Make headline images explicit, add asset credits

- related_assets gains a `headline` boolean (DB-enforced: at most one
  per page), replacing "first image by position" as the headline
  rule. A rake task backfills the current first image on every live
  head/draft, so nothing changes visually until an editor changes it.
- The image picker sidebar gets a star toggle reflecting the flag;
  the TinyMCE inline-image picker's badge now reads it too, instead
  of assuming position 0.
- No headline chosen (or none attached) now falls back to the
  gallery-count caption itself becoming the lightbox trigger, instead
  of the gallery being unreachable.
- Assets gain creator, source_url, and license_key (against a new
  config/asset_licenses.yml dictionary). asset_credit renders a
  degrading attribution line, reused as a hidden per-image glightbox
  caption so credit is one click away for every image, not only the
  headline's always-visible one.
- Fixed: asset thumbnails rendered unconditionally regardless of
  whether a real variant exists on disk. Asset#has_variant? checks
  file existence, not content type -- some legacy PDFs have real
  pre-rewrite thumbnails a content-type check would have hidden.
- assets#new/edit rebuilt onto the same node_description/node_content
  layout as assets#show, picking up the three new fields in the
  process.

4 files changed, 169 insertions, 7 deletions

diff --git a/test/models/asset_license_test.rb b/test/models/asset_license_test.rb
new file mode 100644
index 0000000..9f2d04f
--- /dev/null
+++ b/test/models/asset_license_test.rb
@@ -0,0 +1,31 @@
+require 'test_helper'
+
+class AssetLicenseTest < ActiveSupport::TestCase
+  test "find returns a populated entry for a known key" do
+    entry = AssetLicense.find("cc_by_4")
+
+    assert_equal "cc_by_4", entry.key
+    assert_equal "https://creativecommons.org/licenses/by/4.0/", entry.url
+    assert entry.requires_attribution
+    assert_equal "license", entry.style
+  end
+
+  test "find returns nil for an unknown or blank key" do
+    assert_nil AssetLicense.find("not_a_real_license")
+    assert_nil AssetLicense.find(nil)
+    assert_nil AssetLicense.find("")
+  end
+
+  test "keys includes every dictionary entry" do
+    assert_includes AssetLicense.keys, "cc0"
+    assert_includes AssetLicense.keys, "own_work"
+  end
+
+  test "a note-style entry has no attribution requirement and no url" do
+    entry = AssetLicense.find("own_work")
+
+    assert_not entry.requires_attribution
+    assert_nil entry.url
+    assert_equal "note", entry.style
+  end
+end
diff --git a/test/models/asset_test.rb b/test/models/asset_test.rb
index a1041e4..d246abe 100644
--- a/test/models/asset_test.rb
+++ b/test/models/asset_test.rb
@@ -19,5 +19,26 @@ class AssetTest < ActiveSupport::TestCase
     assert_equal 0, draft.assets.length
     assert_equal 0, RelatedAsset.count
   end
-  
+
+  test "image? is true for supported image content types" do
+    assert Asset.new(:upload_content_type => "image/png").image?
+    assert Asset.new(:upload_content_type => "image/jpeg").image?
+  end
+
+  test "image? is false for non-image content types" do
+    assert_not Asset.new(:upload_content_type => "application/pdf").image?
+    assert_not Asset.new(:upload_content_type => nil).image?
+  end
+
+  test "license_key must be a known dictionary key" do
+    asset = Asset.new(:license_key => "not_a_real_license")
+    I18n.with_locale(:en) do
+      assert_not asset.valid?
+      assert_includes asset.errors[:license_key], "is not included in the list"
+    end
+  end
+
+  test "license_key may be blank" do
+    assert Asset.new(:license_key => nil).valid?
+  end  
 end
diff --git a/test/models/helpers/content_helper_test.rb b/test/models/helpers/content_helper_test.rb
index a7ed478..d6c7b43 100644
--- a/test/models/helpers/content_helper_test.rb
+++ b/test/models/helpers/content_helper_test.rb
@@ -2,7 +2,81 @@ require 'test_helper'
 
