// Copyright 2014 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 CC_SURFACES_SURFACE_MANAGER_H_
#define CC_SURFACES_SURFACE_MANAGER_H_

#include <stdint.h>

#include <list>
#include <memory>
#include <unordered_map>
#include <unordered_set>
#include <vector>

#include "base/macros.h"
#include "base/observer_list.h"
#include "base/threading/thread_checker.h"
#include "cc/surfaces/frame_sink_id.h"
#include "cc/surfaces/surface_id.h"
#include "cc/surfaces/surface_observer.h"
#include "cc/surfaces/surface_sequence.h"
#include "cc/surfaces/surfaces_export.h"

namespace cc {
class BeginFrameSource;
class CompositorFrame;
class Surface;
class SurfaceFactoryClient;

class CC_SURFACES_EXPORT SurfaceManager {
 public:
  SurfaceManager();
  ~SurfaceManager();

  void RegisterSurface(Surface* surface);
  void DeregisterSurface(const SurfaceId& surface_id);

  // Destroy the Surface once a set of sequence numbers has been satisfied.
  void Destroy(std::unique_ptr<Surface> surface);

  Surface* GetSurfaceForId(const SurfaceId& surface_id);

  void AddObserver(SurfaceObserver* obs) { observer_list_.AddObserver(obs); }

  void RemoveObserver(SurfaceObserver* obs) {
    observer_list_.RemoveObserver(obs);
  }

  bool SurfaceModified(const SurfaceId& surface_id);

  // Called when a CompositorFrame is submitted to a SurfaceFactory for a given
  // |surface_id| for the first time.
  void SurfaceCreated(const SurfaceId& surface_id,
                      const gfx::Size& frame_size,
                      float device_scale_factor);

  // A frame for a surface satisfies a set of sequence numbers in a particular
  // id namespace.
  void DidSatisfySequences(const FrameSinkId& frame_sink_id,
                           std::vector<uint32_t>* sequence);

  void RegisterFrameSinkId(const FrameSinkId& frame_sink_id);

  // Invalidate a frame_sink_id that might still have associated sequences,
  // possibly because a renderer process has crashed.
  void InvalidateFrameSinkId(const FrameSinkId& frame_sink_id);

  // Adds a reference from a parent surface to a child surface. Any surface
  // embedding a child surface should have a reference added so that the child
  // surface is not garbage collected until after the parent surface.
  void AddSurfaceReference(const SurfaceId& parent_id,
                           const SurfaceId& child_id);

  // Removes a reference from a parent surface to a child surface.
  void RemoveSurfaceReference(const SurfaceId& parent_id,
                              const SurfaceId& child_id);

  // Returns the number of surfaces that have references to |surface_id|. When
  // the count is zero nothing is referencing the surface and it may be garbage
  // collected.
  size_t GetSurfaceReferenceCount(const SurfaceId& surface_id) const;

  // Returns the number of surfaces that |surface_id| has references to.
  size_t GetReferencedSurfaceCount(const SurfaceId& surface_id) const;

  // SurfaceFactoryClient, hierarchy, and BeginFrameSource can be registered
  // and unregistered in any order with respect to each other.
  //
  // This happens in practice, e.g. the relationship to between ui::Compositor /
  // DelegatedFrameHost is known before ui::Compositor has a surface/client).
  // However, DelegatedFrameHost can register itself as a client before its
  // relationship with the ui::Compositor is known.

  // Associates a SurfaceFactoryClient with the surface id frame_sink_id it
  // uses.
  // SurfaceFactoryClient and surface namespaces/allocators have a 1:1 mapping.
  // Caller guarantees the client is alive between register/unregister.
  // Reregistering the same namespace when a previous client is active is not
  // valid.
  void RegisterSurfaceFactoryClient(const FrameSinkId& frame_sink_id,
                                    SurfaceFactoryClient* client);
  void UnregisterSurfaceFactoryClient(const FrameSinkId& frame_sink_id);

  // Associates a |source| with a particular namespace.  That namespace and
  // any children of that namespace with valid clients can potentially use
  // that |source|.
  void RegisterBeginFrameSource(BeginFrameSource* source,
                                const FrameSinkId& frame_sink_id);
  void UnregisterBeginFrameSource(BeginFrameSource* source);

