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 // 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
  
  
 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_;
 };
  
 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&);
 };
  
  
 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
  
  
 template <typename CharType, typename InputByteStream>
 class AutoUTFInputStream {
     RAPIDJSON_STATIC_ASSERT(sizeof(typename InputByteStream::Ch) == 1);
 public:
     typedef CharType Ch;
  
  
     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_;
 };
  
  
 template <typename CharType, typename OutputByteStream>
 class AutoUTFOutputStream {
     RAPIDJSON_STATIC_ASSERT(sizeof(typename OutputByteStream::Ch) == 1);
 public:
     typedef CharType Ch;
  
  
     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_