/**
 * NIP-86 Relay Management API client (with NIP-98 HTTP auth).
 *
 * The SkateSpots community relay (goskatespots.nostr1.com) runs on relay.tools,
 * which implements the NIP-86 management API. As the relay OWNER (or an assigned
 * moderator), an admin can genuinely remove an event from the relay's database —
 * not merely publish a best-effort kind:5 deletion request that other relays may
 * ignore. `banevent` is the method that does this.
 *
 * Auth is a NIP-98 kind:27235 event signed by the caller (via their Amber /
 * NIP-07 / nsec signer). The relay checks the signer's pubkey against its owner
 * / moderator list, so only genuine admins can act.
 *
 * Docs: NIP-86 (relay management), NIP-98 (HTTP auth).
 */

import { sha256 } from '@noble/hashes/sha2.js';
import { bytesToHex } from '@noble/hashes/utils.js';
import { SKATE_RELAY } from '@/lib/types';
import type { NostrSigner } from '@nostrify/nostrify';

/** wss:// → https:// (the management API lives on the same URI as the socket). */
function relayHttpUrl(wss: string): string {
  return wss.replace(/^wss:\/\//i, 'https://').replace(/^ws:\/\//i, 'http://');
}

/** Base64-encode a UTF-8 string (browser-safe). */
function base64(json: string): string {
  // btoa needs a binary string; encode UTF-8 first.
  const bytes = new TextEncoder().encode(json);
  let bin = '';
  for (const b of bytes) bin += String.fromCharCode(b);
  return btoa(bin);
}

interface Nip86Response<T> {
  result?: T;
  error?: string;
}

/**
 * Perform a single NIP-86 JSON-RPC call against a relay's HTTP endpoint,
 * authenticated with a freshly-signed NIP-98 event.
 *
 * @throws if the network request fails, auth is rejected (401), or the relay
 *         returns an `error` field.
 */
export async function relayManagementCall<T = unknown>(opts: {
  signer: NostrSigner;
  method: string;
  params: unknown[];
  relayWss?: string;
  signal?: AbortSignal;
}): Promise<T> {
  const { signer, method, params, relayWss = SKATE_RELAY, signal } = opts;

  const url = relayHttpUrl(relayWss);
  const body = JSON.stringify({ method, params });

  // NIP-98: kind 27235, tags u + method (+ payload hash, required by NIP-86).
  const payloadHash = bytesToHex(sha256(new TextEncoder().encode(body)));
  const authEvent = await signer.signEvent({
    kind: 27235,
    content: '',
    created_at: Math.floor(Date.now() / 1000),
    tags: [
      ['u', url],
      ['method', 'POST'],
      ['payload', payloadHash],
    ],
  });

  const doFetch = (target: string) =>
    fetch(target, {
      method: 'POST',
      headers: {
        'Content-Type': 'application/nostr+json+rpc',
        Authorization: `Nostr ${base64(JSON.stringify(authEvent))}`,
      },
      body,
      signal,
    });

  let res: Response;
  try {
    res = await doFetch(url);
  } catch {
    // Some WebView/browser contexts block the cross-origin POST. Retry once via
    // the configured CORS proxy (auth header + body are preserved).
    const proxied = `https://proxy.shakespeare.diy/?url=${encodeURIComponent(url)}`;
    res = await doFetch(proxied);
  }

  if (res.status === 401) {
    throw new Error(
      'The relay rejected the request. Your account may not be an owner or ' +
        'moderator of this relay.',
    );
  }
  if (!res.ok) {
    throw new Error(`Relay management call failed (HTTP ${res.status}).`);
  }

  const json = (await res.json()) as Nip86Response<T>;
  if (json.error) throw new Error(json.error);
  return json.result as T;
}

/**
 * Ask the community relay which NIP-86 methods it supports. Useful to gate the
 * admin UI (and to confirm the relay speaks NIP-86 at all). Returns [] on any
 * failure so callers can degrade gracefully.
 */
export async function getRelaySupportedMethods(
  signer: NostrSigner,
  relayWss: string = SKATE_RELAY,
  signal?: AbortSignal,
): Promise<string[]> {
  try {
    const methods = await relayManagementCall<string[]>({
      signer,
      method: 'supportedmethods',
      params: [],
      relayWss,
      signal,
    });
    return Array.isArray(methods) ? methods : [];
  } catch {
    return [];
  }
}

/**
 * Remove an event from the community relay's database (NIP-86 `banevent`).
 * This is a REAL takedown on a relay we control — unlike a NIP-09 kind:5
 * request, the relay honors it because the caller is an owner/moderator.
 */
export async function banEventOnRelay(opts: {
  signer: NostrSigner;
  eventId: string;
  reason?: string;
  relayWss?: string;
  signal?: AbortSignal;
}): Promise<void> {
  const { signer, eventId, reason, relayWss, signal } = opts;
  await relayManagementCall({
    signer,
    method: 'banevent',
    params: reason ? [eventId, reason] : [eventId],
    relayWss,
    signal,
  });
}