// Copyright 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 "sync/syncable/syncable_util.h"

#include "base/base64.h"
#include "base/location.h"
#include "base/logging.h"
#include "base/sha1.h"
#include "sync/syncable/directory.h"
#include "sync/syncable/entry.h"
#include "sync/syncable/mutable_entry.h"
#include "sync/syncable/syncable_id.h"
#include "sync/syncable/syncable_write_transaction.h"

namespace syncer {
namespace syncable {

// Returns the number of unsynced entries.
int GetUnsyncedEntries(BaseTransaction* trans,
                       std::vector<int64> *handles) {
  trans->directory()->GetUnsyncedMetaHandles(trans, handles);
  DVLOG_IF(1, !handles->empty()) << "Have " << handles->size()
                                 << " unsynced items.";
  return handles->size();
}

bool IsLegalNewParent(BaseTransaction* trans, const Id& entry_id,
                      const Id& new_parent_id) {
  if (entry_id.IsRoot())
    return false;
  // we have to ensure that the entry is not an ancestor of the new parent.
  Id ancestor_id = new_parent_id;
  while (!ancestor_id.IsRoot()) {
    if (entry_id == ancestor_id)
      return false;
    Entry new_parent(trans, GET_BY_ID, ancestor_id);
    if (!SyncAssert(new_parent.good(),
                    FROM_HERE,
                    "Invalid new parent",
                    trans))
      return false;
    ancestor_id = new_parent.GetParentId();
  }
  return true;
}

void ChangeEntryIDAndUpdateChildren(
    BaseWriteTransaction* trans,
    ModelNeutralMutableEntry* entry,
    const Id& new_id) {
  Id old_id = entry->GetId();
  if (!entry->PutId(new_id)) {
    Entry old_entry(trans, GET_BY_ID, new_id);
    CHECK(old_entry.good());
    LOG(FATAL) << "Attempt to change ID to " << new_id
               << " conflicts with existing entry.\n\n"
               << *entry << "\n\n" << old_entry;
  }
  if (entry->GetIsDir()) {
    // Get all child entries of the old id.
    Directory::Metahandles children;
    trans->directory()->GetChildHandlesById(trans, old_id, &children);
    Directory::Metahandles::iterator i = children.begin();
    while (i != children.end()) {
      ModelNeutralMutableEntry child_entry(trans, GET_BY_HANDLE, *i++);
      CHECK(child_entry.good());
      // Use the unchecked setter here to avoid touching the child's
      // UNIQUE_POSITION field.  In this case, UNIQUE_POSITION among the
      // children will be valid after the loop, since we update all the children
      // at once.
      child_entry.PutParentIdPropertyOnly(new_id);
    }
  }
}

// Function to handle runtime failures on syncable code. Rather than crashing,
// if the |condition| is false the following will happen:
// 1. Sets unrecoverable error on transaction.
// 2. Returns false.
bool SyncAssert(bool condition,
                const tracked_objects::Location& location,
                const char* msg,
                BaseTransaction* trans) {
  if (!condition) {
    trans->OnUnrecoverableError(location, msg);
    return false;
  }
  return true;
}

std::string GenerateSyncableHash(
    ModelType model_type, const std::string& client_tag) {
  // Blank PB with just the field in it has termination symbol,
  // handy for delimiter.
  sync_pb::EntitySpecifics serialized_type;
  AddDefaultFieldValue(model_type, &serialized_type);
  std::string hash_input;
  serialized_type.AppendToString(&hash_input);
  hash_input.append(client_tag);

  std::string encode_output;
  CHECK(base::Base64Encode(base::SHA1HashString(hash_input), &encode_output));
  return encode_output;
}

std::string GenerateSyncableBookmarkHash(
    const std::string& originator_cache_guid,
    const std::string& originator_client_item_id) {
  return syncable::GenerateSyncableHash(
      BOOKMARKS, originator_cache_guid + originator_client_item_id);
}

}  // namespace syncable
}  // namespace syncer