// 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/search_engines/util.h"

#include <set>
#include <string>
#include <map>
#include <vector>

#include "base/logging.h"
#include "base/memory/scoped_vector.h"
#include "base/time.h"
#include "chrome/browser/prefs/pref_service.h"
#include "chrome/browser/profiles/profile.h"
#include "chrome/browser/search_engines/template_url.h"
#include "chrome/browser/search_engines/template_url_prepopulate_data.h"
#include "chrome/browser/search_engines/template_url_service.h"
#include "chrome/browser/search_engines/template_url_service_factory.h"
#include "content/public/browser/browser_thread.h"

using content::BrowserThread;

string16 GetDefaultSearchEngineName(Profile* profile) {
  if (!profile) {
    NOTREACHED();
    return string16();
  }
  const TemplateURL* const default_provider =
      TemplateURLServiceFactory::GetForProfile(profile)->
      GetDefaultSearchProvider();
  if (!default_provider) {
    // TODO(cpu): bug 1187517. It is possible to have no default provider.
    // returning an empty string is a stopgap measure for the crash
    // http://code.google.com/p/chromium/issues/detail?id=2573
    return string16();
  }
  return default_provider->short_name();
}

void RemoveDuplicatePrepopulateIDs(
    WebDataService* service,
    const ScopedVector<TemplateURL>& prepopulated_urls,
    TemplateURL* default_search_provider,
    TemplateURLService::TemplateURLVector* template_urls,
    std::set<std::string>* removed_keyword_guids) {
  DCHECK(service == NULL || BrowserThread::CurrentlyOn(BrowserThread::UI));
  DCHECK(template_urls);

  // For convenience construct an ID->TemplateURL* map from |prepopulated_urls|.
  typedef std::map<int, TemplateURL*> PrepopulatedURLMap;
  PrepopulatedURLMap prepopulated_url_map;
  for (std::vector<TemplateURL*>::const_iterator i(prepopulated_urls.begin());
       i != prepopulated_urls.end(); ++i)
    prepopulated_url_map[(*i)->prepopulate_id()] = *i;

  // Separate |template_urls| into prepopulated and non-prepopulated groups.
  typedef std::multimap<int, TemplateURL*> UncheckedURLMap;
  UncheckedURLMap unchecked_urls;
  TemplateURLService::TemplateURLVector checked_urls;
  for (TemplateURLService::TemplateURLVector::iterator i(
       template_urls->begin()); i != template_urls->end(); ++i) {
    TemplateURL* turl = *i;
    int prepopulate_id = turl->prepopulate_id();
    if (prepopulate_id)
      unchecked_urls.insert(std::make_pair(prepopulate_id, turl));
    else
      checked_urls.push_back(turl);
  }

  // For each group of prepopulated URLs with one ID, find the best URL to use
  // and add it to the (initially all non-prepopulated) URLs we've already OKed.
  // Delete the others from the service and from memory.
  while (!unchecked_urls.empty()) {
    // Find the best URL.
    int prepopulate_id = unchecked_urls.begin()->first;
    PrepopulatedURLMap::const_iterator prepopulated_url =
        prepopulated_url_map.find(prepopulate_id);
    UncheckedURLMap::iterator end = unchecked_urls.upper_bound(prepopulate_id);
    UncheckedURLMap::iterator best = unchecked_urls.begin();
    bool matched_keyword = false;
    for (UncheckedURLMap::iterator i = unchecked_urls.begin(); i != end; ++i) {
      // A URL is automatically the best if it's the default search engine.
      if (i->second == default_search_provider) {
        best = i;
        break;
      }

      // Otherwise, a URL is best if it matches the prepopulated data's keyword;
      // if none match, just fall back to using the one with the lowest ID.
      if (matched_keyword)
        continue;
      if ((prepopulated_url != prepopulated_url_map.end()) &&
           i->second->HasSameKeywordAs(*prepopulated_url->second)) {
        best = i;
        matched_keyword = true;
      } else if (i->second->id() < best->second->id()) {
        best = i;
      }
    }

    // Add the best URL to the checked group and delete the rest.
    checked_urls.push_back(best->second);
    for (UncheckedURLMap::iterator i = unchecked_urls.begin(); i != end; ++i) {
      if (i == best)
        continue;
      if (service) {
        service->RemoveKeyword(i->second->id());
        if (removed_keyword_guids)
          removed_keyword_guids->insert(i->second->sync_guid());
      }
      delete i->second;
    }

