// Copyright(c) 2018, Intel Corporation
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#pragma once
#include <chrono>
#include <cstdint>
#include <initializer_list>
#include <memory>
#include <thread>
#include <vector>

#include <opae/buffer.h>
#include <opae/cxx/core/except.h>
#include <opae/cxx/core/handle.h>

namespace opae {
namespace fpga {
namespace types {

/** Host/AFU shared memory blocks
 *
 * shared_buffer abstracts a memory block that may be shared
 * between the host cpu and an accelerator. The block may
 * be allocated by the shared_buffer class itself (see allocate),
 * or it may be allocated elsewhere and then attached to
 * a shared_buffer object via attach.
 */
class shared_buffer {
 public:
  typedef std::size_t size_t;
  typedef std::shared_ptr<shared_buffer> ptr_t;

  shared_buffer(const shared_buffer &) = delete;
  shared_buffer &operator=(const shared_buffer &) = delete;

  /** shared_buffer destructor.
   */
  virtual ~shared_buffer();

  /** shared_buffer factory method - allocate a shared_buffer.
   * @param[in] handle The handle used to allocate the buffer.
   * @param[in] len    The length in bytes of the requested buffer.
   * @return A valid shared_buffer smart pointer on success, or an
   * empty smart pointer on failure.
   */
  static shared_buffer::ptr_t allocate(handle::ptr_t handle, size_t len,
                                       bool read_only = false);

  /** Attach a pre-allocated buffer to a shared_buffer object.
   *
   * @param[in] handle The handle used to attach the buffer.
   * @param[in] base The base of the pre-allocated memory.
   * @param[in] len The size of the pre-allocated memory,
   * which must be a multiple of the page size.
   * @return A valid shared_buffer smart pointer on success, or an
   * empty smart pointer on failure.
   */
  static shared_buffer::ptr_t attach(handle::ptr_t handle, uint8_t *base,
                                     size_t len, bool read_only = false);

  /**
   * @brief Disassociate the shared_buffer object from the resource used to
   * create it. If the buffer was allocated using the allocate function then
   * the buffer is freed.
   */
  void release();

  /** Retrieve the virtual address of the buffer base.
   *
   *  @note Instances of a shared buffer can only be created using either
   *  'allocate' or 'attach' static factory function. Because these
   *  functions return a shared pointer (std::shared_ptr) to the instance,
   *  references to an instance are counted automatically by design of the
   *  shared_ptr class. Calling 'c_type()' function is provided to get access
   *  to the raw data but isn't used in tracking its reference count.
   *  Assigning this to a variable should be done in limited scopes as this
   *  variable can be defined in an outer scope and may outlive the
   *  shared_buffer object. Once the reference count in the shared_ptr reaches
   *  zero, the shared_buffer object will be released and deallocated, turning
   *  any variables assigned from a call to 'c_type()' into dangling pointers.
   */
  volatile uint8_t *c_type() const { return virt_; }

  /** Retrieve the handle smart pointer associated with
   * this buffer.
   */
  handle::ptr_t owner() const { return handle_; }

  /** Retrieve the length of the buffer in bytes.
   */
  size_t size() const { return len_; }

  /** Retrieve the underlying buffer's workspace id.
   */
  uint64_t wsid() const { return wsid_; }

  /** Retrieve the address of the buffer suitable for
   * programming into the accelerator device.
   */
  uint64_t io_address() const { return io_address_; }

  /** Write c to each byte location in the buffer.
   */
  void fill(int c);

  /** Compare this shared_buffer (the first len bytes)
   * to that held in other, using memcmp().
   */
  int compare(ptr_t other, size_t len) const;

  /** Read a T-sized block of memory at the given location.
   * @param[in] offset The byte offset from the start of the buffer.
   * @return A T from buffer base + offset.
   */
  template <typename T>
  T read(size_t offset) const {
    if ((offset < len_) && (virt_ != nullptr)) {
      return *reinterpret_cast<T *>(virt_ + offset);
    } else if (offset >= len_) {
      throw except(OPAECXX_HERE);
    } else {
      throw except(OPAECXX_HERE);
    }
    return T();
  }

  /** Write a T-sized block of memory to the given location.
   * @param[in] value The value to write.
   * @param[in] offset The byte offset from the start of the buffer.
   */
  template <typename T>
  void write(const T &value, size_t offset) {
    if ((offset < len_) && (virt_ != nullptr)) {
      *reinterpret_cast<T *>(virt_ + offset) = value;
    } else if (offset >= len_) {
      throw except(OPAECXX_HERE);
    } else {
      throw except(OPAECXX_HERE);
    }
  }

 protected:
  shared_buffer(handle::ptr_t handle, size_t len, uint8_t *virt, uint64_t wsid,
                uint64_t io_address);

  handle::ptr_t handle_;
  size_t len_;
  uint8_t *virt_;
  uint64_t wsid_;
  uint64_t io_address_;
};

}  // end of namespace types
}  // end of namespace fpga
}  // end of namespace opae