add FileConversionJob which can convert meshes to 3MF

app/jobs/analysis/file_conversion_job.rb

@@ -0,0 +1,41 @@
+require "string/similarity"
+
+class Analysis::FileConversionJob < ApplicationJob
+  queue_as :analysis
+
+  def perform(file_id, output_format)
+    # Can we output this format?
+    return unless SupportedMimeTypes.can_export?(output_format)
+    # Get model
+    begin
+      file = ModelFile.find(file_id)
+    rescue ActiveRecord::RecordNotFound
+      return
+    end
+    exporter = nil
+    extension = nil
+    case output_format
+    when :threemf
+      return unless file.mesh.manifold?
+      extension = "3mf"
+      exporter = Mittsu::ThreeMFExporter.new
+    end
+    if exporter
+      new_file = ModelFile.new(
+        model: file.model,
+        filename: file.filename.gsub(".#{file.extension}", ".#{extension}")
+      )
+      dedup = 0
+      while File.exist?(new_file.pathname)
+        dedup += 1
+        new_file.filename = file.filename.gsub(".#{file.extension}", "-#{dedup}.#{extension}")
+      end
+      # Save the actual file in new format
+      exporter.export(file.mesh, new_file.pathname)
+      # Store record in database
+      new_file.save
+      # Queue up file scan
+      Analysis::AnalyseModelFileJob.perform_later(new_file.id)
+    end
+  end
+end

app/lib/supported_mime_types.rb

@@ -15,6 +15,10 @@ module SupportedMimeTypes
     Mime::EXTENSION_LOOKUP.filter { |k, v| is_model_mime_type?(v) }.keys
   end
 
+  def self.can_export?(type)
+    [:threemf].include? type
+  end
+
   class << self
     private
 

app/models/model_file.rb

@@ -43,8 +43,12 @@ class ModelFile < ApplicationRecord
     Mime::Type.lookup_by_extension(extension)
   end
 
+  def basename
+    File.basename(filename, ".*")
+  end
+
   def name
-    File.basename(filename, ".*").humanize.titleize
+    basename.humanize.titleize
   end
 
   def pathname

spec/jobs/analysis/file_conversion_job_spec.rb

@@ -0,0 +1,83 @@
+require "rails_helper"
+require "support/mock_directory"
+
+RSpec.describe Analysis::FileConversionJob do
+  around do |ex|
+    MockDirectory.create([
+      "model_one/files/awesome.stl"
+    ]) do |path|
+      @library_path = path
+      ex.run
+    end
+  end
+
+  let(:library) { create(:library, path: @library_path) } # rubocop:todo RSpec/InstanceVariable
+  let(:model) { create(:model, path: "model_one", library: library) }
+  let(:file) { create(:model_file, model: model, filename: "files/awesome.stl") }
+  let(:mesh) do
+    m = Mittsu::Mesh.new(Mittsu::SphereGeometry.new(2.0, 32, 16))
+    m.geometry.merge_vertices
+    m
+  end
+
+  before do
+    ActiveJob::Base.queue_adapter = :test
+    allow(file).to receive(:mesh).and_return(mesh)
+    allow(ModelFile).to receive(:find).with(file.id).and_return(file)
+  end
+
+  context "when converting to 3MF" do
+    it "creates a new file" do
+      expect { described_class.perform_now(file.id, :threemf) }.to change(ModelFile, :count).from(1).to(2)
+    end
+
+    it "creates a file with 3mf extension" do
+      described_class.perform_now(file.id, :threemf)
+      expect(ModelFile.where.not(id: file.id).first.extension).to eq "3mf"
+    end
+
+    it "creates a file with the same basename as the original" do
+      described_class.perform_now(file.id, :threemf)
+      expect(ModelFile.where.not(id: file.id).first.filename).to eq "files/awesome.3mf"
+    end
+
+    it "avoids filenames that already exist" do
+      allow(File).to receive(:exist?).with(file.pathname.gsub(".stl", ".3mf")).and_return(true).once
+      allow(File).to receive(:exist?).with(file.pathname.gsub(".stl", "-1.3mf")).and_return(true).once
+      allow(File).to receive(:exist?).with(file.pathname.gsub(".stl", "-2.3mf")).and_return(false).once
+      described_class.perform_now(file.id, :threemf)
+      expect(ModelFile.where.not(id: file.id).first.filename).to eq "files/awesome-2.3mf"
+    end
+
+    it "creates an actual 3MF file on disk" do
+      described_class.perform_now(file.id, :threemf)
+      pathname = ModelFile.where.not(id: file.id).first.pathname
+      expect(File.exist?(pathname)).to be true
+    end
+
+    it "does not remove the original file" do
+      described_class.perform_now(file.id, :threemf)
+      expect { ModelFile.find(file.id) }.not_to raise_error
+    end
+
+    it "should create a file equivalence with the original file"
+
+    it "does not convert non-manifold meshes" do
+      allow(mesh).to receive(:manifold?).and_return(false)
+      expect { described_class.perform_now(file.id, :threemf) }.not_to change(ModelFile, :count)
+    end
+
+    it "queues up analysis job for new file" do
+      expect { described_class.perform_now(file.id, :threemf) }.to have_enqueued_job(Analysis::AnalyseModelFileJob)
+    end
+  end
+
+  it "does nothing with an invalid file ID" do
+    allow(ModelFile).to receive(:find).with(nil).and_raise(ActiveRecord::RecordNotFound)
+    expect { described_class.perform_now(nil, :threemf) }.not_to raise_error
+  end
+
+  it "does nothing with an invalid output format" do
+    expect { described_class.perform_now(file.id, :ply) }.not_to raise_error
+  end
+end