#include "file_consumer.h"

#include "clang_utils.h"
#include "indexer.h"
#include "platform.h"
#include "utils.h"

#include <loguru.hpp>

namespace {

std::optional<std::string> GetFileContents(
    const std::string& path,
    std::unordered_map<std::string, FileContents>* file_contents) {
  auto it = file_contents->find(path);
  if (it == file_contents->end()) {
    std::optional<std::string> content = ReadContent(path);
    if (content)
      (*file_contents)[path] = FileContents(path, *content);
    return content;
  }
  return it->second.content;
}

}  // namespace

bool operator==(const CXFileUniqueID& a, const CXFileUniqueID& b) {
  return a.data[0] == b.data[0] && a.data[1] == b.data[1] &&
         a.data[2] == b.data[2];
}

FileContents::FileContents() : line_offsets_{0} {}

FileContents::FileContents(const std::string& path, const std::string& content)
    : path(path), content(content) {
  line_offsets_.push_back(0);
  for (size_t i = 0; i < content.size(); i++) {
    if (content[i] == '\n')
      line_offsets_.push_back(i + 1);
  }
}

std::optional<int> FileContents::ToOffset(Position p) const {
  if (0 <= p.line && size_t(p.line) < line_offsets_.size()) {
    int ret = line_offsets_[p.line] + p.column;
    if (size_t(ret) < content.size())
      return ret;
  }
  return std::nullopt;
}

std::optional<std::string> FileContents::ContentsInRange(Range range) const {
  std::optional<int> start_offset = ToOffset(range.start),
                end_offset = ToOffset(range.end);
  if (start_offset && end_offset && *start_offset < *end_offset)
    return content.substr(*start_offset, *end_offset - *start_offset);
  return std::nullopt;
}

bool FileConsumerSharedState::Mark(const std::string& file) {
  std::lock_guard<std::mutex> lock(mutex);
  return used_files.insert(file).second;
}

void FileConsumerSharedState::Reset(const std::string& file) {
  std::lock_guard<std::mutex> lock(mutex);
  auto it = used_files.find(file);
  if (it != used_files.end())
    used_files.erase(it);
}

FileConsumer::FileConsumer(FileConsumerSharedState* shared_state,
                           const std::string& parse_file)
    : shared_(shared_state), parse_file_(parse_file) {}

IndexFile* FileConsumer::TryConsumeFile(
    CXFile file,
    bool* is_first_ownership,
    std::unordered_map<std::string, FileContents>* file_contents_map) {
  assert(is_first_ownership);

  CXFileUniqueID file_id;
  if (clang_getFileUniqueID(file, &file_id) != 0) {
    EmitError(file);
    return nullptr;
  }

  // Try to find cached local result.
  auto it = local_.find(file_id);
  if (it != local_.end()) {
    *is_first_ownership = false;
    return it->second.get();
  }

  std::string file_name = FileName(file);

  // No result in local; we need to query global.
  bool did_insert = shared_->Mark(file_name);

  // We did not take the file from global. Cache that we failed so we don't try
  // again and return nullptr.
  if (!did_insert) {
    local_[file_id] = nullptr;
    return nullptr;
  }

  // Read the file contents, if we fail then we cannot index the file.
  std::optional<std::string> contents =
      GetFileContents(file_name, file_contents_map);
  if (!contents) {
    *is_first_ownership = false;
    return nullptr;
  }

  // Build IndexFile instance.
  *is_first_ownership = true;
  local_[file_id] = std::make_unique<IndexFile>(file_name, *contents);
  return local_[file_id].get();
}

std::vector<std::unique_ptr<IndexFile>> FileConsumer::TakeLocalState() {
  std::vector<std::unique_ptr<IndexFile>> result;
  for (auto& entry : local_) {
    if (entry.second)
      result.push_back(std::move(entry.second));
  }
  return result;
}

void FileConsumer::EmitError(CXFile file) const {
  std::string file_name = ToString(clang_getFileName(file));
  // TODO: Investigate this more, why can we get an empty file name?
  if (!file_name.empty()) {
    LOG_S(ERROR) << "Could not get unique file id for " << file_name
                 << " when parsing " << parse_file_;
  }
}