Use marcel to detect content types

When pages embed content via wikilinks, the behaviour depends on the
content type. For images, we can generate regular image markdown. For
anything else, we generate a link.

Gemfile.lock

@@ -2,6 +2,7 @@ PATH
   remote: .
   specs:
     obsidian-parser (0.7.0)
+      marcel (~> 0.3.1)
       markly (~> 0.7.0)
 
 GEM
@@ -13,8 +14,17 @@ GEM
     json (2.6.3)
     language_server-protocol (3.17.0.3)
     lint_roller (1.1.0)
+    marcel (0.3.3)
+      mimemagic (~> 0.3.2)
     markly (0.7.0)
     method_source (1.0.0)
+    mimemagic (0.3.10)
+      nokogiri (~> 1)
+      rake
+    nokogiri (1.15.4-x86_64-darwin)
+      racc (~> 1.4)
+    nokogiri (1.15.4-x86_64-linux)
+      racc (~> 1.4)
     parallel (1.23.0)
     parser (3.2.2.3)
       ast (~> 2.4.1)

lib/obsidian/parser.rb

@@ -26,17 +26,17 @@ def initialize(vault_directory)
       markdown_parser = MarkdownParser.new
 
       vault_directory.glob("**/*").each do |path|
-        dirname, basename = path.relative_path_from(vault_directory).split
+        next if path.directory?
 
-        next if basename == "."
+        dirname, basename = path.relative_path_from(vault_directory).split
 
         # Remove the path component "./" from the start of the dirname
         parent_slug = dirname.to_s.gsub(/\A\.\/?/, "")
 
         if basename.to_s.end_with?(".md")
           add_markdown_file(basename: basename, parent_slug: parent_slug, path: path, last_modified: path.mtime, markdown_parser: markdown_parser)
         else
-          add_media_file(basename: basename, parent_slug: parent_slug, last_modified: path.mtime)
+          add_media_file(basename: basename, parent_slug: parent_slug, last_modified: path.mtime, path: path)
         end
       end
 
@@ -67,11 +67,11 @@ def add_markdown_file(basename:, parent_slug:, last_modified:, path:, markdown_p
       )
     end
 
-    def add_media_file(basename:, parent_slug:, last_modified:)
+    def add_media_file(basename:, parent_slug:, last_modified:, path:)
       @media_index.add_page(
         Obsidian.build_slug(basename.to_s, parent_slug),
         last_modified: last_modified,
-        content_type: PretendEverythingIsAnImage.new
+        content_type: ContentType.new(path)
       )
     end
   end

lib/obsidian/parser/content_type.rb

@@ -1,5 +1,13 @@
-class PretendEverythingIsAnImage
+require "marcel"
+
+class ContentType
+  def initialize(path)
+    @content_type = Marcel::MimeType.for(path)
+  end
+
   def image?
-    true
+    content_type.start_with?("image/")
   end
+
+  attr_reader :content_type
 end

obsidian-parser.gemspec

@@ -31,6 +31,7 @@ Gem::Specification.new do |spec|
   spec.require_paths = ["lib"]
 
   spec.add_dependency "markly", "~> 0.7.0"
+  spec.add_dependency "marcel", "~> 0.3.1"
 
   # For more information and examples about making a new gem, check out our
   # guide at: https://bundler.io/guides/creating_gem.html

spec/obsidian/parser/markdown_parser_spec.rb

@@ -66,7 +66,11 @@
       let(:media_root) { Obsidian::Page.create_root }
 
       before do
-        media_root.add_page("foo/bar.jpg", content_type: PretendEverythingIsAnImage.new)
+        path = Pathname.new(__dir__).join("../../example_vault/foo/bar.jpg")
+        media_root.add_page("foo/bar.jpg", content_type: ContentType.new(path))
+
+        path = Pathname.new(__dir__).join("../../example_vault/hello_world.txt")
+        media_root.add_page("hello_world.txt", content_type: ContentType.new(path))
       end
 
       it "expands image wikilinks" do
@@ -95,6 +99,11 @@
         expect(result).to eq("[bar](/foo/bar)")
       end
 
+      it "falls back to a link if the target is not an image" do
+        result = parser.expand_attachments("![[hello_world.txt]]", root: index, media_root: media_root)
+        expect(result).to eq("[hello_world.txt](/hello_world.txt)")
+      end
+
       it "falls back to plain text if there is no such page" do
         result = parser.expand_attachments("![[banana|a yellow banana]]", root: index, media_root: media_root)
         expect(result).to eq("a yellow banana")