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// Copyright (c) 2012 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/webui/ntp/suggestions_combiner.h"
#include <algorithm>
#include "base/values.h"
#include "chrome/browser/extensions/api/discovery/suggested_links_registry.h"
#include "chrome/browser/extensions/api/discovery/suggested_links_registry_factory.h"
#include "chrome/browser/profiles/profile.h"
#include "chrome/browser/ui/webui/ntp/suggestions_page_handler.h"
#include "chrome/browser/ui/webui/ntp/suggestions_source.h"
#include "chrome/browser/ui/webui/ntp/suggestions_source_discovery.h"
#include "chrome/browser/ui/webui/ntp/suggestions_source_top_sites.h"
namespace {
static const size_t kSuggestionsCount = 8;
} // namespace
SuggestionsCombiner::SuggestionsCombiner(
SuggestionsCombiner::Delegate* delegate)
: sources_fetching_count_(0),
delegate_(delegate),
suggestions_count_(kSuggestionsCount),
page_values_(new base::ListValue()) {
}
SuggestionsCombiner::~SuggestionsCombiner() {
}
base::ListValue* SuggestionsCombiner::GetPageValues() {
return page_values_.get();
}
void SuggestionsCombiner::FetchItems(Profile* profile) {
sources_fetching_count_ = sources_.size();
for (size_t i = 0; i < sources_.size(); ++i) {
sources_[i]->FetchItems(profile);
}
}
void SuggestionsCombiner::AddSource(SuggestionsSource* source) {
source->SetCombiner(this);
sources_.push_back(source);
}
void SuggestionsCombiner::OnItemsReady() {
DCHECK_GT(sources_fetching_count_, 0);
sources_fetching_count_--;
if (sources_fetching_count_ == 0) {
FillPageValues();
delegate_->OnSuggestionsReady();
}
}
void SuggestionsCombiner::SetSuggestionsCount(size_t suggestions_count) {
suggestions_count_ = suggestions_count;
}
// static
SuggestionsCombiner* SuggestionsCombiner::Create(
SuggestionsCombiner::Delegate* delegate, Profile* profile) {
SuggestionsCombiner* combiner = new SuggestionsCombiner(delegate);
combiner->AddSource(new SuggestionsSourceTopSites());
extensions::SuggestedLinksRegistry* registry =
extensions::SuggestedLinksRegistryFactory::GetForProfile(profile);
scoped_ptr<std::vector<std::string> > list = registry->GetExtensionIds();
for (std::vector<std::string>::iterator it = list->begin();
it != list->end(); ++it) {
combiner->AddSource(new SuggestionsSourceDiscovery(*it));
}
return combiner;
}
void SuggestionsCombiner::FillPageValues() {
int total_weight = 0;
for (size_t i = 0; i < sources_.size(); ++i)
total_weight += sources_[i]->GetWeight();
DCHECK_GT(total_weight, 0);
page_values_.reset(new base::ListValue());
// Evaluate how many items to obtain from each sources. We use error diffusion
// to ensure that we get the total desired number of items.
int error = 0;
// Holds the index at which the next item should be added for each source.
std::vector<size_t> next_item_index_for_source;
next_item_index_for_source.reserve(sources_.size());
for (size_t i = 0; i < sources_.size(); ++i) {
int numerator = sources_[i]->GetWeight() * suggestions_count_ + error;
error = numerator % total_weight;
int item_count = std::min(numerator / total_weight,
sources_[i]->GetItemCount());
for (int j = 0; j < item_count; ++j)
page_values_->Append(sources_[i]->PopItem());
next_item_index_for_source.push_back(page_values_->GetSize());
}
// Fill in extra items, prioritizing the first source.
DictionaryValue* item;
// Rather than updating |next_item_index_for_source| we keep track of the
// number of extra items that were added and offset indices by that much.
size_t extra_items_added = 0;
for (size_t i = 0; i < sources_.size() &&
page_values_->GetSize() < suggestions_count_; ++i) {
size_t index = next_item_index_for_source[i] + extra_items_added;
while (page_values_->GetSize() < suggestions_count_ &&
(item = sources_[i]->PopItem())) {
page_values_->Insert(index++, item);
extra_items_added++;
}
}
}
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