#include "capnp/helpers/capabilityHelper.h"
#include "capnp/lib/capnp_api.h"

::kj::Promise<kj::Own<PyRefCounter>> convert_to_pypromise(capnp::RemotePromise<capnp::DynamicStruct> promise) {
    return promise.then([](capnp::Response<capnp::DynamicStruct>&& response) {
      return stealPyRef(wrap_dynamic_struct_reader(response)); } );
}

void c_reraise_kj_exception() {
  GILAcquire gil;
  try {
    if (PyErr_Occurred())
      ; // let the latest Python exn pass through and ignore the current one
    else
      throw;
  }
  catch (kj::Exception& exn) {
    auto obj = wrap_kj_exception_for_reraise(exn);
    if (obj == nullptr) {
      return;
    }
    PyErr_SetObject((PyObject*)obj->ob_type, obj);
    Py_DECREF(obj);
  }
  catch (const std::exception& exn) {
    PyErr_SetString(PyExc_RuntimeError, exn.what());
  }
  catch (...)
  {
    PyErr_SetString(PyExc_RuntimeError, "Unknown exception");
  }
}

void check_py_error() {
    GILAcquire gil;
    PyObject * err = PyErr_Occurred();
    if(err) {
        PyObject * ptype, *pvalue, *ptraceback;
        PyErr_Fetch(&ptype, &pvalue, &ptraceback);
        if(ptype == NULL || pvalue == NULL || ptraceback == NULL)
          throw kj::Exception(kj::Exception::Type::FAILED, kj::heapString("capabilityHelper.h"), 44, kj::heapString("Unknown error occurred"));

        PyObject * info = get_exception_info(ptype, pvalue, ptraceback);

        PyObject * py_filename = PyTuple_GetItem(info, 0);
        kj::String filename(kj::heapString(PyBytes_AsString(py_filename)));

        PyObject * py_line = PyTuple_GetItem(info, 1);
        int line = PyLong_AsLong(py_line);

        PyObject * py_description = PyTuple_GetItem(info, 2);
        kj::String description(kj::heapString(PyBytes_AsString(py_description)));

        Py_DECREF(ptype);
        Py_DECREF(pvalue);
        Py_DECREF(ptraceback);
        Py_DECREF(info);
        PyErr_Clear();

        throw kj::Exception(kj::Exception::Type::FAILED, kj::mv(filename), line, kj::mv(description));
    }
}

kj::Promise<kj::Own<PyRefCounter>> wrapPyFunc(kj::Own<PyRefCounter> func, kj::Own<PyRefCounter> arg) {
    GILAcquire gil;
    PyObject * result = PyObject_CallFunctionObjArgs(func->obj, arg->obj, NULL);
    check_py_error();
    return stealPyRef(result);
}

::kj::Promise<kj::Own<PyRefCounter>> then(kj::Promise<kj::Own<PyRefCounter>> promise,
                                          kj::Own<PyRefCounter> func, kj::Own<PyRefCounter> error_func) {
  if(error_func->obj == Py_None)
    return promise.then([func=kj::mv(func)](kj::Own<PyRefCounter> arg) mutable {
      return wrapPyFunc(kj::mv(func), kj::mv(arg)); } );
  else
    return promise.then
      ([func=kj::mv(func)](kj::Own<PyRefCounter> arg) mutable {
        return wrapPyFunc(kj::mv(func), kj::mv(arg)); },
        [error_func=kj::mv(error_func)](kj::Exception arg) mutable {
          return wrapPyFunc(kj::mv(error_func), stealPyRef(wrap_kj_exception(arg))); } );
}

kj::Promise<void> PythonInterfaceDynamicImpl::call(capnp::InterfaceSchema::Method method,
                                                   capnp::CallContext< capnp::DynamicStruct,
                                                   capnp::DynamicStruct> context) {
    auto methodName = method.getProto().getName();

