import { sumHex, fromHex } from 'gmsm-sm3js'

// 验证是否为有效的 hex 字符串
const isValidHex = (hex: string): boolean => {
  return /^[0-9a-fA-F]*$/.test(hex) && hex.length % 2 === 0
}

// SM3 计算
export const sm3Digest = (message: string): string => {
  try {
    // 验证消息是否为有效的 hex 字符串
    if (!isValidHex(message)) {
      throw new Error('Invalid message: must be hex string')
    }
    
    console.log('Input hex message:', message)
    
    // 将 hex 字符串转换为 Uint8Array
    const messageBytes = fromHex(message)
    
    // 使用 gmsm-sm3js 计算 SM3
    const result = sumHex(messageBytes)
    console.log('SM3 result:', result)
    
    return result
  } catch (error) {
    console.error('SM3 digest error:', error)
    throw error
  }
}

// HMAC-SM3 计算
export const sm3Hmac = (key: string, message: string): string => {
  try {
    // 验证 key 和 message 是否为有效的 hex 字符串
    if (!isValidHex(key)) {
      throw new Error('Invalid key: must be hex string')
    }
    if (!isValidHex(message)) {
      throw new Error('Invalid message: must be hex string')
    }
    
    console.log('Input key:', key)
    console.log('Input message:', message)
    
    // 将 hex 字符串转换为 Uint8Array
    const keyBytes = fromHex(key)
    const messageBytes = fromHex(message)
    
    // 实现 HMAC-SM3 算法
    const blockSize = 64 // SM3 块大小为 512 位 = 64 字节
    
    // 处理密钥
    let k: Uint8Array
    if (keyBytes.length > blockSize) {
      // 如果密钥长度超过块大小，对密钥进行 SM3 哈希
      k = fromHex(sumHex(keyBytes))
    } else {
      // 否则，用 0 填充到块大小
      k = new Uint8Array(blockSize)
      k.set(keyBytes)
    }
    
    // 计算 inner padding
    const ipad = new Uint8Array(blockSize)
    for (let i = 0; i < blockSize; i++) {
      ipad[i] = k[i] ^ 0x36
    }
    
    // 计算 outer padding
    const opad = new Uint8Array(blockSize)
    for (let i = 0; i < blockSize; i++) {
      opad[i] = k[i] ^ 0x5c
    }
    
    // 计算 inner hash: SM3(ipad || message)
    const innerData = new Uint8Array(ipad.length + messageBytes.length)
    innerData.set(ipad)
    innerData.set(messageBytes, ipad.length)
    const innerHash = fromHex(sumHex(innerData))
    
    // 计算 outer hash: SM3(opad || innerHash)
    const outerData = new Uint8Array(opad.length + innerHash.length)
    outerData.set(opad)
    outerData.set(innerHash, opad.length)
    const result = sumHex(outerData)
    
    console.log('SM3 HMAC result:', result)
    
    return result
  } catch (error) {
    console.error('SM3 HMAC error:', error)
    throw error
  }
}