chromeos/ash/components/file_manager/indexing/token_table.h

// Copyright 2024 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CHROMEOS_ASH_COMPONENTS_FILE_MANAGER_INDEXING_TOKEN_TABLE_H_
#define CHROMEOS_ASH_COMPONENTS_FILE_MANAGER_INDEXING_TOKEN_TABLE_H_

#include <memory>
#include <optional>
#include <string>

#include "base/component_export.h"
#include "chromeos/ash/components/file_manager/indexing/text_table.h"
#include "sql/database.h"

namespace ash::file_manager {

// A table that maintains a mapping from a unique token ID to the token text.
// Tokens for us are any pieces of text associated with some file. For example,
// if a file is labeled as "downloaded", the "downloaded" text is considered
// a token. In this table it is assigned a unique integer ID that is used
// across other tables for information retrieval.
class COMPONENT_EXPORT(FILE_MANAGER) TokenTable : public TextTable {
 public:
  // Creates a new table and passes the pointer to the SQL database to it. The
  // caller must make sure it owns both the sql::Database object and this table.
  // The caller also must make sure that the sql::Database outlives the table.
  explicit TokenTable(sql::Database* db);
  ~TokenTable() override;

  TokenTable(const TokenTable&) = delete;
  TokenTable& operator=(const TokenTable&) = delete;

  // Deletes the given token from the table. Returns -1, if the token was not
  // found. Otherwise, returns the ID that the token was assigned.
  int64_t DeleteToken(const std::string& token_bytes);

  // Gets the token ID for the given token bytes. If the token cannot be found,
  // this method returns -1.
  int64_t GetTokenId(const std::string& token_bytes) const;

  // For the given `token_id` attempts to find the corresponding token value.
  // If one cannot be found, returns -1. Otherwise returns `token_id` and fills
  // the token with the found value.
  std::optional<std::string> GetToken(int64_t token_id) const;

  // Gets or creates the unique token ID for the given token bytes.
  int64_t GetOrCreateTokenId(const std::string& token_bytes);

  // Changes the token value from the `from` value to the `to` value, if the
  // `from` value exists. Returns the ID of the changed token if the operation
  // was successful, or -1 otherwise.
  int64_t ChangeToken(const std::string& from, const std::string& to);

 protected:
  std::unique_ptr<sql::Statement> MakeGetValueIdStatement() const override;
  std::unique_ptr<sql::Statement> MakeGetValueStatement() const override;
  std::unique_ptr<sql::Statement> MakeInsertStatement() const override;
  std::unique_ptr<sql::Statement> MakeDeleteStatement() const override;
  std::unique_ptr<sql::Statement> MakeCreateTableStatement() const override;
  std::unique_ptr<sql::Statement> MakeCreateIndexStatement() const override;
  std::unique_ptr<sql::Statement> MakeChangeValueStatement() const override;
};

}  // namespace ash::file_manager

#endif  // CHROMEOS_ASH_COMPONENTS_FILE_MANAGER_INDEXING_TOKEN_TABLE_H_