From d1d654ebac2d51e3841675faeb56480e440f622f Mon Sep 17 00:00:00 2001
From: Wolfgang Müller
Date: Tue, 5 Mar 2024 18:08:09 +0100
Subject: Initial commit

---
 frontend/src/lib/Shortcuts.ts | 153 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 153 insertions(+)
 create mode 100644 frontend/src/lib/Shortcuts.ts

(limited to 'frontend/src/lib/Shortcuts.ts')

diff --git a/frontend/src/lib/Shortcuts.ts b/frontend/src/lib/Shortcuts.ts
new file mode 100644
index 0000000..063bd40
--- /dev/null
+++ b/frontend/src/lib/Shortcuts.ts
@@ -0,0 +1,153 @@
+import { closeModal, modals } from 'svelte-modals';
+import { get } from 'svelte/store';
+
+type LowercaseLetter =
+	| 'a'
+	| 'b'
+	| 'c'
+	| 'd'
+	| 'e'
+	| 'f'
+	| 'g'
+	| 'h'
+	| 'i'
+	| 'j'
+	| 'l'
+	| 'm'
+	| 'n'
+	| 'o'
+	| 'p'
+	| 'q'
+	| 'r'
+	| 's'
+	| 't'
+	| 'u'
+	| 'v'
+	| 'w'
+	| 'x'
+	| 'y'
+	| 'z';
+
+type UppercaseLetter = Uppercase<LowercaseLetter>;
+type Letter = LowercaseLetter | UppercaseLetter;
+type Special = '?' | 'Enter' | 'Escape' | 'Delete';
+
+const modeSwitches = ['n', 'g', 'i'] as const;
+type ModeSwitch = (typeof modeSwitches)[number];
+
+function isModeSwitch(s: string): s is ModeSwitch {
+	// eslint-disable-next-line @typescript-eslint/no-explicit-any, @typescript-eslint/no-unsafe-argument
+	return modeSwitches.indexOf(s as any) !== -1;
+}
+
+type Key = Letter | Special;
+type KeyCombo = `${ModeSwitch}${Letter}`;
+export type Shortcut = Key | KeyCombo;
+
+type EventAction = (event: KeyboardEvent) => void;
+type FocusAction = HTMLInputElement;
+type ClickAction = HTMLElement;
+
+type Action = EventAction | FocusAction | ClickAction;
+
+const handlers = new Map<string, Action>();
+let mode: ModeSwitch | undefined;
+
+export function handleShortcuts(event: KeyboardEvent) {
+	if (isInputElement(event.target)) {
+		if (event.key === 'Escape') {
+			event.target.blur();
+			event.preventDefault();
+			event.stopImmediatePropagation();
+		}
+		return;
+	}
+
+	if (event.ctrlKey) {
+		return;
+	}
+
+	if (event.key === 'Escape') {
+		if (get(modals).length > 0) {
+			closeModal();
+			event.preventDefault();
+			event.stopImmediatePropagation();
+			return;
+		}
+	}
+
+	if (isModeSwitch(event.key) && mode === undefined) {
+		mode = event.key;
+		event.preventDefault();
+		return;
+	}
+
+	const handler = handlers.get(mode === undefined ? event.key : `${mode}${event.key}`);
+
+	if (!handler || get(modals).length > 0) {
+		mode = undefined;
+		return;
+	}
+
+	if (handler instanceof HTMLInputElement) {
+		handler.focus();
+	} else if (handler instanceof HTMLElement) {
+		handler.click();
+	} else {
+		handler(event);
+	}
+
+	mode = undefined;
+	event.preventDefault();
+}
+
+export function accelerator(node: HTMLElement | HTMLInputElement, sc: Shortcut) {
+	handlers.set(sc, node);
+
+	return {
+		destroy() {
+			handlers.delete(sc);
+		}
+	};
+}
+
+export function binds(node: Document, scs: [string, EventAction][]) {
+	const handlers = new Map<string, EventAction>();
+
+	for (const [k, a] of scs) {
+		handlers.set(k, a);
+	}
+
+	function keydown(event: KeyboardEvent) {
+		if (isInputElement(event.target)) return;
+
+		const handler = handlers.get(event.key);
+
+		if (!handler) return;
+
+		handler(event);
+		event.preventDefault();
+	}
+
+	node.addEventListener('keydown', keydown);
+
+	return {
+		destroy() {
+			node.removeEventListener('keydown', keydown);
+		}
+	};
+}
+
+export function addShortcut(sc: Shortcut, action: EventAction) {
+	handlers.set(sc, action);
+}
+
+function isInputElement(target: EventTarget | null): target is HTMLElement {
+	return (
+		target instanceof HTMLElement &&
+		(target instanceof HTMLInputElement ||
+			target instanceof HTMLSelectElement ||
+			target instanceof HTMLTextAreaElement ||
+			target.isContentEditable)
+	);
+}
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