Class: Chronicle::ChronicleHash

Inherits:
Hash
  • Object
show all
Defined in:
lib/chronicle.rb

Instance Method Summary collapse

Constructor Details

#initialize(collection, options) ⇒ ChronicleHash

Returns a new instance of ChronicleHash.



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# File 'lib/chronicle.rb', line 98

def initialize(collection, options)
  
  eras = options[:eras]
        
  # Remove objects with nil timestamps
  collection.reject! {|obj| obj.send(options[:date_attr]).nil? }
  
  # Determine whether collection contains future or past timestamps
  if collection.all? { |obj| obj.send(options[:date_attr]) < Time.now }
    order = :past
  elsif collection.all? { |obj| obj.send(options[:date_attr]) > Time.now }
    order = :future
  else
    raise "Chronicle collections must be entirely in the past or the future."
  end
        
  # Sort collection by date
  # For past collections, newest objects come first 
  # For future collections, oldest objects come first
  collection = collection.sort_by {|obj| obj.send(options[:date_attr]) }
  collection.reverse! if order == :past

  # Force inclusion of 'now' era in case it's missing.
  eras.push('right now').uniq!
  
  # Parse era strings using Chronic
  # Ensure all eras can be parsed
  # { "7 years ago" => 2006-01-02 23:29:05 -0800, ... }
  era_date_pairs = eras.inject({}) {|h,era|
    h[era] = Chronic.parse(era)
    raise "Could not parse era: #{era}" if h[era].nil?
    h
  }

  # Sort eras by date
  # For past collections, newest eras come first
  # For future collections, oldest eras come first
  eras = eras.sort_by {|era| era_date_pairs[era] }
  eras.reverse! if order == :future

  # Initialize all hash keys chronologically
  eras.reverse.each {|era| self[era] = [] }
  
  collection.each do |obj|
    era = eras.find do |era|
      if order == :future
        # Find newest possible era for the object
        obj.send(options[:date_attr]) > era_date_pairs[era]
      else
        # Find oldest possible era for the object
        obj.send(options[:date_attr]) < era_date_pairs[era]
      end
    end
    self[era] << obj
  end

  # Remove empty eras
  self.keys.each {|k| self.delete(k) if self[k].empty? }

  self
end