//===- lib/Driver/InputGraph.cpp ------------------------------------------===//
//
//                             The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "lld/Core/Resolver.h"
#include "lld/Driver/InputGraph.h"

using namespace lld;

namespace {
bool sortInputElements(const std::unique_ptr<InputElement> &a,
                       const std::unique_ptr<InputElement> &b) {
  return a->getOrdinal() < b->getOrdinal();
}
}

bool InputGraph::addInputElement(std::unique_ptr<InputElement> ie) {
  _inputArgs.push_back(std::move(ie));
  return true;
}

bool InputGraph::assignOrdinals() {
  for (auto &ie : _inputArgs)
    ie->setOrdinal(++_ordinal);
  return true;
}

void InputGraph::doPostProcess() {
  std::stable_sort(_inputArgs.begin(), _inputArgs.end(), sortInputElements);
}

bool InputGraph::validate() {
  for (auto &ie : _inputArgs)
    if (!ie->validate())
      return false;
  return true;
}

bool InputGraph::dump(raw_ostream &diagnostics) {
  for (auto &ie : _inputArgs)
    if (!ie->dump(diagnostics))
      return false;
  return true;
}

/// \brief Insert element at position
void InputGraph::insertElementsAt(
    std::vector<std::unique_ptr<InputElement> > inputElements,
    Position position, size_t pos) {
  if (position == InputGraph::Position::BEGIN)
    pos = 0;
  else if (position == InputGraph::Position::END)
    pos = _inputArgs.size();
  _inputArgs.insert(_inputArgs.begin() + pos,
                    std::make_move_iterator(inputElements.begin()),
                    std::make_move_iterator(inputElements.end()));
}

void InputGraph::insertOneElementAt(std::unique_ptr<InputElement> element,
                                    Position position, size_t pos) {
  if (position == InputGraph::Position::BEGIN)
    pos = 0;
  else if (position == InputGraph::Position::END)
    pos = _inputArgs.size();
  _inputArgs.insert(_inputArgs.begin() + pos, std::move(element));
}

/// \brief Helper functions for the resolver
ErrorOr<InputElement *> InputGraph::getNextInputElement() {
  if (_nextElementIndex >= _inputArgs.size())
    return make_error_code(InputGraphError::no_more_elements);
  return _inputArgs[_nextElementIndex++].get();
}

/// \brief Set the index on what inputElement has to be returned
ErrorOr<void> InputGraph::setNextElementIndex(uint32_t index) {
  if (index > _inputArgs.size())
    return make_error_code(llvm::errc::invalid_argument);
  _nextElementIndex = index;
  return error_code::success();
}

/// InputElement

/// \brief Initialize the Input Element, The ordinal value of an input Element
/// is initially set to -1, if the user wants to override its ordinal,
/// let the user do it
InputElement::InputElement(Kind type, int64_t ordinal)
    : _kind(type), _ordinal(ordinal), _weight(0) {}

/// FileNode
FileNode::FileNode(StringRef path, int64_t ordinal)
    : InputElement(InputElement::Kind::File, ordinal), _path(path),
      _resolveState(Resolver::StateNoChange), _nextFileIndex(0) {}

/// \brief Read the file into _buffer.
error_code
FileNode::readFile(const LinkingContext &ctx, raw_ostream &diagnostics) {
  ErrorOr<StringRef> filePath = getPath(ctx);
  if (!filePath &&
      error_code(filePath) == llvm::errc::no_such_file_or_directory)
    return make_error_code(llvm::errc::no_such_file_or_directory);

  // Create a memory buffer
  OwningPtr<llvm::MemoryBuffer> opmb;

  if (error_code ec = llvm::MemoryBuffer::getFileOrSTDIN(*filePath, opmb))
    return ec;

  std::unique_ptr<MemoryBuffer> mb(opmb.take());
  _buffer = std::move(mb);

  if (ctx.logInputFiles())
    diagnostics << _buffer->getBufferIdentifier() << "\n";

  // YAML file is identified by a .objtxt extension
  // FIXME : Identify YAML files by using a magic
  if (filePath->endswith(".objtxt"))
    if (error_code ec = ctx.getYAMLReader().parseFile(_buffer, _files))
      return ec;
  return error_code::success();
}

// Reset the next file that would be be processed by the resolver.
// Reset the resolve state too.
void FileNode::resetNextIndex() {
  _nextFileIndex = 0;
  setResolveState(Resolver::StateNoChange);
}

/// ControlNode

/// \brief Get the resolver State. The return value of the resolve
/// state for a control node is the or'ed value of the resolve states
/// contained in it.
uint32_t ControlNode::getResolveState() const {
  uint32_t resolveState = Resolver::StateNoChange;
  for (auto &elem : _elements)
    resolveState |= elem->getResolveState();
  return resolveState;
}

/// \brief Set the resolve state for the current element
/// thats processed by the resolver.
void ControlNode::setResolveState(uint32_t resolveState) {
  if (_elements.size() == 0)
    return;
  _elements[_currentElementIndex]->setResolveState(resolveState);
}

/// SimpleFileNode

SimpleFileNode::SimpleFileNode(StringRef path, int64_t ordinal)
    : InputElement(InputElement::Kind::SimpleFile, ordinal), _path(path),
      _nextFileIndex(0), _resolveState(Resolver::StateNoChange) {}

/// Group

/// \brief Return the next file that need to be processed by the resolver.
/// This also processes input elements depending on the resolve status
/// of the input elements contained in the group.
ErrorOr<File &> Group::getNextFile() {
  // If there are no elements, move on to the next input element
  if (_elements.size() == 0)
    return make_error_code(InputGraphError::no_more_files);
  // If we have processed all the elements as part of this node
  // check the resolver status for each input element and if the status
  // has not changed, move onto the next file.
  if (_nextElementIndex == _elements.size()) {
    if (getResolveState() == Resolver::StateNoChange)
      return make_error_code(InputGraphError::no_more_files);
    resetNextIndex();
  }
  _currentElementIndex = _nextElementIndex;
  auto file = _elements[_nextElementIndex]->getNextFile();
  // Move on to the next element if we have finished processing all
  // the files in the input element
  if (error_code(file) == InputGraphError::no_more_files)
    _nextElementIndex++;
  else
    return *file;
  return getNextFile();
}