// A deliberately tiny server-side JMAP client, used only by the indexer.
//
// WHY NOT REUSE lib/jmap/client.ts: that class is a 7400-line renderer object.
// It holds credentials in instance fields, uses `btoa`, opens EventSource /
// WebSocket push connections, and wires itself into Zustand stores and toast
// notifications. Importing it into an API route would drag all of that into the
// server bundle for the sake of four method calls. The existing server-side
// JMAP code in this repo (lib/auth/verify-jmap-auth.ts) already sets the
// precedent: plain fetch + an Authorization header.
//
// Everything here is stateless - the caller supplies the auth header per call,
// so there is no resident credential and nothing to invalidate.

import type { CalendarEvent, ContactCard, Email, FileNode } from '@/lib/jmap/types';

const REQUEST_TIMEOUT_MS = 30_000;

export const CAP_CORE = 'urn:ietf:params:jmap:core';
export const CAP_MAIL = 'urn:ietf:params:jmap:mail';
export const CAP_CALENDARS = 'urn:ietf:params:jmap:calendars';
export const CAP_CONTACTS = 'urn:ietf:params:jmap:contacts';
export const CAP_FILENODE = 'urn:ietf:params:jmap:filenode';

export class JmapIndexError extends Error {
  status: number;
  constructor(message: string, status = 502) {
    super(message);
    this.name = 'JmapIndexError';
    this.status = status;
  }
}

export interface JmapSessionInfo {
  apiUrl: string;
  /** Server-confirmed authenticated login (JMAP Session.username). */
  username?: string;
  primaryAccounts: Record<string, string>;
  accounts: Record<string, { name?: string; isPersonal?: boolean; accountCapabilities?: Record<string, unknown> }>;
  capabilities: Record<string, unknown>;
}

/**
 * Pins a URL advertised by the session to the origin we authenticated against.
 *
 * `lib/jmap/client.ts` does the same thing in its rewriteSessionUrls() for the
 * renderer's benefit. Server-side it is a security control, not a convenience:
 * we attach the user's credentials to this URL, so a session document that
 * advertised an `apiUrl` on someone else's host would turn this into a
 * credential-leaking SSRF. Keep the path and query, take the origin from the
 * server URL we were configured with.
 */
function pinToServerOrigin(advertised: string, serverUrl: string): string {
  const base = new URL(serverUrl);
  let target: URL;
  try {
    target = new URL(advertised, base);
  } catch {
    throw new JmapIndexError('JMAP session advertised an unusable apiUrl');
  }
  return `${base.origin}${target.pathname}${target.search}`;
}

async function fetchWithTimeout(url: string, init: RequestInit): Promise<Response> {
  const controller = new AbortController();
  const timer = setTimeout(() => controller.abort(), REQUEST_TIMEOUT_MS);
  try {
    return await fetch(url, { ...init, signal: controller.signal, redirect: 'manual' });
  } catch (error) {
    if (error instanceof Error && error.name === 'AbortError') {
      throw new JmapIndexError('JMAP request timed out', 504);
    }
    throw new JmapIndexError(`JMAP request failed: ${String(error)}`);
  } finally {
    clearTimeout(timer);
  }
}

export async function fetchJmapSession(serverUrl: string, authHeader: string): Promise<JmapSessionInfo> {
  const response = await fetchWithTimeout(`${serverUrl.replace(/\/+$/, '')}/.well-known/jmap`, {
    method: 'GET',
    headers: { Authorization: authHeader },
  });
  if (response.status === 401 || response.status === 403) {
    throw new JmapIndexError('JMAP authentication failed', 401);
  }
  if (!response.ok) {
    throw new JmapIndexError(`JMAP session fetch failed (${response.status})`);
  }
  const raw = (await response.json().catch(() => null)) as Record<string, unknown> | null;
  if (!raw || typeof raw.apiUrl !== 'string') {
    throw new JmapIndexError('Invalid JMAP session response');
  }
  return {
    apiUrl: pinToServerOrigin(raw.apiUrl, serverUrl),
    username: typeof raw.username === 'string' ? raw.username : undefined,
    primaryAccounts: (raw.primaryAccounts as Record<string, string>) ?? {},
    accounts: (raw.accounts as JmapSessionInfo['accounts']) ?? {},
    capabilities: (raw.capabilities as Record<string, unknown>) ?? {},
  };
}

type MethodCall = [string, Record<string, unknown>, string];

