/**
 * Typed API client for the FamilySync backend.
 *
 * credentials: 'include' is required so the OIDC session cookie is sent with
 * every cross-origin request (Vite dev proxy routes to :3000; production is
 * same-origin via Pangolin).
 *
 * Auth note: the OIDC guard's 302 to Authelia is CORS-blocked for fetch/XHR —
 * browsers do not follow cross-origin redirects from XHR to an external IdP.
 * Re-authentication therefore requires a TOP-LEVEL navigation to /api/login
 * (see apps/pwa/src/lib/loginRedirect.ts). fetchMe and other fetch calls here
 * are pure data fetches; they throw on non-ok responses and leave the redirect
 * decision to the caller (CalendarShell via maybeRedirectToLogin).
 *
 * D-11 (Plan 06-05): All fetch wrappers now use redirect:'manual' and throw a
 * typed SessionExpiredError on 401 / opaqueredirect. The global QueryCache /
 * MutationCache error handler in main.tsx catches this class and arms the
 * session-expiry interstitial. A generic Error is still thrown for other non-ok
 * statuses so error UI can distinguish auth failures from transient errors.
 */

// ── Auth error ────────────────────────────────────────────────────────────

/**
 * Typed error thrown by all fetch wrappers when the server returns a 401 or
 * an opaque redirect (the OIDC guard's 302 to Authelia surfaced as
 * res.type==='opaqueredirect' via redirect:'manual').
 *
 * Object.setPrototypeOf is required so instanceof checks work correctly after
 * TypeScript compilation to ES5 / CommonJS, where extending built-in Error
 * breaks the prototype chain.
 */
export class SessionExpiredError extends Error {
  readonly name = 'SessionExpiredError';
  constructor() {
    super('Session expired — re-authentication required');
    Object.setPrototypeOf(this, SessionExpiredError.prototype);
  }
}

/**
 * Unified auth-response checker applied to every fetch in this module.
 *
 * - 401 or opaqueredirect  → throws SessionExpiredError (caught by global QueryCache handler)
 * - other non-ok           → throws a generic Error (distinguishable from auth failures)
 * - ok                     → no-op (caller proceeds to parse body)
 *
 * @param res   The fetch Response object
 * @param label A short human-readable description for the generic error message
 */
function handleAuthResponse(res: Response, label: string): void {
  if (res.type === 'opaqueredirect' || res.status === 401) {
    throw new SessionExpiredError();
  }
  if (!res.ok) {
    throw new Error(`${label} failed: ${res.status}`);
  }
}

// ── /api/auth/* (Phase 19 — local auth) ───────────────────────────────────

/**
 * Typed error thrown by fetchLocalLogin when the server returns 401/429/423/5xx.
 *
 * Codes:
 *   'invalid'    — 401: incorrect username or password
 *   'rate-limit' — 429: too many attempts within the rate window
 *   'locked'     — 423: account locked (persistent lockout)
 *   'server'     — 5xx or network: transient server error
 *
 * Object.setPrototypeOf is required so instanceof checks work correctly after
 * TypeScript compilation to ES5 / CommonJS (mirrors SessionExpiredError).
 */
export class LoginError extends Error {
  readonly name = 'LoginError';
  constructor(public readonly code: 'invalid' | 'rate-limit' | 'locked' | 'server') {
    super(`Login failed: ${code}`);
    Object.setPrototypeOf(this, LoginError.prototype);
  }
}

/**
 * GET /api/auth/mode — pre-auth endpoint, no session required.
 * Returns whether local-auth and/or OIDC are enabled.
 * staleTime: 60_000 in App.tsx authModeQuery.
 */
export async function fetchAuthMode(): Promise<{ localEnabled: boolean; oidcEnabled: boolean }> {
  const res = await fetch('/api/auth/mode');
  if (!res.ok) {
    throw new Error(`fetchAuthMode failed: ${res.status}`);
  }
  return res.json() as Promise<{ localEnabled: boolean; oidcEnabled: boolean }>;
}

