module ActiveRecord::ConnectionAdapters::SchemaStatements

def add_check_constraint(table_name, expression, if_not_exists: false, **options)
  return unless supports_check_constraints?
  options = check_constraint_options(table_name, expression, options)
  return if if_not_exists && check_constraint_exists?(table_name, **options)
  at = create_alter_table(table_name)
  at.add_check_constraint(expression, options)
  execute schema_creation.accept(at)
end

def add_column(table_name, column_name, type, **options)
  add_column_def = build_add_column_definition(table_name, column_name, type, **options)
  return unless add_column_def
  execute schema_creation.accept(add_column_def)
end

def add_column_for_alter(table_name, column_name, type, **options)
  td = create_table_definition(table_name)
  cd = td.new_column_definition(column_name, type, **options)
  schema_creation.accept(AddColumnDefinition.new(cd))
end

def add_columns(table_name, *column_names, type:, **options) # :nodoc:
  column_names.each do |column_name|
    add_column(table_name, column_name, type, **options)
  end
end

def add_foreign_key(from_table, to_table, **options)
  return unless use_foreign_keys?
  return if options[:if_not_exists] == true && foreign_key_exists?(from_table, to_table, **options.slice(:column))
  options = foreign_key_options(from_table, to_table, options)
  at = create_alter_table from_table
  at.add_foreign_key to_table, options
  execute schema_creation.accept(at)
end

def add_index(table_name, column_name, **options)
  create_index = build_create_index_definition(table_name, column_name, **options)
  execute schema_creation.accept(create_index)
end

def add_index_options(table_name, column_name, name: nil, if_not_exists: false, internal: false, **options) # :nodoc:
  options.assert_valid_keys(:unique, :length, :order, :opclass, :where, :type, :using, :comment, :algorithm, :include, :nulls_not_distinct)
  column_names = index_column_names(column_name)
  index_name = name&.to_s
  index_name ||= index_name(table_name, column_names)
  validate_index_length!(table_name, index_name, internal)
  index = IndexDefinition.new(
    table_name, index_name,
    options[:unique],
    column_names,
    lengths: options[:length] || {},
    orders: options[:order] || {},
    opclasses: options[:opclass] || {},
    where: options[:where],
    type: options[:type],
    using: options[:using],
    include: options[:include],
    nulls_not_distinct: options[:nulls_not_distinct],
    comment: options[:comment]
  )
  [index, index_algorithm(options[:algorithm]), if_not_exists]
end

def add_index_sort_order(quoted_columns, **options)
  orders = options_for_index_columns(options[:order])
  quoted_columns.each do |name, column|
    column << " #{orders[name].upcase}" if orders[name].present?
  end
end

def add_options_for_index_columns(quoted_columns, **options)
  if supports_index_sort_order?
    quoted_columns = add_index_sort_order(quoted_columns, **options)
  end
  quoted_columns
end

def add_reference(table_name, ref_name, **options)
  ReferenceDefinition.new(ref_name, **options).add(table_name, self)
end

def add_timestamps(table_name, **options)
  fragments = add_timestamps_for_alter(table_name, **options)
  execute "ALTER TABLE #{quote_table_name(table_name)} #{fragments.join(', ')}"
end

def add_timestamps_for_alter(table_name, **options)
  options[:null] = false if options[:null].nil?
  if !options.key?(:precision) && supports_datetime_with_precision?
    options[:precision] = 6
  end
  [
    add_column_for_alter(table_name, :created_at, :datetime, **options),
    add_column_for_alter(table_name, :updated_at, :datetime, **options)
  ]
end

def assume_migrated_upto_version(version)
  version = version.to_i
  sm_table = quote_table_name(schema_migration.table_name)
  migrated = migration_context.get_all_versions
  versions = migration_context.migrations.map(&:version)
  unless migrated.include?(version)
    execute "INSERT INTO #{sm_table} (version) VALUES (#{quote(version)})"
  end
  inserting = (versions - migrated).select { |v| v < version }
  if inserting.any?
    if (duplicate = inserting.detect { |v| inserting.count(v) > 1 })
      raise "Duplicate migration #{duplicate}. Please renumber your migrations to resolve the conflict."
    end
    execute insert_versions_sql(inserting)
  end
end

