UPDATE: Adds web app (#79)

Things missing:

* Browse mode
* Front end tests
* Storybook

webapp/src/components/useKeyboardNavigation.ts

@@ -0,0 +1,225 @@
+import { type KeyboardEvent, type RefObject, useCallback } from "react";
+import { type NavigationKey, isEditingKey, isNavigationKey } from "./util";
+
+export enum Border {
+  Top = "top",
+  Bottom = "bottom",
+  Right = "right",
+  Left = "left",
+}
+
+interface Options {
+  onCellsDeleted: () => void;
+  onExpandAreaSelectedKeyboard: (
+    key: "ArrowRight" | "ArrowLeft" | "ArrowUp" | "ArrowDown",
+  ) => void;
+  onEditKeyPressStart: (initText: string) => void;
+  onCellEditStart: () => void;
+  onBold: () => void;
+  onItalic: () => void;
+  onUnderline: () => void;
+  onNavigationToEdge: (direction: NavigationKey) => void;
+  onPageDown: () => void;
+  onPageUp: () => void;
+  onArrowDown: () => void;
+  onArrowUp: () => void;
+  onArrowLeft: () => void;
+  onArrowRight: () => void;
+  onKeyHome: () => void;
+  onKeyEnd: () => void;
+  onUndo: () => void;
+  onRedo: () => void;
+  onNextSheet: () => void;
+  onPreviousSheet: () => void;
+  root: RefObject<HTMLDivElement>;
+}
+
+// # IronCalc Keyboard accessibility:
+// * ArrowKeys: navigation
+// * Enter: ArrowDown (Excel behaviour not g-sheets)
+// * Tab: arrow right
+// * Shift+Tab: arrow left
+// * Home/End: First/last column
+// * Shift+Arrows: selection
+// * Ctrl+Arrows: navigating to edge
+// * Ctrl+Home/End: navigation to end
+// * PagDown/Up scroll Down/Up
+// * Alt+ArrowDown/Up: next/previous sheet
+//   (NB: Excel uses Ctrl+PageUp/Down for this but that highjacks a browser behaviour,
+//    go to next/previous tab)
+// * Ctrl+u/i/b: style
+// * Ctrl+z/y: undo/redo
+// * F2: start editing
+
+// References:
+// In Google Sheets: Ctrl+/ shows the list of keyboard shortcuts
+// https://support.google.com/docs/answer/181110
+// https://support.microsoft.com/en-us/office/keyboard-shortcuts-in-excel-1798d9d5-842a-42b8-9c99-9b7213f0040f
+
+const useKeyboardNavigation = (
+  options: Options,
+): { onKeyDown: (event: KeyboardEvent) => void } => {
+  const onKeyDown = useCallback(
+    (event: KeyboardEvent) => {
+      const { key } = event;
+      const { root } = options;
+      // Silence the linter
+      if (!root.current) {
+        return;
+      }
+      if (event.target !== root.current) {
+        return;
+      }
+      if (event.metaKey || event.ctrlKey) {
+        switch (key) {
+          case "z": {
+            options.onUndo();
+            event.stopPropagation();
+            event.preventDefault();
+
+            break;
+          }
+          case "y": {
+            options.onRedo();
+            event.stopPropagation();
+            event.preventDefault();
+
+            break;
+          }
+          case "b": {
+            options.onBold();
+            event.stopPropagation();
+            event.preventDefault();
+
+            break;
+          }
+          case "i": {
+            options.onItalic();
+            event.stopPropagation();
+            event.preventDefault();
+
+            break;
+          }
+          case "u": {
+            options.onUnderline();
+            event.stopPropagation();
+            event.preventDefault();
+
+            break;
+          }
+          // No default
+        }
+        if (isNavigationKey(key)) {
+          // Ctrl+Arrows, Ctrl+Home/End
+          options.onNavigationToEdge(key);
+          event.stopPropagation();
+          event.preventDefault();
+        }
+        return;
+      }
+      if (event.altKey) {
+        switch (key) {
+          case "ArrowDown": {
+            // select next sheet
+            options.onNextSheet();
+            event.stopPropagation();
+            event.preventDefault();
+            break;
+          }
+          case "ArrowUp": {
+            // select previous sheet
+            options.onPreviousSheet();
+            event.stopPropagation();
+            event.preventDefault();
+            break;
+          }
+        }
+      }
+      if (key === "F2") {
+        options.onCellEditStart();
+        event.stopPropagation();
+        event.preventDefault();
+        return;
+      }
+      if (isEditingKey(key) || key === "Backspace") {
+        const initText = key === "Backspace" ? "" : key;
+        options.onEditKeyPressStart(initText);
+        event.stopPropagation();
+        event.preventDefault();
+        return;
+      }
+      // Worksheet Navigation
+      if (event.shiftKey) {
+        if (
+          key === "ArrowRight" ||
+          key === "ArrowLeft" ||
+          key === "ArrowUp" ||
+          key === "ArrowDown"
+        ) {
+          options.onExpandAreaSelectedKeyboard(key);
+        } else if (key === "Tab") {
+          options.onArrowLeft();
+          event.stopPropagation();
+          event.preventDefault();
+        }
+        return;
+      }
+      switch (key) {
+        case "ArrowRight":
+        case "Tab": {
+          options.onArrowRight();
+
+          break;
+        }
+        case "ArrowLeft": {
+          options.onArrowLeft();
+
+          break;
+        }
+        case "ArrowDown":
+        case "Enter": {
+          options.onArrowDown();
+
+          break;
+        }
+        case "ArrowUp": {
+          options.onArrowUp();
+
+          break;
+        }
+        case "End": {
+          options.onKeyEnd();
+
+          break;
+        }
+        case "Home": {
+          options.onKeyHome();
+
+          break;
+        }
+        case "Delete": {
+          options.onCellsDeleted();
+
+          break;
+        }
+        case "PageDown": {
+          options.onPageDown();
+
+          break;
+        }
+        case "PageUp": {
+          options.onPageUp();
+
+          break;
+        }
+        // No default
+      }
+      event.stopPropagation();
+      event.preventDefault();
+    },
+    [options],
+  );
+  return { onKeyDown };
+};
+
+export default useKeyboardNavigation;