Add markdown export to books and pages

app/controllers/application_controller.rb

@@ -3,4 +3,9 @@ class ApplicationController < ActionController::Base
 
   # Only allow modern browsers supporting webp images, web push, badges, import maps, CSS nesting, and CSS :has.
   allow_browser versions: :modern
+
+  private
+    def set_active_storage_url_options
+      ActiveStorage::Current.url_options = { protocol: request.protocol, host: request.host, port: request.port }
+    end
 end

app/controllers/books_controller.rb

@@ -23,6 +23,14 @@ def create
 
   def show
     @leaves = @book.leaves.active.with_leafables.positioned
+
+    respond_to do |format|
+      format.html
+      format.md do
+        set_active_storage_url_options
+        render plain: @book.to_markdown
+      end
+    end
   end
 
   def edit

app/controllers/leafables_controller.rb

@@ -16,6 +16,13 @@ def create
   end
 
   def show
+    respond_to do |format|
+      format.html
+      format.md do
+        set_active_storage_url_options
+        render plain: @leaf.to_markdown
+      end
+    end
   end
 
   def edit

app/models/book.rb

@@ -12,4 +12,11 @@ class Book < ApplicationRecord
   def press(leafable, leaf_params)
     leaves.create! leaf_params.merge(leafable: leafable)
   end
+
+  def to_markdown(url_options: ActiveStorage::Current.url_options)
+    [ "# #{title}", leaves.active.with_leafables.positioned.map { |leaf| leaf.to_markdown(url_options: url_options) } ]
+      .flatten
+      .reject(&:blank?)
+      .join("\n\n")
+  end
 end

app/models/leaf.rb

@@ -14,4 +14,8 @@ class Leaf < ApplicationRecord
   def slug
     title.parameterize.presence || "-"
   end
+
+  def to_markdown(url_options: ActiveStorage::Current.url_options)
+    leafable.to_markdown(title: title, url_options: url_options)
+  end
 end

app/models/page.rb

@@ -16,6 +16,10 @@ def html_preview
     rendered_html(markdown_source.first(1024))
   end
 
+  def to_markdown(title:, url_options: ActiveStorage::Current.url_options)
+    [ "### #{title}", expand_markdown_urls(markdown_source, url_options: url_options) ].join("\n\n")
+  end
+
   private
     def plain_text
       html_body = rendered_html(markdown_source)
@@ -29,4 +33,13 @@ def rendered_html(source)
     def markdown_source
       body.content.to_s
     end
+
+    def expand_markdown_urls(content, url_options:)
+      return content if url_options.blank?
+
+      content.gsub(%r{(?<=\()\/u\/([^\)\s]+)}) do
+        slug = Regexp.last_match(1)
+        Rails.application.routes.url_helpers.action_text_markdown_upload_url(slug, **url_options)
+      end
+    end
 end

app/models/picture.rb

@@ -4,4 +4,16 @@ class Picture < ApplicationRecord
   has_one_attached :image do |attachable|
     attachable.variant :large, resize_to_limit: [ 1500, 1500 ]
   end
+
+  def to_markdown(title:, url_options: ActiveStorage::Current.url_options)
+    [ "### #{title}", image_markdown(url_options), caption.presence ].compact.join("\n\n")
+  end
+
+  private
+    def image_markdown(url_options)
+      return unless image.attached?
+
+      url = Rails.application.routes.url_helpers.rails_blob_url(image, **url_options)
+      "![#{title}](#{url})"
+    end
 end

app/models/section.rb

@@ -4,4 +4,8 @@ class Section < ApplicationRecord
   def searchable_content
     body
   end
+
+  def to_markdown(title:, url_options: ActiveStorage::Current.url_options)
+    [ "## #{title}", body.to_s ].join("\n\n")
+  end
 end

test/controllers/books_controller_test.rb

@@ -79,6 +79,19 @@ class BooksControllerTest < ActionDispatch::IntegrationTest
     assert_response :success
   end
 
+  test "show exports markdown" do
+    get book_slug_url(books(:handbook), format: :md)
+
+    assert_response :success
+    assert_includes response.body, "# Handbook"
+    assert_includes response.body, "## The Welcome Section"
+    assert_includes response.body, "### Welcome to The Handbook!"
+    assert_includes response.body, "This is _such_ a great handbook."
+
+    url = rails_blob_url(pictures(:reading).image, host: "www.example.com")
+    assert_includes response.body, "![Reading](#{url})"
+  end
+
   test "show includes OG metadata for public access" do
     get book_slug_url(books(:handbook))
     assert_response :success

test/controllers/leafables_controller_test.rb

@@ -12,6 +12,14 @@ class LeafablesControllerTest < ActionDispatch::IntegrationTest
     assert_select "p", "This is such a great handbook."
   end
 
+  test "show markdown export" do
+    get leafable_slug_path(leaves(:welcome_page), format: :md)
+
+    assert_response :success
+    assert_includes response.body, "### Welcome to The Handbook!"
+    assert_includes response.body, "This is _such_ a great handbook."
+  end
+
   test "show with public access to a published book" do
     sign_out
     books(:handbook).update!(published: true)

test/controllers/pages_controller_test.rb

@@ -12,6 +12,14 @@ class PagesControllerTest < ActionDispatch::IntegrationTest
     assert_select "h2", text: /Hello/
   end
 
+  test "show as markdown" do
+    get leafable_path(leaves(:welcome_page), format: :md)
+
+    assert_response :ok
+    assert_includes response.body, "### Welcome to The Handbook!"
+    assert_includes response.body, "This is _such_ a great handbook."
+  end
+
   test "show sanitizes dangerous content" do
     get leafable_path(sample_page_leaf(%(<div id="test"><script>alert("ouch")</script></div>)))