refactor: restructure files to their domains, new preview overlay system, and dep graph

1 files changed, 760 insertions, 0 deletions

diff --git a/apps/web/src/timeline/hooks/element/use-element-interaction.ts b/apps/web/src/timeline/hooks/element/use-element-interaction.ts
new file mode 100644
index 00000000..621259b9
--- /dev/null
+++ b/apps/web/src/timeline/hooks/element/use-element-interaction.ts
@@ -0,0 +1,760 @@
+import {
+	useState,
+	useCallback,
+	useEffect,
+	useRef,
+	type MouseEvent as ReactMouseEvent,
+	type RefObject,
+} from "react";
+import { useEditor } from "@/editor/use-editor";
+import { useShiftKey } from "@/hooks/use-shift-key";
+import { useElementSelection } from "@/timeline/hooks/element/use-element-selection";
+import {
+	buildMoveGroup,
+	resolveGroupMove,
+	snapGroupEdges,
+	type GroupMoveResult,
+	type MoveGroup,
+} from "@/timeline/group-move";
+import { BASE_TIMELINE_PIXELS_PER_SECOND } from "@/timeline/scale";
+import { TICKS_PER_SECOND } from "@/wasm";
+import { TIMELINE_DRAG_THRESHOLD_PX } from "@/timeline/components/interaction";
+import { roundToFrame } from "opencut-wasm";
+import { computeDropTarget } from "@/timeline/components/drop-target";
+import { getMouseTimeFromClientX } from "@/timeline/drag-utils";
+import { generateUUID } from "@/utils/id";
+import type { SnapPoint } from "@/timeline/snapping";
+import { registerCanceller } from "@/editor/cancel-interaction";
+import type {
+	DropTarget,
+	ElementRef,
+	ElementDragState,
+	SceneTracks,
+	TimelineElement,
+	TimelineTrack,
+} from "@/timeline";
+
+interface UseElementInteractionProps {
+	zoomLevel: number;
+	timelineRef: RefObject<HTMLDivElement | null>;
+	tracksContainerRef: RefObject<HTMLDivElement | null>;
+	tracksScrollRef: RefObject<HTMLDivElement | null>;
+	headerRef?: RefObject<HTMLElement | null>;
+	snappingEnabled: boolean;
+	onSnapPointChange?: (snapPoint: SnapPoint | null) => void;
+}
+
+const MOUSE_BUTTON_RIGHT = 2;
+
+const initialDragState: ElementDragState = {
+	isDragging: false,
+	elementId: null,
+	dragElementIds: [],
+	dragTimeOffsets: {},
+	trackId: null,
+	startMouseX: 0,
+	startMouseY: 0,
+	startElementTime: 0,
+	clickOffsetTime: 0,
+	currentTime: 0,
+	currentMouseY: 0,
+};
+
+interface PendingDragState {
+	elementId: string;
+	trackId: string;
+	selectedElements: ElementRef[];
+	startMouseX: number;
+	startMouseY: number;
+	startElementTime: number;
+	clickOffsetTime: number;
+}
+
+function getClickOffsetTime({
+	clientX,
+	elementRect,
+	zoomLevel,
+}: {
+	clientX: number;
+	elementRect: DOMRect;
+	zoomLevel: number;
+}): number {
+	const clickOffsetX = clientX - elementRect.left;
+	const seconds = clickOffsetX / (BASE_TIMELINE_PIXELS_PER_SECOND * zoomLevel);
+	return Math.round(seconds * TICKS_PER_SECOND);
+}
+
+function getVerticalDragDirection({
+	startMouseY,
+	currentMouseY,
+}: {
+	startMouseY: number;
+	currentMouseY: number;
+}): "up" | "down" | null {
+	if (currentMouseY < startMouseY) return "up";
+	if (currentMouseY > startMouseY) return "down";
+	return null;
+}
+
+function getDragDropTarget({
+	clientX,
+	clientY,
+	elementId,
+	trackId,
+	tracks,
+	tracksContainerRef,
+	tracksScrollRef,
+	headerRef,
+	zoomLevel,
+	snappedTime,
+	verticalDragDirection,
+}: {
+	clientX: number;
+	clientY: number;
+	elementId: string;
+	trackId: string;
+	tracks: SceneTracks;
+	tracksContainerRef: RefObject<HTMLDivElement | null>;
+	tracksScrollRef: RefObject<HTMLDivElement | null>;
+	headerRef?: RefObject<HTMLElement | null>;
