// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include "include/dart_api.h"
#include "include/dart_native_api.h"


Dart_NativeFunction ResolveName(Dart_Handle name,
                                int argc,
                                bool* auto_setup_scope);


DART_EXPORT Dart_Handle sample_extension_Init(Dart_Handle parent_library) {
  if (Dart_IsError(parent_library)) {
    return parent_library;
  }

  Dart_Handle result_code =
      Dart_SetNativeResolver(parent_library, ResolveName, NULL);
  if (Dart_IsError(result_code)) {
    return result_code;
  }

  return Dart_Null();
}


Dart_Handle HandleError(Dart_Handle handle) {
  if (Dart_IsError(handle)) {
    Dart_PropagateError(handle);
  }
  return handle;
}


void SystemRand(Dart_NativeArguments arguments) {
  Dart_EnterScope();
  Dart_Handle result = HandleError(Dart_NewInteger(rand()));
  Dart_SetReturnValue(arguments, result);
  Dart_ExitScope();
}


void SystemSrand(Dart_NativeArguments arguments) {
  Dart_EnterScope();
  bool success = false;
  Dart_Handle seed_object = HandleError(Dart_GetNativeArgument(arguments, 0));
  if (Dart_IsInteger(seed_object)) {
    bool fits;
    HandleError(Dart_IntegerFitsIntoInt64(seed_object, &fits));
    if (fits) {
      int64_t seed;
      HandleError(Dart_IntegerToInt64(seed_object, &seed));
      srand(static_cast<unsigned>(seed));
      success = true;
    }
  }
  Dart_SetReturnValue(arguments, HandleError(Dart_NewBoolean(success)));
  Dart_ExitScope();
}


uint8_t* randomArray(int seed, int length) {
  if (length <= 0 || length > 10000000) {
    return NULL;
  }
  uint8_t* values = reinterpret_cast<uint8_t*>(malloc(length));
  if (NULL == values) {
    return NULL;
  }
  srand(seed);
  for (int i = 0; i < length; ++i) {
    values[i] = rand() % 256;
  }
  return values;
}


void wrappedRandomArray(Dart_Port dest_port_id,
                        Dart_CObject* message) {
  Dart_Port reply_port_id = ILLEGAL_PORT;
  if (message->type == Dart_CObject_kArray &&
      3 == message->value.as_array.length) {
    // Use .as_array and .as_int32 to access the data in the Dart_CObject.
    Dart_CObject* param0 = message->value.as_array.values[0];
    Dart_CObject* param1 = message->value.as_array.values[1];
    Dart_CObject* param2 = message->value.as_array.values[2];
    if (param0->type == Dart_CObject_kInt32 &&
        param1->type == Dart_CObject_kInt32 &&
        param2->type == Dart_CObject_kSendPort) {
      int seed = param0->value.as_int32;
      int length = param1->value.as_int32;
      reply_port_id = param2->value.as_send_port.id;
      uint8_t* values = randomArray(seed, length);

      if (values != NULL) {
        Dart_CObject result;
        result.type = Dart_CObject_kTypedData;
        result.value.as_typed_data.type = Dart_TypedData_kUint8;
        result.value.as_typed_data.values = values;
        result.value.as_typed_data.length = length;
        if (Dart_PostCObject(reply_port_id, &result)) {
          Dart_CObject error;
          error.type = Dart_CObject_kNull;
          Dart_PostCObject(reply_port_id, &error);
        }
        free(values);
        // It is OK that result is destroyed when function exits.
        // Dart_PostCObject has copied its data.
        return;
      }
    }
  }
  fprintf(stderr, "Invalid message received, cannot proceed. Aborting the process.\n");
  abort();
}


void randomArrayServicePort(Dart_NativeArguments arguments) {
  Dart_EnterScope();
  Dart_SetReturnValue(arguments, Dart_Null());
  Dart_Port service_port =
      Dart_NewNativePort("RandomArrayService", wrappedRandomArray, true);
  if (service_port != ILLEGAL_PORT) {
    Dart_Handle send_port = HandleError(Dart_NewSendPort(service_port));
    Dart_SetReturnValue(arguments, send_port);
  }
  Dart_ExitScope();
}


struct FunctionLookup {
  const char* name;
  Dart_NativeFunction function;
};


FunctionLookup function_list[] = {
    {"SystemRand", SystemRand},
    {"SystemSrand", SystemSrand},
    {"RandomArray_ServicePort", randomArrayServicePort},
    {NULL, NULL}};


FunctionLookup no_scope_function_list[] = {
  {"NoScopeSystemRand", SystemRand},
  {NULL, NULL}
};

Dart_NativeFunction ResolveName(Dart_Handle name,
                                int argc,
                                bool* auto_setup_scope) {
  if (!Dart_IsString(name)) {
    return NULL;
  }
  Dart_NativeFunction result = NULL;
  if (auto_setup_scope == NULL) {
    return NULL;
  }

  Dart_EnterScope();
  const char* cname;
  HandleError(Dart_StringToCString(name, &cname));

  for (int i=0; function_list[i].name != NULL; ++i) {
    if (strcmp(function_list[i].name, cname) == 0) {
      *auto_setup_scope = true;
      result = function_list[i].function;
      break;
    }
  }

  if (result != NULL) {
    Dart_ExitScope();
    return result;
  }

  for (int i=0; no_scope_function_list[i].name != NULL; ++i) {
    if (strcmp(no_scope_function_list[i].name, cname) == 0) {
      *auto_setup_scope = false;
      result = no_scope_function_list[i].function;
      break;
    }
  }

  Dart_ExitScope();
  return result;
}