def build_add_column_definition(table_name, column_name, type, **options) # :nodoc:
  return if options[:if_not_exists] == true && column_exists?(table_name, column_name)
  if supports_datetime_with_precision?
    if type == :datetime && !options.key?(:precision)
      options[:precision] = 6
    end
  end
  alter_table = create_alter_table(table_name)
  alter_table.add_column(column_name, type, **options)
  alter_table
end

def build_change_column_default_definition(table_name, column_name, default_or_changes) # :nodoc:
  raise NotImplementedError, "build_change_column_default_definition is not implemented"
end

def build_create_index_definition(table_name, column_name, **options) # :nodoc:
  index, algorithm, if_not_exists = add_index_options(table_name, column_name, **options)
  CreateIndexDefinition.new(index, algorithm, if_not_exists)
end

def build_create_join_table_definition(table_1, table_2, column_options: {}, **options) # :nodoc:
  join_table_name = find_join_table_name(table_1, table_2, options)
  column_options.reverse_merge!(null: false, index: false)
  t1_ref, t2_ref = [table_1, table_2].map { |t| reference_name_for_table(t) }
  build_create_table_definition(join_table_name, **options.merge!(id: false)) do |td|
    td.references t1_ref, **column_options
    td.references t2_ref, **column_options
    yield td if block_given?
  end
end

def build_create_table_definition(table_name, id: :primary_key, primary_key: nil, force: nil, **options)
  table_definition = create_table_definition(table_name, **options.extract!(*valid_table_definition_options, :_skip_validate_options))
  table_definition.set_primary_key(table_name, id, primary_key, **options.extract!(*valid_primary_key_options, :_skip_validate_options))
  yield table_definition if block_given?
  table_definition
end

def bulk_change_table(table_name, operations) # :nodoc:
  sql_fragments = []
  non_combinable_operations = []
  operations.each do |command, args|
    table, arguments = args.shift, args
    method = :"#{command}_for_alter"
    if respond_to?(method, true)
      sqls, procs = Array(send(method, table, *arguments)).partition { |v| v.is_a?(String) }
      sql_fragments.concat(sqls)
      non_combinable_operations.concat(procs)
    else
      execute "ALTER TABLE #{quote_table_name(table_name)} #{sql_fragments.join(", ")}" unless sql_fragments.empty?
      non_combinable_operations.each(&:call)
      sql_fragments = []
      non_combinable_operations = []
      send(command, table, *arguments)
    end
  end
  execute "ALTER TABLE #{quote_table_name(table_name)} #{sql_fragments.join(", ")}" unless sql_fragments.empty?
  non_combinable_operations.each(&:call)
end

def can_remove_index_by_name?(column_name, options)
  column_name.nil? && options.key?(:name) && options.except(:name, :algorithm).empty?
end

def change_column(table_name, column_name, type, **options)
  raise NotImplementedError, "change_column is not implemented"
end

def change_column_comment(table_name, column_name, comment_or_changes)
  raise NotImplementedError, "#{self.class} does not support changing column comments"
end

def change_column_default(table_name, column_name, default_or_changes)
  raise NotImplementedError, "change_column_default is not implemented"
end

def change_column_default_for_alter(table_name, column_name, default_or_changes)
  cd = build_change_column_default_definition(table_name, column_name, default_or_changes)
  schema_creation.accept(cd)
end

def change_column_null(table_name, column_name, null, default = nil)
  raise NotImplementedError, "change_column_null is not implemented"
end

def change_table(table_name, base = self, **options)
  if supports_bulk_alter? && options[:bulk]
    recorder = ActiveRecord::Migration::CommandRecorder.new(self)
    yield update_table_definition(table_name, recorder)
    bulk_change_table(table_name, recorder.commands)
  else
    yield update_table_definition(table_name, base)
  end
end

def change_table_comment(table_name, comment_or_changes)
  raise NotImplementedError, "#{self.class} does not support changing table comments"
end

def check_constraint_exists?(table_name, **options)
  if !options.key?(:name) && !options.key?(:expression)
    raise ArgumentError, "At least one of :name or :expression must be supplied"
  end
  check_constraint_for(table_name, **options).present?
end

