#include "auth.h"

#include <crypt.h>
#include <string.h>

#include <stdexcept>
#include <iostream>

// crypt specified password
std::string Auth::generate(const std::string& pw)
{
 struct crypt_data data;
 memset((void *)&data, '\0', sizeof(data));
 
 if (crypt_gensalt_rn("$6$", 2000, nullptr, 0, data.setting, sizeof(data.setting)) == nullptr)
  throw std::runtime_error("Error on crypt_gensalt_r()");

 strncpy(data.input, pw.data(), sizeof(data.input));

 if (crypt_r(data.input, data.setting, &data) == nullptr)
  throw std::runtime_error("Error on crypt_r()");

 return data.output;
}

// validate specified password against crypted hash
bool Auth::validate(const std::string& crypted, const std::string& pw)
{
 struct crypt_data data;
 memset((void *)&data, '\0', sizeof(data));

 size_t pos = crypted.find_last_of('$');
 if (pos == crypted.npos) {
  std::cerr << "Warning: Bad password hash configured (format)" << std::endl;
  return false;
 }

 if (sizeof(data.setting) <= pos) {
  std::cerr << "Warning: Bad password hash configured (salt size)" << std::endl;
  return false;
 }

 memcpy(&data.setting, crypted.data(), pos);

 strncpy(data.input, pw.data(), sizeof(data.input));

 if (crypt_r(data.input, data.setting, &data) == nullptr) {
  std::cerr << "Warning: Error on crypt_r()" << std::endl;
  return false;
 }

 return crypted == data.output;
}