/**  --------------------------------------------------------------------
 *  @file mime-inputsource.h
 *  @brief  The base class of the MIME input source
 *  @author Andreas Aardal Hanssen
 *  @date 2002-2005
 *  -----------------------------------------------------------------  **/
#ifndef mime_inputsource_h_included
#define mime_inputsource_h_included

#include <string.h>
#include <unistd.h>

namespace Binc {

  class MimeInputSource {
  public:
    inline MimeInputSource(int fd, unsigned int start = 0);
    virtual inline ~MimeInputSource(void);

    virtual inline bool fillInputBuffer(void);
    virtual inline void reset(void);

    inline void seek(unsigned int offset);
    inline bool getChar(char *c);
    inline void ungetChar(void);
    inline int getFileDescriptor(void) const;

    inline unsigned int getOffset(void) const;

  private:
    int fd;
    char data[16384];
    unsigned int offset;
    unsigned int tail;
    unsigned int head;
    unsigned int start;
    char lastChar;
  };

  inline MimeInputSource::MimeInputSource(int fd, unsigned int start)
  {
    this->fd = fd;
    this->start = start;
    offset = 0;
    tail = 0;
    head = 0;
    lastChar = '\0';
    memset(data, '\0', sizeof(data));

    seek(start);
  }

  inline MimeInputSource::~MimeInputSource(void)
  {
  }

  inline bool MimeInputSource::fillInputBuffer(void)
  {
    char raw[4096];
    ssize_t nbytes = read(fd, raw, sizeof(raw));
    if (nbytes <= 0) {
      // FIXME: If ferror(crlffile) we should log this.
      return false;
    }

    for (ssize_t i = 0; i < nbytes; ++i) {
      const char c = raw[i];
      if (c == '\r') {
        if (lastChar == '\r') {
          data[tail++ & (0x4000-1)] = '\r';
           data[tail++ & (0x4000-1)] = '\n';
        }
      } else if (c == '\n') {
        data[tail++ & (0x4000-1)] = '\r';
        data[tail++ & (0x4000-1)] = '\n';
      } else {
        if (lastChar == '\r') {
          data[tail++ & (0x4000-1)] = '\r';
          data[tail++ & (0x4000-1)] = '\n';
        }
        data[tail++ & (0x4000-1)] = c;
      }

      lastChar = c;
    }

    return true;
  }

  inline void MimeInputSource::reset(void)
  {
    offset = head = tail = 0;
    lastChar = '\0';

    if (fd != -1)
      lseek(fd, 0, SEEK_SET);
  }

  inline void MimeInputSource::seek(unsigned int seekToOffset)
  {
    if (offset > seekToOffset)
      reset();
   
    char c;
    int n = 0;
    while (seekToOffset > offset) {
      if (!getChar(&c)) break;
      ++n;
    }
  }

  inline bool MimeInputSource::getChar(char *c)
  {
    if (head == tail && !fillInputBuffer())
      return false;

    *c = data[head++ & (0x4000-1)];
    ++offset;
    return true;
  }

  inline void MimeInputSource::ungetChar()
  {
    --head;
    --offset;
  }

  inline int MimeInputSource::getFileDescriptor(void) const
  {
    return fd;
  }

  inline unsigned int MimeInputSource::getOffset(void) const
  {
    return offset;
  }
}

extern Binc::MimeInputSource *mimeSource;

#endif