/**
 * POST /api/auth/local/login — submit username/password credentials.
 *
 * Maps status codes to typed LoginError:
 *   401 → LoginError('invalid')   — incorrect username or password
 *   429 → LoginError('rate-limit') — too many attempts
 *   423 → LoginError('locked')    — account locked
 *   other non-ok → LoginError('server')
 *
 * Throws nothing on 200 OK — the local-session cookie is set by the server.
 */
export async function fetchLocalLogin(body: {
  username: string;
  password: string;
}): Promise<void> {
  const res = await fetch('/api/auth/local/login', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    credentials: 'include',
    redirect: 'manual',
    body: JSON.stringify(body),
  });

  if (res.status === 401) throw new LoginError('invalid');
  if (res.status === 429) throw new LoginError('rate-limit');
  if (res.status === 423) throw new LoginError('locked');
  if (!res.ok) throw new LoginError('server');
}

/**
 * POST /api/auth/local/logout — clear the local-session cookie.
 */
export async function fetchLocalLogout(): Promise<void> {
  const res = await fetch('/api/auth/local/logout', {
    method: 'POST',
    credentials: 'include',
    redirect: 'manual',
  });

  if (!res.ok && res.type !== 'opaqueredirect') {
    throw new Error(`fetchLocalLogout failed: ${res.status}`);
  }
}

/**
 * POST /api/me/password — self-service password change (Phase 19, Surface 12).
 * Requires the user's current password and a new password (min 8 chars).
 *
 * Status codes:
 *   403 → wrong current password (throws Error('wrong-current')) — NOT a session expiry
 *   401 / opaqueredirect → genuine session expiry (throws SessionExpiredError)
 *   other non-ok → generic error (throws Error('server'))
 *
 * CR-03: the server returns 403 (not 401) for an incorrect current password so this
 * client can distinguish an in-app authorization failure from a real session expiry.
 * Treating that case as 401 would route it to the global MutationCache session-expiry
 * handler and forcibly log the user out for a simple mistyped password.
 */
export async function fetchChangePassword(body: {
  currentPassword: string;
  newPassword: string;
}): Promise<void> {
  const res = await fetch('/api/me/password', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    credentials: 'include',
    redirect: 'manual',
    body: JSON.stringify(body),
  });

  // 403 → wrong current password (in-app). Check BEFORE the 401 session-expiry branch.
  if (res.status === 403) throw new Error('wrong-current');
  if (res.type === 'opaqueredirect' || res.status === 401) throw new SessionExpiredError();
  if (!res.ok) {
    const detail = (await res.json().catch(() => ({}))) as { code?: string };
    throw new Error(detail.code ?? 'server');
  }
}

/**
 * POST /api/admin/members — create a new local member account (Phase 19, Surface 11A).
 * Admin-only; server enforces requireAdmin.
 *
 * Request contract: the server's createMemberSchema requires
 *   { displayName, username, initialPassword }
 * (see apps/api/src/routes/admin.ts). The caller-facing `password` field is mapped to
 * `initialPassword` here so the request validates server-side.
 *
 * Status codes:
 *   409 → username already taken (throws Error with message 'conflict')
 *   other non-ok → generic error (throws Error('server'))
 */
export async function fetchCreateMember(body: {
  displayName: string;
  username: string;
  password: string;
}): Promise<void> {
  const res = await fetch('/api/admin/members', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    credentials: 'include',
    redirect: 'manual',
    // CR-02: the server expects `initialPassword`, not `password`. Send the field it
    // validates against — otherwise Zod rejects every create with a generic 400.
    body: JSON.stringify({
      displayName: body.displayName,
      username: body.username,
      initialPassword: body.password,
    }),
  });

  if (res.type === 'opaqueredirect' || res.status === 401) throw new SessionExpiredError();
  // 409 → username conflict. The server returns { error: 'Username already in use' } (no
  // `code` field), so map the status to the 'conflict' sentinel the AdminPage handler expects.
  if (res.status === 409) throw new Error('conflict');
  if (!res.ok) {
    const detail = (await res.json().catch(() => ({}))) as { code?: string };
    throw new Error(detail.code ?? 'server');
  }
}