+	zoomLevel: number;
+	snappedTime: number;
+	verticalDragDirection?: "up" | "down" | null;
+}): DropTarget | null {
+	const containerRect = tracksContainerRef.current?.getBoundingClientRect();
+	const scrollContainer = tracksScrollRef.current;
+	if (!containerRect || !scrollContainer) return null;
+
+	const sourceTrack = [...tracks.overlay, tracks.main, ...tracks.audio].find(
+		({ id }) => id === trackId,
+	);
+	const movingElement = sourceTrack?.elements.find(
+		({ id }) => id === elementId,
+	);
+	if (!movingElement) return null;
+
+	const elementDuration = movingElement.duration;
+	const scrollLeft = scrollContainer.scrollLeft;
+	const scrollTop = scrollContainer.scrollTop;
+	const scrollContainerRect = scrollContainer.getBoundingClientRect();
+	const headerHeight = headerRef?.current?.getBoundingClientRect().height ?? 0;
+	const mouseX = clientX - scrollContainerRect.left + scrollLeft;
+	const mouseY = clientY - scrollContainerRect.top + scrollTop - headerHeight;
+
+	return computeDropTarget({
+		elementType: movingElement.type,
+		mouseX,
+		mouseY,
+		tracks,
+		playheadTime: snappedTime,
+		isExternalDrop: false,
+		elementDuration,
+		pixelsPerSecond: BASE_TIMELINE_PIXELS_PER_SECOND,
+		zoomLevel,
+		startTimeOverride: snappedTime,
+		excludeElementId: movingElement.id,
+		verticalDragDirection,
+	});
+}
+
+interface StartDragParams
+	extends Omit<
+		ElementDragState,
+		"isDragging" | "currentTime" | "currentMouseY"
+	> {
+	initialCurrentTime: number;
+	initialCurrentMouseY: number;
+}
+
+export function useElementInteraction({
+	zoomLevel,
+	timelineRef,
+	tracksContainerRef,
+	tracksScrollRef,
+	headerRef,
+	snappingEnabled,
+	onSnapPointChange,
+}: UseElementInteractionProps) {
+	const editor = useEditor();
+	const isShiftHeldRef = useShiftKey();
+	const sceneTracks = editor.scenes.getActiveScene().tracks;
+	const {
+		selectedElements,
+		isElementSelected,
+		selectElement,
+		handleElementClick: handleSelectionClick,
+	} = useElementSelection();
+
+	const [dragState, setDragState] =
+		useState<ElementDragState>(initialDragState);
+	const [dragDropTarget, setDragDropTarget] = useState<DropTarget | null>(null);
+	const [isPendingDrag, setIsPendingDrag] = useState(false);
+	const pendingDragRef = useRef<PendingDragState | null>(null);
+	const moveGroupRef = useRef<MoveGroup | null>(null);
+	const newTrackIdsRef = useRef<string[]>([]);
+	const groupMoveResultRef = useRef<GroupMoveResult | null>(null);
+	const lastMouseXRef = useRef(0);
+	const mouseDownLocationRef = useRef<{ x: number; y: number } | null>(null);
+
+	const startDrag = useCallback(
+		({
+			elementId,
+			dragElementIds,
+			dragTimeOffsets,
+			trackId,
+			startMouseX,
+			startMouseY,
+			startElementTime,
+			clickOffsetTime,
+			initialCurrentTime,
+			initialCurrentMouseY,
+		}: StartDragParams) => {
+			setDragState({
+				isDragging: true,
+				elementId,
+				dragElementIds,
+				dragTimeOffsets,
+				trackId,
+				startMouseX,
+				startMouseY,
+				startElementTime,
+				clickOffsetTime,
+				currentTime: initialCurrentTime,
+				currentMouseY: initialCurrentMouseY,
+			});
+		},
+		[],
+	);
+
+	const endDrag = useCallback(() => {
+		moveGroupRef.current = null;
+		newTrackIdsRef.current = [];
+		groupMoveResultRef.current = null;
+		setDragState(initialDragState);
+		setDragDropTarget(null);
+	}, []);
+
+	const cancelCurrentDrag = useCallback(() => {
+		pendingDragRef.current = null;
+		mouseDownLocationRef.current = null;