  // Register a relationship between two namespaces.  This relationship means
  // that surfaces from the child namespace will be displayed in the parent.
  // Children are allowed to use any begin frame source that their parent can
  // use.
  void RegisterFrameSinkHierarchy(const FrameSinkId& parent_frame_sink_id,
                                  const FrameSinkId& child_frame_sink_id);
  void UnregisterFrameSinkHierarchy(const FrameSinkId& parent_frame_sink_id,
                                    const FrameSinkId& child_frame_sink_id);

  const SurfaceId& GetRootSurfaceId() { return kRootSurfaceId; }

 private:
  void RecursivelyAttachBeginFrameSource(const FrameSinkId& frame_sink_id,
                                         BeginFrameSource* source);
  void RecursivelyDetachBeginFrameSource(const FrameSinkId& frame_sink_id,
                                         BeginFrameSource* source);
  // Returns true if |child namespace| is or has |search_frame_sink_id| as a
  // child.
  bool ChildContains(const FrameSinkId& child_frame_sink_id,
                     const FrameSinkId& search_frame_sink_id) const;

  void GarbageCollectSurfaces();

  // Removes reference from a parent surface to a child surface. Used to remove
  // references without triggered GC.
  void RemoveSurfaceReferenceImpl(const SurfaceId& parent_id,
                                  const SurfaceId& child_id);

  using SurfaceMap = std::unordered_map<SurfaceId, Surface*, SurfaceIdHash>;
  SurfaceMap surface_map_;
  base::ObserverList<SurfaceObserver> observer_list_;
  base::ThreadChecker thread_checker_;

  // List of surfaces to be destroyed, along with what sequences they're still
  // waiting on.
  using SurfaceDestroyList = std::list<std::unique_ptr<Surface>>;
  SurfaceDestroyList surfaces_to_destroy_;

  // Set of SurfaceSequences that have been satisfied by a frame but not yet
  // waited on.
  std::unordered_set<SurfaceSequence, SurfaceSequenceHash> satisfied_sequences_;

  // Set of valid surface ID namespaces. When a namespace is removed from
  // this set, any remaining sequences with that namespace are considered
  // satisfied.
  std::unordered_set<FrameSinkId, FrameSinkIdHash> valid_frame_sink_ids_;

  // Begin frame source routing. Both BeginFrameSource and SurfaceFactoryClient
  // pointers guaranteed alive by callers until unregistered.
  struct FrameSinkSourceMapping {
    FrameSinkSourceMapping();
    FrameSinkSourceMapping(const FrameSinkSourceMapping& other);
    ~FrameSinkSourceMapping();
    bool is_empty() const { return !client && children.empty(); }
    // The client that's responsible for creating this namespace.  Never null.
    SurfaceFactoryClient* client;
    // The currently assigned begin frame source for this client.
    BeginFrameSource* source;
    // This represents a dag of parent -> children mapping.
    std::vector<FrameSinkId> children;
  };
  std::unordered_map<FrameSinkId, FrameSinkSourceMapping, FrameSinkIdHash>
      frame_sink_source_map_;

  using SurfaceIdSet = std::unordered_set<SurfaceId, SurfaceIdHash>;
  // Tracks references from the child surface to parent surface. If there are
  // zero entries in the set for a SurfaceId then nothing is referencing the
  // surface and it can be garbage collected.
  std::unordered_map<SurfaceId, SurfaceIdSet, SurfaceIdHash>
      child_to_parent_refs_;
  // Tracks references from the parent surface to child surface. Is the inverse
  // of |child_to_parent_refs_|.
  std::unordered_map<SurfaceId, SurfaceIdSet, SurfaceIdHash>
      parent_to_child_refs_;

  // Set of which sources are registered to which namespace.  Any child
  // that is implicitly using this namespace must be reachable by the
  // parent in the dag.
  std::unordered_map<BeginFrameSource*, FrameSinkId> registered_sources_;

  // Root SurfaceId that references display root surfaces. There is no Surface
  // with this id, it's for bookkeeping purposes only.
  const SurfaceId kRootSurfaceId;

  DISALLOW_COPY_AND_ASSIGN(SurfaceManager);
};

}  // namespace cc

#endif  // CC_SURFACES_SURFACE_MANAGER_H_