module ActiveRecord::ConnectionAdapters::MySQL::DatabaseStatements

def combine_multi_statements(total_sql)
  total_sql.each_with_object([]) do |sql, total_sql_chunks|
    previous_packet = total_sql_chunks.last
    if max_allowed_packet_reached?(sql, previous_packet)
      total_sql_chunks << +sql
    else
      previous_packet << ";\n"
      previous_packet << sql
    end
  end
end

def default_insert_value(column)
  super unless column.auto_increment?
end

def exec_delete(sql, name = nil, binds = [])
  if without_prepared_statement?(binds)
    @lock.synchronize do
      execute_and_free(sql, name) { @connection.affected_rows }
    end
  else
    exec_stmt_and_free(sql, name, binds) { |stmt| stmt.affected_rows }
  end
end

def exec_query(sql, name = "SQL", binds = [], prepare: false)
  if without_prepared_statement?(binds)
    execute_and_free(sql, name) do |result|
      if result
        ActiveRecord::Result.new(result.fields, result.to_a)
      else
        ActiveRecord::Result.new([], [])
      end
    end
  else
    exec_stmt_and_free(sql, name, binds, cache_stmt: prepare) do |_, result|
      if result
        ActiveRecord::Result.new(result.fields, result.to_a)
      else
        ActiveRecord::Result.new([], [])
      end
    end
  end
end

def exec_stmt_and_free(sql, name, binds, cache_stmt: false)
  if preventing_writes? && write_query?(sql)
    raise ActiveRecord::ReadOnlyError, "Write query attempted while in readonly mode: #{sql}"
  end
  materialize_transactions
  # make sure we carry over any changes to ActiveRecord::Base.default_timezone that have been
  # made since we established the connection
  @connection.query_options[:database_timezone] = ActiveRecord::Base.default_timezone
  type_casted_binds = type_casted_binds(binds)
  log(sql, name, binds, type_casted_binds) do
    if cache_stmt
      stmt = @statements[sql] ||= @connection.prepare(sql)
    else
      stmt = @connection.prepare(sql)
    end
    begin
      result = ActiveSupport::Dependencies.interlock.permit_concurrent_loads do
        stmt.execute(*type_casted_binds)
      end
    rescue Mysql2::Error => e
      if cache_stmt
        @statements.delete(sql)
      else
        stmt.close
      end
      raise e
    end
    ret = yield stmt, result
    result.free if result
    stmt.close unless cache_stmt
    ret
  end
end

def execute(sql, name = nil)
  if preventing_writes? && write_query?(sql)
    raise ActiveRecord::ReadOnlyError, "Write query attempted while in readonly mode: #{sql}"
  end
  # make sure we carry over any changes to ActiveRecord::Base.default_timezone that have been
  # made since we established the connection
  @connection.query_options[:database_timezone] = ActiveRecord::Base.default_timezone
  super
end

def execute_batch(statements, name = nil)
  combine_multi_statements(statements).each do |statement|
    execute(statement, name)
  end
  @connection.abandon_results!
end

def last_inserted_id(result)
  @connection.last_id
end

def max_allowed_packet
  @max_allowed_packet ||= show_variable("max_allowed_packet")
end

def max_allowed_packet_reached?(current_packet, previous_packet)
  if current_packet.bytesize > max_allowed_packet
    raise ActiveRecordError,
      "Fixtures set is too large #{current_packet.bytesize}. Consider increasing the max_allowed_packet variable."
  elsif previous_packet.nil?
    true
  else
    (current_packet.bytesize + previous_packet.bytesize + 2) > max_allowed_packet
  end
end

def multi_statements_enabled?(flags)
  if flags.is_a?(Array)
    flags.include?("MULTI_STATEMENTS")
  else
    (flags & Mysql2::Client::MULTI_STATEMENTS) != 0
  end
end

def query(sql, name = nil) # :nodoc:
  execute(sql, name).to_a
end

def select_all(*, **) # :nodoc:
  result = if ExplainRegistry.collect? && prepared_statements
    unprepared_statement { super }
  else
    super
  end
  @connection.abandon_results!
  result
end

def supports_set_server_option?
  @connection.respond_to?(:set_server_option)
end

def with_multi_statements
  previous_flags = @config[:flags]
  unless multi_statements_enabled?(previous_flags)
    if supports_set_server_option?
      @connection.set_server_option(Mysql2::Client::OPTION_MULTI_STATEMENTS_ON)
    else
      @config[:flags] = Mysql2::Client::MULTI_STATEMENTS
      reconnect!
    end
  end
  yield
ensure
  unless multi_statements_enabled?(previous_flags)
    if supports_set_server_option?
      @connection.set_server_option(Mysql2::Client::OPTION_MULTI_STATEMENTS_OFF)
    else
      @config[:flags] = previous_flags
      reconnect!
    end
  end
end

def write_query?(sql) # :nodoc:
  !READ_QUERY.match?(sql)
end