refactor(web): extract project drag session

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

@@ -0,0 +1,80 @@
+import { describe, expect, it, vi } from "vitest";
+import { beginProjectDragSession } from "./timelineProjectDragSession.js";
+
+describe("timelineProjectDragSession", () => {
+  it("starts the session, forwards movement, and finalizes on mouseup", () => {
+    const previousCleanup = vi.fn();
+    const setState = vi.fn();
+    const updatePosition = vi.fn();
+    const finalize = vi.fn();
+    const state = { projectId: "project-1", isDragging: true };
+    const cleanupRef = { current: previousCleanup as (() => void) | null };
+    const stateRef = { current: { projectId: null, isDragging: false } };
+    const handlers: {
+      move?: (event: MouseEvent) => void;
+      up?: (event: MouseEvent) => void;
+    } = {};
+
+    const attachDrag = vi.fn((_: Document, onMove: (event: MouseEvent) => void, onUp: (event: MouseEvent) => void) => {
+      handlers.move = onMove;
+      handlers.up = onUp;
+      return vi.fn();
+    });
+
+    beginProjectDragSession({
+      state,
+      cleanupRef,
+      stateRef,
+      setState,
+      documentTarget: {} as Document,
+      attachDrag,
+      updatePosition,
+      finalize,
+    });
+
+    expect(previousCleanup).toHaveBeenCalledOnce();
+    expect(stateRef.current).toBe(state);
+    expect(setState).toHaveBeenCalledWith(state);
+
+    handlers.move?.({ clientX: 42 } as MouseEvent);
+    expect(updatePosition).toHaveBeenCalledWith(42);
+
+    const preventDefault = vi.fn();
+    const attachedCleanup = cleanupRef.current;
+    handlers.up?.({ clientX: 54, preventDefault } as unknown as MouseEvent);
+
+    expect(attachedCleanup).toHaveBeenCalledOnce();
+    expect(cleanupRef.current).toBeNull();
+    expect(finalize).toHaveBeenCalledWith(54);
+    expect(preventDefault).toHaveBeenCalledOnce();
+  });
+
+  it("works when no prior cleanup is registered", () => {
+    const setState = vi.fn();
+    const updatePosition = vi.fn();
+    const finalize = vi.fn().mockResolvedValue(undefined);
+    const cleanupRef = { current: null as (() => void) | null };
+    const stateRef = { current: { projectId: null, isDragging: false } };
+    let upHandler: ((event: MouseEvent) => void) | undefined;
+
+    beginProjectDragSession({
+      state: { projectId: "project-2", isDragging: true },
+      cleanupRef,
+      stateRef,
+      setState,
+      documentTarget: {} as Document,
+      attachDrag: (_documentTarget, _onMove, onUp) => {
+        upHandler = onUp;
+        return vi.fn();
+      },
+      updatePosition,
+      finalize,
+    });
+
+    upHandler?.({ clientX: 12, preventDefault() {} } as MouseEvent);
+
+    expect(updatePosition).not.toHaveBeenCalled();
+    expect(finalize).toHaveBeenCalledWith(12);
+    expect(cleanupRef.current).toBeNull();
+  });
+});