/**
 * Admin client for the central pieced-threema-gateway relay.
 *
 * All calls authenticate with a static admin bearer (THREEMA_RELAY_ADMIN_TOKEN
 * from env, sourced from OpenBao at secret/data/threema-gateway/admin). The
 * portal is the only caller; never expose these functions through a public
 * HTTP surface.
 *
 * Resilience: every method returns a strongly-typed result rather than
 * throwing. Network errors surface as `{ ok: false, kind: 'network' }`,
 * 4xx/5xx as `{ ok: false, kind: 'http', status, ... }`. Callers that need
 * to compensate (e.g. delete a route after a K8s patch failure) can
 * inspect `kind` to decide whether retry is sensible.
 */

const RELAY_URL = (process.env.THREEMA_RELAY_URL ?? "").replace(/\/+$/, "");
const ADMIN_TOKEN = process.env.THREEMA_RELAY_ADMIN_TOKEN ?? "";

function assertConfigured(): void {
  if (!RELAY_URL) throw new Error("THREEMA_RELAY_URL not set");
  if (!ADMIN_TOKEN) throw new Error("THREEMA_RELAY_ADMIN_TOKEN not set");
}

type RelayError =
  | { ok: false; kind: "network"; message: string }
  | { ok: false; kind: "http"; status: number; message: string; body?: unknown };

export type RelayResult<T> = ({ ok: true } & T) | RelayError;

async function call<T>(
  path: string,
  init: RequestInit,
): Promise<RelayResult<T>> {
  assertConfigured();
  try {
    const res = await fetch(`${RELAY_URL}${path}`, {
      ...init,
      headers: {
        ...(init.headers ?? {}),
        Authorization: `Bearer ${ADMIN_TOKEN}`,
        "Content-Type": "application/json",
      },
    });
    let body: unknown = null;
    const text = await res.text().catch(() => "");
    if (text) {
      try {
        body = JSON.parse(text);
      } catch {
        body = text;
      }
    }
    if (!res.ok) {
      const message =
        (body && typeof body === "object" && "error" in body && typeof (body as Record<string, unknown>).error === "string"
          ? ((body as Record<string, unknown>).error as string)
          : `HTTP ${res.status}`);
      return { ok: false, kind: "http", status: res.status, message, body };
    }
    return { ok: true, ...(body as Record<string, unknown>) } as RelayResult<T>;
  } catch (e) {
    return { ok: false, kind: "network", message: (e as Error).message };
  }
}

// ---------------------------------------------------------------------------
// Tokens
// ---------------------------------------------------------------------------

/** Mint (or rotate) per-tenant bearer + HMAC secret. */
export function mintToken(
  tenantName: string,
): Promise<RelayResult<{ token: string; hmacSecret: string }>> {
  return call("/admin/tokens", {
    method: "POST",
    body: JSON.stringify({ tenantName }),
  });
}

/**
 * Revoke per-tenant token. Cascades — relay also deletes all routes
 * owned by this tenant.
 */
export function revokeToken(
  tenantName: string,
): Promise<RelayResult<{ deletedRoutes: number }>> {
  return call(`/admin/tokens/${encodeURIComponent(tenantName)}`, {
    method: "DELETE",
  });
}

export function tokenExists(
  tenantName: string,
): Promise<RelayResult<{ exists: true }>> {
  return call(`/admin/tokens/${encodeURIComponent(tenantName)}`, {
    method: "GET",
  });
}

// ---------------------------------------------------------------------------
// Routes
// ---------------------------------------------------------------------------

export interface RouteRow {
  threema_id: string;
  tenant_name: string;
  created_at: string;
  created_by: string;
}

export function listRoutes(
  tenantName: string,
): Promise<RelayResult<{ routes: RouteRow[] }>> {
  return call(`/admin/routes?tenant=${encodeURIComponent(tenantName)}`, {
    method: "GET",
  });
}

/**
 * Create a route. The relay enforces uniqueness — on conflict returns
 * status 409 with body `{ ownedBy: <tenantName> | null }`. Callers
 * should inspect `kind === 'http'` + status 409 + body.ownedBy to
 * distinguish idempotent self-claim from real conflict.
 */
export function createRoute(
  tenantName: string,
  threemaId: string,
): Promise<RelayResult<{ ok: true }>> {
  return call("/admin/routes", {
    method: "POST",
    body: JSON.stringify({ tenantName, threemaId }),
  });
}

export function deleteRoute(
  tenantName: string,
  threemaId: string,
): Promise<RelayResult<{ ok: true }>> {
  return call(
    `/admin/routes/${encodeURIComponent(threemaId)}?tenant=${encodeURIComponent(tenantName)}`,
    { method: "DELETE" },
  );
}

// ---------------------------------------------------------------------------
// Usage
// ---------------------------------------------------------------------------

export interface UsageBreakdown {
  tenant: string;
  from: string;
  to: string;
  totals: { in: number; out: number };
  daily: Array<{ day: string; direction: "in" | "out"; count: number }>;
}

export function getUsage(
  tenantName: string,
  from?: Date,
  to?: Date,
): Promise<RelayResult<UsageBreakdown>> {
  const qs = new URLSearchParams({ tenant: tenantName });
  if (from) qs.set("from", from.toISOString());
  if (to) qs.set("to", to.toISOString());
  return call(`/admin/usage?${qs.toString()}`, { method: "GET" });
}

// ---------------------------------------------------------------------------
// Health
// ---------------------------------------------------------------------------

export function health(): Promise<RelayResult<{ credits: number }>> {
  return call("/admin/health", { method: "GET" });
}

// ---------------------------------------------------------------------------
// Helpers for caller code
// ---------------------------------------------------------------------------

/**
 * Type guard: did this route-create fail because the ID is owned by
 * someone else? Distinguishes from "owned by SAME tenant" (idempotent).
 */
export function isRouteConflictForOtherTenant(
  result: RelayResult<{ ok: true }>,
  tenantName: string,
): boolean {
  if (result.ok) return false;
  if (result.kind !== "http" || result.status !== 409) return false;
  const body = result.body as { ownedBy?: string | null } | undefined;
  return !!body?.ownedBy && body.ownedBy !== tenantName;
}

export function isRouteConflictForSameTenant(
  result: RelayResult<{ ok: true }>,
  tenantName: string,
): boolean {
  if (result.ok) return false;
  if (result.kind !== "http" || result.status !== 409) return false;
  const body = result.body as { ownedBy?: string | null } | undefined;
  return body?.ownedBy === tenantName;
}