    // Done with this group.
    unchecked_urls.erase(unchecked_urls.begin(), end);
  }

  // Return the checked URLs.
  template_urls->swap(checked_urls);
}

// Returns the TemplateURL with id specified from the list of TemplateURLs.
// If not found, returns NULL.
TemplateURL* GetTemplateURLByID(
    const TemplateURLService::TemplateURLVector& template_urls,
    int64 id) {
  for (TemplateURLService::TemplateURLVector::const_iterator i(
       template_urls.begin()); i != template_urls.end(); ++i) {
    if ((*i)->id() == id) {
      return *i;
    }
  }
  return NULL;
}

// Loads engines from prepopulate data and merges them in with the existing
// engines.  This is invoked when the version of the prepopulate data changes.
// If |removed_keyword_guids| is not NULL, the Sync GUID of each item removed
// from the DB will be added to it.  Note that this function will take
// ownership of |prepopulated_urls| and will clear the vector.
void MergeEnginesFromPrepopulateData(
    Profile* profile,
    WebDataService* service,
    ScopedVector<TemplateURL>* prepopulated_urls,
    size_t default_search_index,
    TemplateURLService::TemplateURLVector* template_urls,
    TemplateURL** default_search_provider,
    std::set<std::string>* removed_keyword_guids) {
  DCHECK(service == NULL || BrowserThread::CurrentlyOn(BrowserThread::UI));
  DCHECK(template_urls);
  DCHECK(default_search_provider);

  // Create a map to hold all provided |template_urls| that originally came from
  // prepopulate data (i.e. have a non-zero prepopulate_id()).
  typedef std::map<int, TemplateURL*> IDMap;
  IDMap id_to_turl;
  for (TemplateURLService::TemplateURLVector::iterator i(
       template_urls->begin()); i != template_urls->end(); ++i) {
    int prepopulate_id = (*i)->prepopulate_id();
    if (prepopulate_id > 0)
      id_to_turl[prepopulate_id] = *i;
  }

  // For each current prepopulated URL, check whether |template_urls| contained
  // a matching prepopulated URL.  If so, update the passed-in URL to match the
  // current data.  (If the passed-in URL was user-edited, we persist the user's
  // name and keyword.)  If not, add the prepopulated URL to |template_urls|.
  // Along the way, point |default_search_provider| at the default prepopulated
  // URL, if the user hasn't already set another URL as default.
  for (size_t i = 0; i < prepopulated_urls->size(); ++i) {
    // We take ownership of |prepopulated_urls[i]|.
    scoped_ptr<TemplateURL> prepopulated_url((*prepopulated_urls)[i]);
    const int prepopulated_id = prepopulated_url->prepopulate_id();
    DCHECK_NE(0, prepopulated_id);

    TemplateURL* url_in_vector = NULL;
    IDMap::iterator existing_url_iter(id_to_turl.find(prepopulated_id));
    if (existing_url_iter != id_to_turl.end()) {
      // Update the data store with the new prepopulated data.  Preserve user
      // edits to the name and keyword.
      TemplateURLData data(prepopulated_url->data());
      scoped_ptr<TemplateURL> existing_url(existing_url_iter->second);
      id_to_turl.erase(existing_url_iter);
      if (!existing_url->safe_for_autoreplace()) {
        data.safe_for_autoreplace = false;
        data.SetKeyword(existing_url->keyword());
        data.short_name = existing_url->short_name();
      }
      data.id = existing_url->id();
      // Update last_modified to ensure that if this entry is later merged with
      // entries from Sync, the conflict resolution logic knows that this was
      // updated and propagates the new values to the server.
      data.last_modified = base::Time::Now();
      data.sync_guid = existing_url->sync_guid();
      if (service)
        service->UpdateKeyword(data);

      // Replace the entry in |template_urls| with the updated one.
      TemplateURLService::TemplateURLVector::iterator j = std::find(
          template_urls->begin(), template_urls->end(), existing_url.get());
      *j = new TemplateURL(profile, data);
      url_in_vector = *j;
      if (*default_search_provider == existing_url.get())
        *default_search_provider = url_in_vector;
    } else {
      template_urls->push_back(prepopulated_url.release());
      url_in_vector = template_urls->back();
    }
    DCHECK(url_in_vector);
    if (i == default_search_index && !*default_search_provider)
      *default_search_provider = url_in_vector;
  }
  // The above loop takes ownership of all the contents of prepopulated_urls.
  // Clear the pointers.
  prepopulated_urls->weak_erase(prepopulated_urls->begin(),
                                prepopulated_urls->end());

