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

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_;
};

//NCBI: added CppIStream
class CppIStream {
public:
    typedef char Ch;    //!< Character type (byte).

	CppIStream(std::istream& in) : in_(&in), count_(0) {
    }
    CppIStream& operator=(CppIStream& i) {
        in_ = i.in_;
        current_ = i.current_;
        count_ = i.count_;
        return *this;
    }

	Ch Peek() const {
        char c = in_->peek();
        if (c == std::istream::traits_type::eof()) { c='\0';}
        return c;
    }
	Ch Take() {
        char c = in_->get();
        return c;
    }
	size_t Tell() const {
        return (size_t)(in_->gcount());
    }

    // 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; }

private:
	void Read() {
        current_ = (Ch)in_->get();
		if (!in_->fail()) {
			count_++;
        }
        else {
			current_ = '\0';
        }
    }
	std::istream* in_;
    Ch current_;
	size_t count_;
};

RAPIDJSON_NAMESPACE_END

#endif // RAPIDJSON_FILESTREAM_H_
