import { config } from './config'

export const AUTH_COOKIE_NAME = 'auth_token'
const SECRET_KEY = config.auth.secret

// Helper to generate a random nonce
function generateNonce() {
  return Math.random().toString(36).substring(2, 15) + Math.random().toString(36).substring(2, 15)
}

// Helper to create a signed token (simplified JWT-like structure)
export async function createToken(username: string) {
  const header = { alg: 'HS256', typ: 'JWT' }
  const payload = {
    sub: username,
    iat: Date.now(),
    exp: Date.now() + 24 * 60 * 60 * 1000, // 24 hours
    nonce: generateNonce() // Ensure token is different every time
  }
  
  const encodedHeader = btoa(JSON.stringify(header))
  const encodedPayload = btoa(JSON.stringify(payload))
  const data = `${encodedHeader}.${encodedPayload}`
  
  const key = await crypto.subtle.importKey(
    'raw',
    new TextEncoder().encode(SECRET_KEY),
    { name: 'HMAC', hash: 'SHA-256' },
    false,
    ['sign']
  )
  
  const signature = await crypto.subtle.sign(
    'HMAC',
    key,
    new TextEncoder().encode(data)
  )
  
  // Convert signature to base64
  const signatureArray = Array.from(new Uint8Array(signature))
  const encodedSignature = btoa(String.fromCharCode.apply(null, signatureArray))
  
  return `${data}.${encodedSignature}`
}

// Helper to verify token
export async function verifyToken(token: string) {
  try {
    const parts = token.split('.')
    if (parts.length !== 3) return false
    
    const [encodedHeader, encodedPayload, encodedSignature] = parts
    const data = `${encodedHeader}.${encodedPayload}`
    
    const key = await crypto.subtle.importKey(
      'raw',
      new TextEncoder().encode(SECRET_KEY),
      { name: 'HMAC', hash: 'SHA-256' },
      false,
      ['verify']
    )
    
    const signature = new Uint8Array(
      atob(encodedSignature).split('').map(c => c.charCodeAt(0))
    )
    
    const isValid = await crypto.subtle.verify(
      'HMAC',
      key,
      signature,
      new TextEncoder().encode(data)
    )
    
    if (!isValid) return false
    
    const payload = JSON.parse(atob(encodedPayload))
    if (payload.exp < Date.now()) return false
    
    return true
  } catch (e) {
    return false
  }
}