// 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.

#include "extensions/common/value_counter.h"

#include <algorithm>
#include <memory>
#include <utility>

#include "base/values.h"

namespace extensions {

struct ValueCounter::Entry {
  explicit Entry(std::unique_ptr<base::Value> value)
      : value(std::move(value)), count(1) {}

  std::unique_ptr<base::Value> value;
  int count;
};

ValueCounter::ValueCounter() {
}

ValueCounter::~ValueCounter() {
}

bool ValueCounter::Add(const base::Value& value) {
  for (const auto& entry : entries_) {
    if (entry->value->Equals(&value)) {
      ++entry->count;
      return false;
    }
  }
  entries_.push_back(std::make_unique<Entry>(value.CreateDeepCopy()));
  return true;
}

bool ValueCounter::Remove(const base::Value& value) {
  for (auto it = entries_.begin(); it != entries_.end(); ++it) {
    if ((*it)->value->Equals(&value)) {
      if (--(*it)->count == 0) {
        std::swap(*it, entries_.back());
        entries_.pop_back();
        return true;  // Removed the last entry.
      }
      return false;  // Removed, but no the last entry.
    }
  }
  return false;  // Nothing to remove.
}

}  // namespace extensions