improving code quality of jwt module

lib/jwt.rb

@@ -22,42 +22,60 @@ def encode(payload, key, algorithm = 'HS256', header_fields = {})
     encoder.segments
   end
 
-  def decode(jwt, key = nil, verify = true, custom_options = {}, &keyfinder)
+  def decode(jwt, key = nil, verify = true, options = {}, &keyfinder)
     raise(JWT::DecodeError, 'Nil JSON web token') unless jwt
 
-    merged_options = DEFAULT_OPTIONS.merge(custom_options)
-
-    decoder = Decode.new jwt, verify
-    header, payload, signature, signing_input = decoder.decode_segments
-    decode_verify_signature(key, header, payload, signature, signing_input, merged_options, &keyfinder) if verify
+    @jwt = jwt
+    @key = key
+    @verify = verify
+    @options = DEFAULT_OPTIONS.merge(options)
+    @header,
+    @payload,
+    @signature,
+    @signing_input = Decode.new(jwt, verify).decode_segments
+    if verify?
+      verify_signature(&keyfinder)
+      verify_claims
+    end
 
-    Verify.verify_claims(payload, merged_options) if verify
 
-    raise(JWT::DecodeError, 'Not enough or too many segments') unless header && payload
+    raise(JWT::DecodeError, 'Not enough or too many segments') unless @header && @payload
 
-    [payload, header]
+    [@payload, @header]
   end
+  private_class_method
+  def verify_signature(&keyfinder)
+    @key = find_key(&keyfinder) if keyfinder
 
-  def decode_verify_signature(key, header, payload, signature, signing_input, options, &keyfinder)
-    algo, key = signature_algorithm_and_key(header, payload, key, &keyfinder)
-
-    raise(JWT::IncorrectAlgorithm, 'An algorithm must be specified') if allowed_algorithms(options).empty?
-    raise(JWT::IncorrectAlgorithm, 'Expected a different algorithm') unless allowed_algorithms(options).include?(algo)
+    raise(JWT::IncorrectAlgorithm, 'An algorithm must be specified') if allowed_algorithms.empty?
+    raise(JWT::IncorrectAlgorithm, 'Expected a different algorithm') unless options_includes_algo_in_header?
 
-    Signature.verify(algo, key, signing_input, signature)
+    Signature.verify(@header['alg'], @key, @signing_input, @signature)
   end
 
-  def signature_algorithm_and_key(header, payload, key, &keyfinder)
-    key = (keyfinder.arity == 2 ? yield(header, payload) : yield(header)) if keyfinder
+  def find_key(&keyfinder)
+    key = (keyfinder.arity == 2 ? yield(@header, @payload) : yield(@header))
     raise JWT::DecodeError, 'No verification key available' unless key
-    [header['alg'], key]
+    key
   end
 
-  def allowed_algorithms(options)
-    if options.key?(:algorithm)
-      [options[:algorithm]]
+  def allowed_algorithms
+    if @options.key?(:algorithm)
+      [@options[:algorithm]]
     else
-      options[:algorithms] || []
+      @options[:algorithms] || []
     end
   end
+
+  def verify?
+    @verify
+  end
+
+  def verify_claims
+    Verify.verify_claims(@payload, @options)
+  end
+
+  def options_includes_algo_in_header?
+    allowed_algorithms.include? @header['alg']
+  end
 end