#pragma once

#include <memory>

#include <string>

#include "envoy/common/pure.h"

#include "envoy/http/header_map.h"

#include "envoy/tracing/trace_reason.h"

namespace Envoy {

namespace Http {

/**

 * Abstract request id utilities for getting/setting the request IDs and tracing status of requests

 */

class RequestIDExtension {

public:

  /**

   *  Get the request ID from the request headers.

   * @param request_headers supplies the incoming request headers for retrieving the request ID.

   * @return the string view or nullopt if the request ID is invalid.

   */

  virtual absl::optional<absl::string_view>

  get(const Http::RequestHeaderMap& request_headers) const PURE;

  /**

   * Get and convert the request ID to a 64-bit integer representation for using in modulo, etc.

   * calculations.

   * @param request_headers supplies the incoming request headers for retrieving the request ID.

   * @return the integer or nullopt if the request ID is invalid.

   */

  virtual absl::optional<uint64_t>

  getInteger(const Http::RequestHeaderMap& request_headers) const PURE;

  /**

   * Directly set a request ID into the provided request headers. Override any previous request ID

   * if any.

   * @param request_headers supplies the incoming request headers for setting a request ID.

   * @param edge_request whether the request is an edge request.

   * @param keep_external_id whether to preserve the request ID from external requests.

   */

  virtual void set(Http::RequestHeaderMap& request_headers, bool edge_request,

                   bool keep_external_id) PURE;

  /**

   * Preserve request ID in response headers if any is set in the request headers.

   * @param response_headers supplies the downstream response headers for setting the request ID.

   * @param request_headers supplies the incoming request headers for retrieving the request ID.

   */

  virtual void setInResponse(Http::ResponseHeaderMap& response_headers,

                             const Http::RequestHeaderMap& request_headers) PURE;

  /**

   * Get the current tracing reason of a request given its headers.

   * @param request_headers supplies the incoming request headers for retrieving the request ID.

   * @return trace reason of the request based on the given headers.

   */

  virtual Tracing::Reason getTraceReason(const Http::RequestHeaderMap& request_headers) PURE;

  /**

   * Set the tracing status of a request.

   * @param request_headers supplies the incoming request headers for setting the trace reason.

   * @param status the trace reason that should be set for this request.

   */

  virtual void setTraceReason(Http::RequestHeaderMap& request_headers, Tracing::Reason reason) PURE;

  /**

   * Get whether to use request_id based sampling policy or not.

   * @return whether to use request_id based sampling policy or not.

   */

  virtual bool useRequestIdForTraceSampling() const PURE;

};

using RequestIDExtensionSharedPtr = std::shared_ptr<RequestIDExtension>;

} // namespace Http

} // namespace Envoy