// Copyright (C) 2011 Milo Yip
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

#ifndef RAPIDJSON_FILEREADSTREAM_H_
#define RAPIDJSON_FILEREADSTREAM_H_

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

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

#endif  // RAPIDJSON_FILESTREAM_H_
