// Copyright (c) 2013 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_INDEXED_DB_INDEXED_DB_TRANSACTION_H_
#define CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_TRANSACTION_H_

#include <queue>
#include <set>
#include <stack>

#include "base/basictypes.h"
#include "base/memory/ref_counted.h"
#include "base/memory/scoped_ptr.h"
#include "base/time/time.h"
#include "content/browser/indexed_db/indexed_db_backing_store.h"
#include "content/browser/indexed_db/indexed_db_database.h"
#include "content/browser/indexed_db/indexed_db_database_error.h"

namespace content {

class IndexedDBCursor;
class IndexedDBDatabaseCallbacks;

class IndexedDBTransaction : public base::RefCounted<IndexedDBTransaction> {
 public:
  typedef base::Callback<void(IndexedDBTransaction*)> Operation;

  IndexedDBTransaction(int64 id,
                       scoped_refptr<IndexedDBDatabaseCallbacks> callbacks,
                       const std::set<int64>& object_store_ids,
                       indexed_db::TransactionMode,
                       IndexedDBDatabase* db);

  virtual void Abort();
  void Commit();

  void Abort(const IndexedDBDatabaseError& error);
  void Run();
  indexed_db::TransactionMode mode() const { return mode_; }
  const std::set<int64>& scope() const { return object_store_ids_; }
  void ScheduleTask(Operation task) {
    ScheduleTask(IndexedDBDatabase::NORMAL_TASK, task);
  }

  void ScheduleTask(Operation task, Operation abort_task);
  void ScheduleTask(IndexedDBDatabase::TaskType, Operation task);
  void RegisterOpenCursor(IndexedDBCursor* cursor);
  void UnregisterOpenCursor(IndexedDBCursor* cursor);
  void AddPreemptiveEvent() { pending_preemptive_events_++; }
  void DidCompletePreemptiveEvent() {
    pending_preemptive_events_--;
    DCHECK_GE(pending_preemptive_events_, 0);
  }
  IndexedDBBackingStore::Transaction* BackingStoreTransaction() {
    return &transaction_;
  }
  int64 id() const { return id_; }

  IndexedDBDatabase* database() const { return database_; }
  IndexedDBDatabaseCallbacks* connection() const { return callbacks_; }
  bool IsRunning() const { return state_ == RUNNING; }

  // The following types/accessors are for diagnostics only.
  enum QueueStatus {
    CREATED,
    BLOCKED,
    UNBLOCKED,
  };

  QueueStatus queue_status() const { return queue_status_; }
  void set_queue_status(QueueStatus status) { queue_status_ = status; }
  base::Time creation_time() const { return creation_time_; }
  base::Time start_time() const { return start_time_; }
  int tasks_scheduled() const { return tasks_scheduled_; }
  int tasks_completed() const { return tasks_completed_; }

 protected:
  virtual ~IndexedDBTransaction();
  friend class base::RefCounted<IndexedDBTransaction>;

 private:
  enum State {
    UNUSED,         // Created, but no tasks yet.
    START_PENDING,  // Enqueued tasks, but backing store transaction not yet
                    // started.
    RUNNING,        // Backing store transaction started but not yet finished.
    FINISHED,       // Either aborted or committed.
  };

  void EnsureTasksRunning();
  void Start();

  bool IsTaskQueueEmpty() const;
  bool HasPendingTasks() const;

  void ProcessTaskQueue();
  void CloseOpenCursors();

  const int64 id_;
  const std::set<int64> object_store_ids_;
  const indexed_db::TransactionMode mode_;

  State state_;
  bool commit_pending_;
  scoped_refptr<IndexedDBDatabaseCallbacks> callbacks_;
  scoped_refptr<IndexedDBDatabase> database_;

  class TaskQueue {
   public:
    TaskQueue();
    ~TaskQueue();
    bool empty() const { return queue_.empty(); }
    void push(Operation task) { queue_.push(task); }
    Operation pop();
    void clear();

   private:
    std::queue<Operation> queue_;
  };

  class TaskStack {
   public:
    TaskStack();
    ~TaskStack();
    bool empty() const { return stack_.empty(); }
    void push(Operation task) { stack_.push(task); }
    Operation pop();
    void clear();

   private:
    std::stack<Operation> stack_;
  };

  TaskQueue task_queue_;
  TaskQueue preemptive_task_queue_;
  TaskStack abort_task_stack_;

  IndexedDBBackingStore::Transaction transaction_;

  bool should_process_queue_;
  int pending_preemptive_events_;

  std::set<IndexedDBCursor*> open_cursors_;

  // The following members are for diagnostics only.
  QueueStatus queue_status_;
  base::Time creation_time_;
  base::Time start_time_;
  int tasks_scheduled_;
  int tasks_completed_;
};

}  // namespace content

#endif  // CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_TRANSACTION_H_