/** Raw method-response tuple, `[name, args, callId]`. `name` is 'error' on failure. */
type MethodResponse = [string, Record<string, unknown>, string];

export async function jmapRequest(
  session: JmapSessionInfo,
  authHeader: string,
  using: readonly string[],
  methodCalls: readonly MethodCall[],
): Promise<MethodResponse[]> {
  const response = await fetchWithTimeout(session.apiUrl, {
    method: 'POST',
    headers: { Authorization: authHeader, 'Content-Type': 'application/json' },
    body: JSON.stringify({ using, methodCalls }),
  });
  if (response.status === 401 || response.status === 403) {
    throw new JmapIndexError('JMAP authentication failed', 401);
  }
  if (response.status === 429) {
    throw new JmapIndexError('JMAP server is rate limiting', 429);
  }
  if (!response.ok) {
    throw new JmapIndexError(`JMAP request failed (${response.status})`);
  }
  const data = (await response.json().catch(() => null)) as { methodResponses?: MethodResponse[] } | null;
  if (!data || !Array.isArray(data.methodResponses)) {
    throw new JmapIndexError('Invalid JMAP response envelope');
  }
  return data.methodResponses;
}

function firstResult(responses: MethodResponse[], expected: string): Record<string, unknown> | null {
  for (const [name, args] of responses) {
    if (name === expected) return args;
    // A method-level error is not fatal for an INDEX: a server that doesn't
    // support one data type should not fail the whole reindex. The caller
    // treats null as "nothing to index for this type".
    if (name === 'error') return null;
  }
  return null;
}

function idsOf(args: Record<string, unknown> | null): string[] {
  const ids = args?.ids;
  return Array.isArray(ids) ? ids.filter((v): v is string => typeof v === 'string') : [];
}

function listOf<T>(args: Record<string, unknown> | null): T[] {
  const list = args?.list;
  return Array.isArray(list) ? (list as T[]) : [];
}

export function accountIdFor(session: JmapSessionInfo, capability: string): string | null {
  const id = session.primaryAccounts[capability];
  return typeof id === 'string' && id.length > 0 ? id : null;
}

export function hasCapability(session: JmapSessionInfo, capability: string): boolean {
  return Object.prototype.hasOwnProperty.call(session.capabilities, capability);
}

/** Per-ACCOUNT capability, mirroring client.ts's supportsFiles() (#563: a server can advertise it while an account has it revoked). */
export function accountHasCapability(
  session: JmapSessionInfo,
  accountId: string,
  capability: string,
): boolean {
  const account = session.accounts[accountId];
  if (!account) return false;
  if (account.accountCapabilities && Object.prototype.hasOwnProperty.call(account.accountCapabilities, capability)) {
    return true;
  }
  return account.isPersonal === false;
}

// ── mail ────────────────────────────────────────────────────────────────────

/** Properties needed to build a mail IndexDoc. Bodies come via bodyValues. */
const EMAIL_INDEX_PROPERTIES = [
  'id', 'threadId', 'mailboxIds', 'keywords', 'size', 'receivedAt',
  'from', 'to', 'cc', 'subject', 'preview', 'hasAttachment',
  'textBody', 'htmlBody', 'bodyValues',
] as const;

export async function getEmailsForIndex(
  session: JmapSessionInfo,
  authHeader: string,
  accountId: string,
  ids: readonly string[],
  maxBodyBytes: number,
): Promise<Email[]> {
  if (ids.length === 0) return [];
  const responses = await jmapRequest(session, authHeader, [CAP_CORE, CAP_MAIL], [
    ['Email/get', {
      accountId,
      ids: [...ids],
      properties: [...EMAIL_INDEX_PROPERTIES],
      // Without these two the bodyValues map comes back EMPTY and every
      // indexed body would silently fall back to `preview`.
      fetchTextBodyValues: true,
      fetchHTMLBodyValues: true,
      maxBodyValueBytes: maxBodyBytes,
    }, 'g'],
  ]);
  return listOf<Email>(firstResult(responses, 'Email/get'));
}

export async function queryRecentEmailIds(
  session: JmapSessionInfo,
  authHeader: string,
  accountId: string,
  afterIso: string,
  limit: number,
): Promise<string[]> {
  const responses = await jmapRequest(session, authHeader, [CAP_CORE, CAP_MAIL], [
    ['Email/query', {
      accountId,
      filter: { after: afterIso },
      sort: [{ property: 'receivedAt', isAscending: false }],
      limit,
      calculateTotal: false,
    }, 'q'],
  ]);
  return idsOf(firstResult(responses, 'Email/query'));
}