+		setIsPendingDrag(false);
+		endDrag();
+		onSnapPointChange?.(null);
+	}, [endDrag, onSnapPointChange]);
+
+	const resolveGroupDragMove = useCallback(
+		({
+			group,
+			snappedTime,
+			dropTarget,
+		}: {
+			group: MoveGroup;
+			snappedTime: number;
+			dropTarget: DropTarget | null;
+		}): GroupMoveResult | null => {
+			if (!dropTarget) {
+				return null;
+			}
+
+			if (dropTarget.isNewTrack) {
+				return resolveGroupMove({
+					group,
+					tracks: sceneTracks,
+					anchorStartTime: snappedTime,
+					target: {
+						kind: "newTracks",
+						anchorInsertIndex: dropTarget.trackIndex,
+						newTrackIds: newTrackIdsRef.current,
+					},
+				});
+			}
+
+			const orderedTracks = [
+				...sceneTracks.overlay,
+				sceneTracks.main,
+				...sceneTracks.audio,
+			];
+			const targetTrack = orderedTracks[dropTarget.trackIndex];
+			if (!targetTrack) {
+				return null;
+			}
+
+			const existingTrackResult = resolveGroupMove({
+				group,
+				tracks: sceneTracks,
+				anchorStartTime: snappedTime,
+				target: {
+					kind: "existingTrack",
+					anchorTargetTrackId: targetTrack.id,
+				},
+			});
+			if (existingTrackResult) {
+				return existingTrackResult;
+			}
+
+			return resolveGroupMove({
+				group,
+				tracks: sceneTracks,
+				anchorStartTime: snappedTime,
+				target: {
+					kind: "newTracks",
+					anchorInsertIndex: dropTarget.trackIndex,
+					newTrackIds: newTrackIdsRef.current,
+				},
+			});
+		},
+		[sceneTracks],
+	);
+
+	useEffect(() => {
+		if (!dragState.isDragging && !isPendingDrag) return;
+
+		return registerCanceller({ fn: cancelCurrentDrag });
+	}, [dragState.isDragging, isPendingDrag, cancelCurrentDrag]);
+
+	const getDragSnapResult = useCallback(
+		({
+			frameSnappedTime,
+			group,
+		}: {
+			frameSnappedTime: number;
+			group: MoveGroup | null;
+		}) => {
+			if (!group || !snappingEnabled || isShiftHeldRef.current) {
+				return { snappedTime: frameSnappedTime, snapPoint: null };
+			}
+
+			const groupSnap = snapGroupEdges({
+				group,
+				anchorStartTime: frameSnappedTime,
+				tracks: sceneTracks,
+				playheadTime: editor.playback.getCurrentTime(),
+				zoomLevel,
+			});
+
+			return {
+				snappedTime: groupSnap.snappedAnchorStartTime,
+				snapPoint: groupSnap.snapPoint,
+			};
+		},
+		[snappingEnabled, editor.playback, sceneTracks, zoomLevel, isShiftHeldRef],
+	);
+
+	useEffect(() => {
+		if (!dragState.isDragging && !isPendingDrag) return;
+
+		const handleMouseMove = ({ clientX, clientY }: MouseEvent) => {
+			let startedDragThisEvent = false;
+			const timeline = timelineRef.current;
+			const scrollContainer = tracksScrollRef.current;
+			if (!timeline || !scrollContainer) return;
+			lastMouseXRef.current = clientX;
+
+			if (isPendingDrag && pendingDragRef.current) {
+				const deltaX = Math.abs(clientX - pendingDragRef.current.startMouseX);
+				const deltaY = Math.abs(clientY - pendingDragRef.current.startMouseY);
+				if (
+					deltaX > TIMELINE_DRAG_THRESHOLD_PX ||
+					deltaY > TIMELINE_DRAG_THRESHOLD_PX
+				) {
+					const activeProject = editor.project.getActive();
+					if (!activeProject) return;
+					const scrollLeft = scrollContainer.scrollLeft;
+					const mouseTime = getMouseTimeFromClientX({
+						clientX,
+						containerRect: scrollContainer.getBoundingClientRect(),
+						zoomLevel,
+						scrollLeft,
+					});
+					const adjustedTime = Math.max(
+						0,
+						mouseTime - pendingDragRef.current.clickOffsetTime,
