Add UCS-2 encoding / decoding for SMS user data

lib/biju/pdu.rb

@@ -1,9 +1,11 @@
 require 'biju/pdu/gsm7bit'
+require 'biju/pdu/ucs2'
 
 module Biju
   module PDU
     ENCODING = {
       gsm7bit: GSM7Bit,
+      ucs2: UCS2,
     }
 
     def self.encode(hash)
@@ -30,7 +32,8 @@ module Biju
           '%S%M%H%d%m%y%Z'),
         user_data_length: string[52..53],
       }
-      res[:sender_number] = string[22..(22 + res[:address_length])]
+      res[:sender_number] = string[22..(22 + res[:address_length])].scan(/../)
+        .map(&:reverse).join.chop
       res[:user_data] = PDU.decode_user_data(string[54..-1],
         encoding: res[:data_coding_scheme],
         length: res[:user_data_length].hex)
@@ -41,8 +44,8 @@ module Biju
     def self.decode_user_data(message, encoding: '00', length: 0)
       encoding = data_coding_scheme(encoding) unless encoding.is_a?(Symbol)
 
-      raise ArgumentError, "Unknown encoding" unless ENCODING.has_key?(:gsm7bit)
-      ENCODING[:gsm7bit].decode(message, length: length)
+      raise ArgumentError, "Unknown encoding" unless ENCODING.has_key?(encoding)
+      ENCODING[encoding].decode(message, length: length)
     end
 
     def self.data_coding_scheme(dcs)

lib/biju/pdu/ucs2.rb

@@ -0,0 +1,14 @@
+module Biju
+  module PDU
+    class UCS2
+      def self.decode(string, length: 0)
+        string.scan(/.{4}/).map { |char| char.hex.chr('UCS-2BE') }.join
+          .encode('UTF-8', 'UCS-2BE')
+      end
+
+      def self.encode(string)
+        string.encode('UCS-2BE').chars.map { |char| "%04x" % char.ord }.join
+      end
+    end
+  end
+end

spec/biju/pdu/ucs2_spec.rb

@@ -0,0 +1,30 @@
+require 'spec_helper'
+require 'biju/pdu/ucs2'
+
+describe Biju::PDU::UCS2 do
+  describe '::decode' do
+    it "decodes string" do
+      expect(Biju::PDU::UCS2.decode('00C700E700E200E300E500E4016B00F80153', length: 4)).to eq('Ççâãåäūøœ')
+    end
+  end
+
+  describe '::encode' do
+    it "encodes string" do
+      expect(Biju::PDU::UCS2.encode('Ççâãåäūøœ').upcase).to eq('00C700E700E200E300E500E4016B00F80153')
+    end
+  end
+
+  it "gives same text after encoding and decoding" do
+    strings = [
+      'My first TEST',
+      '{More çomplicated]',
+      'And on€ More~',
+      'þß®',
+    ]
+
+    strings.each do |string|
+      expect(Biju::PDU::UCS2.decode(
+        Biju::PDU::UCS2.encode(string), length: string.length)).to eq(string)
+    end
+  end
+end