#include "buffer.h"

namespace firebuf {

ConstBuffer::ConstBuffer(const char *buf, size_t len)
    : const_buf_(buf), len_(len) {}

size_t ConstBuffer::ReadMaxLen() const { return len_ - start_; }

const char *ConstBuffer::Read(size_t len) {
  if (ReadMaxLen() < len) {
    return nullptr;
  }
  const auto *ret = &const_buf_[start_];
  start_ += len;
  return ret;
}

bool ConstBuffer::Discard(size_t len) {
  if (len > ReadMaxLen()) {
    return false;
  }
  static_cast<void>(Read(len));
  return true;
}

void ConstBuffer::ResetRead() { start_ = commit_; }

void ConstBuffer::Commit() { commit_ = start_; }

void ConstBuffer::Reset() { commit_ = start_ = 0; }

Buffer::Buffer(char *buf, size_t size, size_t len)
    : ConstBuffer(buf, size), buf_(buf), size_(size) {
  len_ = len;
}

Buffer::Buffer(size_t size) : Buffer(new char[size], size, 0) {
  own_buf_.reset(buf_);
}

char *Buffer::WritePtr() { return &buf_[len_]; }

size_t Buffer::WriteMaxLen() const { return size_ - len_; }

bool Buffer::Write(const std::string_view &str) {
  if (WriteMaxLen() < str.size()) {
    return false;
  }
  memcpy(WritePtr(), str.data(), str.size());
  Wrote(str.size());
  return true;
}

void Buffer::Wrote(ssize_t len) {
  CHECK_LE(len, WriteMaxLen());
  len_ += len;
}

void Buffer::Consume() {
  if (commit_ == 0) {
    return;
  }
  memmove(buf_, &buf_[commit_], len_ - commit_);
  len_ -= commit_;
  start_ -= commit_;
  commit_ = 0;
}

void Buffer::Reset() {
  ConstBuffer::Reset();
  len_ = 0;
}

}  // namespace firebuf