    kj::Promise<void> * promise = call_server_method(this->py_server->obj,
                                                     const_cast<char *>(methodName.cStr()),
                                                     context,
                                                     this->kj_loop->obj);

    check_py_error();

    if(promise == nullptr)
      return kj::READY_NOW;

    kj::Promise<void> ret(kj::mv(*promise));
    delete promise;
    return ret;
};


class ReadPromiseAdapter {
public:
  ReadPromiseAdapter(kj::PromiseFulfiller<size_t>& fulfiller, PyObject* protocol,
                     void* buffer, size_t minBytes, size_t maxBytes)
    : protocol(protocol) {
    _asyncio_stream_read_start(protocol, buffer, minBytes, maxBytes, fulfiller);
  }

  ~ReadPromiseAdapter() {
    _asyncio_stream_read_stop(protocol);
  }

private:
  PyObject* protocol;
};


class WritePromiseAdapter {
public:
  WritePromiseAdapter(kj::PromiseFulfiller<void>& fulfiller, PyObject* protocol,
                      kj::ArrayPtr<const kj::ArrayPtr<const kj::byte>> pieces)
    : protocol(protocol) {
    _asyncio_stream_write_start(protocol, pieces, fulfiller);
  }

  ~WritePromiseAdapter() {
    _asyncio_stream_write_stop(protocol);
  }

private:
  PyObject* protocol;

};

PyAsyncIoStream::~PyAsyncIoStream() {
  _asyncio_stream_close(protocol->obj);
}

kj::Promise<size_t> PyAsyncIoStream::tryRead(void* buffer, size_t minBytes, size_t maxBytes) {
  return kj::newAdaptedPromise<size_t, ReadPromiseAdapter>(protocol->obj, buffer, minBytes, maxBytes);
}

kj::Promise<void> PyAsyncIoStream::write(const void* buffer, size_t size) {
  KJ_UNIMPLEMENTED("No use-case AsyncIoStream::write was found yet.");
}

kj::Promise<void> PyAsyncIoStream::write(kj::ArrayPtr<const kj::ArrayPtr<const kj::byte>> pieces) {
  return kj::newAdaptedPromise<void, WritePromiseAdapter>(protocol->obj, pieces);
}

kj::Promise<void> PyAsyncIoStream::whenWriteDisconnected() {
  // TODO: Possibly connect this to protocol.connection_lost?
  return kj::NEVER_DONE;
}

void PyAsyncIoStream::shutdownWrite() {
  _asyncio_stream_shutdown_write(protocol->obj);
}

class TaskToPromiseAdapter {
public:
  TaskToPromiseAdapter(kj::PromiseFulfiller<void>& fulfiller,
                       kj::Own<PyRefCounter> task, PyObject* callback)
    : task(kj::mv(task)) {
    promise_task_add_done_callback(this->task->obj, callback, fulfiller);
  }

  ~TaskToPromiseAdapter() {
    promise_task_cancel(this->task->obj);
  }

private:
  kj::Own<PyRefCounter> task;
};

kj::Promise<void> taskToPromise(kj::Own<PyRefCounter> task, PyObject* callback) {
  return kj::newAdaptedPromise<void, TaskToPromiseAdapter>(kj::mv(task), callback);
}

::kj::Promise<kj::Own<PyRefCounter>> tryReadMessage(kj::AsyncIoStream& stream, capnp::ReaderOptions opts) {
  return capnp::tryReadMessage(stream, opts)
    .then([](kj::Maybe<kj::Own<capnp::MessageReader>> maybeReader) -> kj::Promise<kj::Own<PyRefCounter>> {
        KJ_IF_MAYBE(reader, maybeReader) {
          PyObject* pyreader = make_async_message_reader(kj::mv(*reader));
          check_py_error();
          return kj::heap<PyRefCounter>(pyreader);
        } else {
          return kj::heap<PyRefCounter>(Py_None);
        }
      });
}

void init_capnp_api() {
    import_capnp__lib__capnp();
}