refactor(web): extract timeline multi-select helpers

apps/web/src/hooks/timelineMultiSelect.test.ts

@@ -0,0 +1,101 @@
+import { describe, expect, it } from "vitest";
+import {
+  createMultiSelectState,
+  finalizeMultiSelectDraft,
+  updateMultiSelectDraft,
+} from "./timelineMultiSelect.js";
+
+type TestMultiSelectState = {
+  isSelecting: boolean;
+  startX: number;
+  startY: number;
+  currentX: number;
+  currentY: number;
+  selectedAllocationIds: string[];
+  selectedResourceIds: string[];
+  dateRange: { start: Date; end: Date } | null;
+  multiDragDaysDelta: number;
+  isMultiDragging: boolean;
+  multiDragMode: "move" | "resize-start" | "resize-end";
+};
+
+describe("timelineMultiSelect", () => {
+  it("creates a fresh drag-selection state with the provided origin", () => {
+    expect(
+      createMultiSelectState<TestMultiSelectState>(120, 240, {
+        selectedAllocationIds: [],
+        selectedResourceIds: [],
+        dateRange: null,
+        multiDragDaysDelta: 0,
+        isMultiDragging: false,
+        multiDragMode: "move",
+      }),
+    ).toEqual({
+      isSelecting: true,
+      startX: 120,
+      startY: 240,
+      currentX: 120,
+      currentY: 240,
+      selectedAllocationIds: [],
+      selectedResourceIds: [],
+      dateRange: null,
+      multiDragDaysDelta: 0,
+      isMultiDragging: false,
+      multiDragMode: "move",
+    });
+  });
+
+  it("updates only the current rectangle coordinates while preserving selection metadata", () => {
+    const state = createMultiSelectState<TestMultiSelectState>(120, 240, {
+      selectedAllocationIds: ["alloc-1"],
+      selectedResourceIds: ["res-1"],
+      dateRange: {
+        start: new Date("2025-01-01T00:00:00.000Z"),
+        end: new Date("2025-01-02T00:00:00.000Z"),
+      },
+      multiDragDaysDelta: 3,
+      isMultiDragging: true,
+      multiDragMode: "resize-end",
+    });
+
+    expect(updateMultiSelectDraft(state, 155, 275)).toEqual({
+      ...state,
+      currentX: 155,
+      currentY: 275,
+    });
+  });
+
+  it("resets minimal right-click movement instead of producing a drag rectangle", () => {
+    const state = createMultiSelectState<TestMultiSelectState>(120, 240, {
+      selectedAllocationIds: [],
+      selectedResourceIds: [],
+      dateRange: null,
+      multiDragDaysDelta: 0,
+      isMultiDragging: false,
+      multiDragMode: "move",
+    });
+
+    expect(finalizeMultiSelectDraft(state, 123, 243)).toBeNull();
+  });
+
+  it("finalizes a real drag by freezing the rectangle and clearing only isSelecting", () => {
+    const state = createMultiSelectState<TestMultiSelectState>(120, 240, {
+      selectedAllocationIds: ["alloc-1"],
+      selectedResourceIds: ["res-1"],
+      dateRange: {
+        start: new Date("2025-01-01T00:00:00.000Z"),
+        end: new Date("2025-01-02T00:00:00.000Z"),
+      },
+      multiDragDaysDelta: 2,
+      isMultiDragging: true,
+      multiDragMode: "resize-start",
+    });
+
+    expect(finalizeMultiSelectDraft(state, 150, 295)).toEqual({
+      ...state,
+      isSelecting: false,
+      currentX: 150,
+      currentY: 295,
+    });
+  });
+});

