// Direct browser <-> Emby calls: catalog, images, streaming. Session/token
// lives in localStorage, scoped to this browser only. Nothing here ever
// talks to our own backend - see party.js for that.
//
// TODO(verify): these calls go cross-origin (this app's domain -> Emby's
// domain), which needs Emby (or its reverse proxy) to answer CORS preflight
// requests. If login/search silently fail with a network error and the
// browser console shows a CORS complaint, this whole approach needs a proxy
// through our own backend instead - see docs/architecture.md.

function authHeaderValue() {
  let deviceId = localStorage.getItem('wp_deviceId');
  if (!deviceId) {
    deviceId = 'watchparty-' + crypto.randomUUID();
    localStorage.setItem('wp_deviceId', deviceId);
  }
  return `MediaBrowser Client="WatchParty", Device="Browser", DeviceId="${deviceId}", Version="0.1.0"`;
}

export const session = {
  get serverUrl() { return localStorage.getItem('wp_serverUrl') || ''; },
  get token() { return localStorage.getItem('wp_token') || ''; },
  get userId() { return localStorage.getItem('wp_userId') || ''; },
  get userName() { return localStorage.getItem('wp_userName') || ''; },
  get isLoggedIn() { return !!(this.serverUrl && this.token && this.userId); },
  set(serverUrl, token, userId, userName) {
    localStorage.setItem('wp_serverUrl', serverUrl);
    localStorage.setItem('wp_token', token);
    localStorage.setItem('wp_userId', userId);
    localStorage.setItem('wp_userName', userName);
  },
  clear() {
    ['wp_serverUrl', 'wp_token', 'wp_userId', 'wp_userName'].forEach((k) => localStorage.removeItem(k));
  }
};

async function embyFetch(path, options = {}) {
  const res = await fetch(session.serverUrl.replace(/\/+$/, '') + path, {
    ...options,
    headers: {
      'X-Emby-Authorization': authHeaderValue(),
      ...(session.token ? { 'X-Emby-Token': session.token } : {}),
      ...(options.headers || {})
    }
  });
  if (!res.ok) {
    throw new Error(`Emby request failed: ${res.status}`);
  }
  const text = await res.text();
  return text ? JSON.parse(text) : null;
}

export async function login(serverUrl, username, password) {
  const cleanUrl = serverUrl.trim().replace(/\/+$/, '');
  const res = await fetch(cleanUrl + '/Users/AuthenticateByName', {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      'X-Emby-Authorization': authHeaderValue()
    },
    body: JSON.stringify({ Username: username, Pw: password })
  });
  if (!res.ok) {
    throw new Error('Identifiants refusés.');
  }
  const data = await res.json();
  session.set(cleanUrl, data.AccessToken, data.User.Id, data.User.Name);
  return data;
}

export async function searchItems(query) {
  if (!query || query.trim().length < 2) {
    return [];
  }
  const params = new URLSearchParams({
    searchTerm: query,
    IncludeItemTypes: 'Movie,Episode,Series',
    Recursive: 'true',
    Fields: 'Overview,ProductionYear',
    ImageTypeLimit: '1',
    Limit: '24'
  });
  const data = await embyFetch(`/Users/${session.userId}/Items?${params.toString()}`);
  return (data && data.Items) || [];
}

export async function getItem(itemId) {
  return embyFetch(`/Users/${session.userId}/Items/${itemId}`);
}

export function imageUrl(itemId, maxWidth = 300) {
  // <img> can't send custom headers, so the token has to ride along in the
  // query string here - the one deliberate exception to keeping tokens out
  // of URLs. This is the same thing Emby's own web client does for images.
  const params = new URLSearchParams({ api_key: session.token, maxWidth: String(maxWidth) });
  return `${session.serverUrl}/Items/${itemId}/Images/Primary?${params.toString()}`;
}

export function streamUrl(itemId) {
  // Same deliberate exception as imageUrl: <video src>/hls.js can't attach
  // headers either. VideoCodec/AudioCodec pinned to a broadly-compatible
  // target so Emby transcodes whatever it needs to - good enough for v1,
  // not tuned for quality/bandwidth yet.
  const params = new URLSearchParams({
    api_key: session.token,
    VideoCodec: 'h264',
    AudioCodec: 'aac'
  });
  return `${session.serverUrl}/Videos/${itemId}/master.m3u8?${params.toString()}`;
}