Add VineJwtService

Generate a JWT token to be used to connect to the VINE api

app/services/vine_jwt_service.rb

@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+class VineJwtService
+  ALGORITHM = "HS256"
+  ISSUER = "openfoodnetwork"
+
+  def initialize(secret: )
+    @secret = secret
+  end
+
+  def generate_token
+    generation_time = Time.zone.now
+    payload = {
+      iss: ISSUER,
+      iat: generation_time.to_i,
+      exp: (generation_time + 1.minute).to_i,
+    }
+
+    JWT.encode(payload, @secret, ALGORITHM)
+  end
+end

spec/services/vine_jwt_service_spec.rb

@@ -0,0 +1,52 @@
+# frozen_string_literal: true
+
+require "spec_helper"
+
+RSpec.describe VineJwtService do
+  describe "#generate_token" do
+    subject { described_class.new(secret: vine_secret) }
+    let(:vine_secret) { "some_secret" }
+
+    it "generate a jwt token" do
+      expect(subject.generate_token).to be_a String
+    end
+
+    it "includes issuing body" do
+      token = subject.generate_token
+
+      payload = decode(token, vine_secret)
+
+      expect(payload["iss"]).to eq("openfoodnetwork")
+    end
+
+    it "includes issuing time" do
+      generate_time = Time.zone.now
+      Timecop.freeze(generate_time) do
+        token = subject.generate_token
+
+        payload = decode(token, vine_secret)
+
+        expect(payload["iat"].to_i).to eq(generate_time.to_i)
+      end
+    end
+
+    it "includes expirations time" do
+      generate_time = Time.zone.now
+      Timecop.freeze(generate_time) do
+        token = subject.generate_token
+
+        payload = decode(token, vine_secret)
+
+        expect(payload["exp"].to_i).to eq((generate_time + 1.minute).to_i)
+      end
+    end
+  end
+
+  def decode(token, secret)
+    JWT.decode(
+      token,
+      secret,
+      true, { algorithm: "HS256" }
+    ).first
+  end
+end