/**
 * TASK-0095 R1 — the LWW timestamp compare (the S12 gate's named unit test:
 * "the two-field split: title consent vs property LWW").
 *
 * Pure (no UI/fetch/store) — the outbox worker + the web UI call this.
 */
import { describe, expect, it } from "vitest";
import {
  compareLwwTimestamps,
  resolveFieldConflict,
  type FieldVersion,
} from "./lww.js";

const local = (value: string, ts: number): FieldVersion => ({ value, ts });
const remote = (value: string, ts: number, author = "Ana"): FieldVersion => ({ value, ts, author });

describe("compareLwwTimestamps (the plain-LWW core)", () => {
  it("the newer write wins (remote newer → remote; local newer → local)", () => {
    expect(compareLwwTimestamps(1000, 2000)).toBe("remote");
    expect(compareLwwTimestamps(2000, 1000)).toBe("local");
  });
  it("a tie resolves to LOCAL (the in-front-of-them intent — conservative)", () => {
    expect(compareLwwTimestamps(1000, 1000)).toBe("local");
  });
});

describe("resolveFieldConflict — title = LWW-with-consent (never auto-overwrite)", () => {
  it("a 409 on the title → the consent outcome (refetch + toast + Apply anyway), even when the local ts is newer", () => {
    // The local write is NEWER, but a title 409 still asks the user (the CAS
    // says the remote write already landed — silently overwriting a title is
    // the unsafe direction).
    const out = resolveFieldConflict("title", local("My title", 2000), remote("Their title", 1000));
    expect(out.kind).toBe("consent");
    if (out.kind === "consent") {
      expect(out.applyAction).toBe("fresh-patch");
      expect(out.localValue).toBe("My title");
      expect(out.toast).toBe(
        "Title was changed by Ana — your change 'My title' was not applied",
      );
    }
  });

  it("the toast names the remote author (and falls back to 'someone')", () => {
    const out = resolveFieldConflict("title", local("X", 100), remote("Y", 200));
    expect(out).toMatchObject({ kind: "consent", toast: expect.stringContaining("Ana") });
    const noAuthor = resolveFieldConflict("title", local("X", 100), { value: "Y", ts: 200 });
    expect(noAuthor).toMatchObject({
      kind: "consent",
      toast: expect.stringContaining("someone"),
    });
  });
});

describe("resolveFieldConflict — property = plain LWW (the newer timestamp wins)", () => {
  it("the local write is newer → keep the local value (no toast)", () => {
    const out = resolveFieldConflict("property", local("local-value", 2000), remote("remote-value", 1000));
    expect(out).toEqual({ kind: "lww-local-wins", value: "local-value" });
  });

  it("the remote write is newer → take the remote value + the 'Updated to the latest value' toast", () => {
    const out = resolveFieldConflict("property", local("local-value", 1000), remote("remote-value", 2000));
    expect(out).toEqual({
      kind: "lww-remote-wins",
      value: "remote-value",
      toast: "Updated to the latest value",
    });
  });

  it("a tie → local wins (the conservative default, no toast)", () => {
    const out = resolveFieldConflict("property", local("local", 1000), remote("remote", 1000));
    expect(out).toEqual({ kind: "lww-local-wins", value: "local" });
  });

  it("the two-field split: the SAME 409 → consent for a title, LWW for a property", () => {
    const a = resolveFieldConflict("title", local("t", 1000), remote("r", 2000));
    const b = resolveFieldConflict("property", local("t", 1000), remote("r", 2000));
    expect(a.kind).toBe("consent"); // the title asks
    expect(b.kind).toBe("lww-remote-wins"); // the property applies (newer wins)
    expect(b).toMatchObject({ toast: "Updated to the latest value" });
  });
});