/**
 * The content script's decisions, kept apart from its DOM so the specs can
 * load them (test/chip.spec.js): which state the chip shows, what it says,
 * and what the Add panel starts out proposing and finally sends.
 *
 * `probe` is /api/extension/probe's answer; `platformName` is the display
 * name (PLATFORMS[key].name), passed in so this file needs no other lib.
 */

function chipState(probe) {
  if (!probe || probe.error) return 'new';
  return ({ source_match: 'source-match', artist_match: 'artist-match', new: 'new' })[probe.state] || 'new';
}

function chipLabel(probe, platformName) {
  if (!probe || probe.error) return '+ Add to FabledCurator';
  const artist = probe.artist?.name || 'artist';
  if (probe.platform === 'discord') {
    const d = probe.discord || {};
    if (probe.state === 'source_match') {
      return probe.covered_by_server
        ? `✓ Whole server in FabledCurator · ${artist}`
        : `✓ In FabledCurator · ${artist}`;
    }
    // Every other Discord state opens the panel: the artist is always chosen.
    return d.channel_id ? `+ Add ${channelLabel(d)} to FabledCurator` : '+ Add server to FabledCurator';
  }
  switch (probe.state) {
    case 'source_match':
      return `✓ In FabledCurator · ${platformName}`;
    case 'artist_match':
      return `+ Add ${platformName} source to ${artist}`;
    default:
      return '+ Add to FabledCurator';
  }
}

/** `#name` when the probe could read it, else a neutral "this channel". */
function channelLabel(d) {
  return d.channel_name ? `#${d.channel_name}` : 'this channel';
}

/** `name` when the probe could read it, else "this server". */
function serverLabel(d) {
  return d.server_name || 'this server';
}

/**
 * What the Add panel opens with, on any platform.
 *
 * Discord: the channel is the default scope when there is one — a server
 * source walks every channel the token can read, which is rarely what a
 * single art channel wants. The artist is the probe's suggestion (the owner
 * of another source on this server), else a new one named after the server.
 *
 * Patreon / SubscribeStar: the page URL is the source. The artist is the one
 * whose slug the URL already names (artist_match), else a new one under the
 * creator's display name — `probe.display_name`, from the probe the panel
 * makes with names=1 — falling back to the URL handle, which the server
 * resolves on its own when it is left untouched (`nameIsHandle`).
 */
function panelDefaults(probe, pageUrl) {
  const d = probe?.discord || {};
  const suggested = probe?.state === 'artist_match' && probe.artist ? probe.artist : null;
  const discord = probe?.platform === 'discord';
  const shown = probe?.display_name || null;
  let artistName = '';
  if (suggested) artistName = suggested.name;
  else if (discord) artistName = d.server_name || '';
  else artistName = shown || probe?.slug || '';
  return {
    platform: probe?.platform || null,
    scope: discord ? (d.channel_id ? 'channel' : 'server') : 'page',
    pageUrl: pageUrl || null,
    channelUrl: d.channel_url || null,
    serverUrl: d.server_url || null,
    artist: suggested ? { id: suggested.id, name: suggested.name } : null,
    artistName,
    nameIsHandle: !discord && !suggested && !shown,
    handle: probe?.slug || '',
    displayName: shown,
    // Patreon is canon: joining an artist known by another name takes the
    // Patreon name, unless the operator unticks it.
    adoptPlatformName: true,
  };
}

/**
 * The rename the panel offers, or null: only on Patreon (the canon name),
 * only when joining an existing artist, only with a name actually read from
 * Patreon, and only when it differs from what the artist is called now.
 */
function renameOffer(choice) {
  if (choice.platform !== 'patreon' || !choice.artist || !choice.displayName) return null;
  if (choice.artist.name === choice.displayName) return null;
  return { from: choice.artist.name, to: choice.displayName };
}

/**
 * The quick-add body for the panel's current choice. A picked artist goes by
 * id — names can collide once slugified — and a typed name creates (or
 * finds) that artist. The URL handle left untouched sends no name, so the
 * server resolves the display name itself. null when there is nothing valid.
 */
function addRequest(choice) {
  let url = choice.pageUrl;
  if (choice.scope === 'server') url = choice.serverUrl;
  else if (choice.scope === 'channel') url = choice.channelUrl;
  if (!url) return null;
  if (choice.artist && choice.artist.id != null && choice.artist.name === choice.artistName) {
    const req = { url, artistId: choice.artist.id };
    if (choice.adoptPlatformName && renameOffer(choice)) req.usePlatformName = true;
    return req;
  }
  const name = (choice.artistName || '').trim();
  if (!name) return null;
  if (choice.nameIsHandle && name === choice.handle) return { url };
  return { url, artistName: name };
}

/**
 * An artist name reduced to what identifies it: lowercase letters and digits
 * of any script, nothing else — so "Tamada Heijun", "tamada_heijun" and
 * "TamadaHeijun" are one name. Mirrors the server's autocomplete (#429).
 */
function squashName(name) {
  return String(name || '').toLowerCase().replace(/[^\p{L}\p{N}]/gu, '');
}

/** The search result that IS the query, spacing aside, else null. */
function exactArtistMatch(query, results) {
  const q = squashName(query);
  if (!q) return null;
  return (results || []).find((a) => squashName(a.name) === q) || null;
}

/**
 * Inline autofill: the first result whose name extends what was typed
 * (case-insensitive), so the panel can fill in the rest and select it —
 * typing on overwrites it, Tab or Enter accepts it. null when none does.
 */
function inlineCompletion(typed, results) {
  const t = String(typed || '').toLowerCase();
  if (!t) return null;
  return (results || []).find((a) => a.name.length > t.length && a.name.toLowerCase().startsWith(t)) || null;
}