def check_constraint_for(table_name, **options)
  return unless supports_check_constraints?
  chk_name = check_constraint_name(table_name, **options)
  check_constraints(table_name).detect { |chk| chk.defined_for?(name: chk_name, **options) }
end

def check_constraint_for!(table_name, expression: nil, **options)
  check_constraint_for(table_name, expression: expression, **options) ||
    raise(ArgumentError, "Table '#{table_name}' has no check constraint for #{expression || options}")
end

def check_constraint_name(table_name, **options)
  options.fetch(:name) do
    expression = options.fetch(:expression)
    identifier = "#{table_name}_#{expression}_chk"
    hashed_identifier = OpenSSL::Digest::SHA256.hexdigest(identifier).first(10)
    "chk_rails_#{hashed_identifier}"
  end
end

def check_constraint_options(table_name, expression, options) # :nodoc:
  options = options.dup
  options[:name] ||= check_constraint_name(table_name, expression: expression, **options)
  options
end

def check_constraints(table_name)
  raise NotImplementedError
end

def column_exists?(table_name, column_name, type = nil, **options)
  column_name = column_name.to_s
  checks = []
  checks << lambda { |c| c.name == column_name }
  checks << lambda { |c| c.type == type.to_sym rescue nil } if type
  column_options_keys.each do |attr|
    checks << lambda { |c| c.send(attr) == options[attr] } if options.key?(attr)
  end
  columns(table_name).any? { |c| checks.all? { |check| check[c] } }
end

def column_options_keys
  [:limit, :precision, :scale, :default, :null, :collation, :comment]
end

def columns(table_name)
  table_name = table_name.to_s
  definitions = column_definitions(table_name)
  definitions.map do |field|
    new_column_from_field(table_name, field, definitions)
  end
end

def columns_for_distinct(columns, orders) # :nodoc:
  columns
end

def create_alter_table(name)
  AlterTable.new create_table_definition(name)
end

def create_join_table(table_1, table_2, column_options: {}, **options)
  join_table_name = find_join_table_name(table_1, table_2, options)
  column_options.reverse_merge!(null: false, index: false)
  t1_ref, t2_ref = [table_1, table_2].map { |t| reference_name_for_table(t) }
  create_table(join_table_name, **options.merge!(id: false)) do |td|
    td.references t1_ref, **column_options
    td.references t2_ref, **column_options
    yield td if block_given?
  end
end

def create_schema_dumper(options) # :nodoc:
  SchemaDumper.create(self, options)
end

def create_table(table_name, id: :primary_key, primary_key: nil, force: nil, **options, &block)
  validate_create_table_options!(options)
  validate_table_length!(table_name) unless options[:_uses_legacy_table_name]
  td = build_create_table_definition(table_name, id: id, primary_key: primary_key, force: force, **options, &block)
  if force
    drop_table(table_name, force: force, if_exists: true)
  else
    schema_cache.clear_data_source_cache!(table_name.to_s)
  end
  result = execute schema_creation.accept(td)
  unless supports_indexes_in_create?
    td.indexes.each do |column_name, index_options|
      add_index(table_name, column_name, **index_options, if_not_exists: td.if_not_exists)
    end
  end
  if supports_comments? && !supports_comments_in_create?
    if table_comment = td.comment.presence
      change_table_comment(table_name, table_comment)
    end
    td.columns.each do |column|
      change_column_comment(table_name, column.name, column.comment) if column.comment.present?
    end
  end
  result
end

def create_table_definition(name, **options)
  TableDefinition.new(self, name, **options)
end

def data_source_exists?(name)
  query_values(data_source_sql(name), "SCHEMA").any? if name.present?
rescue NotImplementedError
  data_sources.include?(name.to_s)
end

def data_source_sql(name = nil, type: nil)
  raise NotImplementedError
end

def data_sources
  query_values(data_source_sql, "SCHEMA")
rescue NotImplementedError
  tables | views
end

