db_indexes.rb

require(File.dirname(__FILE__) + '/../config/environment') unless defined?(Rails)

class DbIndexes
  
  def initialize(app, message = "Database Indexes")
    @app = app
    @message = message
  end

  def call env
    request = Rack::Request.new env
    status, headers, response = @app.call(env)
    begin
      table = request.params['table_name']
      column = request.params['column_name']
      act = request.params['act']

      if table and column
        index_workflow(act, table, column)
      end
    rescue
      response.body += 'Something wrong :('
    end
    [status, headers, response_body(response.body)]
  end

  private

    def response_body(response)

      response += '<h3>Tables indexes:</h3><dl>'


      get_indexes.each{|obj|  response += "<dt>#{obj.table}</dt><dd>#{obj.name}</dd>"}
      response += '</dl>'

      response += '
        <h3> Add/remove index </h3>
        <form method="get" action="">
        <input type="text" name="table_name" id="table_name"/>
        <input type="text" name="column_name" id="column_name"/><br />

        <input type="radio" name="act" value="create">Add<br />
        <input type="radio" name="act" value="destroy">Delete<br />

        <input type="submit" value="Do" name="commit"/>
        </form>'

    end

    def get_indexes
      t = ActiveRecord::Base.connection.tables.\
        collect(&:to_sym).
        reject{|i| i.eql?(:schema_migrations) || i.eql?(:sessions)}
      i = t.collect{|i| ActiveRecord::Base.connection.indexes i}
      return i.reject!(&:blank?)[0]
    end


    def index_workflow(act, table_name, column_name)
      table = table_name.to_sym
      c = column_name
      column = c =~ /,/ ? c.split(', ').collect(&:to_sym) : c.to_sym

      if act.eql?('create')
        ActiveRecord::Migration.add_index(table,column)
      elsif act.eql?('destroy')
        ActiveRecord::Migration.remove_index(table,column)
      end
    end

end