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#include "base/multifile.h"

#include <ios>
#include <memory>
#include <ostream>
#include <string>
#include <vector>

#include "absl/log/log.h"
#include "absl/strings/str_split.h"
#include "absl/strings/string_view.h"
#include "base/file_stream.h"

namespace mozc {

InputMultiFile::InputMultiFile(const absl::string_view filenames,
                               std::ios_base::openmode mode)
    : filenames_(absl::StrSplit(filenames, ',', absl::SkipEmpty())),
      mode_(mode) {
  next_iter_ = filenames_.begin();
  if (next_iter_ != filenames_.end()) {
    OpenNext();
  } else {
    LOG(ERROR) << "empty filenames";
  }
}

bool InputMultiFile::ReadLine(std::string* line) {
  if (ifs_ == nullptr) {
    return false;
  }
  do {
    if (!std::getline(*ifs_, *line).fail()) {
      return true;
    }
  } while (OpenNext());
  return false;
}

bool InputMultiFile::OpenNext() {
  while (next_iter_ != filenames_.end()) {
    const std::vector<std::string>::const_iterator iter = next_iter_++;
    ifs_ = std::make_unique<InputFileStream>(*iter, mode_);
    if (!ifs_->fail()) {
      return true;
    }
    LOG(ERROR) << "Cannot open " << *iter << std::endl;
  }
  ifs_.reset();
  return false;
}

}  // namespace mozc
