import { api } from './api'

interface Challenge {
  algorithm: string
  challenge: string
  maxnumber: number
  salt: string
  signature: string
}

async function hashHex(algorithm: string, data: string): Promise<string> {
  const alg = algorithm.replace('-', '').toUpperCase() === 'SHA256' ? 'SHA-256' : algorithm
  const buf = await crypto.subtle.digest(alg, new TextEncoder().encode(data))
  return Array.from(new Uint8Array(buf)).map(b => b.toString(16).padStart(2, '0')).join('')
}

export async function solveAltcha(difficulty: 'normal' | 'light' = 'normal'): Promise<string> {
  const ch = await api.get<Challenge>(`/altcha/challenge?difficulty=${difficulty}`)

  for (let n = 0; n <= ch.maxnumber; n++) {
    const hash = await hashHex(ch.algorithm, ch.salt + n)
    if (hash === ch.challenge) {
      return btoa(JSON.stringify({
        algorithm: ch.algorithm,
        challenge: ch.challenge,
        number: n,
        salt: ch.salt,
        signature: ch.signature,
      }))
    }
  }

  throw new Error('Failed to solve challenge')
}