def distinct_relation_for_primary_key(relation) # :nodoc:
  primary_key_columns = Array(relation.primary_key).map do |column|
    visitor.compile(relation.table[column])
  end
  values = columns_for_distinct(
    primary_key_columns,
    relation.order_values
  )
  limited = relation.reselect(values).distinct!
  limited_ids = select_rows(limited.arel, "SQL").map do |results|
    results.last(Array(relation.primary_key).length) # ignores order values for MySQL and PostgreSQL
  end
  if limited_ids.empty?
    relation.none!
  else
    relation.where!(**Array(relation.primary_key).zip(limited_ids.transpose).to_h)
  end
  relation.limit_value = relation.offset_value = nil
  relation
end

def drop_join_table(table_1, table_2, **options)
  join_table_name = find_join_table_name(table_1, table_2, options)
  drop_table(join_table_name, **options)
end

def drop_table(table_name, **options)
  schema_cache.clear_data_source_cache!(table_name.to_s)
  execute "DROP TABLE#{' IF EXISTS' if options[:if_exists]} #{quote_table_name(table_name)}"
end

def dump_schema_information # :nodoc:
  versions = schema_migration.versions
  insert_versions_sql(versions) if versions.any?
end

def expression_column_name?(column_name)
  column_name.is_a?(String) && /\W/.match?(column_name)
end

def extract_foreign_key_action(specifier)
  case specifier
  when "CASCADE"; :cascade
  when "SET NULL"; :nullify
  when "RESTRICT"; :restrict
  end
end

def extract_new_default_value(default_or_changes)
  if default_or_changes.is_a?(Hash) && default_or_changes.has_key?(:from) && default_or_changes.has_key?(:to)
    default_or_changes[:to]
  else
    default_or_changes
  end
end

def fetch_type_metadata(sql_type)
  cast_type = lookup_cast_type(sql_type)
  SqlTypeMetadata.new(
    sql_type: sql_type,
    type: cast_type.type,
    limit: cast_type.limit,
    precision: cast_type.precision,
    scale: cast_type.scale,
  )
end

def foreign_key_column_for(table_name, column_name) # :nodoc:
  name = strip_table_name_prefix_and_suffix(table_name)
  "#{name.singularize}_#{column_name}"
end

def foreign_key_exists?(from_table, to_table = nil, **options)
  foreign_key_for(from_table, to_table: to_table, **options).present?
end

def foreign_key_for(from_table, **options)
  return unless use_foreign_keys?
  foreign_keys(from_table).detect { |fk| fk.defined_for?(**options) }
end

def foreign_key_for!(from_table, to_table: nil, **options)
  foreign_key_for(from_table, to_table: to_table, **options) ||
    raise(ArgumentError, "Table '#{from_table}' has no foreign key for #{to_table || options}")
end

def foreign_key_name(table_name, options)
  options.fetch(:name) do
    columns = Array(options.fetch(:column)).map(&:to_s)
    identifier = "#{table_name}_#{columns * '_and_'}_fk"
    hashed_identifier = OpenSSL::Digest::SHA256.hexdigest(identifier).first(10)
    "fk_rails_#{hashed_identifier}"
  end
end

def foreign_key_options(from_table, to_table, options) # :nodoc:
  options = options.dup
  if options[:primary_key].is_a?(Array)
    options[:column] ||= options[:primary_key].map do |pk_column|
      foreign_key_column_for(to_table, pk_column)
    end
  else
    options[:column] ||= foreign_key_column_for(to_table, "id")
  end
  options[:name]   ||= foreign_key_name(from_table, options)
  if options[:column].is_a?(Array) || options[:primary_key].is_a?(Array)
    if Array(options[:primary_key]).size != Array(options[:column]).size
      raise ArgumentError, <<~MSG.squish
        For composite primary keys, specify :column and :primary_key, where
        :column must reference all the :primary_key columns from #{to_table.inspect}
      MSG
    end
  end
  options
end

def foreign_keys(table_name)
  raise NotImplementedError, "foreign_keys is not implemented"
end

def foreign_keys_enabled?
  @config.fetch(:foreign_keys, true)
end

def generate_index_name(table_name, column)
  name = "index_#{table_name}_on_#{Array(column) * '_and_'}"
  return name if name.bytesize <= max_index_name_size
  # Fallback to short version, add hash to ensure uniqueness
  hashed_identifier = "_" + OpenSSL::Digest::SHA256.hexdigest(name).first(10)
  name = "idx_on_#{Array(column) * '_'}"
  short_limit = max_index_name_size - hashed_identifier.bytesize
  short_name = name.mb_chars.limit(short_limit).to_s
  "#{short_name}#{hashed_identifier}"
end

