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

module ActiveRecord
  class SchemaMigration < ActiveRecord::Base

    def self.table_name
      "#{Base.table_name_prefix}schema_migrations#{Base.table_name_suffix}"
    end

    def self.index_name
      "#{Base.table_name_prefix}unique_schema_migrations#{Base.table_name_suffix}"
    end

    def self.create_table
      if connection.table_exists?(table_name)
        cols = connection.columns(table_name).collect { |col| col.name }
        unless cols.include?("migrated_at")
          connection.add_column(table_name, "migrated_at", :datetime)
          q_table_name = connection.quote_table_name(table_name)
          q_timestamp = connection.quoted_date(Time.now)
          connection.update("UPDATE #{q_table_name} SET migrated_at = '#{q_timestamp}' WHERE migrated_at IS NULL")
          connection.change_column(table_name, "migrated_at", :datetime, :null => false)
        end
        unless cols.include?("fingerprint")
          connection.add_column(table_name, "fingerprint", :string, :limit => 32)
        end
        unless cols.include?("name")
          connection.add_column(table_name, "name", :string)
        end
      else
        connection.create_table(table_name, :id => false) do |t|
          t.column :version, :string, :null => false
          t.column :migrated_at, :datetime, :null => false
          t.column :fingerprint, :string, :limit => 32
          t.column :name, :string
        end
        connection.add_index(table_name, "version", :unique => true, :name => index_name)
      end
      reset_column_information
    end

    def self.drop_table
      if connection.table_exists?(table_name)
        if connection.index_exists?(table_name, "version", :unique => true, :name => index_name)
          connection.remove_index(table_name, :name => index_name)
        end
        connection.drop_table(table_name)
      end
    end

    def version
      super.to_i
    end

    # Construct ruby source to include in schema.rb dump for this migration.
    # Pass a string of spaces as +indent+ to allow calling code to control how deeply indented the line is.
    # The generated line includes the migration version, fingerprint, and name. Either fingerprint or name
    # can be an empty string.
    #
    # Example output:
    #
    #   migration 20121129235959, "ee4be703f9e6e2fc0f4baddebe6eb8f7", "add_magic_power_to_unicorns"
    def schema_line(indent)
      %Q(#{indent}migration %s, "%s", "%s") % [version, fingerprint, name]
    end
  end
end