// Tencent is pleased to support the open source community by making RapidJSON available.
//
// Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. All rights reserved.
//
// Licensed under the MIT License (the "License"); you may not use this file except
// in compliance with the License. You may obtain a copy of the License at
//
// http://opensource.org/licenses/MIT
//
// 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.

#ifndef RAPIDJSON_FILEREADSTREAM_H_
#define RAPIDJSON_FILEREADSTREAM_H_

#include "stream.h"
#include <cstdio>

#ifdef __clang__
RAPIDJSON_DIAG_PUSH
RAPIDJSON_DIAG_OFF(padded)
RAPIDJSON_DIAG_OFF(unreachable-code)
RAPIDJSON_DIAG_OFF(missing-noreturn)
#endif

RAPIDJSON_NAMESPACE_BEGIN

//! File byte stream for input using fread().
/*!
    \note implements Stream concept
*/
class FileReadStream
{
public:
  typedef char Ch;    //!< Character type (byte).

  //! Constructor.
  /*!
      \param fp File pointer opened for read.
      \param buffer user-supplied buffer.
      \param bufferSize size of buffer in bytes. Must >=4 bytes.
  */
  FileReadStream(std::FILE* fp, char* buffer, size_t bufferSize) : fp_(fp), buffer_(buffer), bufferSize_(bufferSize), bufferLast_(0), current_(buffer_), readCount_(0), count_(0), eof_(false)
  { RAPIDJSON_ASSERT(fp_ != 0);
    RAPIDJSON_ASSERT(bufferSize >= 4);
    Read();
  }

  Ch Peek() const { return *current_; }
  Ch Take() { Ch c = *current_; Read(); return c; }
  size_t Tell() const { return count_ + static_cast<size_t>(current_ - buffer_); }

  // Not implemented
  void Put(Ch) { RAPIDJSON_ASSERT(false); }
  void Flush() { RAPIDJSON_ASSERT(false); }
  Ch* PutBegin() { RAPIDJSON_ASSERT(false); return 0; }
  size_t PutEnd(Ch*) { RAPIDJSON_ASSERT(false); return 0; }

  // For encoding detection only.
  const Ch* Peek4() const
  { return (current_ + 4 <= bufferLast_) ? current_ : 0;
  }

private:
  void Read()
  { if (current_ < bufferLast_)
      ++current_;
    else if (!eof_)
    { count_ += readCount_;
      readCount_ = fread(buffer_, 1, bufferSize_, fp_);
      bufferLast_ = buffer_ + readCount_ - 1;
      current_ = buffer_;

      if (readCount_ < bufferSize_)
      { buffer_[readCount_] = '\0';
        ++bufferLast_;
        eof_ = true;
      }
    }
  }

  std::FILE* fp_;
  Ch *buffer_;
  size_t bufferSize_;
  Ch *bufferLast_;
  Ch *current_;
  size_t readCount_;
  size_t count_;  //!< Number of characters read
  bool eof_;
};

RAPIDJSON_NAMESPACE_END

#ifdef __clang__
RAPIDJSON_DIAG_POP
#endif

#endif // RAPIDJSON_FILESTREAM_H_