/**
 * POST /api/admin/members/:id/password — admin reset of a member's password (Surface 11B).
 * Admin-only; server enforces requireAdmin. (Route is registered as `/members/:id/password`
 * in apps/api/src/routes/admin.ts — must match exactly or the sheet 404s.)
 */
export async function fetchAdminResetPassword(
  memberId: number,
  newPassword: string,
): Promise<void> {
  const res = await fetch(`/api/admin/members/${memberId}/password`, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    credentials: 'include',
    redirect: 'manual',
    body: JSON.stringify({ newPassword }),
  });

  if (res.type === 'opaqueredirect' || res.status === 401) throw new SessionExpiredError();
  if (!res.ok) {
    throw new Error(`fetchAdminResetPassword failed: ${res.status}`);
  }
}

/**
 * POST /api/me/link-oidc — initiate the OIDC-link flow for the current local user (Surface 13).
 *
 * The server returns the OIDC authorization endpoint URL (with a signed `state` parameter
 * encoding the linkUserId claim) to begin the authorization-code flow. The caller should
 * follow it via top-level navigation (window.location.href = authorizationUrl) when present.
 *
 * authorizationUrl is null when OIDC is not configured in env (the server cannot build the
 * URL); callers MUST handle that case and surface an error instead of navigating to null.
 * The server contract is { signedState, authorizationUrl } (see apps/api/src/routes/me.ts).
 */
export async function fetchLinkOidc(): Promise<{ authorizationUrl: string | null }> {
  const res = await fetch('/api/me/link-oidc', {
    method: 'POST',
    credentials: 'include',
    redirect: 'manual',
  });

  if (res.type === 'opaqueredirect' || res.status === 401) throw new SessionExpiredError();
  if (!res.ok) {
    throw new Error(`fetchLinkOidc failed: ${res.status}`);
  }
  return res.json() as Promise<{ signedState: string; authorizationUrl: string | null }>;
}

// ── /api/me ────────────────────────────────────────────────────────────────

export interface MeUser {
  id: number;
  displayName: string | null;
  color: string;
  isAdmin: boolean; // from users.is_admin — UX gating only (D-03); server enforces 403 on /api/admin/*
  needsProviderSetup: boolean; // true when no member_credentials row exists for this user
  hasLocalCredential: boolean; // true when a local_credentials row exists for this user (Phase 19)
}

export interface MeResponse {
  user: MeUser;
}

export async function fetchMe(): Promise<MeResponse> {
  // redirect: 'manual' is critical. The OIDC guard answers an unauthenticated
  // request with a 302 to Authelia (cross-origin). With the default
  // redirect: 'follow', the browser follows that credentialed cross-origin
  // redirect and the fetch HANGS (never resolves, never rejects) — leaving the
  // query stuck "loading" so the SPA spins forever and the auth-redirect below
  // never fires. With 'manual', the 302 comes back as an opaqueredirect
  // (res.type === 'opaqueredirect', res.status === 0) that we detect immediately.
  const res = await fetch('/api/me', {
    credentials: 'include',
    redirect: 'manual',
  });

  handleAuthResponse(res, 'GET /api/me');

