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

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

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+import Elementary
+
+/// The page links under a card grid; renders nothing for a single page.
+struct Pagination: HTML {
+
+    // MARK: Properties
+
+    /// The page shown, counted from one.
+    let current: Int
+
+    /// The path of a given page.
+    let path: @Sendable (Int) -> String
+
+    /// The number of pages.
+    let total: Int
+
+    // MARK: Initializers
+
+    /// Creates the page links.
+    /// - Parameters:
+    ///   - current: the page shown, counted from one.
+    ///   - total: the number of pages.
+    ///   - path: the path of a given page.
+    init(
+        current: Int,
+        total: Int,
+        path: @escaping @Sendable (Int) -> String
+    ) {
+        self.current = current
+        self.path = path
+        self.total = total
+    }
+
+    // MARK: Computed
+
+    var body: some HTML {
+        if total > 1 {
+            nav(
+                .class("pagination"),
+                .custom(
+                    name: "aria-label",
+                    value: "Pagination"
+                )
+            ) {
+                for page in 1...total {
+                    if page == current {
+                        a(
+                            .class("pagination__page"),
+                            .href(path(page)),
+                            .custom(
+                                name: "aria-current",
+                                value: "page"
+                            )
+                        ) {
+                            "\(page)"
+                        }
+                    } else {
+                        a(
+                            .class("pagination__page"),
+                            .href(path(page))
+                        ) {
+                            "\(page)"
+                        }
+                    }
+                }
+                if current < total {
+                    a(
+                        .class("pagination__next"),
+                        .href(path(current + 1))
+                    ) {
+                        "Next"
+                    }
+                }
+            }
+        }
+    }
+
+}
+
+// MARK: - Extensions
+
+extension Pagination {
+
+    // MARK: Methods
+
+    /// Cuts the items of one page out of a list, clamping the page to the list's range.
+    /// - Parameters:
+    ///   - items: the whole list.
+    ///   - page: the page asked for, counted from one.
+    ///   - size: the number of items on a page.
+    /// - Returns: the page's items, the page actually shown, and the number of pages.
+    static func slice<Item>(
+        _ items: [Item],
+        page: Int,
+        size: Int
+    ) -> (items: [Item], current: Int, total: Int) {
+        let total = max((items.count + size - 1) / size, 1)
+        let current = min(max(page, 1), total)
+
+        return (
+            Array(items.dropFirst((current - 1) * size).prefix(size)),
+            current,
+            total
+        )
+    }
+
+}