Implemented phase 1 for the POC prototype in the Website service.

Services/Website/Sources/Library/Internal/Components/Cover.swift

@@ -0,0 +1,60 @@
+import Elementary
+import Persistence
+
+/// A placeholder cover: lettering on a toned ground, scaling with its width. Stands in until listings carry photos.
+struct Cover: HTML {
+
+    // MARK: Properties
+
+    /// The cover's lettering and tone.
+    let cover: Listing.Cover
+
+    /// A modifier class positioning or sizing the cover, or `nil` for none.
+    let modifier: String?
+
+    // MARK: Initializers
+
+    /// Creates a placeholder cover.
+    /// - Parameters:
+    ///   - cover: the cover's lettering and tone.
+    ///   - modifier: a modifier class positioning or sizing the cover, or `nil` (the default) for none.
+    init(
+        _ cover: Listing.Cover,
+        modifier: String? = nil
+    ) {
+        self.cover = cover
+        self.modifier = modifier
+    }
+
+    // MARK: Computed
+
+    /// Decorative: whatever links to the listing names it.
+    var body: some HTML {
+        div(
+            .class(["cover", "cover--\(cover.tone)", modifier].compactMap(\.self).joined(separator: " ")),
+            .custom(
+                name: "aria-hidden",
+                value: "true"
+            )
+        ) {
+            div(.class("cover__face")) {
+                div(.class("cover__title")) {
+                    for line in cover.title.split(separator: "\n") {
+                        span {
+                            String(line)
+                        }
+                    }
+                }
+                div(.class("cover__foot")) {
+                    span(.class("cover__imprint")) {
+                        cover.imprint
+                    }
+                    span(.class(cover.number.allSatisfy(\.isNumber) ? "cover__number" : "cover__number cover__number--text")) {
+                        cover.number
+                    }
+                }
+            }
+        }
+    }
+
+}