  return res.json() as Promise<MeResponse>;
}

// ── /api/events (windowed — Phase 2) ─────────────────────────────────────

/**
 * A single concrete occurrence of a calendar event.
 *
 * Mirrors the CalendarOccurrence shape produced by the backend's
 * expandOccurrences() helper (apps/api/src/broker/expand.ts).
 *
 * calendarId and ownerUserId are both present:
 *   calendarId    — DB calendar-row id (do NOT use for Schedule-X routing)
 *   ownerUserId   — DB user id (use for Schedule-X calendarId routing)
 *   isShared      — true when this event belongs to the shared-family calendar
 *
 * hydrateEvents() uses isShared/ownerUserId — never String(calendarId) —
 * to build the Schedule-X calendarId that keys into buildCalendarConfig().
 */
export interface CalendarOccurrence {
  id: string; // `ev-<sanitized-uid>-<epochMs>` — stable identity (server: expand.ts makeOccurrenceId)
  uid: string;
  calendarId: number; // DB calendar-row id — do NOT use for SX calendarId routing
  calendarName: string;
  ownerUserId: number; // DB user id — the correct Schedule-X routing key
  /**
   * Display name of the calendar owner (users.displayName from the API).
   * Null when the user has not configured a display name.
   * Popover renders: isShared ? 'Family' : (ownerName ?? calendarName)
   */
  ownerName: string | null;
  color: string; // hex from users.color or shared-family constant
  isShared: boolean; // true → 'shared' slot; false → String(ownerUserId) slot
  title: string;
  start: string; // 'YYYY-MM-DD' for allDay:true; ISO 8601 with IANA tz for timed
  end: string;
  allDay: boolean;
  location: string | null;
  description: string | null;
  /**
   * True when this occurrence belongs to a recurring series (has an RRULE).
   * Mirrors CalendarOccurrence.hasRrule in apps/api/src/broker/expand.ts — must
   * stay in sync with the server type (Pitfall 4 — atomic mirror, Plan 06-05).
   */
  hasRrule: boolean;
  /**
   * Per-event reminder lead in minutes. NULL = no reminder. 0 = same-day all-day
   * (fire 9 AM on event date). Positive integer = N minutes before event start.
   * D-06: NULL and 0 are semantically distinct.
   * Mirrors CalendarOccurrence.reminderLeadMinutes in apps/api/src/broker/expand.ts
   * (atomic mirror, Plan 11-03).
   */
  reminderLeadMinutes: number | null;
  /**
   * True when the event's alarm is custom/absolute/multi-VALARM (not reducible to a
   * single before-event lead). When true, reminderLeadMinutes is always null and the
   * form must initialize to '__custom__' to preserve the VALARM on edit (CR-01, Plan 11-05).
   * Mirrors CalendarOccurrence.reminderIsCustom in apps/api/src/broker/expand.ts
   * (atomic mirror, Plan 11-05).
   */
  reminderIsCustom: boolean;
}

export interface OccurrencesResponse {
  occurrences: CalendarOccurrence[];
}

/**
 * Fetch windowed calendar occurrences.
 *
 * The ?start=&end= window is mandatory — an unwindowed call would expand 500+
 * cached events with all their recurring occurrences (RESEARCH.md Pitfall 5).
 *
 * @param start ISO date string 'YYYY-MM-DD' — window start (inclusive)
 * @param end   ISO date string 'YYYY-MM-DD' — window end (exclusive)
 */
export async function fetchEvents(start: string, end: string): Promise<OccurrencesResponse> {
  const res = await fetch(`/api/events?start=${start}&end=${end}`, {
    credentials: 'include',
    redirect: 'manual',
  });

  handleAuthResponse(res, 'GET /api/events');

  return res.json() as Promise<OccurrencesResponse>;
}

// Phase 1 legacy types (CalendarEvent, EventsResponse, fetchEventsLegacy) removed in Plan 05
// when the Phase 1 broker-proof component was retired.

// ── /api/events (write — Plan 03-05) ─────────────────────────────────────────

/**
 * Recurrence presets supported by the EventForm.
 * Maps 1:1 to the RRULE frequency values the API accepts.
 */
export type RecurrencePreset = 'none' | 'daily' | 'weekly' | 'monthly' | 'yearly';

/**
 * Payload for creating or updating a calendar event.
 * Mirrors the Zod schema on POST /api/events/create and PATCH /api/events/:uid/edit.
 */
export interface CreateEventPayload {
  title: string;
  allDay: boolean;
  start: string; // 'YYYY-MM-DD' for allDay; ISO 8601 for timed
  end: string; // same format as start
  // WR-01: optional. CREATE always sends it; EDIT omits it so the API/worker preserve
  // the event's existing RRULE (the occurrence contract does not expose recurrence, so
  // the form cannot echo it back without silently resetting it to 'none').
  recurrence?: RecurrencePreset;
  /**
   * RRULE UNTIL date (D-06). ISO 'YYYY-MM-DD' string. Only sent when recurrence !== 'none'
   * and the user selects the "On date" bound. Mutually exclusive with recurrenceCount.
   * The outbox worker converts this to RRULE UNTIL format (DATE for all-day, DATETIME UTC for timed).
   */
  recurrenceUntil?: string;
  /**
   * RRULE COUNT (D-06). Integer >= 1. Only sent when recurrence !== 'none' and the user
   * selects the "After N times" bound. Mutually exclusive with recurrenceUntil.
   */
  recurrenceCount?: number;
  location?: string;
  description?: string;
  /**
   * Per-event reminder lead in minutes.
   * absent/undefined = no-change (edit omits field so server preserves existing VALARM, D-08)
   * null             = explicit "None" (clear any VALARM)
   * 0                = same-day all-day (fire 9 AM on event date, D-05)
   * positive integer = N minutes before event start
   */
  reminderLeadMinutes?: number | null;
  calendarUrl?: string; // omit to use the member's default writable calendar (D-01)
}

