// Copyright (c) 2009 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/thumbnail_store.h"

#include <string.h>
#include <algorithm>

#include "base/basictypes.h"
#include "base/pickle.h"
#include "base/file_util.h"
#include "base/gfx/jpeg_codec.h"
#include "base/md5.h"
#include "base/string_util.h"
#include "base/thread.h"
#include "base/values.h"
#include "chrome/browser/browser_process.h"
#include "chrome/browser/history/page_usage_data.h"
#include "chrome/browser/profile.h"
#include "chrome/common/pref_service.h"
#include "chrome/common/thumbnail_score.h"
#include "googleurl/src/gurl.h"
#include "third_party/skia/include/core/SkBitmap.h"


ThumbnailStore::ThumbnailStore()
    : cache_(NULL),
      cache_initialized_(false),
      hs_(NULL),
      url_blacklist_(NULL) {
}

ThumbnailStore::~ThumbnailStore() {
}

void ThumbnailStore::Init(const FilePath& file_path, Profile* profile) {
  file_path_ = file_path;
  hs_ = profile->GetHistoryService(Profile::EXPLICIT_ACCESS);
  url_blacklist_ = profile->GetPrefs()->
      GetMutableDictionary(prefs::kNTPMostVisitedURLsBlacklist);

  g_browser_process->file_thread()->message_loop()->PostTask(FROM_HERE,
      NewRunnableMethod(this, &ThumbnailStore::GetAllThumbnailsFromDisk,
                        file_path_, MessageLoop::current()));

  timer_.Start(base::TimeDelta::FromMinutes(30), this,
      &ThumbnailStore::UpdateMostVisited);
  UpdateMostVisited();
}

void ThumbnailStore::GetAllThumbnailsFromDisk(FilePath filepath,
                                              MessageLoop* cb_loop) {
  ThumbnailStore::Cache* cache = new ThumbnailStore::Cache;

  // Create the specified directory if it does not exist.
  if (!file_util::DirectoryExists(filepath)) {
    file_util::CreateDirectory(filepath);
  } else {
    // Walk the directory and read the thumbnail data from disk.
    FilePath path;
    GURL url;
    RefCountedBytes* data;
    ThumbnailScore score;
    file_util::FileEnumerator fenum(filepath, false,
                                    file_util::FileEnumerator::FILES);

    while (!(path = fenum.Next()).empty()) {
      data = new RefCountedBytes;
      if (GetPageThumbnailFromDisk(path, &url, data, &score))
        (*cache)[url] = std::make_pair(data, score);
      else
        delete data;
    }
  }
  cb_loop->PostTask(FROM_HERE,
      NewRunnableMethod(this, &ThumbnailStore::OnDiskDataAvailable, cache));
}

bool ThumbnailStore::GetPageThumbnailFromDisk(const FilePath& file,
                                              GURL* url,
                                              RefCountedBytes* data,
                                              ThumbnailScore* score) const {
  int64 file_size;
  if (!file_util::GetFileSize(file, &file_size))
    return false;

  // Read the file into a buffer.
  std::vector<char> file_data;
  file_data.resize(static_cast<unsigned int>(file_size));
  if (file_util::ReadFile(file, &file_data[0],
                          static_cast<int>(file_size)) == -1)
    return false;

  // Unpack the url, ThumbnailScore and JPEG size from the buffer.
  std::string url_string;
  unsigned int jpeg_len;
  void* iter = NULL;
  Pickle packed(&file_data[0], static_cast<int>(file_size));

  if (!packed.ReadString(&iter, &url_string) ||
      !UnpackScore(score, packed, iter) ||
      !packed.ReadUInt32(&iter, &jpeg_len))
    return false;

  // Store the url to the out parameter.
  GURL temp_url(url_string);
  url->Swap(&temp_url);

  // Unpack the JPEG data from the buffer.
  const char* jpeg_data = NULL;
  int out_len;

  if (!packed.ReadData(&iter, &jpeg_data, &out_len) ||
      out_len != static_cast<int>(jpeg_len))
    return false;

