#include "node_errors.h"
#include "node_process.h"
#include "util.h"

#ifdef __APPLE__
#include <crt_externs.h>
#define environ (*_NSGetEnviron())
#elif !defined(_MSC_VER)
extern char** environ;
#endif

namespace node {
using v8::Array;
using v8::Boolean;
using v8::Context;
using v8::EscapableHandleScope;
using v8::Integer;
using v8::Isolate;
using v8::Local;
using v8::MaybeLocal;
using v8::Name;
using v8::NamedPropertyHandlerConfiguration;
using v8::NewStringType;
using v8::Object;
using v8::ObjectTemplate;
using v8::PropertyCallbackInfo;
using v8::String;
using v8::Value;

namespace per_process {
Mutex env_var_mutex;
}  // namespace per_process

static void EnvGetter(Local<Name> property,
                      const PropertyCallbackInfo<Value>& info) {
  Isolate* isolate = info.GetIsolate();
  if (property->IsSymbol()) {
    return info.GetReturnValue().SetUndefined();
  }
  Mutex::ScopedLock lock(per_process::env_var_mutex);
#ifdef __POSIX__
  node::Utf8Value key(isolate, property);
  const char* val = getenv(*key);
  if (val) {
    return info.GetReturnValue().Set(
        String::NewFromUtf8(isolate, val, NewStringType::kNormal)
            .ToLocalChecked());
  }
#else  // _WIN32
  node::TwoByteValue key(isolate, property);
  WCHAR buffer[32767];  // The maximum size allowed for environment variables.
  SetLastError(ERROR_SUCCESS);
  DWORD result = GetEnvironmentVariableW(
      reinterpret_cast<WCHAR*>(*key), buffer, arraysize(buffer));
  // If result >= sizeof buffer the buffer was too small. That should never
  // happen. If result == 0 and result != ERROR_SUCCESS the variable was not
  // found.
  if ((result > 0 || GetLastError() == ERROR_SUCCESS) &&
      result < arraysize(buffer)) {
    const uint16_t* two_byte_buffer = reinterpret_cast<const uint16_t*>(buffer);
    v8::MaybeLocal<String> rc = String::NewFromTwoByte(
        isolate, two_byte_buffer, NewStringType::kNormal);
    if (rc.IsEmpty()) {
      isolate->ThrowException(ERR_STRING_TOO_LONG(isolate));
      return;
    }
    return info.GetReturnValue().Set(rc.ToLocalChecked());
  }
#endif
}

static void EnvSetter(Local<Name> property,
                      Local<Value> value,
                      const PropertyCallbackInfo<Value>& info) {
  Environment* env = Environment::GetCurrent(info);
  // calling env->EmitProcessEnvWarning() sets a variable indicating that
  // warnings have been emitted. It should be called last after other
  // conditions leading to a warning have been met.
  if (env->options()->pending_deprecation && !value->IsString() &&
      !value->IsNumber() && !value->IsBoolean() &&
      env->EmitProcessEnvWarning()) {
    if (ProcessEmitDeprecationWarning(
            env,
            "Assigning any value other than a string, number, or boolean to a "
            "process.env property is deprecated. Please make sure to convert "
            "the "
            "value to a string before setting process.env with it.",
            "DEP0104")
            .IsNothing())
      return;
  }

  Mutex::ScopedLock lock(per_process::env_var_mutex);
#ifdef __POSIX__
  node::Utf8Value key(info.GetIsolate(), property);
  node::Utf8Value val(info.GetIsolate(), value);
  setenv(*key, *val, 1);
#else  // _WIN32
  node::TwoByteValue key(info.GetIsolate(), property);
  node::TwoByteValue val(info.GetIsolate(), value);
  WCHAR* key_ptr = reinterpret_cast<WCHAR*>(*key);
  // Environment variables that start with '=' are read-only.
  if (key_ptr[0] != L'=') {
    SetEnvironmentVariableW(key_ptr, reinterpret_cast<WCHAR*>(*val));
  }
#endif
  // Whether it worked or not, always return value.
  info.GetReturnValue().Set(value);
}