+					);
+					const snappedTime =
+						roundToFrame({
+							time: adjustedTime,
+							rate: activeProject.settings.fps,
+						}) ?? adjustedTime;
+					const moveGroup = buildMoveGroup({
+						anchorRef: {
+							trackId: pendingDragRef.current.trackId,
+							elementId: pendingDragRef.current.elementId,
+						},
+						selectedElements: pendingDragRef.current.selectedElements,
+						tracks: sceneTracks,
+					});
+					if (!moveGroup) {
+						return;
+					}
+
+					moveGroupRef.current = moveGroup;
+					newTrackIdsRef.current = moveGroup.members.map(() => generateUUID());
+					const dragTimeOffsets: Record<string, number> = {};
+					for (const member of moveGroup.members) {
+						dragTimeOffsets[member.elementId] = member.timeOffset;
+					}
+					const {
+						snappedTime: initialSnappedTime,
+						snapPoint: initialSnapPoint,
+					} = getDragSnapResult({
+						frameSnappedTime: snappedTime,
+						group: moveGroup,
+					});
+					const verticalDragDirection = getVerticalDragDirection({
+						startMouseY: pendingDragRef.current.startMouseY,
+						currentMouseY: clientY,
+					});
+					const anchorDropTarget = getDragDropTarget({
+						clientX,
+						clientY,
+						elementId: pendingDragRef.current.elementId,
+						trackId: pendingDragRef.current.trackId,
+						tracks: sceneTracks,
+						tracksContainerRef,
+						tracksScrollRef,
+						headerRef,
+						zoomLevel,
+						snappedTime: initialSnappedTime,
+						verticalDragDirection,
+					});
+					const nextGroupMoveResult =
+						anchorDropTarget != null
+							? resolveGroupDragMove({
+									group: moveGroup,
+									snappedTime: initialSnappedTime,
+									dropTarget: anchorDropTarget,
+								})
+							: null;
+					groupMoveResultRef.current = nextGroupMoveResult;
+					setDragDropTarget(
+						anchorDropTarget &&
+							(anchorDropTarget.isNewTrack || !nextGroupMoveResult)
+							? {
+									...anchorDropTarget,
+									isNewTrack: true,
+								}
+							: null,
+					);
+					startDrag({
+						...pendingDragRef.current,
+						dragElementIds: moveGroup.members.map((member) => member.elementId),
+						dragTimeOffsets,
+						initialCurrentTime: initialSnappedTime,
+						initialCurrentMouseY: clientY,
+					});
+					onSnapPointChange?.(initialSnapPoint);
+					startedDragThisEvent = true;
+					pendingDragRef.current = null;
+					setIsPendingDrag(false);
+				} else {
+					return;
+				}
+			}
+
+			if (startedDragThisEvent) {
+				return;
+			}
+
+			if (dragState.elementId && dragState.trackId) {
+				const alreadySelected = isElementSelected({
+					trackId: dragState.trackId,
+					elementId: dragState.elementId,
+				});
+				if (!alreadySelected) {
+					selectElement({
+						trackId: dragState.trackId,
+						elementId: dragState.elementId,
+					});
+				}
+			}
+
+			const activeProject = editor.project.getActive();
+			if (!activeProject) return;
+
+			const scrollLeft = scrollContainer.scrollLeft;
+			const mouseTime = getMouseTimeFromClientX({
+				clientX,
+				containerRect: scrollContainer.getBoundingClientRect(),
+				zoomLevel,
+				scrollLeft,
+			});
+			const adjustedTime = Math.max(0, mouseTime - dragState.clickOffsetTime);
+			const fps = activeProject.settings.fps;
+			const frameSnappedTime =
+				roundToFrame({ time: adjustedTime, rate: fps }) ?? adjustedTime;
+
+			const moveGroup = moveGroupRef.current;
+			const { snappedTime, snapPoint } = getDragSnapResult({
