// 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.

//

// 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_ENCODEDSTREAM_H_

#define RAPIDJSON_ENCODEDSTREAM_H_

#include "stream.h"

#include "memorystream.h"

#ifdef __GNUC__

RAPIDJSON_DIAG_PUSH

RAPIDJSON_DIAG_OFF(effc++)

#endif

#ifdef __clang__

RAPIDJSON_DIAG_PUSH

RAPIDJSON_DIAG_OFF(padded)

#endif

RAPIDJSON_NAMESPACE_BEGIN

//! Input byte stream wrapper with a statically bound encoding.

/*!

    \tparam Encoding The interpretation of encoding of the stream. Either UTF8, UTF16LE, UTF16BE, UTF32LE, UTF32BE.

    \tparam InputByteStream Type of input byte stream. For example, FileReadStream.

*/

template <typename Encoding, typename InputByteStream>

class EncodedInputStream {

    RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);

public:

    typedef typename Encoding::Ch Ch;

    EncodedInputStream(InputByteStream& is) : is_(is) { 

        current_ = Encoding::TakeBOM(is_);

    }

    Ch Peek() const { return current_; }

    Ch Take() { Ch c = current_; current_ = Encoding::Take(is_); return c; }

    size_t Tell() const { return is_.Tell(); }

    // 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:

    EncodedInputStream(const EncodedInputStream&);

    EncodedInputStream& operator=(const EncodedInputStream&);

    InputByteStream& is_;

    Ch current_;

};

//! Specialized for UTF8 MemoryStream.

template <>

class EncodedInputStream<UTF8<>, MemoryStream> {

public:

    typedef UTF8<>::Ch Ch;

    EncodedInputStream(MemoryStream& is) : is_(is) {

        if (static_cast<unsigned char>(is_.Peek()) == 0xEFu) is_.Take();

        if (static_cast<unsigned char>(is_.Peek()) == 0xBBu) is_.Take();

        if (static_cast<unsigned char>(is_.Peek()) == 0xBFu) is_.Take();

    }

    Ch Peek() const { return is_.Peek(); }

    Ch Take() { return is_.Take(); }

    size_t Tell() const { return is_.Tell(); }

    // Not implemented

    void Put(Ch) {}

    void Flush() {} 

    Ch* PutBegin() { return 0; }

    size_t PutEnd(Ch*) { return 0; }

    MemoryStream& is_;

private:

    EncodedInputStream(const EncodedInputStream&);

    EncodedInputStream& operator=(const EncodedInputStream&);

};

//! Output byte stream wrapper with statically bound encoding.

/*!

    \tparam Encoding The interpretation of encoding of the stream. Either UTF8, UTF16LE, UTF16BE, UTF32LE, UTF32BE.

    \tparam OutputByteStream Type of input byte stream. For example, FileWriteStream.

*/

template <typename Encoding, typename OutputByteStream>

class EncodedOutputStream {

    RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);

public:

    typedef typename Encoding::Ch Ch;

    EncodedOutputStream(OutputByteStream& os, bool putBOM = true) : os_(os) { 

        if (putBOM)

            Encoding::PutBOM(os_);

    }

    void Put(Ch c) { Encoding::Put(os_, c);  }

    void Flush() { os_.Flush(); }

    // Not implemented

    Ch Peek() const { RAPIDJSON_ASSERT(false); return 0;}

    Ch Take() { RAPIDJSON_ASSERT(false); return 0;}

    size_t Tell() const { RAPIDJSON_ASSERT(false);  return 0; }

    Ch* PutBegin() { RAPIDJSON_ASSERT(false); return 0; }

    size_t PutEnd(Ch*) { RAPIDJSON_ASSERT(false); return 0; }

private:

    EncodedOutputStream(const EncodedOutputStream&);

    EncodedOutputStream& operator=(const EncodedOutputStream&);

    OutputByteStream& os_;

};

#define RAPIDJSON_ENCODINGS_FUNC(x) UTF8<Ch>::x, UTF16LE<Ch>::x, UTF16BE<Ch>::x, UTF32LE<Ch>::x, UTF32BE<Ch>::x

//! Input stream wrapper with dynamically bound encoding and automatic encoding detection.

/*!

    \tparam CharType Type of character for reading.

    \tparam InputByteStream type of input byte stream to be wrapped.

*/

template <typename CharType, typename InputByteStream>

class AutoUTFInputStream {

    RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);

public:

    typedef CharType Ch;

    //! Constructor.

    /*!

        \param is input stream to be wrapped.

        \param type UTF encoding type if it is not detected from the stream.

    */

    AutoUTFInputStream(InputByteStream& is, UTFType type = kUTF8) : is_(&is), type_(type), hasBOM_(false) {

        RAPIDJSON_ASSERT(type >= kUTF8 && type <= kUTF32BE);        

        DetectType();

        static const TakeFunc f[] = { RAPIDJSON_ENCODINGS_FUNC(Take) };

        takeFunc_ = f[type_];

        current_ = takeFunc_(*is_);

    }

    UTFType GetType() const { return type_; }

    bool HasBOM() const { return hasBOM_; }

    Ch Peek() const { return current_; }

    Ch Take() { Ch c = current_; current_ = takeFunc_(*is_); return c; }

    size_t Tell() const { return is_->Tell(); }

    // 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:

    AutoUTFInputStream(const AutoUTFInputStream&);

    AutoUTFInputStream& operator=(const AutoUTFInputStream&);

    // Detect encoding type with BOM or RFC 4627

    void DetectType() {

        // BOM (Byte Order Mark):

