Class: Dropzone::Item

Inherits:
MessageBase show all
Defined in:
lib/dropzone/item.rb

Defined Under Namespace

Classes: Validator

Constant Summary collapse

EARTH_RADIUS_IN_METERS = 
6_371_000
HASH_160_PARTS = 
/\A(?:mfZ|1DZ)([1-9X]{9})([1-9X]{9})([1-9X]{6}).+/

Constants inherited from MessageBase

MessageBase::DEFAULT_TIP

Instance Attribute Summary collapse

Attributes inherited from MessageBase

#block_height, #sender_addr, #txid

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from MessageBase

attr_message, attr_message_int, attr_message_pkey, #data_to_hash, #data_to_hex, find, #initialize, is_attr_int?, is_attr_pkey?, message_attribs, message_type, new_message_from, #save!, #to_transaction, types_include?

Methods inherited from RecordBase

#blockchain, #errors, #valid?

Constructor Details

This class inherits a constructor from Dropzone::MessageBase

Instance Attribute Details

#latitude ⇒ Object (readonly)

These are receiver address attributes, not message attribs:



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# File 'lib/dropzone/item.rb', line 11

def latitude
  @latitude
end

#longitude ⇒ Object (readonly)

These are receiver address attributes, not message attribs:



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# File 'lib/dropzone/item.rb', line 11

def longitude
  @longitude
end

#radius ⇒ Object (readonly)

These are receiver address attributes, not message attribs:



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# File 'lib/dropzone/item.rb', line 11

def radius
  @radius
end

Class Method Details

.blockchain ⇒ Object 



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# File 'lib/dropzone/item.rb', line 72

def self.blockchain
  Dropzone::RecordBase.blockchain
end

.distance_between(lat1, lon1, lat2, lon2) ⇒ Object

haversine formula, pulled from : www.movable-type.co.uk/scripts/latlong.html



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# File 'lib/dropzone/item.rb', line 97

def self.distance_between(lat1, lon1, lat2, lon2)
  delta_phi = to_rad(lat2-lat1)
  delta_lamba = to_rad(lon2-lon1)

  a = Math.sin(delta_phi/2) ** 2 + [ Math.cos(to_rad(lat1)), 
    Math.cos(to_rad(lat2)), Math.sin(delta_lamba/2), 
    Math.sin(delta_lamba/2) ].reduce(:*)

  c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a))

  EARTH_RADIUS_IN_METERS * c
end

.find_creates_since_block(starting_at, block_depth, &block) ⇒ Object

Returns all *Items created* since (and including) the provided block These are items and not listings, so as to query faster. Items are returned in the order of newest to oldest



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# File 'lib/dropzone/item.rb', line 79

def self.find_creates_since_block(starting_at, block_depth, &block)
  starting_at.downto(starting_at-block_depth).collect{|i|
    blockchain.messages_in_block(i, type: 'ITCRTE').collect do |item|
      (block_given?) ? block.call(item, i) : item
    end
  }.flatten.compact
end

.find_in_radius(starting_at, block_depth, lat, long, in_meters, &block) ⇒ Object 



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# File 'lib/dropzone/item.rb', line 87

def self.find_in_radius(starting_at, block_depth, lat, long, in_meters, &block)
  find_creates_since_block(starting_at, block_depth) do |item, nb|
    if distance_between(item.latitude, item.longitude, lat, long) <= in_meters 
      (block_given?) ? block.call(item, nb) : item
    end
  end
end

.to_rad(angle) ⇒ Object 



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# File 'lib/dropzone/item.rb', line 110

def self.to_rad(angle)
  angle.to_f / 180 * Math::PI
end

Instance Method Details

#message_type ⇒ Object 



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# File 'lib/dropzone/item.rb', line 33

def message_type
  return @message_type if @message_type 

  create_txid ? 'ITUPDT' : 'ITCRTE'
end

#receiver_addr ⇒ Object

This is an easy guide to what we’re doing here: www.reddit.com/r/Bitcoin/comments/2ss3en/calculating_checksum_for_bitcoin_address/

NOTE: There was a digit off in the reference spec, this radius is a seven

digit number, not an eight digit number.



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# File 'lib/dropzone/item.rb', line 44

def receiver_addr
  case 
    when @receiver_addr then @receiver_addr
    when create_txid then @sender_addr
    when latitude && longitude && radius
      receiver_addr_base = ('%s%09d%09d%06d' % [
        (blockchain.is_testing?) ? 'mfZ' : ('1' + BitcoinConnection::PREFIX),
        latlon_to_integer(latitude.to_f), 
        latlon_to_integer(longitude.to_f, 180), 
        radius.abs ]).tr('0','X')

      # The x's pad the checksum component for us to ensure the base conversion
      # produces the correct output. Similarly, we ignore them after the decode:
      hex_address = Bitcoin.decode_base58(receiver_addr_base+'XXXXXXX')[0...42]

      hash160 = [hex_address].pack('H*')
       
      # Bitcoin-ruby has a method to do much of this for us, but it is 
      # broken in that it only supports main-net addresses, and not testnet3
      checksum = Digest::SHA256.digest(Digest::SHA256.digest(hash160))[0,4]
   
      # Return the checksum'd receiver_addr
      Bitcoin.encode_base58((hash160 + checksum).unpack('H*').first)
    else 
      nil
  end
end