#pragma region CPL License
/*
Nuclex Native Framework
Copyright (C) 2002-2021 Nuclex Development Labs

This library is free software; you can redistribute it and/or
modify it under the terms of the IBM Common Public License as
published by the IBM Corporation; either version 1.0 of the
License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
IBM Common Public License for more details.

You should have received a copy of the IBM Common Public
License along with this library
*/
#pragma endregion // CPL License

// If the library is compiled as a DLL, this ensures symbols are exported
#define NUCLEX_STORAGE_SOURCE 1

#include "ZPaqDecompressor.h"

#if defined(NUCLEX_STORAGE_HAVE_ZPAQ)

#include "Nuclex/Storage/Binary/InputStream.h"
#include "Nuclex/Storage/Binary/OutputStream.h"

#include <stdexcept>
#include <cassert>

namespace Nuclex { namespace Storage { namespace Compression { namespace ZPaq {

  // ------------------------------------------------------------------------------------------- //

  ZPaqDecompressor::ZPaqDecompressor() :
    hasFoundBlock(false),
    hasFoundFilename(false),
    isFinishing(false) {

    this->decompressor.setInput(&this->reader);
    this->decompressor.setOutput(&this->writer);
  }

  // ------------------------------------------------------------------------------------------- //

  ZPaqDecompressor::~ZPaqDecompressor() {
  }

  // ------------------------------------------------------------------------------------------- //

  StopReason ZPaqDecompressor::Process(
    const std::uint8_t *compressedBuffer, std::size_t &compressedByteCount,
    std::uint8_t *outputBuffer, std::size_t &outputByteCount
  ) {

    // Because we cannot stop the ZPaq compressor until it has processed all input
    // bytes, it may generate more output than we want. This will have been saved by
    // our special buffer writer. If there's still output waiting in the buffer writer,
    // it'll be written to the output buffer here
    std::size_t overflowedByteCount = this->writer.TargetNewOutputBuffer(
      outputBuffer, outputByteCount
    );
    if(overflowedByteCount >= outputByteCount) {
      return StopReason::OutputBufferFull; // outputByteCount can remain as-is
    }

    // Select the new input buffer and let libzpaq do the compression
    this->reader.SetInputBuffer(compressedBuffer, compressedByteCount);

    // ZPaq comes with a whole container format for backups and archiving. We could either
    // work around the container (requiring this implementation to deal with internal ZPaq
    // classes and maintain it when ZPaq updates) or just go with the smallest container
    // possible and keep things simple at the cost of a few extra bytes.
    //
    // We took the latter choice, so now need to skip some container format data here...
    if(!this->hasFoundBlock) {
      this->hasFoundBlock = this->decompressor.findBlock();
      if(!this->hasFoundBlock) {
        throw std::runtime_error(u8"libzpaq could not find a compression block in the data");
      }
    }
    if(!this->hasFoundFilename) {
      this->hasFoundFilename = this->decompressor.findFilename();
      if(!this->hasFoundFilename) {
        throw std::runtime_error(u8"libzpaq could not find a file header in the data");
      }

      this->decompressor.readComment();
    }

    // Decompress the 
    assert(compressedByteCount < std::numeric_limits<int>::max());
    bool moreInputFollowing = this->decompressor.decompress(
      static_cast<int>(compressedByteCount)
    );
    (void)moreInputFollowing; // Some compilers like to complain even with the assert...
    assert((!moreInputFollowing) && u8"libzpaq accessed more bytes than told to");

    std::size_t remainingOutputByteCount = this->writer.GetRemainingByteCount();
    if(remainingOutputByteCount == 0) {
      return StopReason::OutputBufferFull;
    } else {
      outputByteCount -= remainingOutputByteCount;
      return StopReason::InputBufferExhausted;
    }

  }

  // ------------------------------------------------------------------------------------------- //

  StopReason ZPaqDecompressor::Finish(
    std::uint8_t *outputBuffer, std::size_t &outputByteCount
  ) {

    // Because we cannot stop the ZPaq decompressor until it has processed all input
    // bytes, it may generate more output than we want. This will have been saved by
    // our special buffer writer. If there's still output waiting in the buffer writer,
    // it'll be written to the output buffer here
    std::size_t overflowedByteCount = this->writer.TargetNewOutputBuffer(
      outputBuffer, outputByteCount
    );
    if(overflowedByteCount >= outputByteCount) {
      return StopReason::OutputBufferFull; // outputByteCount can remain as-is
    }

    if(!this->isFinishing) {
      this->decompressor.readSegmentEnd();
      this->isFinishing = true;
    }

    if(this->writer.HasOverflowBytes()) {
      return StopReason::OutputBufferFull;
    } else {
      outputByteCount -= this->writer.GetRemainingByteCount();
      return StopReason::Finished;
    }

  }

  // ------------------------------------------------------------------------------------------- //

}}}} // namespace Nuclex::Storage::Compression::ZPaq

#endif // defined(NUCLEX_STORAGE_HAVE_ZPAQ)