#ifndef SENTRY_MEMSTREAM_H
#define SENTRY_MEMSTREAM_H

#include <istream>
#include <streambuf>

/// Stream buffer for in-memory buffers
///
/// Allows to stream from and to a raw buffer in memory that also implements
/// `seekg` and `tellp`. Since the buffer is const, this buffer can only be used
/// to construct an input stream.
///
/// See `imemstream` for an input stream implementation. Use `ostringstream` for
/// in-memory output operations.
struct membuf : std::streambuf {
  membuf(const char *base, size_t size) {
    char *p(const_cast<char *>(base));
    this->setg(p, p, p + size);
  }

 protected:
  pos_type seekoff(off_type off,
                   std::ios_base::seekdir dir,
                   std::ios_base::openmode which = std::ios_base::in) override {
    if (dir == std::ios_base::cur)
      gbump(off);
    else if (dir == std::ios_base::end)
      setg(eback(), egptr() + off, egptr());
    else if (dir == std::ios_base::beg)
      setg(eback(), eback() + off, egptr());
    return gptr() - eback();
  }

  pos_type seekpos(pos_type sp, std::ios_base::openmode which) override {
    return seekoff(sp - pos_type(off_type(0)), std::ios_base::beg, which);
  }
};

/// In-memory input stream from const raw buffers
///
/// Behaves just like an `istringstream` except that it does not clone the
/// underlying buffer. Use `ostringstream` as in-memory output stream.
struct imemstream : virtual membuf, std::istream {
  imemstream(char const *base, size_t size)
      : membuf(base, size), std::istream(static_cast<std::streambuf *>(this)) {
  }
};

#endif