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#include "base/config_file_stream.h"

#ifdef OS_WIN
#include <windows.h>
#endif  // OS_WIN

#include <cstring>
#include <map>
#include <sstream>
#include <string>

#include "base/file_stream.h"
#include "base/file_util.h"
#include "base/logging.h"
#include "base/port.h"
#include "base/singleton.h"
#include "base/system_util.h"
#include "absl/strings/match.h"

namespace mozc {

namespace {

static constexpr char kSystemPrefix[] = "system://";
static constexpr char kUserPrefix[] = "user://";
static constexpr char kFilePrefix[] = "file://";
static constexpr char kMemoryPrefix[] = "memory://";

struct FileData {
  const char *name;
  const char *data;
  size_t size;
};

std::string RemovePrefix(const char *prefix, const std::string &filename) {
  const size_t size = strlen(prefix);
  if (filename.size() < size) {
    return "";
  }
  return filename.substr(size, filename.size() - size);
}

class OnMemoryFileMap {
 public:
  std::string get(const std::string &key) const {
    std::map<std::string, std::string>::const_iterator it = map_.find(key);
    if (it != map_.end()) {
      return it->second;
    }
    return std::string("");
  }

  void set(const std::string &key, const std::string &value) {
    map_[key] = value;
  }

  void clear() { map_.clear(); }

 private:
  std::map<std::string, std::string> map_;
};

#include "base/config_file_stream_data.inc"
}  // namespace

std::istream *ConfigFileStream::Open(const std::string &filename,
                                     std::ios_base::openmode mode) {
  // system://foo.bar.txt
  if (absl::StartsWith(filename, kSystemPrefix)) {
    const std::string new_filename = RemovePrefix(kSystemPrefix, filename);
    for (size_t i = 0; i < std::size(kFileData); ++i) {
      if (new_filename == kFileData[i].name) {
        std::istringstream *ifs = new std::istringstream(
            std::string(kFileData[i].data, kFileData[i].size), mode);
        CHECK(ifs);
        if (ifs->good()) {
          return ifs;
        }
        delete ifs;
        return nullptr;
      }
    }
    // user://foo.bar.txt
  } else if (absl::StartsWith(filename, kUserPrefix)) {
    const std::string new_filename =
        FileUtil::JoinPath(SystemUtil::GetUserProfileDirectory(),
                           RemovePrefix(kUserPrefix, filename));
    InputFileStream *ifs = new InputFileStream(new_filename.c_str(), mode);
    CHECK(ifs);
    if (ifs->good()) {
      return ifs;
    }
    delete ifs;
    return nullptr;
    // file:///foo.map
  } else if (absl::StartsWith(filename, kFilePrefix)) {
    const std::string new_filename = RemovePrefix(kFilePrefix, filename);
    InputFileStream *ifs = new InputFileStream(new_filename.c_str(), mode);
    CHECK(ifs);
    if (ifs->good()) {
      return ifs;
    }
    delete ifs;
    return nullptr;
  } else if (absl::StartsWith(filename, kMemoryPrefix)) {
    std::istringstream *ifs = new std::istringstream(
        Singleton<OnMemoryFileMap>::get()->get(filename), mode);
    CHECK(ifs);
    if (ifs->good()) {
      return ifs;
    }
    delete ifs;
    return nullptr;
  } else {
    LOG(WARNING) << filename << " has no prefix. open from localfile";
    InputFileStream *ifs = new InputFileStream(filename.c_str(), mode);
    CHECK(ifs);
    if (ifs->good()) {
      return ifs;
    }
    delete ifs;
    return nullptr;
  }

  return nullptr;
}

bool ConfigFileStream::AtomicUpdate(const std::string &filename,
                                    const std::string &new_binary_contens) {
  if (absl::StartsWith(filename, kMemoryPrefix)) {
    Singleton<OnMemoryFileMap>::get()->set(filename, new_binary_contens);
    return true;
  } else if (absl::StartsWith(filename, kSystemPrefix)) {
    LOG(ERROR) << "Cannot update system:// files.";
    return false;
  }
  // We should save the new config first,
  // as we may rewrite the original config according to platform.
  // The original config should be platform independent.
  const std::string real_filename = GetFileName(filename);
  if (real_filename.empty()) {
    return false;
  }

  const std::string tmp_filename = real_filename + ".tmp";
  if (absl::Status s = FileUtil::SetContents(tmp_filename, new_binary_contens);
      !s.ok()) {
    LOG(ERROR) << "Cannot write the contents to " << tmp_filename << ": " << s;
    return false;
  }

  if (absl::Status s = FileUtil::AtomicRename(tmp_filename, real_filename);
      !s.ok()) {
    LOG(ERROR) << "AtomicRename failed: " << s << "; from: " << tmp_filename
               << ", to: " << real_filename;
    return false;
  }

#ifdef OS_WIN
  // If file name doesn't end with ".db", the file
  // is more likely a temporary file.
  if (!absl::EndsWith(real_filename, ".db")) {
    // TODO(yukawa): Provide a way to
    // integrate ::SetFileAttributesTransacted with
    // AtomicRename.
    if (!FileUtil::HideFile(real_filename)) {
      LOG(ERROR) << "Cannot make hidden: " << real_filename << " "
                 << ::GetLastError();
    }
  }
#endif  // OS_WIN
  return true;
}

std::string ConfigFileStream::GetFileName(const std::string &filename) {
  if (absl::StartsWith(filename, kSystemPrefix) ||
      absl::StartsWith(filename, kMemoryPrefix)) {
    return "";
  } else if (absl::StartsWith(filename, kUserPrefix)) {
    return FileUtil::JoinPath(SystemUtil::GetUserProfileDirectory(),
                              RemovePrefix(kUserPrefix, filename));
  } else if (absl::StartsWith(filename, kFilePrefix)) {
    return RemovePrefix(kUserPrefix, filename);
  } else {
    LOG(WARNING) << filename << " has no prefix. open from localfile";
    return filename;
  }
  return "";
}

void ConfigFileStream::ClearOnMemoryFiles() {
  Singleton<OnMemoryFileMap>::get()->clear();
}
}  // namespace mozc