apps/web/src/hooks/timelineMultiSelect.ts

@@ -0,0 +1,67 @@
+type MultiSelectStateLike = {
+  isSelecting: boolean;
+  startX: number;
+  startY: number;
+  currentX: number;
+  currentY: number;
+  selectedAllocationIds: string[];
+  selectedResourceIds: string[];
+  dateRange: { start: Date; end: Date } | null;
+  multiDragDaysDelta: number;
+  isMultiDragging: boolean;
+  multiDragMode: string;
+};
+
+export function createMultiSelectState<TState extends MultiSelectStateLike>(
+  currentX: number,
+  currentY: number,
+  defaults: Pick<
+    TState,
+    | "selectedAllocationIds"
+    | "selectedResourceIds"
+    | "dateRange"
+    | "multiDragDaysDelta"
+    | "isMultiDragging"
+    | "multiDragMode"
+  >,
+): TState {
+  return {
+    isSelecting: true,
+    startX: currentX,
+    startY: currentY,
+    currentX,
+    currentY,
+    ...defaults,
+  } as TState;
+}
+
+export function updateMultiSelectDraft<TState extends MultiSelectStateLike>(
+  state: TState,
+  currentX: number,
+  currentY: number,
+): TState {
+  return {
+    ...state,
+    currentX,
+    currentY,
+  };
+}
+
+export function finalizeMultiSelectDraft<TState extends MultiSelectStateLike>(
+  state: TState,
+  currentX: number,
+  currentY: number,
+  minDistancePx = 5,
+): TState | null {
+  const distance = Math.hypot(currentX - state.startX, currentY - state.startY);
+  if (distance < minDistancePx) {
+    return null;
+  }
+
+  return {
+    ...state,
+    isSelecting: false,
+    currentX,
+    currentY,
+  };
+}

apps/web/src/hooks/useTimelineDrag.ts

@@ -12,6 +12,11 @@ import {
   scheduleLivePreview,
   type LivePreviewSession,
 } from "./timelineLivePreview.js";
+import {
+  createMultiSelectState,
+  finalizeMultiSelectDraft,
+  updateMultiSelectDraft,
+} from "./timelineMultiSelect.js";
 import { getTouchPoint, resolveTouchDragDecision } from "./timelineTouch.js";
 
 const DRAG_CLICK_THRESHOLD_PX = 5;
@@ -958,19 +963,14 @@ export function useTimelineDrag({
     if (e.button !== 2) return;
     e.preventDefault();
 
-    const initial: MultiSelectState = {
-      isSelecting: true,
-      startX: e.clientX,
-      startY: e.clientY,
-      currentX: e.clientX,
-      currentY: e.clientY,
+    const initial = createMultiSelectState<MultiSelectState>(e.clientX, e.clientY, {
       selectedAllocationIds: [],
       selectedResourceIds: [],
       dateRange: null,
       multiDragDaysDelta: 0,
       isMultiDragging: false,
       multiDragMode: "move",
-    };
+    });
     multiSelectRef.current = initial;
     setMultiSelectState(initial);
     multiSelectCleanupRef.current?.();
@@ -979,11 +979,7 @@ export function useTimelineDrag({
       const ms = multiSelectRef.current;
       if (!ms.isSelecting) return;
 
-      const updated: MultiSelectState = {
-        ...ms,
-        currentX: ev.clientX,
-        currentY: ev.clientY,
-      };
+      const updated = updateMultiSelectDraft(ms, ev.clientX, ev.clientY);
       multiSelectRef.current = updated;
       setMultiSelectState(updated);
     }
@@ -995,9 +991,8 @@ export function useTimelineDrag({
       const ms = multiSelectRef.current;
       if (!ms.isSelecting) return;
 
-      const distance = Math.hypot(ev.clientX - ms.startX, ev.clientY - ms.startY);
-
-      if (distance < 5) {
+      const finished = finalizeMultiSelectDraft(ms, ev.clientX, ev.clientY);
+      if (!finished) {
         // Minimal movement → not a drag selection, reset.
         // Let existing onContextMenu handlers on allocation blocks handle right-click.
         multiSelectRef.current = INITIAL_MULTI_SELECT;
@@ -1009,12 +1004,6 @@ export function useTimelineDrag({
       // isSelecting is set to false to indicate the drag is done, but the
       // rectangle data (startX/Y, currentX/Y) is preserved so TimelineView
       // can resolve which allocations/resources fall within the selection.
-      const finished: MultiSelectState = {
-        ...ms,
-        isSelecting: false,
-        currentX: ev.clientX,
-        currentY: ev.clientY,
-      };
       multiSelectRef.current = finished;
       setMultiSelectState(finished);
     }