#include <iostream>
#include <memory>
#include <string>
#include <vector>
#include <cstring>

#include "Utilities/Xerces/interface/Xerces.h"
#include <xercesc/util/XMLString.hpp>
#include <xercesc/util/XMLUni.hpp>
#include <xercesc/sax2/SAX2XMLReader.hpp>
#include <xercesc/sax2/XMLReaderFactory.hpp>

#include "FWCore/Utilities/interface/Exception.h"
#include "FWCore/Utilities/interface/EDMException.h"

#include "Utilities/StorageFactory/interface/IOTypes.h"
#include "Utilities/StorageFactory/interface/Storage.h"

#include "XMLUtils.h"

XERCES_CPP_NAMESPACE_USE

using namespace edm::storage;
namespace lhef {

  StorageWrap::StorageWrap(std::unique_ptr<Storage> storage) : storage(std::move(storage)) {}

  StorageWrap::~StorageWrap() { storage->close(); }

  unsigned int XMLDocument::XercesPlatform::instances = 0;

  XMLDocument::XercesPlatform::XercesPlatform() {
    if (!instances++) {
      try {
        cms::concurrency::xercesInitialize();
      } catch (const XMLException &e) {
        throw cms::Exception("XMLDocument") << "cms::concurrency::xercesInitialize failed "
                                               "because of: "
                                            << XMLSimpleStr(e.getMessage()) << std::endl;
      }
    }
  }

  XMLDocument::XercesPlatform::~XercesPlatform() {
    if (!--instances)
      cms::concurrency::xercesTerminate();
  }

  XMLDocument::XMLDocument(std::unique_ptr<std::istream> &in, Handler &handler)
      : platform(new XercesPlatform()),
        source(new STLInputSource(in)),
        parser(XMLReaderFactory::createXMLReader()),
        done(false) {
    init(handler);
  }

  XMLDocument::XMLDocument(std::unique_ptr<StorageWrap> &in, Handler &handler)
      : platform(new XercesPlatform()),
        source(new StorageInputSource(in)),
        parser(XMLReaderFactory::createXMLReader()),
        done(false) {
    init(handler);
  }

  void XMLDocument::init(Handler &handler) {
    try {
      parser->setFeature(XMLUni::fgSAX2CoreValidation, false);
      parser->setFeature(XMLUni::fgSAX2CoreNameSpaces, false);
      parser->setFeature(XMLUni::fgXercesSchema, false);
      parser->setFeature(XMLUni::fgXercesSchemaFullChecking, false);

      parser->setContentHandler(&handler);
      parser->setLexicalHandler(&handler);
      parser->setErrorHandler(&handler);

      if (!parser->parseFirst(*source, token))
        throw cms::Exception("XMLParseError") << "SAXParser::parseFirst failed" << std::endl;
    } catch (const XMLException &e) {
      throw cms::Exception("XMLDocument")
          << "cms::concurrency::xercesInitialize failed because of " << XMLSimpleStr(e.getMessage()) << std::endl;
    } catch (const SAXException &e) {
      throw cms::Exception("XMLDocument")
          << "XML parser reported: " << XMLSimpleStr(e.getMessage()) << "." << std::endl;
    }
  }

  XMLDocument::~XMLDocument() {}

  bool XMLDocument::parse() {
    try {
      if (done || parser->getErrorCount())
        return false;

      done = !parser->parseNext(token);
    } catch (const XMLException &e) {
      throw cms::Exception("XMLDocument")
          << "cms::concurrency::xercesInitialize failed because of " << XMLSimpleStr(e.getMessage()) << std::endl;
    } catch (const SAXException &e) {
      throw cms::Exception("XMLDocument")
          << "XML parser reported: " << XMLSimpleStr(e.getMessage()) << "." << std::endl;
    }

    return !done;
  }

  CBInputStream::Reader::~Reader() {}

  CBInputStream::CBInputStream(Reader &reader) : reader(reader) {}

  CBInputStream::~CBInputStream() {}

  XMLSize_t CBInputStream::readBytes(XMLByte *const buf, const XMLSize_t size) {
    char *rawBuf = reinterpret_cast<char *>(buf);
    unsigned int bytes = size * sizeof(XMLByte);
    unsigned int read = 0;

    while (read < bytes) {
      if (buffer.empty()) {
        buffer = reader.data();
        if (buffer.empty())
          break;
      }

      unsigned int len = buffer.length();
      unsigned int rem = bytes - read;
      if (rem < len) {
        std::memcpy(rawBuf + read, buffer.c_str(), rem);
        buffer.erase(0, rem);
        read += rem;
        break;
      }

      std::memcpy(rawBuf + read, buffer.c_str(), len);
      buffer.clear();
      read += len;
    }

    read /= sizeof(XMLByte);
    pos += read;

    return read;
  }

  STLInputStream::STLInputStream(std::istream &in) : in(in) {
    if (in.bad())
      throw cms::Exception("FileStreamError") << "I/O stream bad in STLInputStream::STLInputStream()" << std::endl;
  }

