// lib/os.js
function tmpdir() {
  var path;
  if (isWindows) {
    path = process.env.TEMP ||
           process.env.TMP ||
           (process.env.SystemRoot || process.env.windir) + '\\temp';
    if (path.length > 1 && path.endsWith('\\') && !path.endsWith(':\\'))
      path = path.slice(0, -1);
  } else {
    path = safeGetenv('TMPDIR') ||
           safeGetenv('TMP') ||
           safeGetenv('TEMP') ||
           '/tmp';
    if (path.length > 1 && path.endsWith('/'))
      path = path.slice(0, -1);
  }

  return path;
}
tmpdir[Symbol.toPrimitive] = () => tmpdir();

// lib/os.js
module.exports = {
  homedir: getHomeDirectory,
}

// src/node_os.cc
static void GetHomeDirectory(const FunctionCallbackInfo<Value>& args) {
  Environment* env = Environment::GetCurrent(args);
  char buf[PATH_MAX];

  size_t len = sizeof(buf);
  const int err = uv_os_homedir(buf, &len);

  if (err) {
    CHECK_GE(args.Length(), 1);
    env->CollectUVExceptionInfo(args[args.Length() - 1], err, "uv_os_homedir");
    return args.GetReturnValue().SetUndefined();
  }

  Local<String> home = String::NewFromUtf8(env->isolate(),
                                           buf,
                                           v8::NewStringType::kNormal,
                                           len).ToLocalChecked();
  args.GetReturnValue().Set(home);
}

// deps/uv/src/unix/core.c
int uv_os_homedir(char* buffer, size_t* size) {
  uv_passwd_t pwd;
  size_t len;
  int r;

  /* Check if the HOME environment variable is set first. The task of
     performing input validation on buffer and size is taken care of by
     uv_os_getenv(). */
  r = uv_os_getenv("HOME", buffer, size);

  if (r != UV_ENOENT)
    return r;

  /* HOME is not set, so call uv__getpwuid_r() */
  r = uv__getpwuid_r(&pwd);

  if (r != 0) {
    return r;
  }

  len = strlen(pwd.homedir);

  if (len >= *size) {
    *size = len + 1;
    uv_os_free_passwd(&pwd);
    return UV_ENOBUFS;
  }

  memcpy(buffer, pwd.homedir, len + 1);
  *size = len;
  uv_os_free_passwd(&pwd);

  return 0;
}


int uv_os_getenv(const char* name, char* buffer, size_t* size) {
  char* var;
  size_t len;

  if (name == NULL || buffer == NULL || size == NULL || *size == 0)
    return UV_EINVAL;

  var = getenv(name);

  if (var == NULL)
    return UV_ENOENT;

  len = strlen(var);

  if (len >= *size) {
    *size = len + 1;
    return UV_ENOBUFS;
  }

  memcpy(buffer, var, len + 1);
  *size = len;

  return 0;
}

/**
 * 以下测试用例运行于 linux 环境，Window  环境变量名略有区别，可同理参考
 */

const os = require('os');

// tmpdir()

// 默认输出
console.log('default tmpdir():', os.tmpdir());

// 动态修改输出
process.env.TEMP = '/tmp/wadezhan';
console.log('set process.env.TEMP:', os.tmpdir());

// homedir()

// 默认输出
console.log('default homedir():', os.homedir());

// 动态修改输出
// process.env.USERPROFILE = 'C:\\Users\\wadezhan\\AppData'; // window 环境对应环境变量
process.env.HOME = '/home/wadezhan';
console.log('set process.env.HOME:', os.homedir());