+				frameSnappedTime,
+				group: moveGroup,
+			});
+			setDragState((previousDragState) => ({
+				...previousDragState,
+				currentTime: snappedTime,
+				currentMouseY: clientY,
+			}));
+			onSnapPointChange?.(snapPoint);
+
+			if (dragState.elementId && dragState.trackId) {
+				const verticalDragDirection = getVerticalDragDirection({
+					startMouseY: dragState.startMouseY,
+					currentMouseY: clientY,
+				});
+				const anchorDropTarget = getDragDropTarget({
+					clientX,
+					clientY,
+					elementId: dragState.elementId,
+					trackId: dragState.trackId,
+					tracks: sceneTracks,
+					tracksContainerRef,
+					tracksScrollRef,
+					headerRef,
+					zoomLevel,
+					snappedTime,
+					verticalDragDirection,
+				});
+				const nextGroupMoveResult =
+					moveGroup && anchorDropTarget
+						? resolveGroupDragMove({
+								group: moveGroup,
+								snappedTime,
+								dropTarget: anchorDropTarget,
+							})
+						: null;
+				groupMoveResultRef.current = nextGroupMoveResult;
+				setDragDropTarget(
+					anchorDropTarget &&
+						(anchorDropTarget.isNewTrack || !nextGroupMoveResult)
+						? {
+								...anchorDropTarget,
+								isNewTrack: true,
+							}
+						: null,
+				);
+			}
+		};
+
+		document.addEventListener("mousemove", handleMouseMove);
+		return () => document.removeEventListener("mousemove", handleMouseMove);
+	}, [
+		dragState.isDragging,
+		dragState.clickOffsetTime,
+		dragState.elementId,
+		dragState.startMouseY,
+		dragState.trackId,
+		zoomLevel,
+		isElementSelected,
+		selectElement,
+		editor.project,
+		timelineRef,
+		tracksScrollRef,
+		tracksContainerRef,
+		headerRef,
+		isPendingDrag,
+		startDrag,
+		getDragSnapResult,
+		resolveGroupDragMove,
+		sceneTracks,
+		onSnapPointChange,
+	]);
+
+	useEffect(() => {
+		if (!dragState.isDragging) return;
+
+		const handleMouseUp = ({ clientX, clientY }: MouseEvent) => {
+			if (!dragState.elementId || !dragState.trackId) return;
+
+			if (mouseDownLocationRef.current) {
+				const deltaX = Math.abs(clientX - mouseDownLocationRef.current.x);
+				const deltaY = Math.abs(clientY - mouseDownLocationRef.current.y);
+				if (
+					deltaX <= TIMELINE_DRAG_THRESHOLD_PX &&
+					deltaY <= TIMELINE_DRAG_THRESHOLD_PX
+				) {
+					mouseDownLocationRef.current = null;
+					endDrag();
+					onSnapPointChange?.(null);
+					return;
+				}
+			}
+
+			const moveGroup = moveGroupRef.current;
+			if (!moveGroup) {
+				endDrag();
+				onSnapPointChange?.(null);
+				return;
+			}
+
+			const groupMoveResult = groupMoveResultRef.current;
+			if (!groupMoveResult) {
+				endDrag();
+				onSnapPointChange?.(null);
+				return;
+			}
+
+			const didMove = groupMoveResult.moves.some((move) => {
+				const currentMember = moveGroup.members.find(
+					(member) => member.elementId === move.elementId,
+				);
+				const originalStartTime =
+					dragState.startElementTime + (currentMember?.timeOffset ?? 0);
+				return (
+					currentMember?.trackId !== move.targetTrackId ||
+					originalStartTime !== move.newStartTime
+				);
+			});
+			if (!didMove && groupMoveResult.createTracks.length === 0) {
+				endDrag();
+				onSnapPointChange?.(null);
+				return;
+			}
+
+			editor.timeline.moveElements({
+				moves: groupMoveResult.moves,
+				createTracks: groupMoveResult.createTracks,
+			});
+			endDrag();
+			onSnapPointChange?.(null);
+		};
+
+		document.addEventListener("mouseup", handleMouseUp);
+		return () => document.removeEventListener("mouseup", handleMouseUp);