/** Response from POST /api/events/create and PATCH /api/events/:uid/edit */
export interface CreateEventResponse {
  uid: string;
}

/**
 * A writable calendar returned by GET /api/events/writable-calendars.
 * The server is the authoritative source of the writable set (D-03).
 * The client never derives writability — it reads this endpoint verbatim.
 */
export interface WritableCalendar {
  url: string;
  displayName: string;
  color: string;
  isShared: boolean;
}

/**
 * Create a new calendar event.
 *
 * POSTs to /api/events/create and returns immediately with 202 + uid.
 * The server enqueues the write to CalDAV asynchronously (D-05/D-12).
 */
export async function createEvent(payload: CreateEventPayload): Promise<CreateEventResponse> {
  const res = await fetch('/api/events/create', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    credentials: 'include',
    redirect: 'manual',
    body: JSON.stringify(payload),
  });

  handleAuthResponse(res, 'POST /api/events/create');

  return res.json() as Promise<CreateEventResponse>;
}

/**
 * Update an existing calendar event.
 *
 * PATCHes /api/events/:uid/edit with the updated payload.
 * Returns 202 + uid; the write is enqueued asynchronously (D-05).
 */
export async function updateEvent(
  uid: string,
  payload: CreateEventPayload,
): Promise<CreateEventResponse> {
  const res = await fetch(`/api/events/${uid}/edit`, {
    method: 'PATCH',
    headers: { 'Content-Type': 'application/json' },
    credentials: 'include',
    redirect: 'manual',
    body: JSON.stringify(payload),
  });

  handleAuthResponse(res, `PATCH /api/events/${uid}/edit`);

  return res.json() as Promise<CreateEventResponse>;
}

/**
 * Delete a calendar event.
 *
 * DELETEs /api/events/:uid; the API enqueues the delete to the outbox (D-05).
 * Returns 202 Accepted (async). Throws on any non-ok response.
 */
export async function deleteEvent(uid: string): Promise<void> {
  const res = await fetch(`/api/events/${uid}`, {
    method: 'DELETE',
    credentials: 'include',
    redirect: 'manual',
  });

  handleAuthResponse(res, `DELETE /api/events/${uid}`);
}

// ── /api/events/sync-status (Plan 03-06) ─────────────────────────────────────

/**
 * Status values for an outbox write operation.
 * Mirrors the calendarOutbox.status enum on the server.
 */
export type SyncStatusValue = 'pending' | 'done' | 'failed' | 'dead';

/**
 * Response from GET /api/events/sync-status?uid=
 * The server returns the current outbox status for the given UID + member.
 */
export interface SyncStatus {
  uid: string;
  status: SyncStatusValue;
  /** Present on failed status — may contain '412' prefix for conflict detection. */
  error?: string;
}

/**
 * Poll the sync-status for a specific event UID.
 *
 * Used by SyncStateToast to track pending → done | failed | dead transitions.
 * The server filters by the current member so no cross-member leakage (T-03-19).
 */
export async function fetchSyncStatus(uid: string): Promise<SyncStatus> {
  const res = await fetch(`/api/events/sync-status?uid=${uid}`, {
    credentials: 'include',
    redirect: 'manual',
  });

  handleAuthResponse(res, 'GET /api/events/sync-status');

  return res.json() as Promise<SyncStatus>;
}

/**
 * Fetch the authoritative list of writable calendars for the current member.
 *
 * The server owns the D-03 writable set (WHERE userId=currentUser.id OR isShared=1).
 * The client NEVER derives writability — it reads this endpoint verbatim.
 * Drives the calendar picker visibility (D-02: hidden when only 1 writable calendar).
 */
export async function fetchWritableCalendars(): Promise<WritableCalendar[]> {
  const res = await fetch('/api/events/writable-calendars', {
    credentials: 'include',
    redirect: 'manual',
  });

  handleAuthResponse(res, 'GET /api/events/writable-calendars');

  const body = (await res.json()) as { calendars: WritableCalendar[] };
  return body.calendars;
}