  // Copy jpeg data to the out parameter.
  data->data.resize(jpeg_len);
  memcpy(&data->data[0], jpeg_data, jpeg_len);

  return true;
}

void ThumbnailStore::OnDiskDataAvailable(ThumbnailStore::Cache* cache) {
  if (cache) {
    cache_.reset(cache);
    cache_initialized_ = true;
  }
}

bool ThumbnailStore::SetPageThumbnail(const GURL& url,
                                      const SkBitmap& thumbnail,
                                      const ThumbnailScore& score,
                                      bool write_to_disk) {
  if (!cache_initialized_)
    return false;

  if (!ShouldStoreThumbnailForURL(url) ||
      (cache_->find(url) != cache_->end() &&
      !ShouldReplaceThumbnailWith((*cache_)[url].second, score)))
    return true;

  base::TimeTicks encode_start = base::TimeTicks::Now();

  // Encode the SkBitmap to jpeg and add to cache.
  scoped_refptr<RefCountedBytes> jpeg_data = new RefCountedBytes;
  SkAutoLockPixels thumbnail_lock(thumbnail);
  bool encoded = JPEGCodec::Encode(
      reinterpret_cast<unsigned char*>(thumbnail.getAddr32(0, 0)),
      JPEGCodec::FORMAT_BGRA, thumbnail.width(),
      thumbnail.height(),
      static_cast<int>(thumbnail.rowBytes()), 90,
      &jpeg_data->data);

  base::TimeDelta delta = base::TimeTicks::Now() - encode_start;
  HISTOGRAM_TIMES("Thumbnail.Encode", delta);

  if (!encoded)
    return false;

  // Update the cache_ with the new thumbnail.
  (*cache_)[url] = std::make_pair(jpeg_data, score);

  // Write the new thumbnail data to disk in the background on file_thread.
  if (write_to_disk) {
    g_browser_process->file_thread()->message_loop()->PostTask(FROM_HERE,
        NewRunnableMethod(this, &ThumbnailStore::WriteThumbnailToDisk, url));
  }
  return true;
}

bool ThumbnailStore::WriteThumbnailToDisk(const GURL& url) const {
  Pickle packed;
  FilePath file = file_path_.AppendASCII(MD5String(url.spec()));
  scoped_refptr<RefCountedBytes> data((*cache_)[url].first);
  ThumbnailScore score = (*cache_)[url].second;

  // Pack the url, ThumbnailScore, and the JPEG data.
  packed.WriteString(url.spec());
  PackScore(score, &packed);
  packed.WriteUInt32(data->data.size());
  packed.WriteData(reinterpret_cast<char*>(&data->data[0]), data->data.size());

  // Write the packed data to a file.
  file_util::Delete(file, false);
  return file_util::WriteFile(file,
                              reinterpret_cast<const char*>(packed.data()),
                              packed.size()) != -1;
}

ThumbnailStore::GetStatus ThumbnailStore::GetPageThumbnail(
    const GURL& url,
    RefCountedBytes** data) {
  if (!cache_initialized_ || IsURLBlacklisted(url))
    return ThumbnailStore::FAIL;

  // We need to check if the URL was redirected so that we can return the
  // thumbnail for the final destination.  Redirect information needs to be
  // fetched asynchronously from the HistoryService and is stored in a map
  // of the form "url => {redirect1 -> redirect2 -> .... -> final url}".
  // If the redirect info has not been cached, tell the caller to call
  // GetPageThumbnailAsync instead which will wait for the redirect info
  // and return the thumbnail data when it becomes available.
  ThumbnailStore::RedirectMap::iterator it = redirect_urls_.find(url);
  if (it == redirect_urls_.end())
    return ThumbnailStore::ASYNC;

  // Return the first available thumbnail starting at the end of the
  // redirect list.
  HistoryService::RedirectList::reverse_iterator rit;
  for (rit = it->second->data.rbegin();
       rit != it->second->data.rend(); ++rit) {
    if (cache_->find(*rit) != cache_->end()) {
      *data = (*cache_)[*rit].first;
      (*data)->AddRef();
      return ThumbnailStore::SUCCESS;
    }
  }