// ── calendar ────────────────────────────────────────────────────────────────

export async function getCalendarEventsForIndex(
  session: JmapSessionInfo,
  authHeader: string,
  accountId: string,
  ids: readonly string[],
): Promise<CalendarEvent[]> {
  if (ids.length === 0) return [];
  const responses = await jmapRequest(session, authHeader, [CAP_CORE, CAP_CALENDARS], [
    ['CalendarEvent/get', { accountId, ids: [...ids] }, 'g'],
  ]);
  return listOf<CalendarEvent>(firstResult(responses, 'CalendarEvent/get'));
}

export async function queryCalendarEventIds(
  session: JmapSessionInfo,
  authHeader: string,
  accountId: string,
  afterIso: string,
  beforeIso: string,
  limit: number,
): Promise<string[]> {
  const responses = await jmapRequest(session, authHeader, [CAP_CORE, CAP_CALENDARS], [
    ['CalendarEvent/query', {
      accountId,
      // LocalDateTime, per the note in lib/jmap/client.ts:307-312 - Stalwart
      // parses these without a zone suffix and ignores unparseable values.
      filter: { after: toLocalDateTime(afterIso), before: toLocalDateTime(beforeIso) },
      limit,
      calculateTotal: false,
    }, 'q'],
  ]);
  return idsOf(firstResult(responses, 'CalendarEvent/query'));
}

/** JSCalendar LocalDateTime: `YYYY-MM-DDTHH:MM:SS`, no zone designator. */
function toLocalDateTime(iso: string): string {
  return iso.replace(/\.\d+/, '').replace(/Z$/, '').slice(0, 19);
}

// ── contacts ────────────────────────────────────────────────────────────────

export async function getContactsForIndex(
  session: JmapSessionInfo,
  authHeader: string,
  accountId: string,
  ids: readonly string[],
): Promise<ContactCard[]> {
  if (ids.length === 0) return [];
  const responses = await jmapRequest(session, authHeader, [CAP_CORE, CAP_CONTACTS], [
    ['ContactCard/get', { accountId, ids: [...ids] }, 'g'],
  ]);
  return listOf<ContactCard>(firstResult(responses, 'ContactCard/get'));
}

export async function queryContactIds(
  session: JmapSessionInfo,
  authHeader: string,
  accountId: string,
  limit: number,
): Promise<string[]> {
  const responses = await jmapRequest(session, authHeader, [CAP_CORE, CAP_CONTACTS], [
    ['ContactCard/query', { accountId, limit, calculateTotal: false }, 'q'],
  ]);
  return idsOf(firstResult(responses, 'ContactCard/query'));
}

// ── files ───────────────────────────────────────────────────────────────────

const FILENODE_INDEX_PROPERTIES = [
  'id', 'parentId', 'name', 'type', 'blobId', 'size', 'created', 'modified',
] as const;

export async function getFilesForIndex(
  session: JmapSessionInfo,
  authHeader: string,
  accountId: string,
  ids: readonly string[],
): Promise<FileNode[]> {
  if (ids.length === 0) return [];
  const responses = await jmapRequest(session, authHeader, [CAP_CORE], [
    ['FileNode/get', { accountId, ids: [...ids], properties: [...FILENODE_INDEX_PROPERTIES] }, 'g'],
  ]);
  return listOf<FileNode>(firstResult(responses, 'FileNode/get'));
}

export async function queryFileIds(
  session: JmapSessionInfo,
  authHeader: string,
  accountId: string,
  limit: number,
): Promise<string[]> {
  const responses = await jmapRequest(session, authHeader, [CAP_CORE], [
    ['FileNode/query', { accountId, filter: {}, limit, calculateTotal: false }, 'q'],
  ]);
  return idsOf(firstResult(responses, 'FileNode/query'));
}

/**
 * Builds `id -> "Parent/Child"` paths for the given nodes, walking `parentId`
 * upward. FileNode only knows its parent, so the caller has to assemble this;
 * unresolvable ancestors just truncate the path rather than failing.
 */
export function buildFilePaths(nodes: readonly FileNode[]): Map<string, string> {
  const byId = new Map(nodes.map((n) => [n.id, n]));
  const cache = new Map<string, string>();

  const resolve = (id: string, depth: number): string => {
    if (depth > 32) return '';
    const cached = cache.get(id);
    if (cached !== undefined) return cached;
    const node = byId.get(id);
    if (!node) return '';
    const parent = node.parentId ? resolve(node.parentId, depth + 1) : '';
    const full = parent ? `${parent}/${node.name}` : node.name;
    cache.set(id, full);
    return full;
  };

  const out = new Map<string, string>();
  for (const n of nodes) {
    // The document's own `path` metadata is its PARENT directory chain, so a
    // search for "Invoices" matches files inside it without the filename
    // being duplicated into the body.
    out.set(n.id, n.parentId ? resolve(n.parentId, 0) : '');
  }
  return out;
}