// Copyright 2020 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef SRC_LIB_ANALYTICS_CPP_GOOGLE_ANALYTICS_CLIENT_H_
#define SRC_LIB_ANALYTICS_CPP_GOOGLE_ANALYTICS_CLIENT_H_

#include <lib/fpromise/promise.h>

#include <string>

#include "src/lib/analytics/cpp/google_analytics/general_parameters.h"
#include "src/lib/analytics/cpp/google_analytics/hit.h"

namespace analytics::google_analytics {

// This is an abstract class for Google Analytics client, where the actual HTTP communications are
// left unimplemented. This is because to provide non-blocking HTTP communications, we have to rely
// on certain async mechanism (such as message loop), which is usually chosen by the embedding app.
// To use this class, the embedding app only needs to implement the SendData() method.
//
// Example usage:
//
//     auto ga_client = SomeClientImplementation();
//     ga_client.SetTrackingId("UA-123456-1");
//     ga_client.SetClientId("5555");
//     ga_client.SetUserAgent("Example Agent")
//     int64_t value = 12345;
//     auto event = Event("category", "action", "label", value);
//     ga_client.AddHit(event)
//
// For an example implementation, please see
// //src/developer/debug/zxdb/console/google_analytics_client.[cc,h]
// For a full usage example, please see
// //src/developer/debug/zxdb/console/google_analytics_client_manualtest.[cc,h]
class Client {
 public:
  static constexpr char kEndpoint[] = "https://www.google-analytics.com/collect";

  Client();
  Client(const Client&) = delete;

  virtual ~Client() = default;

  void SetUserAgent(std::string_view user_agent) { user_agent_ = user_agent; }
  void SetTrackingId(std::string_view tracking_id);
  void SetClientId(std::string_view client_id);
  // Add parameters shared by all metrics, for example, an (application name).
  void AddSharedParameters(const GeneralParameters& shared_parameters);

  void AddHit(const Hit& hit);

 private:
  bool IsReady() const;
  virtual void SendData(std::string_view user_agent,
                        std::map<std::string, std::string> parameters) = 0;

  std::string user_agent_;
  // Stores shared parameters
  std::map<std::string, std::string> shared_parameters_;
};

}  // namespace analytics::google_analytics

#endif  // SRC_LIB_ANALYTICS_CPP_GOOGLE_ANALYTICS_CLIENT_H_