First working version

Sources/App/Extensions/Array+Extensions.swift

@@ -1,6 +1,27 @@
 import Foundation
 
 extension Array {
+
+    func at(_ index: Int) -> Element? {
+        guard index < count else {
+            return nil
+        }
+        return self[index]
+    }
+
+    func rotatedByOne() -> [Element] {
+        guard !isEmpty else {
+            return []
+        }
+        return self[1...] + [self[0]]
+    }
+
+    mutating func rotateByOne() {
+        guard !isEmpty else {
+            return
+        }
+        append(removeFirst())
+    }
     
     func rotated(toStartAt index: Int) -> [Element] {
         guard index != 0 else {
@@ -13,3 +34,35 @@ extension Array {
         sorted { converting($0) < converting($1) }
     }
 }
+
+extension Array where Element: Equatable {
+
+    func index(of element: Element) -> Index {
+        firstIndex(of: element)!
+    }
+}
+
+extension Array where Element: Player {
+
+    var names: [PlayerName] {
+        map { $0.name }
+    }
+
+    func index(of player: PlayerName) -> Int {
+        firstIndex { $0.name == player }!
+    }
+
+    func player(named name: PlayerName) -> Element? {
+        first { $0.name == name }
+    }
+
+    func contains(player: PlayerName) -> Bool {
+        contains { $0.name == player }
+    }
+
+    func next(after player: Element) -> Element {
+        let i = index(of: player)
+        let newIndex = (i + 1) % maximumPlayersPerTable
+        return self[newIndex]
+    }
+}