import { describe, expect, it } from "vitest";

import { resolveAssignment, TaskServiceError } from "./taskService.server";

/**
 * Single-assignee rule (AK-P4b DoD 2): a task is assigned to exactly one of a
 * user or a group; default = creator. Pure logic, no DB.
 */
describe("resolveAssignment", () => {
  it("defaults to the creator when neither user nor group is given", () => {
    expect(resolveAssignment({ creatorUserId: "u-creator" })).toEqual({
      assignedToUserId: "u-creator",
      assignedToGroupId: null,
    });
  });

  it("keeps a single user assignment", () => {
    expect(resolveAssignment({ creatorUserId: "u-creator", assignedToUserId: "u-1" })).toEqual({
      assignedToUserId: "u-1",
      assignedToGroupId: null,
    });
  });

  it("keeps a single group assignment", () => {
    expect(resolveAssignment({ creatorUserId: "u-creator", assignedToGroupId: "g-1" })).toEqual({
      assignedToUserId: null,
      assignedToGroupId: "g-1",
    });
  });

  it("rejects assigning to both a user and a group", () => {
    expect(() => resolveAssignment({ creatorUserId: "u-creator", assignedToUserId: "u-1", assignedToGroupId: "g-1" })).toThrow(TaskServiceError);
  });
});