From 3e89d2998588f8e35c524e523ba2ee853f0f6475 Mon Sep 17 00:00:00 2001
From: Maze Winther <mazewinther@gmail.com>
Date: Mon, 20 Apr 2026 11:31:17 +0200
Subject: refactor: restructure files to their domains,  new preview overlay
 system, and dep graph

---
 apps/web/src/selection/selectable-surface.tsx | 288 ++++++++++++++++++++++++++
 1 file changed, 288 insertions(+)
 create mode 100644 apps/web/src/selection/selectable-surface.tsx

(limited to 'apps/web/src/selection/selectable-surface.tsx')

diff --git a/apps/web/src/selection/selectable-surface.tsx b/apps/web/src/selection/selectable-surface.tsx
new file mode 100644
index 00000000..24166daf
--- /dev/null
+++ b/apps/web/src/selection/selectable-surface.tsx
@@ -0,0 +1,288 @@
+"use client";
+
+import { useCallback, useEffect, useMemo, useRef, useState } from "react";
+import { SelectionBox } from "@/selection/selection-box";
+import { SelectionContext } from "@/selection/context";
+import { SELECTABLE_ITEM_ATTRIBUTE } from "@/selection/attributes";
+import { resolveElementIntersections } from "@/selection/hit-testing";
+import {
+	applyBoxSelection,
+	clearSelection,
+	isSelected as getIsSelected,
+	pruneSelection,
+	replaceSelection,
+	selectRange,
+	toggleSelection,
+} from "@/selection/state";
+import type {
+	SelectableSurfaceProps,
+	SelectionState,
+} from "@/selection/types";
+import { useBoxSelect } from "@/selection/hooks/use-box-select";
+import { cn } from "@/utils/ui";
+
+export function SelectableSurface({
+	orderedIds,
+	children,
+	className,
+	ariaLabel = "Selectable items",
+	revealId = null,
+	onRevealComplete,
+	onSelectionChange,
+}: SelectableSurfaceProps) {
+	const [selectionState, setSelectionState] = useState<SelectionState>(() =>
+		clearSelection(),
+	);
+	const [highlightedId, setHighlightedId] = useState<string | null>(null);
+	const containerRef = useRef<HTMLDivElement>(null);
+	const itemElementsRef = useRef<Map<string, HTMLElement>>(new Map());
+
+	const registerItem = useCallback(
+		(id: string, element: HTMLElement | null) => {
+			if (element) {
+				itemElementsRef.current.set(id, element);
+			} else {
+				itemElementsRef.current.delete(id);
+			}
+		},
+		[],
+	);
+
+	const getSelectableElements = useCallback(() => {
+		return itemElementsRef.current;
+	}, []);
+
+	const getItemElement = useCallback((id: string) => {
+		return itemElementsRef.current.get(id) ?? null;
+	}, []);
+	const shouldStartSelection = useCallback(
+		(event: React.MouseEvent<Element>) => {
+			return !(
+				event.target instanceof Element &&
+				event.target.closest(`[${SELECTABLE_ITEM_ATTRIBUTE}='true']`)
+			);
+		},
+		[],
+	);
+	const resolveIntersections = useCallback(
+		({
+			startPos,
+			currentPos,
+		}: {
+			startPos: { x: number; y: number };
+			currentPos: { x: number; y: number };
+		}) => {
+			return resolveElementIntersections({
+				startPos,
+				currentPos,
+				elements: getSelectableElements(),
+			});
+		},
+		[getSelectableElements],
+	);
+
+	const clearSelectionState = useCallback(() => {
+		setSelectionState(clearSelection());
+	}, []);
+
+	const selectedIdSet = useMemo(
+		() => new Set(selectionState.selectedIds),
+		[selectionState.selectedIds],
+	);
+
+	const isSelected = useCallback(
+		(id: string) => selectedIdSet.has(id),
+		[selectedIdSet],
+	);
+
+	const handleItemClick = useCallback(
+		({
+			event,
+			id,
+		}: {
+			event:
+				| React.MouseEvent<HTMLDivElement>
+				| React.KeyboardEvent<HTMLDivElement>;
+			id: string;
+		}) => {
+			setSelectionState((state) => {
+				const isToggleSelection = event.ctrlKey || event.metaKey;
+
+				if (event.shiftKey) {
+					return selectRange({
+						state,
+						orderedIds,
+						targetId: id,
+						isAdditive: isToggleSelection,
+					});
+				}
+
+				if (isToggleSelection) {
+					return toggleSelection({