// ── /api/admin/* (Phase 10, Plan 04) ─────────────────────────────────────────

/**
 * A member row as returned by GET /api/admin/members.
 * Matches the Plan-03 shape: { id, displayName, color, hasCredential }.
 */
export interface AdminMember {
  id: number;
  displayName: string | null;
  color: string;
  hasCredential: boolean;
  hasLocalCredential: boolean; // true when a local_credentials row exists for this member (Phase 19)
}

export interface AdminMembersResponse {
  members: AdminMember[];
}

/**
 * Payload for POST /api/admin/credentials (admin-managed rotation).
 * NOTE: includes userId (the member being rotated) — admin-scoped.
 * The app password MUST NOT be logged or stored beyond the in-flight request body (T-10-15).
 */
export interface SaveCredentialPayload {
  userId: number;
  providerType: 'caldav';
  fastmailEmail: string;
  appPassword: string;
}

/**
 * A synced calendar row as returned by GET /api/admin/calendars.
 * Matches the Plan-03 shape: { id, displayName, isShared }.
 */
export interface AdminCalendar {
  id: number;
  displayName: string;
  isShared: boolean;
}

export interface AdminCalendarsResponse {
  calendars: AdminCalendar[];
}

/**
 * Payload for POST /api/me/credential (self-service, member-scoped).
 * NOTE: no userId field — the server resolves userId from the session (Pitfall 6 / T-10-12).
 * The app password MUST NOT be logged or stored beyond the in-flight request body (T-10-15).
 */
export interface SaveMyCredentialPayload {
  providerType: 'caldav';
  fastmailEmail: string;
  appPassword: string;
}

/**
 * Fetch the list of all members with their credential status.
 * Admin-only: the server enforces requireAdmin (403 for non-admins).
 */
export async function fetchAdminMembers(): Promise<AdminMembersResponse> {
  const res = await fetch('/api/admin/members', {
    credentials: 'include',
    redirect: 'manual',
  });

  handleAuthResponse(res, 'GET /api/admin/members');

  return res.json() as Promise<AdminMembersResponse>;
}

/**
 * Save (add or rotate) a credential for any member.
 * Admin-only: requires userId in payload; server enforces requireAdmin.
 * The app password is sent in the request body and NEVER stored client-side.
 */
export async function saveCredential(payload: SaveCredentialPayload): Promise<void> {
  const res = await fetch('/api/admin/credentials', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    credentials: 'include',
    redirect: 'manual',
    body: JSON.stringify(payload),
  });

  handleAuthResponse(res, 'POST /api/admin/credentials');
}

/**
 * Fetch the list of synced calendars with their shared status.
 * Admin-only: the server enforces requireAdmin (403 for non-admins).
 */
export async function fetchAdminCalendars(): Promise<AdminCalendarsResponse> {
  const res = await fetch('/api/admin/calendars', {
    credentials: 'include',
    redirect: 'manual',
  });

  handleAuthResponse(res, 'GET /api/admin/calendars');

  return res.json() as Promise<AdminCalendarsResponse>;
}

/**
 * Set the shared calendar (ADMIN-02: exclusive single-select, D-06).
 * Admin-only: the server enforces requireAdmin.
 * Clears is_shared on all other calendars and sets it on the given id.
 */
export async function setSharedCalendar(calendarId: number): Promise<void> {
  const res = await fetch(`/api/admin/calendars/${calendarId}/shared`, {
    method: 'PUT',
    credentials: 'include',
    redirect: 'manual',
  });

  handleAuthResponse(res, `PUT /api/admin/calendars/${calendarId}/shared`);
}

/**
 * Response shape for GET /api/admin/config/timezone.
 * isExplicitlySet is false when the household timezone has not been saved yet
 * (the server returns the process.env.TZ / Intl fallback in that case — D-06).
 */
export interface AdminTimezoneResponse {
  timezone: string;
  isExplicitlySet: boolean;
}