def index_algorithm(algorithm) # :nodoc:
  index_algorithms.fetch(algorithm) do
    raise ArgumentError, "Algorithm must be one of the following: #{index_algorithms.keys.map(&:inspect).join(', ')}"
  end if algorithm
end

def index_column_names(column_names)
  if expression_column_name?(column_names)
    column_names
  else
    Array(column_names)
  end
end

def index_exists?(table_name, column_name, **options)
  indexes(table_name).any? { |i| i.defined_for?(column_name, **options) }
end

def index_name(table_name, options) # :nodoc:
  if Hash === options
    if options[:column]
      generate_index_name(table_name, options[:column])
    elsif options[:name]
      options[:name]
    else
      raise ArgumentError, "You must specify the index name"
    end
  else
    index_name(table_name, index_name_options(options))
  end
end

def index_name_exists?(table_name, index_name)
  index_name = index_name.to_s
  indexes(table_name).detect { |i| i.name == index_name }
end

def index_name_for_remove(table_name, column_name, options)
  return options[:name] if can_remove_index_by_name?(column_name, options)
  checks = []
  if !options.key?(:name) && expression_column_name?(column_name)
    options[:name] = index_name(table_name, column_name)
    column_names = []
  else
    column_names = index_column_names(column_name || options[:column])
  end
  checks << lambda { |i| i.name == options[:name].to_s } if options.key?(:name)
  if column_names.present? && !(options.key?(:name) && expression_column_name?(column_names))
    checks << lambda { |i| index_name(table_name, i.columns) == index_name(table_name, column_names) }
  end
  raise ArgumentError, "No name or columns specified" if checks.none?
  matching_indexes = indexes(table_name).select { |i| checks.all? { |check| check[i] } }
  if matching_indexes.count > 1
    raise ArgumentError, "Multiple indexes found on #{table_name} columns #{column_names}. " \
      "Specify an index name from #{matching_indexes.map(&:name).join(', ')}"
  elsif matching_indexes.none?
    raise ArgumentError, "No indexes found on #{table_name} with the options provided."
  else
    matching_indexes.first.name
  end
end

def index_name_options(column_names)
  if expression_column_name?(column_names)
    column_names = column_names.scan(/\w+/).join("_")
  end
  { column: column_names }
end

def indexes(table_name)
  raise NotImplementedError, "#indexes is not implemented"
end

def insert_versions_sql(versions)
  sm_table = quote_table_name(schema_migration.table_name)
  if versions.is_a?(Array)
    sql = +"INSERT INTO #{sm_table} (version) VALUES\n"
    sql << versions.reverse.map { |v| "(#{quote(v)})" }.join(",\n")
    sql << ";"
    sql
  else
    "INSERT INTO #{sm_table} (version) VALUES (#{quote(versions)});"
  end
end

def internal_string_options_for_primary_key # :nodoc:
  { primary_key: true }
end

def max_index_name_size
  62
end

def native_database_types
  {}
end

def options_for_index_columns(options)
  if options.is_a?(Hash)
    options.symbolize_keys
  else
    Hash.new { |hash, column| hash[column] = options }
  end
end

def options_include_default?(options)
  options.include?(:default) && !(options[:null] == false && options[:default].nil?)
end

def primary_key(table_name)
  pk = primary_keys(table_name)
  pk = pk.first unless pk.size > 1
  pk
end

def quoted_columns_for_index(column_names, options) # :nodoc:
  quoted_columns = column_names.each_with_object({}) do |name, result|
    result[name.to_sym] = quote_column_name(name).dup
  end
  add_options_for_index_columns(quoted_columns, **options).values.join(", ")
end