  STLInputStream::~STLInputStream() {}

  XMLSize_t STLInputStream::readBytes(XMLByte *const buf, const XMLSize_t size) {
    char *rawBuf = reinterpret_cast<char *>(buf);
    unsigned int bytes = size * sizeof(XMLByte);
    in.read(rawBuf, bytes);
    unsigned int readBytes = in.gcount();

    if (in.bad())
      throw cms::Exception("FileStreamError") << "I/O stream bad in STLInputStream::readBytes()" << std::endl;

    unsigned int read = (unsigned int)(readBytes / sizeof(XMLByte));
    unsigned int rest = (unsigned int)(readBytes % sizeof(XMLByte));
    for (unsigned int i = 1; i <= rest; i++)
      in.putback(rawBuf[readBytes - i]);

    pos += read;
    return read;
  }

  StorageInputStream::StorageInputStream(StorageWrap &in)
      : in(in), lstr(LZMA_STREAM_INIT), compression_(false), lasttotal_(0) {
    buffer_.reserve(bufferSize_);
    // Check the kind of file.
    char header[6];
    /*unsigned int s = */ in->read(header, 6);
    in->position(0, Storage::SET);
    // Let's use lzma to start with.
    if (header[1] == '7' && header[2] == 'z' && header[3] == 'X' && header[4] == 'Z') {
      compression_ = true;
      lstr = LZMA_STREAM_INIT;
      // We store the beginning of the outBuffer to make sure
      // we can always update previous results.

#if LZMA_VERSION <= UINT32_C(49990030)
      int ret = lzma_auto_decoder(&lstr, NULL, NULL);
#else
      int ret = lzma_auto_decoder(&lstr, -1, 0);
#endif

      if (ret != LZMA_OK) {
        lzma_end(&lstr);
        throw cms::Exception("IO") << "Error while reading compressed LHE file";
      }
    }
  }

  StorageInputStream::~StorageInputStream() { lzma_end(&(lstr)); }

  XMLSize_t StorageInputStream::readBytes(XMLByte *const buf, const XMLSize_t size) {
    // Compression code is not able to handle sizeof(XMLByte) > 1.
    assert(sizeof(XMLByte) == sizeof(unsigned char));

    if (!(buffLoc_ < buffTotal_)) {
      int rd = in->read((void *)&buffer_[0], buffer_.capacity());
      // Storage layer is supposed to throw exceptions instead of returning errors; just-in-case
      if (rd < 0) {
        edm::Exception ex(edm::errors::FileReadError);
        ex << "Error while reading buffered LHE file";
        throw ex;
      }
      buffLoc_ = 0;
      buffTotal_ = rd;
      if (buffTotal_ == 0) {
        return 0;
      }
    }
    unsigned int dataRead;
    if (!compression_) {
      dataRead = std::min(buffTotal_ - buffLoc_, static_cast<unsigned int>(size));
      memcpy(buf, &buffer_[buffLoc_], dataRead);
      buffLoc_ += dataRead;
    } else {
      dataRead = buffTotal_ - buffLoc_;
      lstr.next_in = &buffer_[buffLoc_];
      lstr.avail_in = dataRead;
      lstr.next_out = buf;
      lstr.avail_out = size;
      int ret = lzma_code(&lstr, LZMA_RUN);
      if (ret != LZMA_OK && ret != LZMA_STREAM_END) { /* decompression error */
        lzma_end(&lstr);
        throw cms::Exception("IO") << "Error while reading compressed LHE file (error code " << ret << ")";
      }
      dataRead -= lstr.avail_in;
      buffLoc_ += dataRead;
      // Decoder was unable to make progress; reset stream and try again.
      // If this becomes problematic, we can make the buffer circular.
      if (!dataRead) {
        // NOTE: lstr.avail_in == buffTotal-buffLoc_
        in->position(-(IOOffset)(lstr.avail_in), Storage::CURRENT);
        buffLoc_ = 0;
        buffTotal_ = 0;
        return readBytes(buf, size);
      }
      dataRead = (size - lstr.avail_out);
    }
    return dataRead;
  }

}  // namespace lhef