magic_spell.rb

=begin
Given a hash of business hours that looks like:
{
    "wed"=>{
        "endtime"=>"08:00pm",
        "starttime"=>"10:00am"
    },
    "sun"=>{
        "endtime"=>"06:00pm",
        "starttime"=>"10:00am"
    },
    "thu"=>{
        "endtime"=>"08:00pm",
        "starttime"=>"10:00am"
    },
    "tue"=>{
        "endtime"=>"08:00pm",
        "starttime"=>"10:00am"
    },
    "mon"=>{
        "endtime"=>"08:00pm",
        "starttime"=>"10:00am"
    },
    "fri"=>{
        "endtime"=>"08:00pm",
        "starttime"=>"10:00am"
    },
    "sat"=>{
        "endtime"=>"08:00pm",
        "starttime"=>"10:00am"
    }
}
When a user wants to retrive the start or end time
Then method missing to the rescue
=end

def start_time(hash)
  #takes in a hash and returns the value at the starttime key
  return nil unless hash["starttime"].present?
  return hash["starttime"] unless hash["starttime"][0] == "0"  
  #trim leading zero
  #return 9:00am instead of 09:00am
  hash["starttime"][1..-1]
end

def end_time(hash)
  #takes a hash and returns the value at the endtime key
  return nil unless hash["endtime"].present?
  return hash["endtime"] unless hash["endtime"][0] == "0"
  #trim leading zero
  hash["endtime"][1..-1]
end

=begin
can take:
  self.monday_end or self.mon_end
  self.monday_start or self.mon_start
  self.monday_open or self.mon_opened or self.mon_opens
  self.monday_close or self.mon_closed or self.mon_closed
=end
def method_missing(method, *args, &block)
  # don't alter the method parameter before call super
  # no method.gsub
  # method is a symbol at this point
  # convert to string and downcase
  name = method.to_s.downcase
  
  # split the name by the underscore and take the first three char
  day = name.split('_').first[0..2]
  # split the name by the undersore, should be start or end
  period = name.split('_').last
  
  return super unless %w[ mon tue wed thu fri sat sun ].include?(day)
  
  if %w[ start open opens opened ].include?(period)
    # pass it to start_time if period is start
    start_time(hours[day])
  elsif %w[ end close closes closed ].include?(period)
    # pass it to end_time if period is end
    end_time(hours[day])
  else
    # don't get too deep in the stack
    super
  end
end