/**
 * NIP-98 HTTP Auth implementation
 * Generates authentication tokens for HTTP requests using Nostr events
 * See: https://github.com/nostr-protocol/nips/blob/master/98.md
 */

import type { EventTemplate } from 'nostr-tools'
import { nostrRemoteSigner } from './nostrRemoteSigner'
import { nostrService } from './nostr'

/**
 * Generate NIP-98 authentication token for HTTP request
 * @param method HTTP method (GET, POST, etc.)
 * @param url Full URL of the request
 * @param payloadHash Optional SHA256 hash of the request body (for POST/PUT)
 * @returns Base64-encoded signed event token
 */
export async function generateNip98Token(method: string, url: string, payloadHash?: string): Promise<string> {
  const pubkey = nostrService.getPublicKey()
  if (!pubkey) {
    throw new Error('Public key required for NIP-98 authentication. Please connect with a Nostr extension.')
  }

  // Parse URL to get components
  const urlObj = new URL(url)
  const path = urlObj.pathname + urlObj.search

  // Build event template for NIP-98
  const tags: string[][] = [
    ['u', urlObj.origin + path],
    ['method', method],
  ]

  // Add payload hash if provided (for POST/PUT requests)
  if (payloadHash) {
    tags.push(['payload', payloadHash])
  }

  const eventTemplate: EventTemplate = {
    kind: 27235, // NIP-98 kind for HTTP auth
    created_at: Math.floor(Date.now() / 1000),
    tags: tags,
    content: '',
  }

  // Sign the event
  const signedEvent = await nostrRemoteSigner.signEvent(eventTemplate)
  if (!signedEvent) {
    throw new Error('Failed to sign NIP-98 authentication event')
  }

  // Encode event as base64 JSON
  const eventJson = JSON.stringify(signedEvent)
  const eventBytes = new TextEncoder().encode(eventJson)
  const base64Token = btoa(String.fromCharCode(...eventBytes))

  return base64Token
}

/**
 * Check if NIP-98 authentication is available
 */
export function isNip98Available(): boolean {
  return nostrRemoteSigner.isAvailable()
}