def quoted_scope(name = nil, type: nil)
  raise NotImplementedError
end

def reference_name_for_table(table_name)
  table_name.to_s.singularize
end

def remove_check_constraint(table_name, expression = nil, if_exists: false, **options)
  return unless supports_check_constraints?
  return if if_exists && !check_constraint_exists?(table_name, **options)
  chk_name_to_delete = check_constraint_for!(table_name, expression: expression, **options).name
  at = create_alter_table(table_name)
  at.drop_check_constraint(chk_name_to_delete)
  execute schema_creation.accept(at)
end

def remove_column(table_name, column_name, type = nil, **options)
  return if options[:if_exists] == true && !column_exists?(table_name, column_name)
  execute "ALTER TABLE #{quote_table_name(table_name)} #{remove_column_for_alter(table_name, column_name, type, **options)}"
end

def remove_column_for_alter(table_name, column_name, type = nil, **options)
  "DROP COLUMN #{quote_column_name(column_name)}"
end

def remove_columns(table_name, *column_names, type: nil, **options)
  if column_names.empty?
    raise ArgumentError.new("You must specify at least one column name. Example: remove_columns(:people, :first_name)")
  end
  remove_column_fragments = remove_columns_for_alter(table_name, *column_names, type: type, **options)
  execute "ALTER TABLE #{quote_table_name(table_name)} #{remove_column_fragments.join(', ')}"
end

def remove_columns_for_alter(table_name, *column_names, **options)
  column_names.map { |column_name| remove_column_for_alter(table_name, column_name) }
end

def remove_foreign_key(from_table, to_table = nil, **options)
  return unless use_foreign_keys?
  return if options.delete(:if_exists) == true && !foreign_key_exists?(from_table, to_table)
  fk_name_to_delete = foreign_key_for!(from_table, to_table: to_table, **options).name
  at = create_alter_table from_table
  at.drop_foreign_key fk_name_to_delete
  execute schema_creation.accept(at)
end

def remove_index(table_name, column_name = nil, **options)
  return if options[:if_exists] && !index_exists?(table_name, column_name, **options)
  index_name = index_name_for_remove(table_name, column_name, options)
  execute "DROP INDEX #{quote_column_name(index_name)} ON #{quote_table_name(table_name)}"
end

def remove_reference(table_name, ref_name, foreign_key: false, polymorphic: false, **options)
  conditional_options = options.slice(:if_exists, :if_not_exists)
  if foreign_key
    reference_name = Base.pluralize_table_names ? ref_name.to_s.pluralize : ref_name
    if foreign_key.is_a?(Hash)
      foreign_key_options = foreign_key.merge(conditional_options)
    else
      foreign_key_options = { to_table: reference_name, **conditional_options }
    end
    foreign_key_options[:column] ||= "#{ref_name}_id"
    remove_foreign_key(table_name, **foreign_key_options)
  end
  remove_column(table_name, "#{ref_name}_id", **conditional_options)
  remove_column(table_name, "#{ref_name}_type", **conditional_options) if polymorphic
end

def remove_timestamps(table_name, **options)
  remove_columns table_name, :updated_at, :created_at
end

def remove_timestamps_for_alter(table_name, **options)
  remove_columns_for_alter(table_name, :updated_at, :created_at)
end

def rename_column(table_name, column_name, new_column_name)
  raise NotImplementedError, "rename_column is not implemented"
end

def rename_column_indexes(table_name, column_name, new_column_name)
  column_name, new_column_name = column_name.to_s, new_column_name.to_s
  indexes(table_name).each do |index|
    next unless index.columns.include?(new_column_name)
    old_columns = index.columns.dup
    old_columns[old_columns.index(new_column_name)] = column_name
    generated_index_name = index_name(table_name, column: old_columns)
    if generated_index_name == index.name
      rename_index table_name, generated_index_name, index_name(table_name, column: index.columns)
    end
  end
end

def rename_column_sql(table_name, column_name, new_column_name)
  "RENAME COLUMN #{quote_column_name(column_name)} TO #{quote_column_name(new_column_name)}"
end

def rename_index(table_name, old_name, new_name)
  old_name = old_name.to_s
  new_name = new_name.to_s
  validate_index_length!(table_name, new_name)
  # this is a naive implementation; some DBs may support this more efficiently (PostgreSQL, for instance)
  old_index_def = indexes(table_name).detect { |i| i.name == old_name }
  return unless old_index_def
  add_index(table_name, old_index_def.columns, name: new_name, unique: old_index_def.unique)
  remove_index(table_name, name: old_name)
end