  // The block above removed all the URLs from the |id_to_turl| map that were
  // found in the prepopulate data.  Any remaining URLs that haven't been
  // user-edited or made default can be removed from the data store.
  for (IDMap::iterator i(id_to_turl.begin()); i != id_to_turl.end(); ++i) {
    const TemplateURL* template_url = i->second;
    if ((template_url->safe_for_autoreplace()) &&
        (template_url != *default_search_provider)) {
      TemplateURLService::TemplateURLVector::iterator j =
          std::find(template_urls->begin(), template_urls->end(), template_url);
      DCHECK(j != template_urls->end());
      template_urls->erase(j);
       if (service) {
         service->RemoveKeyword(template_url->id());
         if (removed_keyword_guids)
           removed_keyword_guids->insert(template_url->sync_guid());
       }
      delete template_url;
    }
  }
}

void GetSearchProvidersUsingKeywordResult(
    const WDTypedResult& result,
    WebDataService* service,
    Profile* profile,
    TemplateURLService::TemplateURLVector* template_urls,
    TemplateURL** default_search_provider,
    int* new_resource_keyword_version,
    std::set<std::string>* removed_keyword_guids) {
  DCHECK(service == NULL || BrowserThread::CurrentlyOn(BrowserThread::UI));
  DCHECK(template_urls);
  DCHECK(template_urls->empty());
  DCHECK(default_search_provider);
  DCHECK(*default_search_provider == NULL);
  DCHECK_EQ(KEYWORDS_RESULT, result.GetType());
  DCHECK(new_resource_keyword_version);

  *new_resource_keyword_version = 0;
  WDKeywordsResult keyword_result = reinterpret_cast<
      const WDResult<WDKeywordsResult>*>(&result)->GetValue();

  for (KeywordTable::Keywords::iterator i(keyword_result.keywords.begin());
       i != keyword_result.keywords.end(); ++i) {
    // Fix any duplicate encodings in the local database.  Note that we don't
    // adjust the last_modified time of this keyword; this way, we won't later
    // overwrite any changes on the sync server that happened to this keyword
    // since the last time we synced.  Instead, we also run a de-duping pass on
    // the server-provided data in
    // TemplateURLService::CreateTemplateURLFromTemplateURLAndSyncData() and
    // update the server with the merged, de-duped results at that time.  We
    // still fix here, though, to correct problems in clients that have disabled
    // search engine sync, since in that case that code will never be reached.
    if (DeDupeEncodings(&i->input_encodings) && service)
      service->UpdateKeyword(*i);
    template_urls->push_back(new TemplateURL(profile, *i));
  }

  int64 default_search_provider_id = keyword_result.default_search_provider_id;
  if (default_search_provider_id) {
    *default_search_provider =
        GetTemplateURLByID(*template_urls, default_search_provider_id);
  }

  ScopedVector<TemplateURL> prepopulated_urls;
  size_t default_search_index;
  TemplateURLPrepopulateData::GetPrepopulatedEngines(profile,
      &prepopulated_urls.get(), &default_search_index);
  RemoveDuplicatePrepopulateIDs(service, prepopulated_urls,
                                *default_search_provider, template_urls,
                                removed_keyword_guids);

  const int resource_keyword_version =
      TemplateURLPrepopulateData::GetDataVersion(
          profile ? profile->GetPrefs() : NULL);
  if (keyword_result.builtin_keyword_version != resource_keyword_version) {
    MergeEnginesFromPrepopulateData(profile, service, &prepopulated_urls,
        default_search_index, template_urls, default_search_provider,
        removed_keyword_guids);
    *new_resource_keyword_version = resource_keyword_version;
  }
}

bool DeDupeEncodings(std::vector<std::string>* encodings) {
  std::vector<std::string> deduped_encodings;
  std::set<std::string> encoding_set;
  for (std::vector<std::string>::const_iterator i(encodings->begin());
       i != encodings->end(); ++i) {
    if (encoding_set.insert(*i).second)
      deduped_encodings.push_back(*i);
  }
  encodings->swap(deduped_encodings);
  return encodings->size() != deduped_encodings.size();
}