/**
 * Hook + provider smoke. Uses react-dom/server to avoid bringing JSDOM
 * + testing-library into this leaf package. Asserts via the
 * server-rendered HTML which is enough to prove the context wiring.
 */
import { describe, expect, it } from "vitest";
import { renderToString } from "react-dom/server";
import { createElement } from "react";
import { FeatureFlagProvider, useFeatureFlag, useFeatureFlagEnabled, useFeatureFlagVariant } from "./context.js";

function Probe(props: { flag: string }) {
  const r = useFeatureFlag(props.flag);
  const en = useFeatureFlagEnabled(props.flag);
  const variant = useFeatureFlagVariant(props.flag) ?? "none";
  return createElement(
    "div",
    null,
    `enabled=${r.enabled} reason=${r.reason} bool=${en} variant=${variant}`,
  );
}

describe("FeatureFlagProvider + useFeatureFlag", () => {
  it("returns hydrated value when present", () => {
    const html = renderToString(
      createElement(
        FeatureFlagProvider,
        { flags: { foo: { enabled: true, reason: "matched" } } },
        createElement(Probe, { flag: "foo" }),
      ),
    );
    expect(html).toContain("enabled=true");
    expect(html).toContain("reason=matched");
    expect(html).toContain("bool=true");
  });

  it("returns fallback when flag absent", () => {
    const html = renderToString(
      createElement(
        FeatureFlagProvider,
        { flags: {} },
        createElement(Probe, { flag: "missing" }),
      ),
    );
    expect(html).toContain("enabled=false");
    expect(html).toContain("reason=flag-not-found");
  });

  it("exposes variant key", () => {
    const html = renderToString(
      createElement(
        FeatureFlagProvider,
        {
          flags: {
            ab: { enabled: true, reason: "matched", variant: { key: "treatment", value: 1 } },
          },
        },
        createElement(Probe, { flag: "ab" }),
      ),
    );
    expect(html).toContain("variant=treatment");
  });

  it("returns fallback outside of a Provider (default context)", () => {
    const html = renderToString(createElement(Probe, { flag: "x" }));
    expect(html).toContain("enabled=false");
    expect(html).toContain("reason=flag-not-found");
  });
});