/**
 * Fetch the current household timezone setting.
 * Admin-only: the server enforces requireAdmin (403 for non-admins).
 */
export async function fetchAdminTimezone(): Promise<AdminTimezoneResponse> {
  const res = await fetch('/api/admin/config/timezone', {
    credentials: 'include',
    redirect: 'manual',
  });

  handleAuthResponse(res, 'GET /api/admin/config/timezone');

  return res.json() as Promise<AdminTimezoneResponse>;
}

/**
 * Set the household timezone.
 * Admin-only: the server enforces requireAdmin and IANA validation (Plan 02).
 * @param timezone A valid IANA timezone identifier (e.g. 'America/Chicago').
 */
export async function setAdminTimezone(timezone: string): Promise<void> {
  const res = await fetch('/api/admin/config/timezone', {
    method: 'PUT',
    headers: { 'Content-Type': 'application/json' },
    credentials: 'include',
    redirect: 'manual',
    body: JSON.stringify({ timezone }),
  });

  handleAuthResponse(res, 'PUT /api/admin/config/timezone');
}

/**
 * Self-service: save (add) the current member's own credential.
 * Member-scoped: NO userId in payload — server resolves from session (Pitfall 6 / T-10-12).
 * The app password is sent in the request body and NEVER stored client-side.
 * On success, /api/me re-fetched via ['me'] cache invalidation → needsProviderSetup becomes false.
 */
export async function saveMyCredential(payload: SaveMyCredentialPayload): Promise<void> {
  const res = await fetch('/api/me/credential', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    credentials: 'include',
    redirect: 'manual',
    body: JSON.stringify(payload),
  });

  handleAuthResponse(res, 'POST /api/me/credential');
}

// ── /api/setup/* (Phase 12 — initial setup wizard) ───────────────────────────

/**
 * Response from GET /api/setup/status.
 * setupComplete: false → the wizard has not been completed; redirect to /setup.
 * setupComplete: true  → normal app boot proceeds.
 */
export interface SetupStatusResponse {
  setupComplete: boolean;
  /**
   * Non-secret database name (process.env.DB_NAME) surfaced for the wizard's
   * read-only "database connection verified" referent (gap 3). Never includes
   * DB_HOST/DB_USER/DB_PASSWORD.
   */
  dbName?: string | null;
}

/**
 * Payload for POST /api/setup/config.
 * Collects non-secret runtime config written to the app_config table (D-02).
 * No secrets — VAPID private key and encryption key stay in Docker env.
 *
 * Field names match the API's configSchema exactly (camelCase).
 * API contract: { oidcIssuer, oidcClientId, vapidPublicKey, appExternalUrl }
 */
export interface SetupConfigPayload {
  appExternalUrl: string;
  oidcIssuer: string;
  oidcClientId: string;
  vapidPublicKey: string;
}

/**
 * Payload for POST /api/setup/credential.
 * The Fastmail app password is sent once and NEVER stored client-side (T-12-15).
 */
export interface SetupCredentialPayload {
  fastmailEmail: string;
  appPassword: string;
}

/**
 * GET /api/setup/status — unauthenticated; fetched before the OIDC guard.
 * staleTime: 0 — always fresh (the gate must not be stale; mirrors D-10 spirit).
 */
export async function fetchSetupStatus(): Promise<SetupStatusResponse> {
  const res = await fetch('/api/setup/status', {
    // No credentials: 'include' needed — this is a pre-auth endpoint.
    // No redirect: 'manual' — setup endpoints never redirect to Authelia.
  });

  if (!res.ok) {
    throw new Error(`GET /api/setup/status failed: ${res.status}`);
  }

  return res.json() as Promise<SetupStatusResponse>;
}

/**
 * POST /api/setup/config — writes non-secret config values to app_config.
 * Must be called before the validation step so the OIDC issuer is persisted
 * for the server-side discovery check.
 */
export async function postSetupConfig(payload: SetupConfigPayload): Promise<void> {
  const res = await fetch('/api/setup/config', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify(payload),
  });

