/*
 * Copyright (C) 2019 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "fields/custom_field_fixed_size.h"

#include "util.h"

const std::string CustomFieldFixedSize::kFieldType = "CustomField";

CustomFieldFixedSize::CustomFieldFixedSize(std::string name, std::string type_name, int size,
                                           ParseLocation loc)
    : ScalarField(name, size, loc), type_name_(type_name) {}

const std::string& CustomFieldFixedSize::GetFieldType() const {
  return CustomFieldFixedSize::kFieldType;
}

std::string CustomFieldFixedSize::GetDataType() const { return type_name_; }

int CustomFieldFixedSize::GenBounds(std::ostream& s, Size start_offset, Size end_offset,
                                    Size size) const {
  if (!start_offset.empty()) {
    // Default to start if available.
    if (!start_offset.has_dynamic()) {
      s << "auto " << GetName() << "_it = to_bound + " << (start_offset.bits() / 8) << ";";
    } else {
      s << "auto " << GetName() << "_it = to_bound + (" << start_offset << ") / 8;";
    }
  } else if (!end_offset.empty()) {
    Size byte_offset = size + end_offset;
    s << "auto " << GetName() << "_it = to_bound (+ to_bound.NumBytesRemaining() - (" << byte_offset
      << ") / 8);";
  } else {
    ERROR(this) << "Ambiguous offset for field.";
  }
  return 0;  // num_leading_bits
}

void CustomFieldFixedSize::GenExtractor(std::ostream& s, int, bool) const {
  if (GetDataType() == "Address") {
    s << "*" << GetName() << "_ptr = ::bluetooth::packet::extract" << GetDataType() << "("
      << GetName() << "_it);";
  } else {
    s << "*" << GetName() << "_ptr = " << GetName() << "_it.extract<" << GetDataType() << ">();";
  }
}

void CustomFieldFixedSize::GenGetter(std::ostream& s, Size start_offset, Size end_offset) const {
  s << GetDataType() << " " << GetGetterFunctionName() << "() const {";
  s << "ASSERT(was_validated_);";

  if (!start_offset.empty() && (start_offset.bits() % 8 == 0) && !start_offset.has_dynamic()) {
    int offset = start_offset.bits() / 8;
    if (GetDataType() == "Address") {
      s << "auto it = begin() + " << offset << ";";
      s << "return ::bluetooth::packet::extract" << GetDataType() << "(it);";
    } else {
      s << "return (begin() + " << offset << ").extract<" << GetDataType() << ">();";
    }
    s << "}";
    return;
  }

  s << "auto to_bound = begin();";
  int num_leading_bits = GenBounds(s, start_offset, end_offset, GetSize());

  s << GetDataType() << " " << GetName() << "_value{};";
  s << GetDataType() << "* " << GetName() << "_ptr = &" << GetName() << "_value;";
  GenExtractor(s, num_leading_bits, false);
  s << "return " << GetName() << "_value;";
  s << "}";
}

bool CustomFieldFixedSize::HasParameterValidator() const { return false; }

void CustomFieldFixedSize::GenParameterValidator(std::ostream&) const {
  // Do nothing.
}

void CustomFieldFixedSize::GenInserter(std::ostream& s) const {
  if (GetDataType() == "Address") {
    s << "::bluetooth::packet::insertAddress(" << GetName() << "_, i);";
  } else {
    s << "insert(" << GetName() << "_, i);";
  }
}

void CustomFieldFixedSize::GenValidator(std::ostream&) const {
  // Do nothing.
}

void CustomFieldFixedSize::GenStringRepresentation(std::ostream& s, std::string accessor) const {
  // We assume that custom fields will have a ToString() method
  s << accessor << ".ToString()";
}