  // TODO(meelapshah) bug 14643: check past redirect lists

  if (cache_->find(url) == cache_->end())
    return ThumbnailStore::FAIL;

  *data = (*cache_)[url].first;
  (*data)->AddRef();
  return ThumbnailStore::SUCCESS;
}

void ThumbnailStore::GetPageThumbnailAsync(const GURL& url,
    int request_id,
    ThumbnailStore::ThumbnailDataCallback* cb) {
  DCHECK(redirect_requests_.find(request_id) == redirect_requests_.end());

  HistoryService::Handle handle = hs_->QueryRedirectsFrom(
      url, &hs_consumer_,
      NewCallback(this, &ThumbnailStore::OnRedirectQueryComplete));
  hs_consumer_.SetClientData(hs_, handle, request_id);
  redirect_requests_[request_id] = std::make_pair(cb, handle);
}

void ThumbnailStore::OnRedirectQueryComplete(
    HistoryService::Handle request_handle,
    GURL url,
    bool success,
    HistoryService::RedirectList* redirects) {
  if (!success)
    return;

  // Copy the redirects list returned by the HistoryService into our cache.
  redirect_urls_[url] = new RefCountedVector<GURL>(*redirects);

  // Get the request_id associated with this request.
  int request_id = hs_consumer_.GetClientData(hs_, request_handle);

  // Return if no callback was associated with this redirect query.
  // (The request for redirect info was made from UpdateMostVisited().)
  if (request_id == -1)
    return;

  // Run the callback if a thumbnail was requested for the URL.
  ThumbnailStore::RequestMap::iterator it =
      redirect_requests_.find(request_id);
  if (it != redirect_requests_.end()) {
    ThumbnailStore::ThumbnailDataCallback* cb = it->second.first;
    RefCountedBytes* data = NULL;

    redirect_requests_.erase(it);
    GetPageThumbnail(url, &data);
    cb->Run(request_id, data);
  }
}

void ThumbnailStore::CancelPendingRequests(
    const std::set<int>& pending_requests) {
  ThumbnailStore::RequestMap::iterator req_it;
  for (std::set<int>::const_iterator it = pending_requests.begin();
       it != pending_requests.end(); ++it) {
    req_it = redirect_requests_.find(*it);

    // Cancel the request and delete the callback.
    DCHECK(req_it != redirect_requests_.end());
    hs_->CancelRequest(req_it->second.second);
    delete req_it->second.first;
    redirect_requests_.erase(req_it);
  }
}

void ThumbnailStore::UpdateMostVisited() {
  int result_count = ThumbnailStore::kMaxCacheSize;
  if (url_blacklist_)
    result_count += url_blacklist_->GetSize();

  hs_->QuerySegmentUsageSince(
      &cancelable_consumer_,
      base::Time::Now() -
          base::TimeDelta::FromDays(ThumbnailStore::kMostVisitedScope),
      result_count,
      NewCallback(this, &ThumbnailStore::OnMostVisitedURLsAvailable));
}

void ThumbnailStore::OnMostVisitedURLsAvailable(
    CancelableRequestProvider::Handle handle,
    std::vector<PageUsageData*>* data) {
  most_visited_urls_.clear();

  // Extract the top kMaxCacheSize + |url_blacklist_| most visited URLs.
  GURL url;
  size_t data_index = 0;
  size_t output_index = 0;

  while (output_index < ThumbnailStore::kMaxCacheSize &&
         data_index < data->size()) {
    url = (*data)[data_index]->GetURL();
    ++data_index;

    if (!IsURLBlacklisted(url)) {
      most_visited_urls_.push_back(url);
      ++output_index;
    }

    // Preemptively fetch the redirect lists for the current URL if we don't
    // already have it cached.
    if (redirect_urls_.find(url) == redirect_urls_.end()) {
      hs_->QueryRedirectsFrom(url, &hs_consumer_,
          NewCallback(this, &ThumbnailStore::OnRedirectQueryComplete));
    }
  }
  CleanCacheData();
}

void ThumbnailStore::CleanCacheData() {
  if (!cache_initialized_)
    return;

