// 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 "net/base/sdch_dictionary_fetcher.h"

#include "base/bind.h"
#include "base/compiler_specific.h"
#include "base/message_loop/message_loop.h"
#include "net/base/load_flags.h"
#include "net/url_request/url_fetcher.h"
#include "net/url_request/url_request_context_getter.h"
#include "net/url_request/url_request_status.h"

namespace net {

SdchDictionaryFetcher::SdchDictionaryFetcher(
    SdchManager* manager,
    URLRequestContextGetter* context)
    : manager_(manager),
      weak_factory_(this),
      task_is_pending_(false),
      context_(context) {
  DCHECK(CalledOnValidThread());
  DCHECK(manager);
}

SdchDictionaryFetcher::~SdchDictionaryFetcher() {
  DCHECK(CalledOnValidThread());
}

void SdchDictionaryFetcher::Schedule(const GURL& dictionary_url) {
  DCHECK(CalledOnValidThread());

  // Avoid pushing duplicate copy onto queue.  We may fetch this url again later
  // and get a different dictionary, but there is no reason to have it in the
  // queue twice at one time.
  if (!fetch_queue_.empty() && fetch_queue_.back() == dictionary_url) {
    SdchManager::SdchErrorRecovery(
        SdchManager::DICTIONARY_ALREADY_SCHEDULED_TO_DOWNLOAD);
    return;
  }
  if (attempted_load_.find(dictionary_url) != attempted_load_.end()) {
    SdchManager::SdchErrorRecovery(
        SdchManager::DICTIONARY_ALREADY_TRIED_TO_DOWNLOAD);
    return;
  }
  attempted_load_.insert(dictionary_url);
  fetch_queue_.push(dictionary_url);
  ScheduleDelayedRun();
}

void SdchDictionaryFetcher::Cancel() {
  DCHECK(CalledOnValidThread());

  while (!fetch_queue_.empty())
    fetch_queue_.pop();
  attempted_load_.clear();
  weak_factory_.InvalidateWeakPtrs();
  current_fetch_.reset(NULL);
}

void SdchDictionaryFetcher::ScheduleDelayedRun() {
  if (fetch_queue_.empty() || current_fetch_.get() || task_is_pending_)
    return;
  base::MessageLoop::current()->PostDelayedTask(FROM_HERE,
      base::Bind(&SdchDictionaryFetcher::StartFetching,
                 weak_factory_.GetWeakPtr()),
      base::TimeDelta::FromMilliseconds(kMsDelayFromRequestTillDownload));
  task_is_pending_ = true;
}

void SdchDictionaryFetcher::StartFetching() {
  DCHECK(CalledOnValidThread());
  DCHECK(task_is_pending_);
  task_is_pending_ = false;

  // Handle losing the race against Cancel().
  if (fetch_queue_.empty())
    return;

  DCHECK(context_.get());
  current_fetch_.reset(URLFetcher::Create(
      fetch_queue_.front(), URLFetcher::GET, this));
  fetch_queue_.pop();
  current_fetch_->SetRequestContext(context_.get());
  current_fetch_->SetLoadFlags(LOAD_DO_NOT_SEND_COOKIES |
                               LOAD_DO_NOT_SAVE_COOKIES);
  current_fetch_->Start();
}

void SdchDictionaryFetcher::OnURLFetchComplete(
    const URLFetcher* source) {
  DCHECK(CalledOnValidThread());
  if ((200 == source->GetResponseCode()) &&
      (source->GetStatus().status() == URLRequestStatus::SUCCESS)) {
    std::string data;
    source->GetResponseAsString(&data);
    manager_->AddSdchDictionary(data, source->GetURL());
  }
  current_fetch_.reset(NULL);
  ScheduleDelayedRun();
}

}  // namespace net