+						state,
+						id,
+					});
+				}
+
+				return replaceSelection({
+					ids: [id],
+					anchorId: id,
+				});
+			});
+		},
+		[orderedIds],
+	);
+
+	const selectUnselectedItem = useCallback((id: string) => {
+		setSelectionState((state) => {
+			if (getIsSelected({ state, id })) {
+				return state;
+			}
+
+			return replaceSelection({ ids: [id], anchorId: id });
+		});
+	}, []);
+
+	const handleItemMouseDown = useCallback(
+		({
+			event,
+			id,
+		}: {
+			event: React.MouseEvent<HTMLDivElement>;
+			id: string;
+		}) => {
+			if (event.button !== 2) {
+				return;
+			}
+
+			selectUnselectedItem(id);
+		},
+		[selectUnselectedItem],
+	);
+
+	const handleBoxSelectionChange = useCallback(
+		(change: Parameters<typeof applyBoxSelection>[0]) => {
+			setSelectionState(applyBoxSelection(change));
+		},
+		[],
+	);
+
+	const { selectionBox, handleMouseDown, shouldIgnoreClick } = useBoxSelect({
+		containerRef,
+		resolveIntersections,
+		selectedIds: selectionState.selectedIds,
+		anchorId: selectionState.anchorId,
+		onSelectionChange: handleBoxSelectionChange,
+		shouldStartSelection,
+	});
+
+	const handleBackgroundClick = useCallback(
+		(event: React.MouseEvent<HTMLDivElement>) => {
+			const clickedSelectableItem =
+				event.target instanceof Element &&
+				event.target.closest(`[${SELECTABLE_ITEM_ATTRIBUTE}='true']`);
+			const isIgnoringClick = shouldIgnoreClick();
+			if (clickedSelectableItem || isIgnoringClick) {
+				return;
+			}
+
+			clearSelectionState();
+		},
+		[clearSelectionState, shouldIgnoreClick],
+	);
+
+	const handleBackgroundKeyDown = useCallback(
+		(event: React.KeyboardEvent<HTMLDivElement>) => {
+			if (event.target !== event.currentTarget) {
+				return;
+			}
+
+			if (event.key !== "Enter" && event.key !== " " && event.key !== "Escape") {
+				return;
+			}
+
+			event.preventDefault();
+			clearSelectionState();
+		},
+		[clearSelectionState],
+	);
+
+	useEffect(() => {
+		setSelectionState((state) =>
+			pruneSelection({
+				state,
+				orderedIds,
+			}),
+		);
+	}, [orderedIds]);
+
+	useEffect(() => {
+		onSelectionChange?.(selectionState);
+	}, [onSelectionChange, selectionState]);
+
+	useEffect(() => {
+		if (!revealId) {
+			return;
+		}
+
+		setHighlightedId(revealId);
+		getItemElement(revealId)?.scrollIntoView({ block: "center" });
+
+		const timer = setTimeout(() => {
+			setHighlightedId(null);
+			onRevealComplete?.();
+		}, 1500);
+
+		return () => clearTimeout(timer);
+	}, [getItemElement, onRevealComplete, revealId]);
+
+	const isBoxSelecting = selectionBox?.isActive ?? false;
+
+	const contextValue = useMemo(() => {
+		return {
+			selectedIds: selectionState.selectedIds,
+			anchorId: selectionState.anchorId,
+			highlightedId,
+			isBoxSelecting,
+			isSelected,
+			clearSelection: clearSelectionState,
+			handleItemClick,
+			handleItemMouseDown,
+			registerItem,
+		};
+	}, [
+		clearSelectionState,
+		handleItemClick,
+		handleItemMouseDown,
+		highlightedId,
+		isBoxSelecting,
+		isSelected,
+		registerItem,
+		selectionState.anchorId,
+		selectionState.selectedIds,
+	]);
+
+	return (
+		<SelectionContext.Provider value={contextValue}>
+			<div
+				ref={containerRef}
+				className={cn("relative min-h-full", className)}
+				role="listbox"
+				aria-label={ariaLabel}
+				aria-multiselectable="true"
+				tabIndex={0}
+				onMouseDown={handleMouseDown}
+				onClick={handleBackgroundClick}
+				onKeyDown={handleBackgroundKeyDown}
+			>
+				{children}
+				<SelectionBox
+					startPos={selectionBox?.startPos ?? null}
+					currentPos={selectionBox?.currentPos ?? null}
+					containerRef={containerRef}
+					isActive={selectionBox?.isActive ?? false}
+				/>
+			</div>
+		</SelectionContext.Provider>
+	);
+}
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