1 files changed, 114 insertions, 0 deletions
diff --git a/frontend/src/lib/Navigation.ts b/frontend/src/lib/Navigation.ts
new file mode 100644
index 0000000..e6b17cd
--- /dev/null
+++ b/frontend/src/lib/Navigation.ts
@@ -0,0 +1,114 @@
+import { goto as svelteGoto } from '$app/navigation';
+import { SortDirection } from '$gql/graphql';
+import JsonURL from '@jsonurl/jsonurl';
+import { type PaginationData } from './Pagination';
+import { type SortData } from './Sort';
+import { toastError } from './Toasts';
+
+function paramToNum<T>(value: string | null, fallback: T) {
+	if (value) {
+		const number = +value;
+
+		if (Number.isNaN(number) || number < 0) {
+			return fallback;
+		}
+
+		return number;
+	}
+
+	return fallback;
+}
+
+export function parseSortData<T>(params: URLSearchParams, fallback: T): SortData<T> {
+	return {
+		on: (params.get('s') as T) || fallback,
+		direction: (params.get('d') as SortDirection) || SortDirection.Ascending,
+		seed: paramToNum(params.get('r'), undefined)
+	};
+}
+
+export function parsePaginationData(params: URLSearchParams, defaultItems = 120): PaginationData {
+	return {
+		page: paramToNum(params.get('p'), 1),
+		items: paramToNum(params.get('i'), defaultItems)
+	};
+}
+
+export function parseFilter<T>(params: URLSearchParams): T {
+	const param = params.get('f');
+
+	if (!param) return {} as T;
+
+	try {
+		return JsonURL.parse(param, { AQF: true, impliedObject: {} }) as T;
+	} catch (e) {
+		return {} as T;
+	}
+}
+
+interface NavigationOptions {
+	to?: string;
+	params: URLSearchParams;
+	options?: Parameters<typeof svelteGoto>[1];
+}
+
+export function goto({ to = '', params, options }: NavigationOptions) {
+	svelteGoto(`${to}?${params.toString()}`, options).catch(() => toastError('Navigation failed'));
+}
+
+interface NavigationParameters<T> {
+	filter?: T;
+	sort?: Partial<SortData<string>>;
+	pagination?: Partial<PaginationData>;
+}
+
+function paramsFrom<T>(
+	{ pagination, filter, sort }: NavigationParameters<T>,
+	current?: URLSearchParams
+) {
+	const params = new URLSearchParams(current);
+
+	if (filter !== undefined) {
+		const json = JsonURL.stringify(filter, { AQF: true, impliedObject: true });
+		if (json) {
+			params.set('f', json);
+		} else {
+			params.delete('f');
+		}
+	}
+
+	if (sort !== undefined) {
+		if (sort.on !== undefined) {
+			params.set('s', sort.on);
+		}
+		if (sort.direction !== undefined) {
+			params.set('d', sort.direction);
+		}
+		if (sort.seed !== undefined) {
+			params.set('r', sort.seed.toString());
+		}
+	}
+
+	params.delete('p');
+
+	if (pagination?.items) {
+		params.set('i', pagination.items.toString());
+	}
+
+	if (pagination?.page) {
+		params.set('p', pagination.page.toString());
+	}
+
+	return params;
+}
+
+export function navigate(parameters: NavigationParameters<object>, current?: URLSearchParams) {
+	goto({
+		params: paramsFrom(parameters, current),
+		options: { noScroll: false, keepFocus: true, replaceState: true }
+	});
+}
+
+export function href<T>(base: string, params: NavigationParameters<T>) {
+	return `/${base}/?${paramsFrom(params).toString()}`;
+}