent = original;
    }
  }

  // ---- Discord Add panel ----
  // Where: this channel or the whole server. Who: the suggested artist, one
  // found by search, or a new one by name. Built with createElement only —
  // server, channel and artist names are other people's text.

  function el(tag, props = {}, children = []) {
    const node = document.createElement(tag);
    const { class: className, text, ...rest } = props;
    if (className) node.className = className;
    if (text != null) node.textContent = text;
    Object.assign(node, rest);
    for (const c of children) node.appendChild(c);
    return node;
  }

  function closePanel() {
    document.getElementById('fc-discord-panel')?.remove();
  }

  function openDiscordPanel(probe) {
    closePanel();
    const d = probe.discord || {};
    const choice = discordPanelDefaults(probe);
    let searchSeq = 0;

    const scopeRow = (value, label, disabled) => {
      const input = el('input', {
        type: 'radio', name: 'fc-discord-scope', value,
        checked: choice.scope === value, disabled,
      });
      input.addEventListener('change', () => { choice.scope = value; refresh(); });
      return el('label', { class: 'fc-panel__radio' }, [input, el('span', { text: label })]);
    };

    const nameInput = el('input', {
      type: 'text', class: 'fc-panel__input', value: choice.artistName,
      placeholder: 'Artist name — search or type a new one',
      autocomplete: 'off', spellcheck: false,
    });
    const results = el('div', { class: 'fc-panel__results' });
    const hint = el('div', { class: 'fc-panel__hint' });
    const addBtn = el('button', { class: 'fc-panel__btn fc-panel__btn--primary', text: 'Add' });
    const cancelBtn = el('button', { class: 'fc-panel__btn', text: 'Cancel' });

    const panel = el('div', { id: 'fc-discord-panel', class: 'fc-panel' }, [
      el('div', { class: 'fc-panel__title', text: 'Add Discord source' }),
      el('div', { class: 'fc-panel__sub', text: serverLabel(d) }),
      el('div', { class: 'fc-panel__label', text: 'Follow' }),
      scopeRow('channel', d.channel_id ? channelLabel(d) : 'this channel', !d.channel_id),
      scopeRow('server', `Every channel in ${serverLabel(d)}`, false),
      el('div', { class: 'fc-panel__label', text: 'Artist' }),
      nameInput,
      results,
      hint,
      el('div', { class: 'fc-panel__actions' }, [cancelBtn, addBtn]),
    ]);

    function refresh() {
      const req = discordAddRequest(choice);
      addBtn.disabled = !req;
      if (!req) hint.textContent = 'Pick an artist or type a name.';
      else if (req.artistId != null) hint.textContent = `Connects to ${choice.artist.name} in FabledCurator.`;
      else hint.textContent = `Adds to “${req.artistName}” — created if FabledCurator has no artist by that name.`;
    }

    function showResults(rows) {
      results.replaceChildren(...rows.map((a) => {
        const row = el('button', { class: 'fc-panel__result', text: a.name });
        row.addEventListener('click', () => {
          choice.artist = { id: a.id, name: a.name };
          choice.artistName = a.name;
          nameInput.value = a.name;
          results.replaceChildren();
          refresh();
        });
        return row;
      }));
    }

    let debounce = null;
    nameInput.addEventListener('input', () => {
      choice.artistName = nameInput.value;
      refresh();
      clearTimeout(debounce);
      const q = nameInput.value.trim();
      if (!q) { results.replaceChildren(); return; }
      debounce = setTimeout(async () => {
        const mine = ++searchSeq;
        let r;
        try {
          r = await browser.runtime.sendMessage({ type: 'SEARCH_ARTISTS', q });
        } catch {
          return;
        }
        if (mine !== searchSeq || r?.error) return;
        showResults(r.artists || []);
      }, 200);
    });
    // Keep Discord's global shortcuts from eating keystrokes meant for us.
    panel.addEventListener('keydown', (e) => {
      e.stopPropagation();
      if (e.key === 'Escape') closePanel();
      if (e.key === 'Enter' && e.target === nameInput && !addBtn.disabled) addBtn.click();
    });

    cancelBtn.addEventListener('click', closePanel);
    addBtn.addEventListener('click', async () => {
      const req = discordAddRequest(choice);
      if (!req) return;
      const btn = document.getElementById('fc-add-source-btn');
      addBtn.disabled = true;
      const ok = await add(btn || addBtn, req);
      if (ok) closePanel();
      else refresh();
    });

    document.body.appendChild(panel);
    refresh();
    nameInput.focus();
  }

  function showToast(text, kind) {
    const t = document.createElement('div');
    t.className = `fc-toast fc-toast--${kind}`;
    t.textContent = text;
    document.body.appendChild(t);
    setTimeout(() => t.remove(), 4000);
  }
})();