refactor(web): extract timeline range selection helpers

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

@@ -0,0 +1,85 @@
+import { describe, expect, it } from "vitest";
+import { finalizeRangeSelection, updateRangeSelectionDraft } from "./timelineRangeSelection.js";
+
+type TestRangeState = {
+  isSelecting: boolean;
+  resourceId: string | null;
+  startDate: Date | null;
+  currentDate: Date | null;
+  suggestedProjectId: string | null;
+  startClientX: number;
+};
+
+describe("timelineRangeSelection", () => {
+  it("ignores updates when no full day boundary was crossed", () => {
+    const state: TestRangeState = {
+      isSelecting: true,
+      resourceId: "res-1",
+      startDate: new Date("2025-01-15T12:00:00.000Z"),
+      currentDate: new Date("2025-01-15T12:00:00.000Z"),
+      suggestedProjectId: "proj-1",
+      startClientX: 100,
+    };
+
+    expect(updateRangeSelectionDraft(state, 115, 32)).toBeNull();
+  });
+
+  it("updates the preview date when drag distance crosses into another day", () => {
+    const state: TestRangeState = {
+      isSelecting: true,
+      resourceId: "res-1",
+      startDate: new Date("2025-01-15T12:00:00.000Z"),
+      currentDate: new Date("2025-01-15T12:00:00.000Z"),
+      suggestedProjectId: "proj-1",
+      startClientX: 100,
+    };
+
+    const updated = updateRangeSelectionDraft(state, 168, 32);
+
+    expect(updated).toMatchObject({
+      ...state,
+      currentDate: new Date("2025-01-17T12:00:00.000Z"),
+    });
+  });
+
+  it("returns null when finalizing an incomplete range selection", () => {
+    expect(
+      finalizeRangeSelection(
+        {
+          isSelecting: true,
+          resourceId: null,
+          startDate: new Date("2025-01-15T12:00:00.000Z"),
+          currentDate: null,
+          suggestedProjectId: null,
+          startClientX: 100,
+        },
+        200,
+        300,
+      ),
+    ).toBeNull();
+  });
+
+  it("orders the final range chronologically even when the user dragged backwards", () => {
+    expect(
+      finalizeRangeSelection(
+        {
+          isSelecting: true,
+          resourceId: "res-1",
+          startDate: new Date("2025-01-15T12:00:00.000Z"),
+          currentDate: new Date("2025-01-12T12:00:00.000Z"),
+          suggestedProjectId: "proj-1",
+          startClientX: 100,
+        },
+        200,
+        300,
+      ),
+    ).toEqual({
+      resourceId: "res-1",
+      startDate: new Date("2025-01-12T12:00:00.000Z"),
+      endDate: new Date("2025-01-15T12:00:00.000Z"),
+      suggestedProjectId: "proj-1",
+      anchorX: 200,
+      anchorY: 300,
+    });
+  });
+});

apps/web/src/hooks/timelineRangeSelection.ts

@@ -0,0 +1,64 @@
+import { pixelsToDays } from "~/components/timeline/dragMath.js";
+
+type RangeStateLike = {
+  isSelecting: boolean;
+  resourceId: string | null;
+  startDate: Date | null;
+  currentDate: Date | null;
+  suggestedProjectId: string | null;
+  startClientX: number;
+};
+
+export type RangeSelectionResult = {
+  resourceId: string;
+  startDate: Date;
+  endDate: Date;
+  suggestedProjectId: string | null;
+  anchorX: number;
+  anchorY: number;
+};
+
+export function updateRangeSelectionDraft<TState extends RangeStateLike>(
+  state: TState,
+  currentClientX: number,
+  cellWidth: number,
+): TState | null {
+  if (!state.isSelecting || !state.startDate) return null;
+
+  const daysDelta = pixelsToDays(currentClientX - state.startClientX, cellWidth);
+  const currentDate = new Date(state.startDate);
+  currentDate.setDate(currentDate.getDate() + daysDelta);
+
+  const prevDelta = state.currentDate
+    ? Math.round((state.currentDate.getTime() - state.startDate.getTime()) / 86400000)
+    : 0;
+  if (daysDelta === prevDelta) return null;
+
+  return {
+    ...state,
+    currentDate,
+  };
+}
+
+export function finalizeRangeSelection<TState extends RangeStateLike>(
+  state: TState,
+  anchorX: number,
+  anchorY: number,
+): RangeSelectionResult | null {
+  if (!state.isSelecting || !state.resourceId || !state.startDate) {
+    return null;
+  }
+
+  const endDate = state.currentDate ?? state.startDate;
+  const [startDate, finalEnd] =
+    state.startDate <= endDate ? [state.startDate, endDate] : [endDate, state.startDate];
+
+  return {
+    resourceId: state.resourceId,
+    startDate,
+    endDate: finalEnd,
+    suggestedProjectId: state.suggestedProjectId,
+    anchorX,
+    anchorY,
+  };
+}

apps/web/src/hooks/useTimelineDrag.ts

@@ -17,6 +17,7 @@ import {
   finalizeMultiSelectDraft,
   updateMultiSelectDraft,
 } from "./timelineMultiSelect.js";
+import { finalizeRangeSelection, updateRangeSelectionDraft } from "./timelineRangeSelection.js";
 import { getTouchPoint, resolveTouchDragDecision } from "./timelineTouch.js";
 
 const DRAG_CLICK_THRESHOLD_PX = 5;
@@ -893,18 +894,8 @@ export function useTimelineDrag({
 
       // Range select
       const range = rangeStateRef.current;
-      if (range.isSelecting && range.startDate) {
-        const deltaX = e.clientX - range.startClientX;
-        const daysDelta = pixelsToDays(deltaX, cellWidthRef.current);
-        const currentDate = new Date(range.startDate);
-        currentDate.setDate(currentDate.getDate() + daysDelta);
-
-        const prevDelta = range.currentDate
-          ? Math.round((range.currentDate.getTime() - range.startDate.getTime()) / 86400000)
-          : 0;
-        if (daysDelta === prevDelta) return;
-
-        const updated: RangeState = { ...range, currentDate };
+      const updated = updateRangeSelectionDraft(range, e.clientX, cellWidthRef.current);
+      if (updated) {
         rangeStateRef.current = updated;
         setRangeState(updated);
       }
@@ -927,19 +918,9 @@ export function useTimelineDrag({
 
       // Range select
       const range = rangeStateRef.current;
-      if (range.isSelecting && range.resourceId && range.startDate) {
-        const endDate = range.currentDate ?? range.startDate;
-        const [startDate, finalEnd] =
-          range.startDate <= endDate ? [range.startDate, endDate] : [endDate, range.startDate];
-
-        onRangeSelected?.({
-          resourceId: range.resourceId,
-          startDate,
-          endDate: finalEnd,
-          suggestedProjectId: range.suggestedProjectId,
-          anchorX: e.clientX,
-          anchorY: e.clientY,
-        });
+      const selection = finalizeRangeSelection(range, e.clientX, e.clientY);
+      if (selection) {
+        onRangeSelected?.(selection);
 
         rangeStateRef.current = INITIAL_RANGE_STATE;
         setRangeState(INITIAL_RANGE_STATE);