#ifndef STAN_MATH_REV_CORE_RECOVER_MEMORY_NESTED_HPP
#define STAN_MATH_REV_CORE_RECOVER_MEMORY_NESTED_HPP

#include <stan/math/rev/core/chainable_alloc.hpp>
#include <stan/math/rev/core/chainablestack.hpp>
#include <stan/math/rev/core/empty_nested.hpp>
#include <stdexcept>

namespace stan {
namespace math {

/**
 * Recover only the memory used for the top nested call.  If there
 * is nothing on the nested stack, then a
 * <code>std::logic_error</code> exception is thrown.
 *
 * It is preferred to use the <code>nested_rev_autodiff</code> class for
 * nested autodiff as it handles recovery of memory automatically.
 *
 * @throw std::logic_error if <code>empty_nested()</code> returns
 * <code>true</code>
 */
static inline void recover_memory_nested() {
  if (empty_nested()) {
    throw std::logic_error(
        "empty_nested() must be false"
        " before calling recover_memory_nested()");
  }

  ChainableStack::instance_->var_stack_.resize(
      ChainableStack::instance_->nested_var_stack_sizes_.back());
  ChainableStack::instance_->nested_var_stack_sizes_.pop_back();

  ChainableStack::instance_->var_nochain_stack_.resize(
      ChainableStack::instance_->nested_var_nochain_stack_sizes_.back());
  ChainableStack::instance_->nested_var_nochain_stack_sizes_.pop_back();

  for (size_t i
       = ChainableStack::instance_->nested_var_alloc_stack_starts_.back();
       i < ChainableStack::instance_->var_alloc_stack_.size(); ++i) {
    delete ChainableStack::instance_->var_alloc_stack_[i];
  }
  ChainableStack::instance_->var_alloc_stack_.resize(
      ChainableStack::instance_->nested_var_alloc_stack_starts_.back());
  ChainableStack::instance_->nested_var_alloc_stack_starts_.pop_back();

  ChainableStack::instance_->memalloc_.recover_nested();
}

}  // namespace math
}  // namespace stan
#endif