static void EnvQuery(Local<Name> property,
                     const PropertyCallbackInfo<Integer>& info) {
  Mutex::ScopedLock lock(per_process::env_var_mutex);
  int32_t rc = -1;  // Not found unless proven otherwise.
  if (property->IsString()) {
#ifdef __POSIX__
    node::Utf8Value key(info.GetIsolate(), property);
    if (getenv(*key)) rc = 0;
#else  // _WIN32
    node::TwoByteValue key(info.GetIsolate(), property);
    WCHAR* key_ptr = reinterpret_cast<WCHAR*>(*key);
    SetLastError(ERROR_SUCCESS);
    if (GetEnvironmentVariableW(key_ptr, nullptr, 0) > 0 ||
        GetLastError() == ERROR_SUCCESS) {
      rc = 0;
      if (key_ptr[0] == L'=') {
        // Environment variables that start with '=' are hidden and read-only.
        rc = static_cast<int32_t>(v8::ReadOnly) |
             static_cast<int32_t>(v8::DontDelete) |
             static_cast<int32_t>(v8::DontEnum);
      }
    }
#endif
  }
  if (rc != -1) info.GetReturnValue().Set(rc);
}

static void EnvDeleter(Local<Name> property,
                       const PropertyCallbackInfo<Boolean>& info) {
  Mutex::ScopedLock lock(per_process::env_var_mutex);
  if (property->IsString()) {
#ifdef __POSIX__
    node::Utf8Value key(info.GetIsolate(), property);
    unsetenv(*key);
#else
    node::TwoByteValue key(info.GetIsolate(), property);
    WCHAR* key_ptr = reinterpret_cast<WCHAR*>(*key);
    SetEnvironmentVariableW(key_ptr, nullptr);
#endif
  }

  // process.env never has non-configurable properties, so always
  // return true like the tc39 delete operator.
  info.GetReturnValue().Set(true);
}

static void EnvEnumerator(const PropertyCallbackInfo<Array>& info) {
  Environment* env = Environment::GetCurrent(info);
  Isolate* isolate = env->isolate();

  Mutex::ScopedLock lock(per_process::env_var_mutex);
  Local<Array> envarr;
  int env_size = 0;
#ifdef __POSIX__
  while (environ[env_size]) {
    env_size++;
  }
  std::vector<Local<Value>> env_v(env_size);

  for (int i = 0; i < env_size; ++i) {
    const char* var = environ[i];
    const char* s = strchr(var, '=');
    const int length = s ? s - var : strlen(var);
    env_v[i] = String::NewFromUtf8(isolate, var, NewStringType::kNormal, length)
                   .ToLocalChecked();
  }
#else  // _WIN32
  std::vector<Local<Value>> env_v;
  WCHAR* environment = GetEnvironmentStringsW();
  if (environment == nullptr) return;  // This should not happen.
  WCHAR* p = environment;
  while (*p) {
    WCHAR* s;
    if (*p == L'=') {
      // If the key starts with '=' it is a hidden environment variable.
      p += wcslen(p) + 1;
      continue;
    } else {
      s = wcschr(p, L'=');
    }
    if (!s) {
      s = p + wcslen(p);
    }
    const uint16_t* two_byte_buffer = reinterpret_cast<const uint16_t*>(p);
    const size_t two_byte_buffer_len = s - p;
    v8::MaybeLocal<String> rc = String::NewFromTwoByte(
        isolate, two_byte_buffer, NewStringType::kNormal, two_byte_buffer_len);
    if (rc.IsEmpty()) {
      isolate->ThrowException(ERR_STRING_TOO_LONG(isolate));
      FreeEnvironmentStringsW(environment);
      return;
    }
    env_v.push_back(rc.ToLocalChecked());
    p = s + wcslen(s) + 1;
  }
  FreeEnvironmentStringsW(environment);
#endif

  envarr = Array::New(isolate, env_v.data(), env_v.size());
  info.GetReturnValue().Set(envarr);
}

MaybeLocal<Object> CreateEnvVarProxy(Local<Context> context,
                                     Isolate* isolate,
                                     Local<Value> data) {
  EscapableHandleScope scope(isolate);
  Local<ObjectTemplate> env_proxy_template = ObjectTemplate::New(isolate);
  env_proxy_template->SetHandler(NamedPropertyHandlerConfiguration(
      EnvGetter, EnvSetter, EnvQuery, EnvDeleter, EnvEnumerator, data));
  return scope.EscapeMaybe(env_proxy_template->NewInstance(context));
}
}  // namespace node