// Copyright 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.

#include "chrome/browser/ui/app_list/search/history_data_store.h"

#include "base/callback.h"
#include "base/json/json_file_value_serializer.h"
#include "base/json/json_string_value_serializer.h"
#include "base/logging.h"
#include "base/strings/string_number_conversions.h"
#include "base/task_runner_util.h"
#include "base/threading/sequenced_worker_pool.h"
#include "base/values.h"
#include "content/public/browser/browser_thread.h"

using content::BrowserThread;

namespace app_list {

namespace {

const char kKeyVersion[] = "version";
const char kCurrentVersion[] = "1";

const char kKeyAssociations[] = "associations";
const char kKeyPrimary[] = "p";
const char kKeySecondary[] = "s";
const char kKeyUpdateTime[] = "t";

// Extracts strings from ListValue.
void GetSecondary(const base::ListValue* list,
                  HistoryData::SecondaryDeque* secondary) {
  HistoryData::SecondaryDeque results;
  for (base::ListValue::const_iterator it = list->begin();
       it != list->end(); ++it) {
    std::string str;
    if (!(*it)->GetAsString(&str))
      return;

    results.push_back(str);
  }

  secondary->swap(results);
}

// V1 format json dictionary:
//  {
//    "version": "1",
//    "associations": {
//      "user typed query": {
//        "p" : "result id of primary association",
//        "s" : [
//                "result id of 1st (oldest) secondary association",
//                ...
//                "result id of the newest secondary association"
//              ],
//        "t" : "last_update_timestamp"
//      },
//      ...
//    }
//  }
scoped_ptr<HistoryData::Associations> Parse(
    scoped_ptr<base::DictionaryValue> dict) {
  std::string version;
  if (!dict->GetStringWithoutPathExpansion(kKeyVersion, &version) ||
      version != kCurrentVersion) {
    return scoped_ptr<HistoryData::Associations>();
  }

  const base::DictionaryValue* assoc_dict = NULL;
  if (!dict->GetDictionaryWithoutPathExpansion(kKeyAssociations,
                                               &assoc_dict) ||
      !assoc_dict) {
    return scoped_ptr<HistoryData::Associations>();
  }

  scoped_ptr<HistoryData::Associations> data(new HistoryData::Associations);
  for (base::DictionaryValue::Iterator it(*assoc_dict);
       !it.IsAtEnd(); it.Advance()) {
    const base::DictionaryValue* entry_dict = NULL;
    if (!it.value().GetAsDictionary(&entry_dict))
      continue;

    std::string primary;
    std::string update_time_string;
    if (!entry_dict->GetStringWithoutPathExpansion(kKeyPrimary, &primary) ||
        !entry_dict->GetStringWithoutPathExpansion(kKeyUpdateTime,
                                                   &update_time_string)) {
      continue;
    }

    const base::ListValue* secondary_list = NULL;
    HistoryData::SecondaryDeque secondary;
    if (entry_dict->GetListWithoutPathExpansion(kKeySecondary, &secondary_list))
      GetSecondary(secondary_list, &secondary);

    const std::string& query = it.key();
    HistoryData::Data& association_data = (*data.get())[query];
    association_data.primary = primary;
    association_data.secondary.swap(secondary);

    int64 update_time_val;
    base::StringToInt64(update_time_string, &update_time_val);
    association_data.update_time =
        base::Time::FromInternalValue(update_time_val);
  }

  return data.Pass();
}

}  // namespace

HistoryDataStore::HistoryDataStore(const base::FilePath& data_file)
    : data_store_(new DictionaryDataStore(data_file)) {
  base::DictionaryValue* dict = data_store_->cached_dict();
  DCHECK(dict);
  dict->SetString(kKeyVersion, kCurrentVersion);
  dict->Set(kKeyAssociations, new base::DictionaryValue);
}

HistoryDataStore::~HistoryDataStore() {
}

void HistoryDataStore::Flush(
    const DictionaryDataStore::OnFlushedCallback& on_flushed) {
  data_store_->Flush(on_flushed);
}

void HistoryDataStore::Load(
    const HistoryDataStore::OnLoadedCallback& on_loaded) {
  data_store_->Load(base::Bind(&HistoryDataStore::OnDictionaryLoadedCallback,
                               this,
                               on_loaded));
}

void HistoryDataStore::SetPrimary(const std::string& query,
                                  const std::string& result) {
  base::DictionaryValue* entry_dict = GetEntryDict(query);
  entry_dict->SetWithoutPathExpansion(kKeyPrimary,
                                      new base::StringValue(result));
  data_store_->ScheduleWrite();
}

void HistoryDataStore::SetSecondary(
    const std::string& query,
    const HistoryData::SecondaryDeque& results) {
  scoped_ptr<base::ListValue> results_list(new base::ListValue);
  for (size_t i = 0; i< results.size(); ++i)
    results_list->AppendString(results[i]);

  base::DictionaryValue* entry_dict = GetEntryDict(query);
  entry_dict->SetWithoutPathExpansion(kKeySecondary, results_list.release());
  data_store_->ScheduleWrite();
}

void HistoryDataStore::SetUpdateTime(const std::string& query,
                                     const base::Time& update_time) {
  base::DictionaryValue* entry_dict = GetEntryDict(query);
  entry_dict->SetWithoutPathExpansion(kKeyUpdateTime,
                                      new base::StringValue(base::Int64ToString(
                                          update_time.ToInternalValue())));
  data_store_->ScheduleWrite();
}

void HistoryDataStore::Delete(const std::string& query) {
  base::DictionaryValue* assoc_dict = GetAssociationDict();
  assoc_dict->RemoveWithoutPathExpansion(query, NULL);
  data_store_->ScheduleWrite();
}

base::DictionaryValue* HistoryDataStore::GetAssociationDict() {
  base::DictionaryValue* cached_dict = data_store_->cached_dict();
  DCHECK(cached_dict);

  base::DictionaryValue* assoc_dict = NULL;
  CHECK(cached_dict->GetDictionary(kKeyAssociations, &assoc_dict) &&
        assoc_dict);

  return assoc_dict;
}

base::DictionaryValue* HistoryDataStore::GetEntryDict(
    const std::string& query) {
  base::DictionaryValue* assoc_dict = GetAssociationDict();

  base::DictionaryValue* entry_dict = NULL;
  if (!assoc_dict->GetDictionaryWithoutPathExpansion(query, &entry_dict)) {
    // Creates one if none exists. Ownership is taken in the set call after.
    entry_dict = new base::DictionaryValue;
    assoc_dict->SetWithoutPathExpansion(query, entry_dict);
  }

  return entry_dict;
}

void HistoryDataStore::OnDictionaryLoadedCallback(
    OnLoadedCallback callback, scoped_ptr<base::DictionaryValue> dict) {
  if (!dict) {
    callback.Run(scoped_ptr<HistoryData::Associations>());
  } else {
    callback.Run(Parse(dict.Pass()).Pass());
  }
}

}  // namespace app_list