def rename_table(table_name, new_name, **)
  raise NotImplementedError, "rename_table is not implemented"
end

def rename_table_indexes(table_name, new_name)
  indexes(new_name).each do |index|
    generated_index_name = index_name(table_name, column: index.columns)
    if generated_index_name == index.name
      rename_index new_name, generated_index_name, index_name(new_name, column: index.columns)
    end
  end
end

def schema_creation # :nodoc:
  SchemaCreation.new(self)
end

def strip_table_name_prefix_and_suffix(table_name)
  prefix = Base.table_name_prefix
  suffix = Base.table_name_suffix
  table_name.to_s =~ /#{prefix}(.+)#{suffix}/ ? $1 : table_name.to_s
end

def table_alias_for(table_name)
  table_name[0...table_alias_length].tr(".", "_")
end

def table_comment(table_name)
  nil
end

def table_exists?(table_name)
  query_values(data_source_sql(table_name, type: "BASE TABLE"), "SCHEMA").any? if table_name.present?
rescue NotImplementedError
  tables.include?(table_name.to_s)
end

def table_options(table_name)
  nil
end

def tables
  query_values(data_source_sql(type: "BASE TABLE"), "SCHEMA")
end

def type_to_sql(type, limit: nil, precision: nil, scale: nil, **) # :nodoc:
  type = type.to_sym if type
  if native = native_database_types[type]
    column_type_sql = (native.is_a?(Hash) ? native[:name] : native).dup
    if type == :decimal # ignore limit, use precision and scale
      scale ||= native[:scale]
      if precision ||= native[:precision]
        if scale
          column_type_sql << "(#{precision},#{scale})"
        else
          column_type_sql << "(#{precision})"
        end
      elsif scale
        raise ArgumentError, "Error adding decimal column: precision cannot be empty if scale is specified"
      end
    elsif [:datetime, :timestamp, :time, :interval].include?(type) && precision ||= native[:precision]
      if (0..6) === precision
        column_type_sql << "(#{precision})"
      else
        raise ArgumentError, "No #{native[:name]} type has precision of #{precision}. The allowed range of precision is from 0 to 6"
      end
    elsif (type != :primary_key) && (limit ||= native.is_a?(Hash) && native[:limit])
      column_type_sql << "(#{limit})"
    end
    column_type_sql
  else
    type.to_s
  end
end

def update_table_definition(table_name, base) # :nodoc:
  Table.new(table_name, base)
end

def use_foreign_keys?
  supports_foreign_keys? && foreign_keys_enabled?
end

def valid_column_definition_options # :nodoc:
  ColumnDefinition::OPTION_NAMES
end

def valid_primary_key_options # :nodoc:
  [:limit, :default, :precision]
end

def valid_table_definition_options # :nodoc:
  [:temporary, :if_not_exists, :options, :as, :comment, :charset, :collation]
end

def validate_change_column_null_argument!(value)
  unless value == true || value == false
    raise ArgumentError, "change_column_null expects a boolean value (true for NULL, false for NOT NULL). Got: #{value.inspect}"
  end
end

def validate_create_table_options!(options)
  unless options[:_skip_validate_options]
    options
      .except(:_uses_legacy_table_name, :_skip_validate_options)
      .assert_valid_keys(valid_table_definition_options, valid_primary_key_options)
  end
end

def validate_index_length!(table_name, new_name, internal = false)
  if new_name.length > index_name_length
    raise ArgumentError, "Index name '#{new_name}' on table '#{table_name}' is too long; the limit is #{index_name_length} characters"
  end
end

def validate_table_length!(table_name)
  if table_name.length > table_name_length
    raise ArgumentError, "Table name '#{table_name}' is too long; the limit is #{table_name_length} characters"
  end
end

def view_exists?(view_name)
  query_values(data_source_sql(view_name, type: "VIEW"), "SCHEMA").any? if view_name.present?
rescue NotImplementedError
  views.include?(view_name.to_s)
end

def views
  query_values(data_source_sql(type: "VIEW"), "SCHEMA")
end