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require 'active_record/scoping/default'
require 'active_record/scoping/named'

module ActiveRecord
  # This class is used to create a table that keeps track of values and keys such
  # as which environment migrations were run in.
  class InternalMetadata < ActiveRecord::Base # :nodoc:
    # Keys in mysql are limited to 191 characters, due to this no adapter can
    # use a longer key
    KEY_LIMIT = 191

    class << self
      def primary_key
        "key"
      end

      def table_name
        "#{table_name_prefix}#{ActiveRecord::Base.internal_metadata_table_name}#{table_name_suffix}"
      end

      def []=(key, value)
        first_or_initialize(key: key).update_attributes!(value: value)
      end

      def [](key)
        where(key: key).pluck(:value).first
      end

      def table_exists?
        ActiveSupport::Deprecation.silence { connection.table_exists?(table_name) }
      end

      # Creates an internal metadata table with columns +key+ and +value+
      def create_table
        unless table_exists?
          connection.create_table(table_name, id: false) do |t|
            t.string :key, primary_key: true, limit: KEY_LIMIT
            t.string :value
            t.timestamps
          end
        end
      end
    end
  end
end