@seller = User.find(params[:tid])  #finds seller's 
  @buyer = User.find(current_user.id) #finds buyer
  @shift = @seller.shifts.find(params[:sid]) #finds seller's 
  @bshift = @buyer.shifts.find_by(:date => @shift.date)  #finds buyer's shift on date that wants to pick up
  if @bshift.nil? or [email protected]?(@shift) #if empty or shift does not overlap with buyers original shift then proceed for swap.
    @nshift = @buyer.shifts.new
    @nshift = @shift.dup
    @nshift.owner_id = @buyer.id
    @nshift.shift_posted = "Not Posted"
    @nshift.save
    @shift.posted_shift.status = "Traded"
    @shift.posted_shift.save
    @shift.save
    @shift.destroy