Added font synchronizer

Ensures the local public fonts folder is in sync with the Core server fonts. This includes deleting files that are no longer registered.

Issue: 287
Milestone: minor

app/aspects/fonts/synchronizer.rb

@@ -0,0 +1,55 @@
+# frozen_string_literal: true
+
+require "initable"
+require "refinements/pathname"
+
+module Terminus
+  module Aspects
+    module Fonts
+      # Synchronizes TRMNL Framework fonts for local use.
+      class Synchronizer
+        include Deps[:settings, "aspects.downloader"]
+        include Initable[
+          root_uri: "https://trmnl.com/fonts",
+          names: %w[
+            BlockKie.ttf
+            Inter-Italic.ttf
+            Inter.ttf
+            NicoBold-Regular.ttf
+            NicoClean-Regular.ttf
+            NicoPups-Regular.ttf
+            dogicapixel.ttf
+            dogicapixelbold.ttf
+          ]
+        ]
+        include Dry::Monads[:result]
+
+        using Refinements::Pathname
+
+        def call
+          root = settings.fonts_root.make_dir
+
+          delete_unknown_files_in root
+          names.map { download_to root, it }
+        end
+
+        private
+
+        def delete_unknown_files_in root
+          root.files
+              .map { it.basename.to_s }
+              .then { |locals| locals - names }
+              .each { root.join(it).delete }
+        end
+
+        def download_to root, name
+          path = root.join name
+
+          return Success path if path.exist?
+
+          downloader.call("#{root_uri}/#{name}").fmap { |response| path.write response.body }
+        end
+      end
+    end
+  end
+end

spec/app/aspects/fonts/synchronizer_spec.rb

@@ -0,0 +1,94 @@
+# frozen_string_literal: true
+
+require "hanami_helper"
+require "trmnl/api"
+
+RSpec.describe Terminus::Aspects::Fonts::Synchronizer do
+  using Refinements::Pathname
+
+  subject(:synchronizer) { described_class.new downloader: }
+
+  include_context "with application dependencies"
+
+  let(:downloader) { instance_double Terminus::Aspects::Downloader, call: response }
+
+  let :response do
+    Success(
+      HTTP::Response.new(
+        uri: "https://trmnl-oss.s3-us-east-2.amazonaws.com/fonts/test.ttf",
+        verb: :get,
+        body: [123].pack("N"),
+        status: 200,
+        version: 1.0
+      )
+    )
+  end
+
+  describe "#call" do
+    it "deletes unknown files" do
+      temp_dir.join("test.txt").touch
+      synchronizer.call
+
+      expect(temp_dir.files).not_to include(temp_dir.join("test.txt"))
+    end
+
+    it "doesn't download files that exist" do
+      downloader = instance_double Terminus::Aspects::Downloader, call: Failure("Skip.")
+      synchronizer = described_class.new(downloader:)
+
+      temp_dir.join("BlockKie.ttf").touch
+      synchronizer.call
+
+      expect(temp_dir.files).to contain_exactly(temp_dir.join("BlockKie.ttf"))
+    end
+
+    it "answers array of mixed results" do
+      count = 0
+
+      allow(downloader).to receive(:call) do
+        count += 1
+        count.even? ? response : Failure("Danger!")
+      end
+
+      expect(synchronizer.call).to eq(
+        [
+          Failure("Danger!"),
+          Success(temp_dir.join("Inter-Italic.ttf")),
+          Failure("Danger!"),
+          Success(temp_dir.join("NicoBold-Regular.ttf")),
+          Failure("Danger!"),
+          Success(temp_dir.join("NicoPups-Regular.ttf")),
+          Failure("Danger!"),
+          Success(temp_dir.join("dogicapixelbold.ttf"))
+        ]
+      )
+    end
+
+    it "downloads remote files" do
+      synchronizer.call
+
+      expect(temp_dir.files).to eq(
+        [
+          temp_dir.join("BlockKie.ttf"),
+          temp_dir.join("Inter-Italic.ttf"),
+          temp_dir.join("Inter.ttf"),
+          temp_dir.join("NicoBold-Regular.ttf"),
+          temp_dir.join("NicoClean-Regular.ttf"),
+          temp_dir.join("NicoPups-Regular.ttf"),
+          temp_dir.join("dogicapixel.ttf"),
+          temp_dir.join("dogicapixelbold.ttf")
+        ]
+      )
+    end
+
+    context "with failure" do
+      subject(:synchronizer) { described_class.new names: ["test.ttf"], downloader: }
+
+      let(:response) { Failure "Danger!" }
+
+      it "answers message" do
+        expect(synchronizer.call).to contain_exactly(Failure("Danger!"))
+      end
+    end
+  end
+end