+	}, [
+		dragState.isDragging,
+		dragState.elementId,
+		dragState.startElementTime,
+		dragState.trackId,
+		endDrag,
+		onSnapPointChange,
+		editor.timeline,
+	]);
+
+	useEffect(() => {
+		if (!isPendingDrag) return;
+
+		const handleMouseUp = () => {
+			pendingDragRef.current = null;
+			setIsPendingDrag(false);
+			onSnapPointChange?.(null);
+		};
+
+		document.addEventListener("mouseup", handleMouseUp);
+		return () => document.removeEventListener("mouseup", handleMouseUp);
+	}, [isPendingDrag, onSnapPointChange]);
+
+	const handleElementMouseDown = useCallback(
+		({
+			event,
+			element,
+			track,
+		}: {
+			event: ReactMouseEvent;
+			element: TimelineElement;
+			track: TimelineTrack;
+		}) => {
+			const isRightClick = event.button === MOUSE_BUTTON_RIGHT;
+
+			// right-click: don't stop propagation so ContextMenu can open
+			if (isRightClick) {
+				const alreadySelected = isElementSelected({
+					trackId: track.id,
+					elementId: element.id,
+				});
+				if (!alreadySelected) {
+					handleSelectionClick({
+						trackId: track.id,
+						elementId: element.id,
+						isMultiKey: false,
+					});
+				}
+				return;
+			}
+
+			event.stopPropagation();
+			mouseDownLocationRef.current = { x: event.clientX, y: event.clientY };
+
+			const isMultiSelect = event.metaKey || event.ctrlKey || event.shiftKey;
+
+			if (isMultiSelect) {
+				handleSelectionClick({
+					trackId: track.id,
+					elementId: element.id,
+					isMultiKey: true,
+				});
+			}
+
+			const clickOffsetTime = getClickOffsetTime({
+				clientX: event.clientX,
+				elementRect: event.currentTarget.getBoundingClientRect(),
+				zoomLevel,
+			});
+			const elementRef = {
+				trackId: track.id,
+				elementId: element.id,
+			};
+			const pendingSelectedElements = isElementSelected(elementRef)
+				? selectedElements
+				: [elementRef];
+			pendingDragRef.current = {
+				elementId: element.id,
+				trackId: track.id,
+				selectedElements: pendingSelectedElements,
+				startMouseX: event.clientX,
+				startMouseY: event.clientY,
+				startElementTime: element.startTime,
+				clickOffsetTime,
+			};
+			setIsPendingDrag(true);
+		},
+		[zoomLevel, isElementSelected, handleSelectionClick, selectedElements],
+	);
+
+	const handleElementClick = useCallback(
+		({
+			event,
+			element,
+			track,
+		}: {
+			event: ReactMouseEvent;
+			element: TimelineElement;
+			track: TimelineTrack;
+		}) => {
+			event.stopPropagation();
+
+			if (mouseDownLocationRef.current) {
+				const deltaX = Math.abs(event.clientX - mouseDownLocationRef.current.x);
+				const deltaY = Math.abs(event.clientY - mouseDownLocationRef.current.y);
+				if (
+					deltaX > TIMELINE_DRAG_THRESHOLD_PX ||
+					deltaY > TIMELINE_DRAG_THRESHOLD_PX
+				) {
+					mouseDownLocationRef.current = null;
+					return;
+				}
+			}
+
+			// modifier keys already handled in mousedown
+			if (event.metaKey || event.ctrlKey || event.shiftKey) return;
+
+			const alreadySelected = isElementSelected({
+				trackId: track.id,
+				elementId: element.id,
+			});
+			if (!alreadySelected || selectedElements.length > 1) {
+				selectElement({ trackId: track.id, elementId: element.id });
+				return;
+			}
+
+			editor.selection.clearKeyframeSelection();
+		},
+		[editor.selection, isElementSelected, selectElement, selectedElements],
+	);
+
+	return {
+		dragState,
+		dragDropTarget,
+		handleElementMouseDown,
+		handleElementClick,
+		lastMouseXRef,
+	};
+}