  if (res.status === 423) {
    throw new SetupAlreadyLockedError();
  }

  if (!res.ok) {
    const body = (await res.json().catch(() => ({}))) as {
      error?: string | { name?: string; issues?: Array<{ message: string }> };
    };
    // body.error may be a ZodError object ({ name: "ZodError", issues: [...] })
    // rather than a plain string — extract the first issue message to avoid
    // "[object Object]" appearing in the UI (BUG 2 fix).
    let message: string;
    if (typeof body.error === 'string') {
      message = body.error;
    } else if (
      body.error &&
      typeof body.error === 'object' &&
      Array.isArray((body.error as { issues?: unknown[] }).issues) &&
      (body.error as { issues: Array<{ message: string }> }).issues.length > 0
    ) {
      message = (body.error as { issues: Array<{ message: string }> }).issues[0].message;
    } else {
      message = `POST /api/setup/config failed: ${res.status}`;
    }
    throw new Error(message);
  }
}

/**
 * POST /api/setup/validate/db — confirms DB connectivity.
 * Returns void on success; throws on failure with a typed message.
 */
export async function validateSetupDb(): Promise<void> {
  const res = await fetch('/api/setup/validate/db', { method: 'POST' });

  if (res.status === 423) throw new SetupAlreadyLockedError();

  if (!res.ok) {
    throw new Error(
      'Cannot reach the database. Check DB_HOST, DB_PORT, DB_USER, DB_PASSWORD in your Docker environment and try again.',
    );
  }
}

/**
 * POST /api/setup/validate/oidc — fetches the OIDC discovery document.
 * Requires that POST /api/setup/config has already been called with a valid oidc_issuer.
 */
export async function validateSetupOidc(): Promise<void> {
  const res = await fetch('/api/setup/validate/oidc', { method: 'POST' });

  if (res.status === 423) throw new SetupAlreadyLockedError();

  if (!res.ok) {
    throw new Error(
      'OIDC discovery failed. Check the issuer URL and that Authelia is reachable from the server.',
    );
  }
}

/**
 * POST /api/setup/validate/vapid — structural check of the VAPID key pair.
 */
export async function validateSetupVapid(): Promise<void> {
  const res = await fetch('/api/setup/validate/vapid', { method: 'POST' });

  if (res.status === 423) throw new SetupAlreadyLockedError();

  if (!res.ok) {
    throw new Error(
      'VAPID validation failed. Check that your VAPID keys were generated with `npm run generate-secrets`.',
    );
  }
}

/**
 * POST /api/setup/credential — validates the Fastmail app password against
 * CalDAV PROPFIND and inserts the local wizard user + credential row.
 * The password is never stored client-side (T-12-15).
 */
export async function postSetupCredential(payload: SetupCredentialPayload): Promise<void> {
  const res = await fetch('/api/setup/credential', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({
      fastmailEmail: payload.fastmailEmail,
      appPassword: payload.appPassword,
      // providerType omitted — not in credentialSchema; server hard-codes 'caldav'
    }),
  });

  if (res.status === 423) throw new SetupAlreadyLockedError();

  if (!res.ok) {
    throw new Error(
      "Invalid password — CalDAV validation failed. Check the scope is 'Calendars & Contacts (CalDAV)' and try again.",
    );
  }
}

/**
 * POST /api/setup/complete — flips setup_complete in app_config.
 * Returns 200 on first call; throws SetupAlreadyLockedError on 423.
 */
export async function postSetupComplete(): Promise<void> {
  const res = await fetch('/api/setup/complete', { method: 'POST' });

  if (res.status === 423) throw new SetupAlreadyLockedError();

  if (!res.ok) {
    throw new Error(`POST /api/setup/complete failed: ${res.status}`);
  }
}

/**
 * Thrown when any setup endpoint returns 423 (setup already locked).
 * SetupPage catches this and renders Surface 8 (Already Locked screen).
 */
export class SetupAlreadyLockedError extends Error {
  readonly name = 'SetupAlreadyLockedError';
  constructor() {
    super('Setup is already complete and locked.');
    Object.setPrototypeOf(this, SetupAlreadyLockedError.prototype);
  }
}