  // For each URL in the cache, search the RedirectMap for the originating URL.
  // If this URL is blacklisted or not in the most visited list, delete the
  // thumbnail data for it from the cache and from disk in the background.
  scoped_refptr<RefCountedVector<GURL> > delete_me = new RefCountedVector<GURL>;
  for (ThumbnailStore::Cache::iterator cache_it = cache_->begin();
       cache_it != cache_->end();) {
    const GURL* url = NULL;
    for (ThumbnailStore::RedirectMap::iterator it = redirect_urls_.begin();
         it != redirect_urls_.end(); ++it) {
      if (cache_it->first == it->first ||
          (it->second->data.size() &&
          cache_it->first == it->second->data.back())) {
        url = &it->first;
        break;
      }
    }

    // If there was no entry in the RedirectMap for the URL cache_it->first,
    // that means SetPageThumbnail was called but GetPageThumbnail was not
    // called.  Since we do not have a reverse redirect lookup (i.e. we have
    // a final destination such as http://www.google.com/ but we cannot get
    // what the user typed such as google.com from it), we cannot
    // check if this cache entry is blacklisted or if it is popular.
    // TODO(meelapshah) bug 14644: Fix this.
    if (url == NULL) {
      cache_it++;
      continue;
    }

    if (IsURLBlacklisted(*url) || !IsPopular(*url)) {
      delete_me->data.push_back(cache_it->first);
      cache_->erase(cache_it++);
    } else {
      cache_it++;
    }
  }

  if (delete_me->data.size()) {
    g_browser_process->file_thread()->message_loop()->PostTask(FROM_HERE,
        NewRunnableMethod(this, &ThumbnailStore::DeleteThumbnails, delete_me));
  }
}

bool ThumbnailStore::ShouldStoreThumbnailForURL(const GURL& url) const {
  if (IsURLBlacklisted(url) || cache_->size() >= ThumbnailStore::kMaxCacheSize)
    return false;

  return most_visited_urls_.size() < ThumbnailStore::kMaxCacheSize ||
         IsPopular(url);
}

void ThumbnailStore::PackScore(const ThumbnailScore& score,
                               Pickle* packed) const {
  // Pack the contents of the given ThumbnailScore into the given Pickle.
  packed->WriteData(reinterpret_cast<const char*>(&score.boring_score),
                    sizeof(score.boring_score));
  packed->WriteBool(score.at_top);
  packed->WriteBool(score.good_clipping);
  packed->WriteInt64(score.time_at_snapshot.ToInternalValue());
}

bool ThumbnailStore::UnpackScore(ThumbnailScore* score, const Pickle& packed,
                                 void*& iter) const {
  // Unpack a ThumbnailScore from the given Pickle and iterator.
  const char* boring = NULL;
  int out_len;
  int64 us;

  if (!packed.ReadData(&iter, &boring, &out_len) ||
      !packed.ReadBool(&iter, &score->at_top) ||
      !packed.ReadBool(&iter, &score->good_clipping) ||
      !packed.ReadInt64(&iter, &us))
    return false;

  if (out_len != sizeof(score->boring_score))
    return false;

  memcpy(&score->boring_score, boring, sizeof(score->boring_score));
  score->time_at_snapshot = base::Time::FromInternalValue(us);
  return true;
}

void ThumbnailStore::DeleteThumbnails(
    scoped_refptr<RefCountedVector<GURL> > thumbnail_urls) const {
  for (std::vector<GURL>::iterator it = thumbnail_urls->data.begin();
       it != thumbnail_urls->data.end(); ++it)
    file_util::Delete(file_path_.AppendASCII(MD5String(it->spec())), false);
}

bool ThumbnailStore::IsURLBlacklisted(const GURL& url) const {
  if (url_blacklist_)
    return url_blacklist_->HasKey(GetDictionaryKeyForURL(url.spec()));
  return false;
}

std::wstring ThumbnailStore::GetDictionaryKeyForURL(
    const std::string& url) const {
  return ASCIIToWide(MD5String(url));
}

bool ThumbnailStore::IsPopular(const GURL& url) const {
  return most_visited_urls_.end() != find(most_visited_urls_.begin(),
                                          most_visited_urls_.end(),
                                          url);
}