 class ContentHelperTest < ActionView::TestCase
   test "weekday_abbr delegates through the current I18n locale" do
-    I18n.locale = :de
-    assert_equal "Mo", weekday_abbr(Time.parse("2026-07-06"))
+    I18n.with_locale(:de) do
+      assert_equal "Mo", weekday_abbr(Time.parse("2026-07-06"))
+    end
+  end
+
+  test "asset_credit returns nil for a nil asset" do
+    assert_nil asset_credit(nil)
+  end
+
+  test "asset_credit returns nil when creator, source, and license are all blank" do
+    assert_nil asset_credit(Asset.new(:name => "blank"))
+  end
+
+  test "asset_credit renders creator, source link, and license link when all are present" do
+    asset = Asset.new(:name => "demo", :creator => "Jane Doe",
+                       :source_url => "https://example.org/photo", :license_key => "cc_by_4")
+
+    result = I18n.with_locale(:en) { asset_credit(asset) }
+
+    assert_match %r{<a href="https://example.org/photo">Photo demo</a>}, result
+    assert_match "by Jane Doe", result
+    assert_match %r{<a href="https://creativecommons.org/licenses/by/4.0/">Licensed under CC BY 4.0</a>}, result
+  end
+
+  test "asset_credit falls back to plain text when source_url is blank" do
+    asset = Asset.new(:name => "demo", :creator => "Jane Doe", :license_key => "cc_by_4")
+    assert_no_match %r{<a href="[^"]*">Photo demo</a>}, I18n.with_locale(:en) { asset_credit(asset) }
+  end
+
+  test "asset_credit omits the 'by' clause when creator is blank" do
+    asset = Asset.new(:name => "demo", :source_url => "https://example.org/photo", :license_key => "cc_by_4")
+    assert_no_match "by ", I18n.with_locale(:en) { asset_credit(asset) }
+  end
+
+  test "a note-style license renders with no 'Licensed under' prefix and no link" do
+    asset = Asset.new(:name => "demo", :creator => "CCC", :license_key => "own_work")
+    result = I18n.with_locale(:en) { asset_credit(asset) }
+
+    assert_match "Own work", result
+    assert_no_match "Licensed under", result
+    assert_no_match "<a", result
+  end
+
+  test "asset_credit degrades gracefully when the license_key is no longer in the dictionary" do
+    asset = Asset.new(:name => "demo", :creator => "Jane Doe")
+    asset.license_key = "a_retired_key"
+
+    result = I18n.with_locale(:en) { asset_credit(asset) }
+
+    assert_match "Photo demo by Jane Doe", result
+    assert_no_match "Licensed under", result
+  end
+
+  test "headline_image renders nothing when no images are attached" do
+    node = Node.root.children.create!(:slug => "headline_image_empty_test")
+    @page = node.draft
+    assert_nil headline_image
+  end
+
+  test "headline_image renders the flagged headline asset" do
+    node = Node.root.children.create!(:slug => "headline_image_flagged_test")
+    asset = Asset.create!(:name => "flagged", :upload_content_type => "image/png")
+    node.draft.assets << asset
+    node.draft.related_assets.find_by(:asset_id => asset.id).update!(:headline => true)
+    @page = node.draft
+
+    assert_match "glightbox", headline_image
+  end
+
+  test "headline_image falls back to a gallery-open caption when no headline is flagged" do
+    node = Node.root.children.create!(:slug => "headline_image_no_flag_test")
+    asset = Asset.create!(:name => "unflagged", :upload_content_type => "image/png")
+    node.draft.assets << asset
+    @page = node.draft
+
+    I18n.with_locale(:en) { assert_match t(:open_gallery), headline_image }
   end
 end
diff --git a/test/models/related_asset_test.rb b/test/models/related_asset_test.rb
index a739e6b..710b4cc 100644
--- a/test/models/related_asset_test.rb
+++ b/test/models/related_asset_test.rb
@@ -1,8 +1,44 @@
 require 'test_helper'
 
-class RelatedImageTest < ActiveSupport::TestCase
-  # Replace this with your real tests.
-  test "the truth" do
-    assert true
+class RelatedAssetTest < ActiveSupport::TestCase
+  test "headline can be set on an image asset" do
+    node = Node.root.children.create!(:slug => "related_asset_headline_image_test")
+    asset = Asset.create!(:name => "photo", :upload_content_type => "image/png")
+    node.draft.assets << asset
+    related = node.draft.related_assets.find_by(:asset_id => asset.id)
+
+    related.headline = true
+    assert related.valid?
+  end
+
+  test "headline cannot be set on a non-image asset" do
+    node = Node.root.children.create!(:slug => "related_asset_headline_pdf_test")
+    asset = Asset.create!(:name => "programme", :upload_content_type => "application/pdf")
+    node.draft.assets << asset
+    related = node.draft.related_assets.find_by(:asset_id => asset.id)
+
+    related.headline = true
+    assert_not related.valid?
+    assert_includes related.errors[:headline], "can only be set on image assets"
+  end
+
+  test "the headline validation does not raise when asset is missing" do
+    related = RelatedAsset.new(:headline => true)
+    assert_not related.valid?
+  end
+
+  test "at most one headline per page is enforced at the database level" do
+    node = Node.root.children.create!(:slug => "related_asset_headline_uniqueness_test")
+    first  = Asset.create!(:name => "first", :upload_content_type => "image/png")
+    second = Asset.create!(:name => "second", :upload_content_type => "image/png")
+    node.draft.assets << first
+    node.draft.assets << second
+
+    node.draft.related_assets.find_by(:asset_id => first.id).update!(:headline => true)
+    second_related = node.draft.related_assets.find_by(:asset_id => second.id)
+
+    assert_raises(ActiveRecord::RecordNotUnique) do
+      RelatedAsset.where(:id => second_related.id).update_all(:headline => true)
+    end
   end
 end