// Copyright 2016 The Chromium 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 CONTENT_BROWSER_DEVTOOLS_DEVTOOLS_SESSION_H_
#define CONTENT_BROWSER_DEVTOOLS_DEVTOOLS_SESSION_H_

#include <list>
#include <map>
#include <memory>
#include <string>

#include "base/containers/flat_map.h"
#include "base/containers/span.h"
#include "base/memory/weak_ptr.h"
#include "base/optional.h"
#include "base/values.h"
#include "content/browser/devtools/protocol/forward.h"
#include "content/public/browser/devtools_agent_host_client_channel.h"
#include "content/public/browser/devtools_external_agent_proxy.h"
#include "mojo/public/cpp/bindings/associated_receiver.h"
#include "mojo/public/cpp/bindings/associated_remote.h"
#include "mojo/public/cpp/bindings/remote.h"
#include "third_party/blink/public/mojom/devtools/devtools_agent.mojom.h"

namespace content {

class DevToolsAgentHostClient;
class DevToolsAgentHostImpl;
class DevToolsExternalAgentProxyDelegate;

namespace protocol {
class DevToolsDomainHandler;
}

class DevToolsSession : public protocol::FrontendChannel,
                        public blink::mojom::DevToolsSessionHost,
                        public DevToolsExternalAgentProxy,
                        public content::DevToolsAgentHostClientChannel {
 public:
  DevToolsSession(DevToolsAgentHostClient* client,
                  const std::string& session_id);
  ~DevToolsSession() override;

  void SetAgentHost(DevToolsAgentHostImpl* agent_host);
  void SetRuntimeResumeCallback(base::OnceClosure runtime_resume);
  bool IsWaitingForDebuggerOnStart() const;
  void Dispose();

  // content::DevToolsAgentHostClientChannel implementation.
  content::DevToolsAgentHost* GetAgentHost() override;
  content::DevToolsAgentHostClient* GetClient() override;

  DevToolsSession* GetRootSession();

  // Browser-only sessions do not talk to mojom::DevToolsAgent, but instead
  // handle all protocol messages locally in the browser process.
  void SetBrowserOnly(bool browser_only);
  void AddHandler(std::unique_ptr<protocol::DevToolsDomainHandler> handler);
  void TurnIntoExternalProxy(DevToolsExternalAgentProxyDelegate* delegate);

  void AttachToAgent(blink::mojom::DevToolsAgent* agent,
                     bool force_using_io_session);
  void DispatchProtocolMessage(base::span<const uint8_t> message);
  void SuspendSendingMessagesToAgent();
  void ResumeSendingMessagesToAgent();
  void ClearPendingMessages();

  using HandlersMap =
      base::flat_map<std::string,
                     std::unique_ptr<protocol::DevToolsDomainHandler>>;
  HandlersMap& handlers() { return handlers_; }

  DevToolsSession* AttachChildSession(const std::string& session_id,
                                      DevToolsAgentHostImpl* agent_host,
                                      DevToolsAgentHostClient* client);
  void DetachChildSession(const std::string& session_id);
  bool HasChildSession(const std::string& session_id);

 private:
  struct PendingMessage {
    int call_id;
    std::string method;
    std::vector<uint8_t> payload;

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

    PendingMessage(PendingMessage&&);
    PendingMessage(int call_id,
                   crdtp::span<uint8_t> method,
                   crdtp::span<uint8_t> payload);
    ~PendingMessage();
  };

  void MojoConnectionDestroyed();
  void DispatchToAgent(const PendingMessage& message);
  void HandleCommand(base::span<const uint8_t> message);
  void HandleCommandInternal(crdtp::Dispatchable dispatchable,
                             base::span<const uint8_t> message);
  void DispatchProtocolMessageInternal(crdtp::Dispatchable dispatchable,
                                       base::span<const uint8_t> message);

  // protocol::FrontendChannel implementation.
  void SendProtocolResponse(
      int call_id,
      std::unique_ptr<protocol::Serializable> message) override;
  void SendProtocolNotification(
      std::unique_ptr<protocol::Serializable> message) override;
  void FlushProtocolNotifications() override;
  void FallThrough(int call_id,
                   crdtp::span<uint8_t> method,
                   crdtp::span<uint8_t> message) override;

  // content::DevToolsAgentHostClientChannel implementation.
  void DispatchProtocolMessageToClient(std::vector<uint8_t> message) override;

  // blink::mojom::DevToolsSessionHost implementation.
  void DispatchProtocolResponse(
      blink::mojom::DevToolsMessagePtr message,
      int call_id,
      blink::mojom::DevToolsSessionStatePtr updates) override;
  void DispatchProtocolNotification(
      blink::mojom::DevToolsMessagePtr message,
      blink::mojom::DevToolsSessionStatePtr updates) override;

  // DevToolsExternalAgentProxy implementation.
  void DispatchOnClientHost(base::span<const uint8_t> message) override;
  void ConnectionClosed() override;

  // Merges the |updates| received from the renderer into session_state_cookie_.
  void ApplySessionStateUpdates(blink::mojom::DevToolsSessionStatePtr updates);

  mojo::AssociatedReceiver<blink::mojom::DevToolsSessionHost> receiver_{this};
  mojo::AssociatedRemote<blink::mojom::DevToolsSession> session_;
  mojo::Remote<blink::mojom::DevToolsSession> io_session_;
  bool use_io_session_{false};
  DevToolsAgentHostImpl* agent_host_ = nullptr;
  DevToolsAgentHostClient* client_;
  bool browser_only_ = false;
  HandlersMap handlers_;
  std::unique_ptr<protocol::UberDispatcher> dispatcher_;

  bool suspended_sending_messages_to_agent_ = false;

  // Messages that were sent to the agent or queued after suspending.
  std::list<PendingMessage> pending_messages_;
  // Pending messages that were sent and are thus waiting for a response.
  base::flat_map<int, std::list<PendingMessage>::iterator>
      waiting_for_response_;

  // |session_state_cookie_| always corresponds to a state before
  // any of the waiting for response messages have been handled.
  // |session_state_cookie_| is nullptr before first attach.
  blink::mojom::DevToolsSessionStatePtr session_state_cookie_;

  DevToolsSession* root_session_ = nullptr;
  std::string session_id_;  // empty if this is the root session.
  base::flat_map<std::string, DevToolsSession*> child_sessions_;
  base::OnceClosure runtime_resume_;
  DevToolsExternalAgentProxyDelegate* proxy_delegate_ = nullptr;

  base::WeakPtrFactory<DevToolsSession> weak_factory_{this};
};

}  // namespace content

#endif  // CONTENT_BROWSER_DEVTOOLS_DEVTOOLS_SESSION_H_