        // 00 00 FE FF  UTF-32BE

        // FF FE 00 00  UTF-32LE

        // FE FF        UTF-16BE

        // FF FE        UTF-16LE

        // EF BB BF     UTF-8

        const unsigned char* c = reinterpret_cast<const unsigned char *>(is_->Peek4());

        if (!c)

            return;

        unsigned bom = static_cast<unsigned>(c[0] | (c[1] << 8) | (c[2] << 16) | (c[3] << 24));

        hasBOM_ = false;

        if (bom == 0xFFFE0000)                  { type_ = kUTF32BE; hasBOM_ = true; is_->Take(); is_->Take(); is_->Take(); is_->Take(); }

        else if (bom == 0x0000FEFF)             { type_ = kUTF32LE; hasBOM_ = true; is_->Take(); is_->Take(); is_->Take(); is_->Take(); }

        else if ((bom & 0xFFFF) == 0xFFFE)      { type_ = kUTF16BE; hasBOM_ = true; is_->Take(); is_->Take();                           }

        else if ((bom & 0xFFFF) == 0xFEFF)      { type_ = kUTF16LE; hasBOM_ = true; is_->Take(); is_->Take();                           }

        else if ((bom & 0xFFFFFF) == 0xBFBBEF)  { type_ = kUTF8;    hasBOM_ = true; is_->Take(); is_->Take(); is_->Take();              }

        // RFC 4627: Section 3

        // "Since the first two characters of a JSON text will always be ASCII

        // characters [RFC0020], it is possible to determine whether an octet

        // stream is UTF-8, UTF-16 (BE or LE), or UTF-32 (BE or LE) by looking

        // at the pattern of nulls in the first four octets."

        // 00 00 00 xx  UTF-32BE

        // 00 xx 00 xx  UTF-16BE

        // xx 00 00 00  UTF-32LE

        // xx 00 xx 00  UTF-16LE

        // xx xx xx xx  UTF-8

        if (!hasBOM_) {

            int pattern = (c[0] ? 1 : 0) | (c[1] ? 2 : 0) | (c[2] ? 4 : 0) | (c[3] ? 8 : 0);

            switch (pattern) {

            case 0x08: type_ = kUTF32BE; break;

            case 0x0A: type_ = kUTF16BE; break;

            case 0x01: type_ = kUTF32LE; break;

            case 0x05: type_ = kUTF16LE; break;

            case 0x0F: type_ = kUTF8;    break;

            default: break; // Use type defined by user.

            }

        }

        // Runtime check whether the size of character type is sufficient. It only perform checks with assertion.

        if (type_ == kUTF16LE || type_ == kUTF16BE) RAPIDJSON_ASSERT(sizeof(Ch) >= 2);

        if (type_ == kUTF32LE || type_ == kUTF32BE) RAPIDJSON_ASSERT(sizeof(Ch) >= 4);

    }

    typedef Ch (*TakeFunc)(InputByteStream& is);

    InputByteStream* is_;

    UTFType type_;

    Ch current_;

    TakeFunc takeFunc_;

    bool hasBOM_;

};

//! Output stream wrapper with dynamically bound encoding and automatic encoding detection.

/*!

    \tparam CharType Type of character for writing.

    \tparam OutputByteStream type of output byte stream to be wrapped.

*/

template <typename CharType, typename OutputByteStream>

class AutoUTFOutputStream {

    RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);

public:

    typedef CharType Ch;

    //! Constructor.

    /*!

        \param os output stream to be wrapped.

        \param type UTF encoding type.

        \param putBOM Whether to write BOM at the beginning of the stream.

    */

    AutoUTFOutputStream(OutputByteStream& os, UTFType type, bool putBOM) : os_(&os), type_(type) {

        RAPIDJSON_ASSERT(type >= kUTF8 && type <= kUTF32BE);

        // Runtime check whether the size of character type is sufficient. It only perform checks with assertion.

        if (type_ == kUTF16LE || type_ == kUTF16BE) RAPIDJSON_ASSERT(sizeof(Ch) >= 2);

        if (type_ == kUTF32LE || type_ == kUTF32BE) RAPIDJSON_ASSERT(sizeof(Ch) >= 4);

        static const PutFunc f[] = { RAPIDJSON_ENCODINGS_FUNC(Put) };

        putFunc_ = f[type_];

        if (putBOM)

            PutBOM();

    }

    UTFType GetType() const { return type_; }

    void Put(Ch c) { putFunc_(*os_, c); }

    void Flush() { os_->Flush(); } 

    // Not implemented

    Ch Peek() const { RAPIDJSON_ASSERT(false); return 0;}

    Ch Take() { RAPIDJSON_ASSERT(false); return 0;}

    size_t Tell() const { RAPIDJSON_ASSERT(false); return 0; }

    Ch* PutBegin() { RAPIDJSON_ASSERT(false); return 0; }

    size_t PutEnd(Ch*) { RAPIDJSON_ASSERT(false); return 0; }

private:

    AutoUTFOutputStream(const AutoUTFOutputStream&);

    AutoUTFOutputStream& operator=(const AutoUTFOutputStream&);

    void PutBOM() { 

        typedef void (*PutBOMFunc)(OutputByteStream&);

        static const PutBOMFunc f[] = { RAPIDJSON_ENCODINGS_FUNC(PutBOM) };

        f[type_](*os_);

    }

    typedef void (*PutFunc)(OutputByteStream&, Ch);

    OutputByteStream* os_;

    UTFType type_;

    PutFunc putFunc_;

};

#undef RAPIDJSON_ENCODINGS_FUNC

RAPIDJSON_NAMESPACE_END

#ifdef __clang__

RAPIDJSON_DIAG_POP

#endif

#ifdef __GNUC__

RAPIDJSON_DIAG_POP

#endif

#endif // RAPIDJSON_FILESTREAM_H_