const CryptoJS = require('crypto-js')

const SIGNATURE_SECRET = 'NovalonManageSystemSecretKey2026'

/**
 * 生成 HMAC-SHA256 签名
 */
function generateSignature(method, path, query, body, timestamp, nonce) {
  const stringToSign = [method, path, query || '', body || '', String(timestamp), nonce].join('\n')
  const signature = CryptoJS.HmacSHA256(stringToSign, SIGNATURE_SECRET)
  return CryptoJS.enc.Base64.stringify(signature)
}

/**
 * 生成随机 nonce
 */
function generateNonce() {
  const timestamp = Date.now().toString(36)
  const randomPart = Math.random().toString(36).substring(2, 15)
  return timestamp + '-' + randomPart
}

/**
 * 从 URL 解析 path 和 query
 */
function parseUrl(url) {
  if (url.startsWith('http://') || url.startsWith('https://')) {
    const withoutProtocol = url.substring(url.indexOf('://') + 3)
    const pathStart = withoutProtocol.indexOf('/')
    if (pathStart === -1) return { path: '/', query: '' }
    const pathAndQuery = withoutProtocol.substring(pathStart)
    const queryIndex = pathAndQuery.indexOf('?')
    if (queryIndex === -1) return { path: pathAndQuery, query: '' }
    return { path: pathAndQuery.substring(0, queryIndex), query: pathAndQuery.substring(queryIndex + 1) }
  }
  const queryIndex = url.indexOf('?')
  if (queryIndex === -1) return { path: url, query: '' }
  return { path: url.substring(0, queryIndex), query: url.substring(queryIndex + 1) }
}

/**
 * 生成签名请求头
 */
function generateSignatureHeaders(method, url, body) {
  const timestamp = Date.now()
  const nonce = generateNonce()
  const { path, query } = parseUrl(url)
  const bodyStr = body ? (typeof body === 'string' ? body : JSON.stringify(body)) : ''

  const signature = generateSignature(method.toUpperCase(), path, query, bodyStr, timestamp, nonce)

  return {
    'X-Signature': signature,
    'X-Timestamp': String(timestamp),
    'X-Nonce': nonce
  }
}

module.exports = { generateSignatureHeaders }