From 8db3bead13441a5882d8689dfc6a9f09c82375d9 Mon Sep 17 00:00:00 2001
From: Maze Winther <mazewinther@gmail.com>
Date: Wed, 25 Mar 2026 16:47:22 +0100
Subject: feat: masks, properties refactor, shaders, storage migrations, and
 more

---
 apps/web/src/lib/selection/state.ts | 165 ++++++++++++++++++++++++++++++++++++
 1 file changed, 165 insertions(+)
 create mode 100644 apps/web/src/lib/selection/state.ts

(limited to 'apps/web/src/lib/selection/state.ts')

diff --git a/apps/web/src/lib/selection/state.ts b/apps/web/src/lib/selection/state.ts
new file mode 100644
index 00000000..b4c454fb
--- /dev/null
+++ b/apps/web/src/lib/selection/state.ts
@@ -0,0 +1,165 @@
+import type {
+	BoxSelectionChange,
+	SelectionState,
+} from "@/lib/selection/types";
+
+function dedupeIds({ ids }: { ids: string[] }) {
+	return [...new Set(ids)];
+}
+
+function getRangeIds({
+	orderedIds,
+	anchorId,
+	targetId,
+}: {
+	orderedIds: string[];
+	anchorId: string;
+	targetId: string;
+}) {
+	const anchorIndex = orderedIds.indexOf(anchorId);
+	const targetIndex = orderedIds.indexOf(targetId);
+
+	if (anchorIndex === -1 || targetIndex === -1) {
+		return [targetId];
+	}
+
+	const rangeStart = Math.min(anchorIndex, targetIndex);
+	const rangeEnd = Math.max(anchorIndex, targetIndex);
+	return orderedIds.slice(rangeStart, rangeEnd + 1);
+}
+
+export function replaceSelection({
+	ids,
+	anchorId,
+}: {
+	ids: string[];
+	anchorId?: string | null;
+}): SelectionState {
+	const selectedIds = dedupeIds({ ids });
+	return {
+		selectedIds,
+		anchorId: anchorId ?? selectedIds[selectedIds.length - 1] ?? null,
+	};
+}
+
+export function clearSelection(): SelectionState {
+	return {
+		selectedIds: [],
+		anchorId: null,
+	};
+}
+
+export function pruneSelection({
+	state,
+	orderedIds,
+}: {
+	state: SelectionState;
+	orderedIds: string[];
+}): SelectionState {
+	const validIds = new Set(orderedIds);
+	const selectedIds = state.selectedIds.filter((id) => validIds.has(id));
+	const anchorId =
+		state.anchorId && validIds.has(state.anchorId)
+			? state.anchorId
+			: selectedIds[selectedIds.length - 1] ?? null;
+	const isUnchanged =
+		selectedIds.length === state.selectedIds.length &&
+		anchorId === state.anchorId;
+
+	if (isUnchanged) {
+		return state;
+	}
+
+	return {
+		selectedIds,
+		anchorId,
+	};
+}
+
+export function isSelected({
+	state,
+	id,
+}: {
+	state: SelectionState;
+	id: string;
+}) {
+	return state.selectedIds.includes(id);
+}
+
+export function toggleSelection({
+	state,
+	id,
+}: {
+	state: SelectionState;
+	id: string;
+}): SelectionState {
+	if (isSelected({ state, id })) {
+		const selectedIds = state.selectedIds.filter((selectedId) => selectedId !== id);
+		const anchorId =
+			state.anchorId === id
+				? selectedIds[selectedIds.length - 1] ?? null
+				: state.anchorId;
+		return replaceSelection({
+			ids: selectedIds,
+			anchorId,
+		});
+	}
+
+	return replaceSelection({
+		ids: [...state.selectedIds, id],
+		anchorId: id,
+	});
+}
+
+export function selectRange({
+	state,
+	orderedIds,
+	targetId,
+	isAdditive,
+}: {
+	state: SelectionState;
+	orderedIds: string[];
+	targetId: string;
+	isAdditive: boolean;
+}): SelectionState {
+	const anchorId =
+		state.anchorId ??
+		state.selectedIds[state.selectedIds.length - 1] ??
+		targetId;
+	const rangeIds = getRangeIds({
+		orderedIds,
+		anchorId,
+		targetId,
+	});
+	const selectedIds = isAdditive
+		? dedupeIds({
+				ids: [...state.selectedIds, ...rangeIds],
+			})
+		: rangeIds;
+
+	return replaceSelection({
+		ids: selectedIds,
+		anchorId,
+	});
+}
+
+export function applyBoxSelection({
+	intersectedIds,
+	initialSelectedIds,
+	initialAnchorId,
+	isAdditive,
+}: BoxSelectionChange): SelectionState {
+	const selectedIds = isAdditive
+		? dedupeIds({
+				ids: [...initialSelectedIds, ...intersectedIds],
+			})
+		: intersectedIds;
+	const anchorId = isAdditive
+		? initialAnchorId ?? intersectedIds[intersectedIds.length - 1] ?? null
+		: intersectedIds[intersectedIds.length - 1] ?? null;
+
+	return replaceSelection({
+		ids: selectedIds,
+		anchorId,
+	});
+}
-- 
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