import { describe, it, expect } from "vitest";
import { flattenMetadata } from "../metadata";

describe("flattenMetadata", () => {
  it("flattens nested objects to dot-notation entries", () => {
    const entries = flattenMetadata({
      kind: "action.completed",
      envelope: { messageId: "m1", correlationId: "c1" },
    });
    const map = Object.fromEntries(entries.map((e) => [e.path, e.value]));
    expect(map.kind).toBe("action.completed");
    expect(map["envelope.messageId"]).toBe("m1");
    expect(map["envelope.correlationId"]).toBe("c1");
  });

  it("indexes arrays by position", () => {
    const entries = flattenMetadata({ items: [{ id: "a" }, { id: "b" }] });
    const paths = entries.map((e) => e.path);
    expect(paths).toContain("items.0.id");
    expect(paths).toContain("items.1.id");
  });

  it("tags each entry with its value type", () => {
    const entries = flattenMetadata({ s: "x", n: 3, b: true, z: null });
    const byPath = Object.fromEntries(entries.map((e) => [e.path, e.type]));
    expect(byPath.s).toBe("string");
    expect(byPath.n).toBe("number");
    expect(byPath.b).toBe("boolean");
    expect(byPath.z).toBe("null");
  });

  it("drops undefined and functions", () => {
    const entries = flattenMetadata({ keep: 1, gone: undefined, fn: () => 0 });
    expect(entries.map((e) => e.path)).toEqual(["keep"]);
  });

  it("guards against cycles", () => {
    const a: Record<string, unknown> = { name: "a" };
    a.self = a;
    const entries = flattenMetadata(a);
    expect(entries.some((e) => e.value === "[circular]")).toBe(true);
  });

  it("wraps a bare primitive under `value`", () => {
    expect(flattenMetadata("hi")).toEqual([{ path: "value", value: "hi", type: "string" }]);
  });
});