/*
  pdu.h

  Copyright (c) 2020 Kevin Matz (kevin.matz@gmail.com)

  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.
*/
#pragma once

#include <cstdint>
#include <functional>
#include <istream>
#include <memory>
#include <vector>

namespace ACN {
namespace PDU {

using std::uint8_t;
using std::uint16_t;
using std::uint32_t;
using std::vector;
using std::shared_ptr;

// 2.4.1. Flags
// Flags is a 4-bit field containing flags L, V, H and D which declare how the PDU is packed.
struct pdu_flags {
  bool hasLength  : 1;
  bool hasVector  : 1;
  bool hasHeader  : 1;
  bool hasData    : 1;
  pdu_flags(uint8_t);
};

// MAYBE: remove virtuals?
// Arduino doen't enable RTTI for run-time polymorphism.
struct pdu_header { virtual ~pdu_header() {} };
struct pdu_data { virtual ~pdu_data() {} };


/**
    Memory buffer of uint8_t data.
*/
class pdu_buffer
  : public std::basic_streambuf<uint8_t>
{
public:
  pdu_buffer(uint8_t * p, size_t l) { setg(p, p, p + l); };
  uint8_t * in_ptr() { return gptr(); };
};
/**
    Input/Output stream of nested PDU
*/
class pdu_stream
  : public std::basic_istream<uint8_t>
{
public:
  pdu_stream(uint8_t * p, size_t l)
    : std::basic_istream<uint8_t>(&_buffer)
    , _buffer(p, l)           { rdbuf(&_buffer); }
  uint32_t  available() { return _buffer.in_avail(); }
  uint8_t * data()      { return _buffer.in_ptr(); };
  template<typename T> T readType() {
      if (available() < sizeof(T)) {
        setstate(std::ios_base::failbit);
        return 0;
      }
      T ret = 0;
      auto data = reinterpret_cast<uint8_t*>(&ret);
      for (int i = sizeof(T);  --i >= 0; )
          data[i] = get();
      if (!available())
        setstate(std::ios_base::eofbit);
      return ret;
  }

private:
  pdu_buffer _buffer;
};
using Stream = shared_ptr<pdu_stream>;


/**
  Base class PDU

  All PDU share common structure of:
    flags, length, vector,
    and protocol specific header/data.

  Flag values indicate if lenght, vector, header or data
  are present in the PDU, or if they should be inherited from the
  preceding PDU.
*/
class Pdu {
public:
  Pdu(Stream, size_t vector_size);
  ~Pdu();

  // getters
  const pdu_flags flags()  {return flags_;}
  const uint32_t  length() {return length_;}
  const uint32_t  vector(); // may inherit
  pdu_header    * header(); // may inherit
  pdu_data      * data();   // may inherit
  shared_ptr<Pdu> parent() {return parent_;}
  Stream          stream() {return stream_;}

  // setters
  void setParent (shared_ptr<Pdu> pdu) {parent_ = pdu;}
  void setInherit(shared_ptr<Pdu> pdu) {inherit_ = pdu;}

protected:
  pdu_flags       flags_;
  uint32_t        length_;
  uint32_t        vector_;
  shared_ptr<Pdu> parent_;
  shared_ptr<Pdu> inherit_;
  Stream          stream_;

  // private setters
  void setHeader (pdu_header * h) {header_ = h;}
  void setData   (pdu_data   * d) {data_ = d;}

private:
  pdu_header * header_;
  pdu_data   * data_;

  void readLength(Stream);
  void readVector(uint8_t);
};


template <typename T>
using Handler = std::function<void(std::shared_ptr<T>)>;

template <typename T>
using Block = std::shared_ptr<std::vector<std::shared_ptr<T>>>;

/**
  Template creator of a PDU Block.

  @param std::shared_ptr<PDU::pdu_stream> The stream to read from.
  @return std::shared_ptr<std::vector<std::shared_ptr<T>>> A block of PDU
*/
template<typename T>
Block<T> readBlock(Stream buffer, shared_ptr<PDU::Pdu> parent = 0) {
  auto block = Block<T>(new vector<shared_ptr<T>>);
  while(buffer->good()) {
    shared_ptr<T> pdu(new T(buffer));
    if (buffer->fail())        // stream failed during pdu constructor
      break;
    if (pdu->stream()->fail()) // pdu buffer errors
      continue;
    if (parent != 0)           // set parent
      pdu->setParent(parent);
    if (!block->empty())       // set inheritee
      pdu->setInherit(block->back());
    block->push_back(pdu);     // add to block
  }
  return block;
}



} // PDU
} // ACN